From: Alejandro Colomar <alx@kernel.org>
Date: Sat, 16 Nov 2024 15:51:31 +0000 (+0100)
Subject: Silence most -Wzero-as-null-pointer-constant diagnostics
X-Git-Tag: glibc-2.41~441
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=53fcdf5f743aa9b02972eec658e66f96d6a63386;p=thirdparty%2Fglibc.git

Silence most -Wzero-as-null-pointer-constant diagnostics

Replace 0 by NULL and {0} by {}.

Omit a few cases that aren't so trivial to fix.

Link: <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117059>
Link: <https://software.codidact.com/posts/292718/292759#answer-292759>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
---

diff --git a/argp/argp-fmtstream.c b/argp/argp-fmtstream.c
index eb0a886c723..35b5b1d0fec 100644
--- a/argp/argp-fmtstream.c
+++ b/argp/argp-fmtstream.c
@@ -74,7 +74,7 @@ __argp_make_fmtstream (FILE *stream,
       if (! fs->buf)
 	{
 	  free (fs);
-	  fs = 0;
+	  fs = NULL;
 	}
       else
 	{
diff --git a/argp/argp-help.c b/argp/argp-help.c
index cc43f376d43..5c41fdcd593 100644
--- a/argp/argp-help.c
+++ b/argp/argp-help.c
@@ -443,7 +443,7 @@ make_hol (const struct argp *argp, struct hol_cluster *cluster)
   assert (hol);
 
   hol->num_entries = 0;
-  hol->clusters = 0;
+  hol->clusters = NULL;
 
   if (opts)
     {
@@ -615,7 +615,7 @@ static char
 hol_entry_first_short (const struct hol_entry *entry)
 {
   return hol_entry_short_iterate (entry, until_short,
-				  entry->argp->argp_domain, 0);
+				  entry->argp->argp_domain, NULL);
 }
 
 /* Returns the first valid long option in ENTRY, or NULL if there is none.  */
@@ -627,7 +627,7 @@ hol_entry_first_long (const struct hol_entry *entry)
   for (opt = entry->opt, num = entry->num; num > 0; opt++, num--)
     if (opt->name && ovisible (opt))
       return opt->name;
-  return 0;
+  return NULL;
 }
 
 /* Returns the entry in HOL with the long option name NAME, or NULL if there is
@@ -652,7 +652,7 @@ hol_find_entry (struct hol *hol, const char *name)
       entry++;
     }
 
-  return 0;
+  return NULL;
 }
 
 /* If an entry with the long option NAME occurs in HOL, set it's special
@@ -926,7 +926,7 @@ hol_append (struct hol *hol, struct hol *more)
   while (*cl_end)
     cl_end = &(*cl_end)->next;
   *cl_end = more->clusters;
-  more->clusters = 0;
+  more->clusters = NULL;
 
   /* Merge entries.  */
   if (more->num_entries > 0)
@@ -1299,7 +1299,7 @@ hol_entry_help (struct hol_entry *entry, const struct argp_state *state,
     {
       const char *tstr = real->doc ? dgettext (state == NULL ? NULL
 					       : state->root_argp->argp_domain,
-					       real->doc) : 0;
+					       real->doc) : NULL;
       const char *fstr = filter_doc (tstr, real->key, entry->argp, state);
       if (fstr && *fstr)
 	{
@@ -1339,7 +1339,7 @@ hol_help (struct hol *hol, const struct argp_state *state,
 {
   unsigned num;
   struct hol_entry *entry;
-  struct hol_help_state hhstate = { 0, 0, 0 };
+  struct hol_help_state hhstate = { NULL, 0, 0 };
 
   for (entry = hol->entries, num = hol->num_entries; num > 0; entry++, num--)
     hol_entry_help (entry, state, stream, &hhstate);
@@ -1351,7 +1351,7 @@ hol_help (struct hol *hol, const struct argp_state *state,
 Mandatory or optional arguments to long options are also mandatory or \
 optional for any corresponding short options.");
       const char *fstr = filter_doc (tstr, ARGP_KEY_HELP_DUP_ARGS_NOTE,
-				     state ? state->root_argp : 0, state);
+				     state ? state->root_argp : NULL, state);
       if (fstr && *fstr)
 	{
 	  __argp_fmtstream_putc (stream, '\n');
@@ -1511,7 +1511,7 @@ argp_args_usage (const struct argp *argp, const struct argp_state *state,
   char *our_level = *levels;
   int multiple = 0;
   const struct argp_child *child = argp->children;
-  const char *tdoc = dgettext (argp->argp_domain, argp->args_doc), *nl = 0;
+  const char *tdoc = dgettext (argp->argp_domain, argp->args_doc), *nl = NULL;
   const char *fdoc = filter_doc (tdoc, ARGP_KEY_HELP_ARGS_DOC, argp, state);
 
   if (fdoc)
@@ -1573,7 +1573,7 @@ argp_doc (const struct argp *argp, const struct argp_state *state,
 {
   const char *text;
   const char *inp_text;
-  void *input = 0;
+  void *input = NULL;
   int anything = 0;
   size_t inp_text_limit = 0;
   const char *doc = dgettext (argp->argp_domain, argp->doc);
@@ -1582,11 +1582,11 @@ argp_doc (const struct argp *argp, const struct argp_state *state,
   if (doc)
     {
       char *vt = strchr (doc, '\v');
-      inp_text = post ? (vt ? vt + 1 : 0) : doc;
+      inp_text = post ? (vt ? vt + 1 : NULL) : doc;
       inp_text_limit = (!post && vt) ? (vt - doc) : 0;
     }
   else
-    inp_text = 0;
+    inp_text = NULL;
 
   if (argp->help_filter)
     /* We have to filter the doc strings.  */
@@ -1628,7 +1628,7 @@ argp_doc (const struct argp *argp, const struct argp_state *state,
   if (post && argp->help_filter)
     /* Now see if we have to output a ARGP_KEY_HELP_EXTRA text.  */
     {
-      text = (*argp->help_filter) (ARGP_KEY_HELP_EXTRA, 0, input);
+      text = (*argp->help_filter) (ARGP_KEY_HELP_EXTRA, NULL, input);
       if (text)
 	{
 	  if (anything || pre_blank)
@@ -1661,7 +1661,7 @@ _help (const struct argp *argp, const struct argp_state *state, FILE *stream,
        unsigned flags, char *name)
 {
   int anything = 0;		/* Whether we've output anything.  */
-  struct hol *hol = 0;
+  struct hol *hol = NULL;
   argp_fmtstream_t fs;
 
   if (! stream)
@@ -1684,7 +1684,7 @@ _help (const struct argp *argp, const struct argp_state *state, FILE *stream,
 
   if (flags & (ARGP_HELP_USAGE | ARGP_HELP_SHORT_USAGE | ARGP_HELP_LONG))
     {
-      hol = argp_hol (argp, 0);
+      hol = argp_hol (argp, NULL);
 
       /* If present, these options always come last.  */
       hol_set_group (hol, "help", -1);
@@ -1801,7 +1801,7 @@ Try `%s --help' or `%s --usage' for more information.\n"),
 void __argp_help (const struct argp *argp, FILE *stream,
 		  unsigned flags, char *name)
 {
-  _help (argp, 0, stream, flags, name);
+  _help (argp, NULL, stream, flags, name);
 }
 #ifdef weak_alias
 weak_alias (__argp_help, argp_help)
@@ -1843,7 +1843,7 @@ __argp_state_help (const struct argp_state *state, FILE *stream, unsigned flags)
       if (state && (state->flags & ARGP_LONG_ONLY))
 	flags |= ARGP_HELP_LONG_ONLY;
 
-      _help (state ? state->root_argp : 0, state, stream, flags,
+      _help (state ? state->root_argp : NULL, state, stream, flags,
 	     state ? state->name : __argp_short_program_name ());
 
       if (!state || ! (state->flags & ARGP_NO_EXIT))
diff --git a/argp/argp-parse.c b/argp/argp-parse.c
index 9b7b91f65d9..7a75fa35061 100644
--- a/argp/argp-parse.c
+++ b/argp/argp-parse.c
@@ -83,13 +83,13 @@ static volatile int _argp_hang;
 
 static const struct argp_option argp_default_options[] =
 {
-  {"help",	  '?',	  	0, 0,  N_("Give this help list"), -1},
-  {"usage",	  OPT_USAGE,	0, 0,  N_("Give a short usage message")},
+  {"help",	  '?',	  	NULL, 0,  N_("Give this help list"), -1},
+  {"usage",	  OPT_USAGE,	NULL, 0,  N_("Give a short usage message")},
   {"program-name",OPT_PROGNAME, N_("NAME"), OPTION_HIDDEN,
    N_("Set the program name")},
   {"HANG",	  OPT_HANG,    N_("SECS"), OPTION_ARG_OPTIONAL | OPTION_HIDDEN,
    N_("Hang for SECS seconds (default 3600)")},
-  {0, 0}
+  {NULL, 0}
 };
 
 static error_t
@@ -149,8 +149,8 @@ static const struct argp argp_default_argp =
 
 static const struct argp_option argp_version_options[] =
 {
-  {"version",	  'V',	  	0, 0,  N_("Print program version"), -1},
-  {0, 0}
+  {"version",	  'V',	  	NULL, 0,  N_("Print program version"), -1},
+  {NULL, 0}
 };
 
 static error_t
@@ -341,7 +341,7 @@ convert_options (const struct argp *argp,
 			  ? optional_argument
 			  : required_argument)
 		       : no_argument);
-		    cvt->long_end->flag = 0;
+		    cvt->long_end->flag = NULL;
 		    /* we add a disambiguating code to all the user's
 		       values (which is removed before we actually call
 		       the function to parse the value); this means that
@@ -364,9 +364,9 @@ convert_options (const struct argp *argp,
       group->args_processed = 0;
       group->parent = parent;
       group->parent_index = parent_index;
-      group->input = 0;
-      group->hook = 0;
-      group->child_inputs = 0;
+      group->input = NULL;
+      group->hook = NULL;
+      group->child_inputs = NULL;
 
       if (children)
 	/* Assign GROUP's CHILD_INPUTS field some space from
@@ -382,7 +382,7 @@ convert_options (const struct argp *argp,
       parent = group++;
     }
   else
-    parent = 0;
+    parent = NULL;
 
   if (children)
     {
@@ -417,7 +417,7 @@ parser_convert (struct parser *parser, const struct argp *argp, int flags)
   parser->argp = argp;
 
   if (argp)
-    parser->egroup = convert_options (argp, 0, 0, parser->groups, &cvt);
+    parser->egroup = convert_options (argp, NULL, 0, parser->groups, &cvt);
   else
     parser->egroup = parser->groups; /* No parsers at all! */
 }
@@ -530,7 +530,7 @@ parser_init (struct parser *parser, const struct argp *argp,
 	   makes very simple wrapper argps more convenient).  */
 	group->child_inputs[0] = group->input;
 
-      err = group_parse (group, &parser->state, ARGP_KEY_INIT, 0);
+      err = group_parse (group, &parser->state, ARGP_KEY_INIT, NULL);
     }
   if (err == EBADKEY)
     err = 0;			/* Some parser didn't understand.  */
@@ -582,11 +582,11 @@ parser_finalize (struct parser *parser,
 	       group < parser->egroup && (!err || err==EBADKEY);
 	       group++)
 	    if (group->args_processed == 0)
-	      err = group_parse (group, &parser->state, ARGP_KEY_NO_ARGS, 0);
+	      err = group_parse (group, &parser->state, ARGP_KEY_NO_ARGS, NULL);
 	  for (group = parser->egroup - 1;
 	       group >= parser->groups && (!err || err==EBADKEY);
 	       group--)
-	    err = group_parse (group, &parser->state, ARGP_KEY_END, 0);
+	    err = group_parse (group, &parser->state, ARGP_KEY_END, NULL);
 
 	  if (err == EBADKEY)
 	    err = 0;		/* Some parser didn't understand.  */
@@ -625,7 +625,7 @@ parser_finalize (struct parser *parser,
 
       /* Since we didn't exit, give each parser an error indication.  */
       for (group = parser->groups; group < parser->egroup; group++)
-	group_parse (group, &parser->state, ARGP_KEY_ERROR, 0);
+	group_parse (group, &parser->state, ARGP_KEY_ERROR, NULL);
     }
   else
     /* Notify parsers of success, and propagate back values from parsers.  */
@@ -636,14 +636,14 @@ parser_finalize (struct parser *parser,
       for (group = parser->egroup - 1
 	   ; group >= parser->groups && (!err || err == EBADKEY)
 	   ; group--)
-	err = group_parse (group, &parser->state, ARGP_KEY_SUCCESS, 0);
+	err = group_parse (group, &parser->state, ARGP_KEY_SUCCESS, NULL);
       if (err == EBADKEY)
 	err = 0;		/* Some parser didn't understand.  */
     }
 
   /* Call parsers once more, to do any final cleanup.  Errors are ignored.  */
   for (group = parser->egroup - 1; group >= parser->groups; group--)
-    group_parse (group, &parser->state, ARGP_KEY_FINI, 0);
+    group_parse (group, &parser->state, ARGP_KEY_FINI, NULL);
 
   if (err == EBADKEY)
     err = EINVAL;
@@ -682,7 +682,7 @@ parser_parse_arg (struct parser *parser, char *val)
 	{
 	  parser->state.next--;	/* For ARGP_KEY_ARGS, put back the arg.  */
 	  key = ARGP_KEY_ARGS;
-	  err = group_parse (group, &parser->state, key, 0);
+	  err = group_parse (group, &parser->state, key, NULL);
 	}
     }
 
@@ -792,11 +792,11 @@ parser_parse_next (struct parser *parser, int *arg_ebadkey)
       parser->opt_data.optopt = KEY_END;
       if (parser->state.flags & ARGP_LONG_ONLY)
 	opt = _getopt_long_only_r (parser->state.argc, parser->state.argv,
-				   parser->short_opts, parser->long_opts, 0,
+				   parser->short_opts, parser->long_opts, NULL,
 				   &parser->opt_data);
       else
 	opt = _getopt_long_r (parser->state.argc, parser->state.argv,
-			      parser->short_opts, parser->long_opts, 0,
+			      parser->short_opts, parser->long_opts, NULL,
 			      &parser->opt_data);
       /* And see what getopt did.  */
       parser->state.next = parser->opt_data.optind;
@@ -893,7 +893,7 @@ __argp_parse (const struct argp *argp, int argc, char **argv, unsigned flags,
       child[child_index++].argp = &argp_default_argp;
       if (argp_program_version || argp_program_version_hook)
 	child[child_index++].argp = &argp_version_argp;
-      child[child_index].argp = 0;
+      child[child_index].argp = NULL;
 
       argp = &top_argp;
     }
@@ -930,7 +930,7 @@ __argp_input (const struct argp *argp, const struct argp_state *state)
 	  return group->input;
     }
 
-  return 0;
+  return NULL;
 }
 #ifdef weak_alias
 weak_alias (__argp_input, _argp_input)
diff --git a/catgets/gencat.c b/catgets/gencat.c
index 7110970bd51..51700a47259 100644
--- a/catgets/gencat.c
+++ b/catgets/gencat.c
@@ -429,7 +429,7 @@ read_input_file (struct catalog *current, const char *fname)
 
 		      /* Test whether the identifier was already used.  */
 		      runp = current->all_sets;
-		      while (runp != 0)
+		      while (runp != NULL)
 			if (runp->symbol != NULL
 			    && strcmp (runp->symbol, symbol) == 0)
 			  break;
diff --git a/debug/backtracesyms.c b/debug/backtracesyms.c
index c1f6322981a..9a8c9e53a6e 100644
--- a/debug/backtracesyms.c
+++ b/debug/backtracesyms.c
@@ -82,7 +82,7 @@ __backtrace_symbols (void *const *array, int size)
 		   relative to the file.  */
 		info[cnt].dli_saddr = info[cnt].dli_fbase;
 
-	      if (info[cnt].dli_sname == NULL && info[cnt].dli_saddr == 0)
+	      if (info[cnt].dli_sname == NULL && info[cnt].dli_saddr == NULL)
 		last += 1 + sprintf (last, "%s(%s) [%p]",
 				     info[cnt].dli_fname ?: "",
 				     info[cnt].dli_sname ?: "",
diff --git a/elf/dl-find_object.c b/elf/dl-find_object.c
index ae18b438d32..0bb070916a5 100644
--- a/elf/dl-find_object.c
+++ b/elf/dl-find_object.c
@@ -861,6 +861,6 @@ _dl_find_object_freeres (void)
           seg = previous;
         }
       /* Stop searching in shared objects.  */
-      _dlfo_loaded_mappings[idx] = 0;
+      _dlfo_loaded_mappings[idx] = NULL;
     }
 }
diff --git a/elf/dl-load.c b/elf/dl-load.c
index 335b34c56d2..e986d7faaba 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -1215,7 +1215,7 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
       }
 
     /* This check recognizes most separate debuginfo files.  */
-    if (__glibc_unlikely ((l->l_ld == 0 && type == ET_DYN) || empty_dynamic))
+    if (__glibc_unlikely ((l->l_ld == NULL && type == ET_DYN) || empty_dynamic))
       {
 	errstring = N_("object file has no dynamic section");
 	goto lose;
@@ -1238,7 +1238,7 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
       }
   }
 
-  if (l->l_ld != 0)
+  if (l->l_ld != NULL)
     l->l_ld = (ElfW(Dyn) *) ((ElfW(Addr)) l->l_ld + l->l_addr);
 
   elf_get_dynamic_info (l, false, false);
diff --git a/elf/dl-load.h b/elf/dl-load.h
index 656ec229bfa..ea6d9177101 100644
--- a/elf/dl-load.h
+++ b/elf/dl-load.h
@@ -88,7 +88,7 @@ static __always_inline void
 _dl_postprocess_loadcmd (struct link_map *l, const ElfW(Ehdr) *header,
                          const struct loadcmd *c)
 {
-  if (l->l_phdr == 0
+  if (l->l_phdr == NULL
       && c->mapoff <= header->e_phoff
       && ((size_t) (c->mapend - c->mapstart + c->mapoff)
           >= header->e_phoff + header->e_phnum * sizeof (ElfW(Phdr))))
diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
index 6d74332c0f7..f8af87c720f 100644
--- a/elf/dl-lookup.c
+++ b/elf/dl-lookup.c
@@ -801,7 +801,7 @@ _dl_lookup_symbol_x (const char *undef_name, struct link_map *undef_map,
 	  _dl_exception_free (&exception);
 	}
       *ref = NULL;
-      return 0;
+      return NULL;
     }
 
   int protected = (*ref
diff --git a/elf/dl-minimal-malloc.c b/elf/dl-minimal-malloc.c
index 25d870728d5..69fc19c1b79 100644
--- a/elf/dl-minimal-malloc.c
+++ b/elf/dl-minimal-malloc.c
@@ -34,7 +34,7 @@ static void *alloc_ptr, *alloc_end, *alloc_last_block;
 void *
 __minimal_malloc (size_t n)
 {
-  if (alloc_end == 0)
+  if (alloc_end == NULL)
     {
       /* Consume any unused space in the last page of our data segment.  */
       extern int _end attribute_hidden;
@@ -57,7 +57,7 @@ __minimal_malloc (size_t n)
       if (__glibc_unlikely (nup == 0 && n != 0))
 	return NULL;
       nup += GLRO(dl_pagesize);
-      page = __mmap (0, nup, PROT_READ|PROT_WRITE,
+      page = __mmap (NULL, nup, PROT_READ|PROT_WRITE,
 		     MAP_ANON|MAP_PRIVATE, -1, 0);
       if (page == MAP_FAILED)
 	return NULL;
diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c
index 147cc4cf23f..acf2d5d73a5 100644
--- a/elf/dl-tunables.c
+++ b/elf/dl-tunables.c
@@ -252,7 +252,7 @@ parse_tunable_print_error (const struct tunable_toset_t *toset)
 static void
 parse_tunables (const char *valstring)
 {
-  struct tunable_toset_t tunables[tunables_list_size] = { 0 };
+  struct tunable_toset_t tunables[tunables_list_size] = {};
   if (parse_tunables_string (valstring, tunables) == -1)
     {
       _dl_error_printf (
@@ -301,7 +301,7 @@ __tunables_init (char **envp)
     return;
 
   enum { tunable_num_env_alias = array_length (tunable_env_alias_list) };
-  struct tunable_toset_t tunables_env_alias[tunable_num_env_alias] = { 0 };
+  struct tunable_toset_t tunables_env_alias[tunable_num_env_alias] = {};
 
   while ((envp = get_next_env (envp, &envname, &envval, &prev_envp)) != NULL)
     {
diff --git a/elf/dynamic-link.h b/elf/dynamic-link.h
index 83d834ecaf6..370b0e872e4 100644
--- a/elf/dynamic-link.h
+++ b/elf/dynamic-link.h
@@ -152,7 +152,7 @@ elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[],
 
 # define ELF_DYNAMIC_DO_RELR(map)					      \
   do {									      \
-    ElfW(Addr) l_addr = (map)->l_addr, *where = 0;			      \
+    ElfW(Addr) l_addr = (map)->l_addr, *where = NULL;			      \
     const ElfW(Relr) *r, *end;						      \
     if ((map)->l_info[DT_RELR] == NULL)					      \
       break;								      \
diff --git a/elf/readlib.c b/elf/readlib.c
index f3129c4557c..0a25bbc70b3 100644
--- a/elf/readlib.c
+++ b/elf/readlib.c
@@ -107,7 +107,7 @@ process_file (const char *real_file_name, const char *file_name,
       return 1;
     }
 
-  file_contents = mmap (0, statbuf.st_size, PROT_READ, MAP_SHARED,
+  file_contents = mmap (NULL, statbuf.st_size, PROT_READ, MAP_SHARED,
 			fileno (file), 0);
   if (file_contents == MAP_FAILED)
     {
diff --git a/elf/tlsdeschtab.h b/elf/tlsdeschtab.h
index 07e109842e5..0b1b7cedc81 100644
--- a/elf/tlsdeschtab.h
+++ b/elf/tlsdeschtab.h
@@ -93,7 +93,7 @@ _dl_make_tlsdesc_dynamic (struct link_map *map, size_t ti_offset)
     {
       ht = htab_create ();
       if (! ht)
-	return 0;
+	return NULL;
       map->l_mach.tlsdesc_table = ht;
     }
 
@@ -101,7 +101,7 @@ _dl_make_tlsdesc_dynamic (struct link_map *map, size_t ti_offset)
   test.tlsinfo.ti_offset = ti_offset;
   entry = htab_find_slot (ht, &test, 1, hash_tlsdesc, eq_tlsdesc);
   if (! entry)
-    return 0;
+    return NULL;
 
   if (*entry)
     {
@@ -111,7 +111,7 @@ _dl_make_tlsdesc_dynamic (struct link_map *map, size_t ti_offset)
 
   *entry = td = malloc (sizeof (struct tlsdesc_dynamic_arg));
   if (! td)
-    return 0;
+    return NULL;
   /* This may be higher than the map's generation, but it doesn't
      matter much.  Worst case, we'll have one extra DTV update per
      thread.  */
diff --git a/hesiod/hesiod.c b/hesiod/hesiod.c
index ee087b0392f..0354e16ead4 100644
--- a/hesiod/hesiod.c
+++ b/hesiod/hesiod.c
@@ -80,7 +80,7 @@ hesiod_init(void **context) {
 	char *cp;
 
 	ctx = malloc(sizeof(struct hesiod_p));
-	if (ctx == 0)
+	if (ctx == NULL)
 		return (-1);
 
 	ctx->LHS = NULL;
@@ -247,7 +247,7 @@ parse_config_file(struct hesiod_p *ctx, const char *filename) {
 	 */
 	free(ctx->RHS);
 	free(ctx->LHS);
-	ctx->RHS = ctx->LHS = 0;
+	ctx->RHS = ctx->LHS = NULL;
 	/* Set default query classes. */
 	ctx->classes[0] = C_IN;
 	ctx->classes[1] = C_HS;
@@ -316,7 +316,7 @@ parse_config_file(struct hesiod_p *ctx, const char *filename) {
 	fclose(fp);
 	free(ctx->RHS);
 	free(ctx->LHS);
-	ctx->RHS = ctx->LHS = 0;
+	ctx->RHS = ctx->LHS = NULL;
 	return (-1);
 }
 
diff --git a/inet/rcmd.c b/inet/rcmd.c
index dcf4f4ffd11..0abbdc89fe6 100644
--- a/inet/rcmd.c
+++ b/inet/rcmd.c
@@ -179,7 +179,7 @@ rcmd: socket: All ports in use\n"));
 			else
 				__fxprintf(NULL, "rcmd: socket: %m\n");
 
-			__sigprocmask (SIG_SETMASK, &omask, 0);
+			__sigprocmask (SIG_SETMASK, &omask, NULL);
 			freeaddrinfo(res);
 			return -1;
 		}
@@ -209,7 +209,7 @@ rcmd: socket: All ports in use\n"));
 			    free (buf);
 			  }
 			__set_errno (oerrno);
-			perror(0);
+			perror(NULL);
 			ai = ai->ai_next;
 			getnameinfo(ai->ai_addr, ai->ai_addrlen,
 				    paddr, sizeof(paddr),
@@ -232,11 +232,11 @@ rcmd: socket: All ports in use\n"));
 		freeaddrinfo(res);
 		(void)__fxprintf(NULL, "%s: %s\n", *ahost,
 				 __strerror_r(errno, errbuf, sizeof (errbuf)));
-		__sigprocmask (SIG_SETMASK, &omask, 0);
+		__sigprocmask (SIG_SETMASK, &omask, NULL);
 		return -1;
 	}
 	lport--;
-	if (fd2p == 0) {
+	if (fd2p == NULL) {
 		__write(s, "", 1);
 		lport = 0;
 	} else {
@@ -344,7 +344,7 @@ socket: protocol failure in circuit setup\n")) >= 0)
 		}
 		goto bad2;
 	}
-	__sigprocmask (SIG_SETMASK, &omask, 0);
+	__sigprocmask (SIG_SETMASK, &omask, NULL);
 	freeaddrinfo(res);
 	return s;
 bad2:
@@ -352,7 +352,7 @@ bad2:
 		(void)__close(*fd2p);
 bad:
 	(void)__close(s);
-	__sigprocmask (SIG_SETMASK, &omask, 0);
+	__sigprocmask (SIG_SETMASK, &omask, NULL);
 	freeaddrinfo(res);
 	return -1;
 }
diff --git a/inet/rexec.c b/inet/rexec.c
index d479753fc28..8e8653f30f2 100644
--- a/inet/rexec.c
+++ b/inet/rexec.c
@@ -103,7 +103,7 @@ retry:
 		perror(res0->ai_canonname);
 		goto bad;
 	}
-	if (fd2p == 0) {
+	if (fd2p == NULL) {
 		(void) __write(s, "", 1);
 		port = 0;
 	} else {
diff --git a/inet/ruserpass.c b/inet/ruserpass.c
index 75e2a065524..903fc966fde 100644
--- a/inet/ruserpass.c
+++ b/inet/ruserpass.c
@@ -157,7 +157,7 @@ next:
 
 		case LOGIN:
 			if (token()) {
-				if (*aname == 0) {
+				if (*aname == NULL) {
 				  char *newp;
 				  newp = malloc((unsigned) strlen(tokval) + 1);
 				  if (newp == NULL)
@@ -180,7 +180,7 @@ next:
 	warnx(_("Remove 'password' line or make file unreadable by others."));
 				goto bad;
 			}
-			if (token() && *apass == 0) {
+			if (token() && *apass == NULL) {
 				char *newp;
 				newp = malloc((unsigned) strlen(tokval) + 1);
 				if (newp == NULL)
diff --git a/libio/fileops.c b/libio/fileops.c
index 4db4a76f755..759d737ec7e 100644
--- a/libio/fileops.c
+++ b/libio/fileops.c
@@ -220,7 +220,7 @@ _IO_new_file_fopen (FILE *fp, const char *filename, const char *mode,
   const char *last_recognized;
 
   if (_IO_file_is_open (fp))
-    return 0;
+    return NULL;
   switch (*mode)
     {
     case 'r':
diff --git a/libio/genops.c b/libio/genops.c
index 6f20d496692..9f18861d7b4 100644
--- a/libio/genops.c
+++ b/libio/genops.c
@@ -489,8 +489,8 @@ _IO_default_setbuf (FILE *fp, char *p, ssize_t len)
 	fp->_flags &= ~_IO_UNBUFFERED;
 	_IO_setb (fp, p, p+len, 0);
       }
-    fp->_IO_write_base = fp->_IO_write_ptr = fp->_IO_write_end = 0;
-    fp->_IO_read_base = fp->_IO_read_ptr = fp->_IO_read_end = 0;
+    fp->_IO_write_base = fp->_IO_write_ptr = fp->_IO_write_end = NULL;
+    fp->_IO_read_base = fp->_IO_read_ptr = fp->_IO_read_end = NULL;
     return fp;
 }
 
@@ -971,7 +971,7 @@ _IO_unsave_markers (FILE *fp)
   struct _IO_marker *mark = fp->_markers;
   if (mark)
     {
-      fp->_markers = 0;
+      fp->_markers = NULL;
     }
 
   if (_IO_have_backup (fp))
diff --git a/libio/iopopen.c b/libio/iopopen.c
index 352513a2914..6bf187e2d5f 100644
--- a/libio/iopopen.c
+++ b/libio/iopopen.c
@@ -106,7 +106,7 @@ spawn_process (posix_spawn_file_actions_t *fa, FILE *fp, const char *command,
 	}
     }
 
-  err = __posix_spawn (&((_IO_proc_file *) fp)->pid, _PATH_BSHELL, fa, 0,
+  err = __posix_spawn (&((_IO_proc_file *) fp)->pid, _PATH_BSHELL, fa, NULL,
 		       (char *const[]){ (char*) "sh", (char*) "-c", (char*) "--",
 		       (char *) command, NULL }, __environ);
   if (err != 0)
diff --git a/libio/libioP.h b/libio/libioP.h
index a83a411fdf7..34bf91fcd89 100644
--- a/libio/libioP.h
+++ b/libio/libioP.h
@@ -915,9 +915,10 @@ extern int _IO_vscanf (const char *, va_list) __THROW;
 # else
 #  define FILEBUF_LITERAL(CHAIN, FLAGS, FD, WDP) \
        { _IO_MAGIC+_IO_LINKED+_IO_IS_FILEBUF+FLAGS, \
-	 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, (FILE *) CHAIN, FD, \
+	 NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, \
+	 NULL, NULL, (FILE *) CHAIN, FD, \
 	 0, _IO_pos_BAD, 0, 0, { 0 }, &_IO_stdfile_##FD##_lock, _IO_pos_BAD,\
-	 NULL, WDP, 0 }
+	 NULL, WDP, NULL }
 # endif
 #else
 # ifdef _IO_USE_OLD_IO_FILE
diff --git a/libio/wfileops.c b/libio/wfileops.c
index fdbe8692e89..16beab1f3ae 100644
--- a/libio/wfileops.c
+++ b/libio/wfileops.c
@@ -416,7 +416,7 @@ _IO_wfile_overflow (FILE *f, wint_t wch)
       || f->_wide_data->_IO_write_base == NULL)
     {
       /* Allocate a buffer if needed. */
-      if (f->_wide_data->_IO_write_base == 0)
+      if (f->_wide_data->_IO_write_base == NULL)
 	{
 	  _IO_wdoallocbuf (f);
 	  _IO_free_wbackup_area (f);
diff --git a/libio/wgenops.c b/libio/wgenops.c
index adfb97014ff..f77a2d22f03 100644
--- a/libio/wgenops.c
+++ b/libio/wgenops.c
@@ -601,7 +601,7 @@ _IO_unsave_wmarkers (FILE *fp)
   struct _IO_marker *mark = fp->_markers;
   if (mark)
     {
-      fp->_markers = 0;
+      fp->_markers = NULL;
     }
 
   if (_IO_have_backup (fp))
diff --git a/locale/programs/xmalloc.c b/locale/programs/xmalloc.c
index 4ae46b9003c..38f2bc8a2c9 100644
--- a/locale/programs/xmalloc.c
+++ b/locale/programs/xmalloc.c
@@ -56,10 +56,10 @@ fixup_null_alloc (size_t n)
 {
   VOID *p;
 
-  p = 0;
+  p = NULL;
   if (n == 0)
     p = malloc ((size_t) 1);
-  if (p == 0)
+  if (p == NULL)
     error (xmalloc_exit_failure, 0, _("memory exhausted"));
   return p;
 }
@@ -72,7 +72,7 @@ xmalloc (size_t n)
   VOID *p;
 
   p = malloc (n);
-  if (p == 0)
+  if (p == NULL)
     p = fixup_null_alloc (n);
   return p;
 }
@@ -85,7 +85,7 @@ xcalloc (size_t n, size_t s)
   VOID *p;
 
   p = calloc (n, s);
-  if (p == 0)
+  if (p == NULL)
     p = fixup_null_alloc (n);
   return p;
 }
@@ -97,10 +97,10 @@ xcalloc (size_t n, size_t s)
 VOID *
 xrealloc (VOID *p, size_t n)
 {
-  if (p == 0)
+  if (p == NULL)
     return xmalloc (n);
   p = realloc (p, n);
-  if (p == 0)
+  if (p == NULL)
     p = fixup_null_alloc (n);
   return p;
 }
diff --git a/locale/setlocale.c b/locale/setlocale.c
index 7bd27e5398e..fc5bf5c427c 100644
--- a/locale/setlocale.c
+++ b/locale/setlocale.c
@@ -52,7 +52,7 @@ static char *const _nl_current_used[] =
 # undef	DEFINE_CATEGORY
   };
 
-# define CATEGORY_USED(category)	(_nl_current_used[category] != 0)
+# define CATEGORY_USED(category)	(_nl_current_used[category] != NULL)
 
 #else
 
diff --git a/locale/uselocale.c b/locale/uselocale.c
index 8136caf61b4..5c7c1ad66b3 100644
--- a/locale/uselocale.c
+++ b/locale/uselocale.c
@@ -54,7 +54,7 @@ __uselocale (locale_t newloc)
 	extern char _nl_current_##category##_used;			      \
 	weak_extern (_nl_current_##category##_used)			      \
 	weak_extern (_nl_current_##category)				      \
-	if (&_nl_current_##category##_used != 0)			      \
+	if (&_nl_current_##category##_used != NULL)			      \
 	  _nl_current_##category = &locobj->__locales[category];	      \
       }
 # include "categories.def"
diff --git a/malloc/arena.c b/malloc/arena.c
index cfb1ff88545..91a43ee394a 100644
--- a/malloc/arena.c
+++ b/malloc/arena.c
@@ -389,7 +389,7 @@ alloc_new_heap  (size_t size, size_t top_pad, size_t pagesize,
   else if (size + top_pad <= max_size)
     size += top_pad;
   else if (size > max_size)
-    return 0;
+    return NULL;
   else
     size = max_size;
   size = ALIGN_UP (size, pagesize);
@@ -411,7 +411,7 @@ alloc_new_heap  (size_t size, size_t top_pad, size_t pagesize,
     }
   if (p2 == MAP_FAILED)
     {
-      p1 = (char *) MMAP (0, max_size << 1, PROT_NONE, mmap_flags);
+      p1 = (char *) MMAP (NULL, max_size << 1, PROT_NONE, mmap_flags);
       if (p1 != MAP_FAILED)
         {
           p2 = (char *) (((uintptr_t) p1 + (max_size - 1))
@@ -427,21 +427,21 @@ alloc_new_heap  (size_t size, size_t top_pad, size_t pagesize,
         {
           /* Try to take the chance that an allocation of only max_size
              is already aligned. */
-          p2 = (char *) MMAP (0, max_size, PROT_NONE, mmap_flags);
+          p2 = (char *) MMAP (NULL, max_size, PROT_NONE, mmap_flags);
           if (p2 == MAP_FAILED)
-            return 0;
+            return NULL;
 
           if ((unsigned long) p2 & (max_size - 1))
             {
               __munmap (p2, max_size);
-              return 0;
+              return NULL;
             }
         }
     }
   if (__mprotect (p2, size, mtag_mmap_flags | PROT_READ | PROT_WRITE) != 0)
     {
       __munmap (p2, max_size);
-      return 0;
+      return NULL;
     }
 
   /* Only considere the actual usable range.  */
@@ -644,7 +644,7 @@ _int_new_arena (size_t size)
          to deal with the large request via mmap_chunk().  */
       h = new_heap (sizeof (*h) + sizeof (*a) + MALLOC_ALIGNMENT, mp_.top_pad);
       if (!h)
-        return 0;
+        return NULL;
     }
   a = h->ar_ptr = (mstate) (h + 1);
   malloc_init_state (a);
diff --git a/malloc/malloc-check.c b/malloc/malloc-check.c
index da1158b3332..6ac71df5d58 100644
--- a/malloc/malloc-check.c
+++ b/malloc/malloc-check.c
@@ -245,7 +245,7 @@ static void *
 realloc_check (void *oldmem, size_t bytes)
 {
   INTERNAL_SIZE_T chnb;
-  void *newmem = 0;
+  void *newmem = NULL;
   unsigned char *magic_p;
   size_t rb;
 
@@ -254,7 +254,7 @@ realloc_check (void *oldmem, size_t bytes)
       __set_errno (ENOMEM);
       return NULL;
     }
-  if (oldmem == 0)
+  if (oldmem == NULL)
     return malloc_check (bytes);
 
   if (bytes == 0)
diff --git a/malloc/malloc.c b/malloc/malloc.c
index 06c7847ef28..32dbc272a82 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -369,7 +369,7 @@
 #include "morecore.c"
 
 #define MORECORE         (*__glibc_morecore)
-#define MORECORE_FAILURE 0
+#define MORECORE_FAILURE  NULL
 
 /* Memory tagging.  */
 
@@ -2420,7 +2420,7 @@ sysmalloc_mmap (INTERNAL_SIZE_T nb, size_t pagesize, int extra_flags, mstate av)
   if ((unsigned long) (size) <= (unsigned long) (nb))
     return MAP_FAILED;
 
-  char *mm = (char *) MMAP (0, size,
+  char *mm = (char *) MMAP (NULL, size,
 			    mtag_mmap_flags | PROT_READ | PROT_WRITE,
 			    extra_flags);
   if (mm == MAP_FAILED)
@@ -2507,7 +2507,7 @@ sysmalloc_mmap_fallback (long int *s, INTERNAL_SIZE_T nb,
   if ((unsigned long) (size) <= (unsigned long) (nb))
     return MORECORE_FAILURE;
 
-  char *mbrk = (char *) (MMAP (0, size,
+  char *mbrk = (char *) (MMAP (NULL, size,
 			       mtag_mmap_flags | PROT_READ | PROT_WRITE,
 			       extra_flags));
   if (mbrk == MAP_FAILED)
@@ -2583,7 +2583,7 @@ sysmalloc (INTERNAL_SIZE_T nb, mstate av)
 
   /* There are no usable arenas and mmap also failed.  */
   if (av == NULL)
-    return 0;
+    return NULL;
 
   /* Record incoming configuration of top */
 
@@ -2743,7 +2743,7 @@ sysmalloc (INTERNAL_SIZE_T nb, mstate av)
 
       if (brk != (char *) (MORECORE_FAILURE))
         {
-          if (mp_.sbrk_base == 0)
+          if (mp_.sbrk_base == NULL)
             mp_.sbrk_base = brk;
           av->system_mem += size;
 
@@ -2942,7 +2942,7 @@ sysmalloc (INTERNAL_SIZE_T nb, mstate av)
 
   /* catch all failure paths */
   __set_errno (ENOMEM);
-  return 0;
+  return NULL;
 }
 
 
@@ -3080,7 +3080,7 @@ mremap_chunk (mchunkptr p, size_t new_size)
                           MREMAP_MAYMOVE);
 
   if (cp == MAP_FAILED)
-    return 0;
+    return NULL;
 
   madvise_thp (cp, new_size);
 
@@ -3295,7 +3295,7 @@ static void
 tcache_init(void)
 {
   mstate ar_ptr;
-  void *victim = 0;
+  void *victim = NULL;
   const size_t bytes = sizeof (tcache_perthread_struct);
 
   if (tcache_shutting_down)
@@ -3413,7 +3413,7 @@ __libc_free (void *mem)
   mstate ar_ptr;
   mchunkptr p;                          /* chunk corresponding to mem */
 
-  if (mem == 0)                              /* free(0) has no effect */
+  if (mem == NULL)                              /* free(0) has no effect */
     return;
 
   /* Quickly check that the freed pointer matches the tag for the memory.
@@ -3469,12 +3469,12 @@ __libc_realloc (void *oldmem, size_t bytes)
 #if REALLOC_ZERO_BYTES_FREES
   if (bytes == 0 && oldmem != NULL)
     {
-      __libc_free (oldmem); return 0;
+      __libc_free (oldmem); return NULL;
     }
 #endif
 
   /* realloc of null is supposed to be same as malloc */
-  if (oldmem == 0)
+  if (oldmem == NULL)
     return __libc_malloc (bytes);
 
   /* Perform a quick check to ensure that the pointer's tag matches the
@@ -3548,8 +3548,8 @@ __libc_realloc (void *oldmem, size_t bytes)
 
       /* Must alloc, copy, free. */
       newmem = __libc_malloc (bytes);
-      if (newmem == 0)
-        return 0;              /* propagate failure */
+      if (newmem == NULL)
+        return NULL;              /* propagate failure */
 
       memcpy (newmem, oldmem, oldsize - CHUNK_HDR_SZ);
       munmap_chunk (oldp);
@@ -3617,7 +3617,7 @@ aligned_alloc (size_t alignment, size_t bytes)
   if (!powerof2 (alignment) || alignment == 0)
     {
       __set_errno (EINVAL);
-      return 0;
+      return NULL;
     }
 
   void *address = RETURN_ADDRESS (0);
@@ -3643,7 +3643,7 @@ _mid_memalign (size_t alignment, size_t bytes, void *address)
   if (alignment > SIZE_MAX / 2 + 1)
     {
       __set_errno (EINVAL);
-      return 0;
+      return NULL;
     }
 
 
@@ -3740,7 +3740,7 @@ __libc_pvalloc (size_t bytes)
 						&rounded_bytes)))
     {
       __set_errno (ENOMEM);
-      return 0;
+      return NULL;
     }
   rounded_bytes = rounded_bytes & -(pagesize - 1);
 
@@ -3801,7 +3801,7 @@ __libc_calloc (size_t n, size_t elem_size)
   else
     {
       /* No usable arenas.  */
-      oldtop = 0;
+      oldtop = NULL;
       oldtopsize = 0;
     }
   mem = _int_malloc (av, sz);
@@ -3811,7 +3811,7 @@ __libc_calloc (size_t n, size_t elem_size)
 
   if (!SINGLE_THREAD_P)
     {
-      if (mem == 0 && av != NULL)
+      if (mem == NULL && av != NULL)
 	{
 	  LIBC_PROBE (memory_calloc_retry, 1, sz);
 	  av = arena_get_retry (av, sz);
@@ -3823,8 +3823,8 @@ __libc_calloc (size_t n, size_t elem_size)
     }
 
   /* Allocation failed even after a retry.  */
-  if (mem == 0)
-    return 0;
+  if (mem == NULL)
+    return NULL;
 
   mchunkptr p = mem2chunk (mem);
 
@@ -4056,7 +4056,7 @@ _int_malloc (mstate av, size_t bytes)
 	      while (tcache->counts[tc_idx] < mp_.tcache_count
 		     && (tc_victim = last (bin)) != bin)
 		{
-		  if (tc_victim != 0)
+		  if (tc_victim != NULL)
 		    {
 		      bck = tc_victim->bk;
 		      set_inuse_bit_at_offset (tc_victim, nb);
@@ -4876,7 +4876,7 @@ static void malloc_consolidate(mstate av)
   fb = &fastbin (av, 0);
   do {
     p = atomic_exchange_acquire (fb, NULL);
-    if (p != 0) {
+    if (p != NULL) {
       do {
 	{
 	  if (__glibc_unlikely (misaligned_chunk (p)))
@@ -4935,7 +4935,7 @@ static void malloc_consolidate(mstate av)
 	  av->top = p;
 	}
 
-      } while ( (p = nextp) != 0);
+      } while ( (p = nextp) != NULL);
 
     }
   } while (fb++ != maxfb);
@@ -5010,8 +5010,8 @@ _int_realloc (mstate av, mchunkptr oldp, INTERNAL_SIZE_T oldsize,
       else
         {
           newmem = _int_malloc (av, nb - MALLOC_ALIGN_MASK);
-          if (newmem == 0)
-            return 0; /* propagate failure */
+          if (newmem == NULL)
+            return NULL; /* propagate failure */
 
           newp = mem2chunk (newmem);
           newsize = chunksize (newp);
@@ -5105,8 +5105,8 @@ _int_memalign (mstate av, size_t alignment, size_t bytes)
   /* Call malloc with worst case padding to hit alignment. */
   m = (char *) (_int_malloc (av, nb + alignment + MINSIZE));
 
-  if (m == 0)
-    return 0;           /* propagate failure */
+  if (m == NULL)
+    return NULL;           /* propagate failure */
 
   p = mem2chunk (m);
 
@@ -5318,7 +5318,7 @@ int_mallinfo (mstate av, struct mallinfo2 *m)
   for (i = 0; i < NFASTBINS; ++i)
     {
       for (p = fastbin (av, i);
-	   p != 0;
+	   p != NULL;
 	   p = REVEAL_PTR (p->fd))
         {
 	  if (__glibc_unlikely (misaligned_chunk (p)))
diff --git a/malloc/obstack.c b/malloc/obstack.c
index 579c693939d..6e8299a73c1 100644
--- a/malloc/obstack.c
+++ b/malloc/obstack.c
@@ -107,7 +107,7 @@ int obstack_exit_failure = EXIT_FAILURE;
 /* A looong time ago (before 1994, anyway; we're not sure) this global variable
    was used by non-GNU-C macros to avoid multiple evaluation.  The GNU C
    library still exports it because somebody might use it.  */
-struct obstack *_obstack_compat = 0;
+struct obstack *_obstack_compat = NULL;
 compat_symbol (libc, _obstack_compat, _obstack, GLIBC_2_0);
 #  endif
 # endif
@@ -180,7 +180,7 @@ _obstack_begin (struct obstack *h,
 					       alignment - 1);
   h->chunk_limit = chunk->limit
     = (char *) chunk + h->chunk_size;
-  chunk->prev = 0;
+  chunk->prev = NULL;
   /* The initial chunk now contains no empty object.  */
   h->maybe_empty_object = 0;
   h->alloc_failed = 0;
@@ -228,7 +228,7 @@ _obstack_begin_1 (struct obstack *h, int size, int alignment,
 					       alignment - 1);
   h->chunk_limit = chunk->limit
     = (char *) chunk + h->chunk_size;
-  chunk->prev = 0;
+  chunk->prev = NULL;
   /* The initial chunk now contains no empty object.  */
   h->maybe_empty_object = 0;
   h->alloc_failed = 0;
@@ -328,12 +328,12 @@ _obstack_allocated_p (struct obstack *h, void *obj)
   /* We use >= rather than > since the object cannot be exactly at
      the beginning of the chunk but might be an empty object exactly
      at the end of an adjacent chunk.  */
-  while (lp != 0 && ((void *) lp >= obj || (void *) (lp)->limit < obj))
+  while (lp != NULL && ((void *) lp >= obj || (void *) (lp)->limit < obj))
     {
       plp = lp->prev;
       lp = plp;
     }
-  return lp != 0;
+  return lp != NULL;
 }
 
 /* Free objects in obstack H, including OBJ and everything allocate
@@ -351,7 +351,7 @@ __obstack_free (struct obstack *h, void *obj)
   /* We use >= because there cannot be an object at the beginning of a chunk.
      But there can be an empty object at that address
      at the end of another chunk.  */
-  while (lp != 0 && ((void *) lp >= obj || (void *) (lp)->limit < obj))
+  while (lp != NULL && ((void *) lp >= obj || (void *) (lp)->limit < obj))
     {
       plp = lp->prev;
       CALL_FREEFUN (h, lp);
@@ -366,7 +366,7 @@ __obstack_free (struct obstack *h, void *obj)
       h->chunk_limit = lp->limit;
       h->chunk = lp;
     }
-  else if (obj != 0)
+  else if (obj != NULL)
     /* obj is not in any of the chunks! */
     abort ();
 }
@@ -383,7 +383,7 @@ _obstack_memory_used (struct obstack *h)
   struct _obstack_chunk *lp;
   int nbytes = 0;
 
-  for (lp = h->chunk; lp != 0; lp = lp->prev)
+  for (lp = h->chunk; lp != NULL; lp = lp->prev)
     {
       nbytes += lp->limit - (char *) lp;
     }
diff --git a/malloc/reallocarray.c b/malloc/reallocarray.c
index 2a5f2a446d9..0118f882539 100644
--- a/malloc/reallocarray.c
+++ b/malloc/reallocarray.c
@@ -27,7 +27,7 @@ __libc_reallocarray (void *optr, size_t nmemb, size_t elem_size)
   if (__builtin_mul_overflow (nmemb, elem_size, &bytes))
     {
       __set_errno (ENOMEM);
-      return 0;
+      return NULL;
     }
   return realloc (optr, bytes);
 }
diff --git a/misc/getttyent.c b/misc/getttyent.c
index 92d92b026fb..0df7c28ce1c 100644
--- a/misc/getttyent.c
+++ b/misc/getttyent.c
@@ -126,7 +126,7 @@ __getttyent (void)
 			;
 	tty.ty_comment = p;
 	if (*p == 0)
-		tty.ty_comment = 0;
+		tty.ty_comment = NULL;
 	if ((p = strchr (p, '\n')))
 		*p = '\0';
 	return (&tty);
diff --git a/misc/sbrk.c b/misc/sbrk.c
index 8578666ed03..06aa02179d9 100644
--- a/misc/sbrk.c
+++ b/misc/sbrk.c
@@ -56,7 +56,7 @@ __sbrk (intptr_t increment)
 #endif
 
   if (update_brk)
-    if (__brk (0) < 0)		/* Initialize the break.  */
+    if (__brk (NULL) < 0)		/* Initialize the break.  */
       return (void *) -1;
 
   if (increment == 0)
diff --git a/nis/nis_server.c b/nis/nis_server.c
index 622204f9b57..255b2f85144 100644
--- a/nis/nis_server.c
+++ b/nis/nis_server.c
@@ -29,7 +29,7 @@ nis_servstate (const nis_server *serv, const nis_tag *tags,
   nis_taglist taglist;
   nis_taglist tagres;
 
-  *result = 0;
+  *result = NULL;
   tagres.tags.tags_len = 0;
   tagres.tags.tags_val = NULL;
   taglist.tags.tags_len = numtags;
diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
index ef3ec332902..a6254b1204c 100644
--- a/nptl/pthread_create.c
+++ b/nptl/pthread_create.c
@@ -239,7 +239,7 @@ static int create_thread (struct pthread *pd, const struct pthread_attr *attr,
      stopped since we have to set the scheduling parameters or set the
      affinity.  */
   bool need_setaffinity = (attr != NULL && attr->extension != NULL
-			   && attr->extension->cpuset != 0);
+			   && attr->extension->cpuset != NULL);
   if (attr != NULL
       && (__glibc_unlikely (need_setaffinity)
 	  || __glibc_unlikely ((attr->flags & ATTR_FLAG_NOTINHERITSCHED) != 0)))
diff --git a/nptl_db/fetch-value.c b/nptl_db/fetch-value.c
index bdf1f444d69..5d7474b18d0 100644
--- a/nptl_db/fetch-value.c
+++ b/nptl_db/fetch-value.c
@@ -69,7 +69,7 @@ _td_locate_field (td_thragent_t *ta,
 	}
     }
 
-  if (idx != 0 && DB_DESC_NELEM (desc) != 0
+  if (idx != NULL && DB_DESC_NELEM (desc) != 0
       && idx - (psaddr_t) 0 > DB_DESC_NELEM (desc))
     /* This is an internal indicator to callers with nonzero IDX
        that the IDX value is too big.  */
diff --git a/nptl_db/td_init.c b/nptl_db/td_init.c
index f47b68d92c0..b431ea63601 100644
--- a/nptl_db/td_init.c
+++ b/nptl_db/td_init.c
@@ -32,7 +32,7 @@ td_init (void)
 bool
 __td_ta_rtld_global (td_thragent_t *ta)
 {
-  if (ta->ta_addr__rtld_global == 0)
+  if (ta->ta_addr__rtld_global == NULL)
     {
       psaddr_t rtldglobalp;
       if (DB_GET_VALUE (rtldglobalp, ta, __nptl_rtld_global, 0) == TD_OK)
diff --git a/nptl_db/td_ta_clear_event.c b/nptl_db/td_ta_clear_event.c
index ebba4e83dc7..6322d800af5 100644
--- a/nptl_db/td_ta_clear_event.c
+++ b/nptl_db/td_ta_clear_event.c
@@ -25,7 +25,7 @@ td_ta_clear_event (const td_thragent_t *ta_arg, td_thr_events_t *event)
 {
   td_thragent_t *const ta = (td_thragent_t *) ta_arg;
   td_err_e err;
-  psaddr_t eventmask = 0;
+  psaddr_t eventmask = NULL;
   void *copy = NULL;
 
   LOG ("td_ta_clear_event");
diff --git a/nptl_db/td_ta_event_getmsg.c b/nptl_db/td_ta_event_getmsg.c
index 8598716c741..d199546f597 100644
--- a/nptl_db/td_ta_event_getmsg.c
+++ b/nptl_db/td_ta_event_getmsg.c
@@ -46,7 +46,7 @@ td_ta_event_getmsg (const td_thragent_t *ta_arg, td_event_msg_t *msg)
   if (err != TD_OK)
     return err;
 
-  if (thp == 0)
+  if (thp == NULL)
     /* Nothing waiting.  */
     return TD_NOMSG;
 
@@ -95,9 +95,9 @@ td_ta_event_getmsg (const td_thragent_t *ta_arg, td_event_msg_t *msg)
   if (err != TD_OK)
     return err;
 
-  if (next != 0)
+  if (next != NULL)
     /* Clear the next pointer in the current descriptor.  */
-    err = DB_PUT_FIELD (ta, thp, pthread, nextevent, 0, 0);
+    err = DB_PUT_FIELD (ta, thp, pthread, nextevent, 0, NULL);
 
   return err;
 }
diff --git a/nptl_db/td_ta_map_lwp2thr.c b/nptl_db/td_ta_map_lwp2thr.c
index 1bd1fe9ec74..ab16e40119d 100644
--- a/nptl_db/td_ta_map_lwp2thr.c
+++ b/nptl_db/td_ta_map_lwp2thr.c
@@ -119,7 +119,7 @@ __td_ta_lookup_th_unique (const td_thragent_t *ta_arg,
       if (ps_lgetregs (ta->ph, lwpid, regs) != PS_OK)
 	return TD_ERR;
       terr = _td_fetch_value_local (ta, ta->ta_howto_data.reg, -1,
-				    0, regs, &addr);
+				    NULL, regs, &addr);
       if (terr != TD_OK)
 	return terr;
 
@@ -149,7 +149,7 @@ __td_ta_lookup_th_unique (const td_thragent_t *ta_arg,
       if (ps_lgetregs (ta->ph, lwpid, regs) != PS_OK)
 	return TD_ERR;
       terr = _td_fetch_value_local (ta, ta->ta_howto_data.reg_thread_area,
-				    -1, 0, regs, &addr);
+				    -1, NULL, regs, &addr);
       if (terr != TD_OK)
 	return terr;
       /* In this descriptor the nelem word is overloaded as scale factor.  */
@@ -195,12 +195,12 @@ td_ta_map_lwp2thr (const td_thragent_t *ta_arg,
   if (err != TD_OK)
     return err;
 
-  if (list == 0)
+  if (list == NULL)
     {
       if (ps_getpid (ta->ph) != lwpid)
 	return TD_ERR;
       th->th_ta_p = ta;
-      th->th_unique = 0;
+      th->th_unique = NULL;
       return TD_OK;
     }
 
diff --git a/nptl_db/td_ta_set_event.c b/nptl_db/td_ta_set_event.c
index ee674b35fc8..ee3d63e4e6d 100644
--- a/nptl_db/td_ta_set_event.c
+++ b/nptl_db/td_ta_set_event.c
@@ -25,7 +25,7 @@ td_ta_set_event (const td_thragent_t *ta_arg, td_thr_events_t *event)
 {
   td_thragent_t *const ta = (td_thragent_t *) ta_arg;
   td_err_e err;
-  psaddr_t eventmask = 0;
+  psaddr_t eventmask = NULL;
   void *copy = NULL;
 
   LOG ("td_ta_set_event");
diff --git a/nptl_db/td_ta_thr_iter.c b/nptl_db/td_ta_thr_iter.c
index ce0c06cb3a8..cb3d8abb613 100644
--- a/nptl_db/td_ta_thr_iter.c
+++ b/nptl_db/td_ta_thr_iter.c
@@ -37,19 +37,19 @@ iterate_thread_list (td_thragent_t *ta, td_thr_iter_f *callback,
   if (err != TD_OK)
     return err;
 
-  if (next == 0 && fake_empty)
+  if (next == NULL && fake_empty)
     {
       /* __pthread_initialize_minimal has not run.  There is just the main
 	 thread to return.  We cannot rely on its thread register.  They
 	 sometimes contain garbage that would confuse us, left by the
 	 kernel at exec.  So if it looks like initialization is incomplete,
 	 we only fake a special descriptor for the initial thread.  */
-      td_thrhandle_t th = { ta, 0 };
+      td_thrhandle_t th = { ta, NULL };
       return callback (&th, cbdata_p) != 0 ? TD_DBERR : TD_OK;
     }
 
   /* Cache the offset from struct pthread to its list_t member.  */
-  err = DB_GET_FIELD_ADDRESS (ofs, ta, 0, pthread, list, 0);
+  err = DB_GET_FIELD_ADDRESS (ofs, ta, NULL, pthread, list, 0);
   if (err != TD_OK)
     return err;
 
@@ -66,7 +66,7 @@ iterate_thread_list (td_thragent_t *ta, td_thr_iter_f *callback,
       psaddr_t addr, schedpolicy, schedprio;
 
       addr = next - (ofs - (psaddr_t) 0);
-      if (next == 0 || addr == 0) /* Sanity check.  */
+      if (next == NULL || addr == NULL) /* Sanity check.  */
 	return TD_DBERR;
 
       /* Copy the whole descriptor in once so we can access the several
@@ -117,7 +117,7 @@ td_ta_thr_iter (const td_thragent_t *ta_arg, td_thr_iter_f *callback,
 {
   td_thragent_t *const ta = (td_thragent_t *) ta_arg;
   td_err_e err;
-  psaddr_t list = 0;
+  psaddr_t list = NULL;
 
   LOG ("td_ta_thr_iter");
 
diff --git a/nptl_db/td_ta_tsd_iter.c b/nptl_db/td_ta_tsd_iter.c
index 58d68eb871e..592d43ecc29 100644
--- a/nptl_db/td_ta_tsd_iter.c
+++ b/nptl_db/td_ta_tsd_iter.c
@@ -38,7 +38,7 @@ td_ta_tsd_iter (const td_thragent_t *ta_arg, td_key_iter_f *callback,
     return TD_BADTA;
 
   /* This makes sure we have the size information on hand.  */
-  addr = 0;
+  addr = NULL;
   err = _td_locate_field (ta,
 			  ta->ta_var___pthread_keys, SYM_DESC___pthread_keys,
 			  (psaddr_t) 0 + 1, &addr);
diff --git a/nptl_db/td_thr_event_enable.c b/nptl_db/td_thr_event_enable.c
index 48c474c6674..c630722a884 100644
--- a/nptl_db/td_thr_event_enable.c
+++ b/nptl_db/td_thr_event_enable.c
@@ -24,7 +24,7 @@ td_thr_event_enable (const td_thrhandle_t *th, int onoff)
 {
   LOG ("td_thr_event_enable");
 
-  if (th->th_unique != 0)
+  if (th->th_unique != NULL)
     {
       /* Write the new value into the thread data structure.  */
       td_err_e err = DB_PUT_FIELD (th->th_ta_p, th->th_unique, pthread,
diff --git a/nptl_db/td_thr_event_getmsg.c b/nptl_db/td_thr_event_getmsg.c
index c0db52dd626..aa5f5528913 100644
--- a/nptl_db/td_thr_event_getmsg.c
+++ b/nptl_db/td_thr_event_getmsg.c
@@ -74,7 +74,7 @@ td_thr_event_getmsg (const td_thrhandle_t *th, td_event_msg_t *msg)
   if (err != TD_OK)
     return err;
 
-  while (thp != 0)
+  while (thp != NULL)
     {
       psaddr_t next;
       err = DB_GET_FIELD (next, th->th_ta_p, th->th_unique, pthread,
@@ -97,13 +97,13 @@ td_thr_event_getmsg (const td_thrhandle_t *th, td_event_msg_t *msg)
 
 	  err = _td_store_value (th->th_ta_p,
 				 th->th_ta_p->ta_var___nptl_last_event, -1,
-				 0, prevp, next);
+				 NULL, prevp, next);
 	  if (err != TD_OK)
 	    return err;
 
 	  /* Now clear this thread's own next pointer so it's not dangling
 	     when the thread resumes and then chains on for its next event.  */
-	  return DB_PUT_FIELD (th->th_ta_p, thp, pthread, nextevent, 0, 0);
+	  return DB_PUT_FIELD (th->th_ta_p, thp, pthread, nextevent, 0, NULL);
 	}
 
       err = DB_GET_FIELD_ADDRESS (prevp, th->th_ta_p, thp, pthread,
diff --git a/nptl_db/td_thr_get_info.c b/nptl_db/td_thr_get_info.c
index 84765d7c91d..6584a692579 100644
--- a/nptl_db/td_thr_get_info.c
+++ b/nptl_db/td_thr_get_info.c
@@ -31,21 +31,21 @@ td_thr_get_info (const td_thrhandle_t *th, td_thrinfo_t *infop)
 
   LOG ("td_thr_get_info");
 
-  if (th->th_unique == 0)
+  if (th->th_unique == NULL)
     {
       /* Special case for the main thread before initialization.  */
       copy = NULL;
-      tls = 0;
-      cancelhandling = 0;
+      tls = NULL;
+      cancelhandling = NULL;
       schedpolicy = SCHED_OTHER;
-      schedprio = 0;
-      tid = 0;
+      schedprio = NULL;
+      tid = NULL;
 
       /* Ignore errors to obtain the __nptl_initial_report_events
 	 value because GDB no longer uses the events interface, and
 	 other libthread_db consumers hopefully can handle different
 	 libpthread/lds.o load orders.  */
-      report_events = 0;
+      report_events = NULL;
       (void) DB_GET_VALUE (report_events, th->th_ta_p,
 			   __nptl_initial_report_events, 0);
       err = TD_OK;
@@ -105,8 +105,8 @@ td_thr_get_info (const td_thrhandle_t *th, td_thrinfo_t *infop)
 
   /* Initialization which are the same in both cases.  */
   infop->ti_ta_p = th->th_ta_p;
-  infop->ti_lid = tid == 0 ? ps_getpid (th->th_ta_p->ph) : (uintptr_t) tid;
-  infop->ti_traceme = report_events != 0;
+  infop->ti_lid = tid == NULL ? ps_getpid (th->th_ta_p->ph) : (uintptr_t) tid;
+  infop->ti_traceme = report_events != NULL;
 
   if (copy != NULL)
     err = DB_GET_FIELD_LOCAL (infop->ti_startfunc, th->th_ta_p, copy, pthread,
diff --git a/nptl_db/td_thr_getfpregs.c b/nptl_db/td_thr_getfpregs.c
index 81bbcdffb62..0af1e44331c 100644
--- a/nptl_db/td_thr_getfpregs.c
+++ b/nptl_db/td_thr_getfpregs.c
@@ -27,7 +27,7 @@ td_thr_getfpregs (const td_thrhandle_t *th, prfpregset_t *regset)
 
   LOG ("td_thr_getfpregs");
 
-  if (th->th_unique == 0)
+  if (th->th_unique == NULL)
     /* Special case for the main thread before initialization.  */
     return ps_lgetfpregs (th->th_ta_p->ph, ps_getpid (th->th_ta_p->ph),
 			  regset) != PS_OK ? TD_ERR : TD_OK;
diff --git a/nptl_db/td_thr_getgregs.c b/nptl_db/td_thr_getgregs.c
index eb075473aa2..1dc0ec70632 100644
--- a/nptl_db/td_thr_getgregs.c
+++ b/nptl_db/td_thr_getgregs.c
@@ -27,7 +27,7 @@ td_thr_getgregs (const td_thrhandle_t *th, prgregset_t regset)
 
   LOG ("td_thr_getgregs");
 
-  if (th->th_unique == 0)
+  if (th->th_unique == NULL)
     /* Special case for the main thread before initialization.  */
     return ps_lgetregs (th->th_ta_p->ph, ps_getpid (th->th_ta_p->ph),
 			regset) != PS_OK ? TD_ERR : TD_OK;
diff --git a/nptl_db/td_thr_setfpregs.c b/nptl_db/td_thr_setfpregs.c
index dae133464c0..11b2fa814f7 100644
--- a/nptl_db/td_thr_setfpregs.c
+++ b/nptl_db/td_thr_setfpregs.c
@@ -27,7 +27,7 @@ td_thr_setfpregs (const td_thrhandle_t *th, const prfpregset_t *fpregs)
 
   LOG ("td_thr_setfpregs");
 
-  if (th->th_unique == 0)
+  if (th->th_unique == NULL)
     /* Special case for the main thread before initialization.  */
     return ps_lsetfpregs (th->th_ta_p->ph, ps_getpid (th->th_ta_p->ph),
 			  fpregs) != PS_OK ? TD_ERR : TD_OK;
diff --git a/nptl_db/td_thr_setgregs.c b/nptl_db/td_thr_setgregs.c
index aa51885fd32..9f6c3a35479 100644
--- a/nptl_db/td_thr_setgregs.c
+++ b/nptl_db/td_thr_setgregs.c
@@ -27,7 +27,7 @@ td_thr_setgregs (const td_thrhandle_t *th, prgregset_t gregs)
 
   LOG ("td_thr_setgregs");
 
-  if (th->th_unique == 0)
+  if (th->th_unique == NULL)
     /* Special case for the main thread before initialization.  */
     return ps_lsetregs (th->th_ta_p->ph, ps_getpid (th->th_ta_p->ph),
 			gregs) != PS_OK ? TD_ERR : TD_OK;
diff --git a/nptl_db/td_thr_tlsbase.c b/nptl_db/td_thr_tlsbase.c
index a952eea7980..9a3f59aa804 100644
--- a/nptl_db/td_thr_tlsbase.c
+++ b/nptl_db/td_thr_tlsbase.c
@@ -37,14 +37,14 @@ dtv_slotinfo_list (td_thragent_t *ta,
     }
   else
     {
-      if (ta->ta_addr__dl_tls_dtv_slotinfo_list == 0
+      if (ta->ta_addr__dl_tls_dtv_slotinfo_list == NULL
 	  && td_mod_lookup (ta->ph, NULL, SYM__dl_tls_dtv_slotinfo_list,
 			    &ta->ta_addr__dl_tls_dtv_slotinfo_list) != PS_OK)
 	return TD_ERR;
 
       err = _td_fetch_value (ta, ta->ta_var__dl_tls_dtv_slotinfo_list,
-			     SYM_DESC__dl_tls_dtv_slotinfo_list,
-			     0, ta->ta_addr__dl_tls_dtv_slotinfo_list, &head);
+			     SYM_DESC__dl_tls_dtv_slotinfo_list, NULL,
+			     ta->ta_addr__dl_tls_dtv_slotinfo_list, &head);
       if (err != TD_OK)
 	return err;
     }
@@ -129,7 +129,7 @@ td_thr_tlsbase (const td_thrhandle_t *th,
     return TD_NOTLS;
 
   psaddr_t pd = th->th_unique;
-  if (pd == 0)
+  if (pd == NULL)
     {
       /* This is the fake handle for the main thread before libpthread
 	 initialization.  We are using 0 for its th_unique because we can't
@@ -145,7 +145,7 @@ td_thr_tlsbase (const td_thrhandle_t *th,
 				      &main_th);
       if (err == 0)
 	pd = main_th.th_unique;
-      if (pd == 0)
+      if (pd == NULL)
 	return TD_TLSDEFER;
     }
 
diff --git a/nptl_db/td_thr_tsd.c b/nptl_db/td_thr_tsd.c
index 234e894dbb8..19dc2e77493 100644
--- a/nptl_db/td_thr_tsd.c
+++ b/nptl_db/td_thr_tsd.c
@@ -42,8 +42,8 @@ td_thr_tsd (const td_thrhandle_t *th, const thread_key_t tk, void **data)
     return TD_BADKEY;
 
   /* This makes sure we have the size information on hand.  */
-  err = DB_GET_FIELD_ADDRESS (level2, th->th_ta_p, 0, pthread_key_data_level2,
-			      data, 1);
+  err = DB_GET_FIELD_ADDRESS (level2, th->th_ta_p, NULL,
+			      pthread_key_data_level2, data, 1);
   if (err != TD_OK)
     return err;
 
@@ -62,7 +62,7 @@ td_thr_tsd (const td_thrhandle_t *th, const thread_key_t tk, void **data)
     return err;
 
   /* Check the pointer to the second level array.  */
-  if (level1 == 0)
+  if (level1 == NULL)
     return TD_NOTSD;
 
   /* Locate the element within the second level array.  */
diff --git a/nptl_db/td_thr_validate.c b/nptl_db/td_thr_validate.c
index 0c3afe346f1..76c4cf547b0 100644
--- a/nptl_db/td_thr_validate.c
+++ b/nptl_db/td_thr_validate.c
@@ -27,7 +27,7 @@ __td_ta_stack_user (td_thragent_t *ta, psaddr_t *plist)
 				 rtld_global, _dl_stack_user, 0);
   else
     {
-      if (ta->ta_addr__dl_stack_user == 0
+      if (ta->ta_addr__dl_stack_user == NULL
 	  && td_mod_lookup (ta->ph, NULL, SYM__dl_stack_user,
 			    &ta->ta_addr__dl_stack_user) != PS_OK)
 	return TD_ERR;
@@ -45,7 +45,7 @@ __td_ta_stack_used (td_thragent_t *ta, psaddr_t *plist)
 				 rtld_global, _dl_stack_used, 0);
   else
     {
-      if (ta->ta_addr__dl_stack_used == 0
+      if (ta->ta_addr__dl_stack_used == NULL
 	  && td_mod_lookup (ta->ph, NULL, SYM__dl_stack_used,
 			    &ta->ta_addr__dl_stack_used) != PS_OK)
 	return TD_ERR;
@@ -63,12 +63,12 @@ check_thread_list (const td_thrhandle_t *th, psaddr_t head, bool *uninit)
   err = DB_GET_FIELD (next, th->th_ta_p, head, list_t, next, 0);
   if (err == TD_OK)
     {
-      if (next == 0)
+      if (next == NULL)
 	{
 	  *uninit = true;
 	  return TD_NOTHR;
 	}
-      err = DB_GET_FIELD_ADDRESS (ofs, th->th_ta_p, 0, pthread, list, 0);
+      err = DB_GET_FIELD_ADDRESS (ofs, th->th_ta_p, NULL, pthread, list, 0);
     }
 
   while (err == TD_OK)
@@ -108,7 +108,7 @@ td_thr_validate (const td_thrhandle_t *th)
       if (err == TD_OK)
 	err = check_thread_list (th, list, &uninit);
 
-      if (err == TD_NOTHR && uninit && th->th_unique == 0)
+      if (err == TD_NOTHR && uninit && th->th_unique == NULL)
 	/* __pthread_initialize_minimal has not run yet.
 	   There is only the special case thread handle.  */
 	err = TD_OK;
diff --git a/nptl_db/thread_dbP.h b/nptl_db/thread_dbP.h
index 72d55588457..24960d048e6 100644
--- a/nptl_db/thread_dbP.h
+++ b/nptl_db/thread_dbP.h
@@ -158,7 +158,7 @@ extern ps_err_e td_mod_lookup (struct ps_prochandle *ps, const char *modname,
 
 /* Store in psaddr_t VAR the address of inferior's symbol NAME.  */
 #define DB_GET_SYMBOL(var, ta, name)					      \
-  (((ta)->ta_addr_##name == 0						      \
+  (((ta)->ta_addr_##name == NULL					      \
     && td_lookup ((ta)->ph, SYM_##name, &(ta)->ta_addr_##name) != PS_OK)      \
    ? TD_ERR : ((var) = (ta)->ta_addr_##name, TD_OK))
 
@@ -199,7 +199,7 @@ extern td_err_e _td_locate_field (td_thragent_t *ta,
 /* Store in psaddr_t VAR the value of variable NAME[IDX] in the inferior.
    A target value smaller than psaddr_t is zero-extended.  */
 #define DB_GET_VALUE(var, ta, name, idx)				      \
-  (((ta)->ta_addr_##name == 0						      \
+  (((ta)->ta_addr_##name == NULL					      \
     && td_lookup ((ta)->ph, SYM_##name, &(ta)->ta_addr_##name) != PS_OK)      \
    ? TD_ERR								      \
    : _td_fetch_value ((ta), (ta)->ta_var_##name, SYM_DESC_##name, 	      \
@@ -231,7 +231,7 @@ extern td_err_e _td_fetch_value_local (td_thragent_t *ta,
 /* Store psaddr_t VALUE in variable NAME[IDX] in the inferior.
    A target field smaller than psaddr_t is zero-extended.  */
 #define DB_PUT_VALUE(ta, name, idx, value)				      \
-  (((ta)->ta_addr_##name == 0						      \
+  (((ta)->ta_addr_##name == NULL					      \
     && td_lookup ((ta)->ph, SYM_##name, &(ta)->ta_addr_##name) != PS_OK)      \
    ? TD_ERR								      \
    : _td_store_value ((ta), (ta)->ta_var_##name, SYM_DESC_##name, 	      \
diff --git a/nss/getaddrinfo.c b/nss/getaddrinfo.c
index 3ccd3905fa0..78f50954df1 100644
--- a/nss/getaddrinfo.c
+++ b/nss/getaddrinfo.c
@@ -1144,8 +1144,8 @@ gaih_inet (const char *name, const struct gaih_service *service,
   struct gaih_addrtuple *addrmem = NULL;
   int result = 0;
 
-  struct gaih_result res = {0};
-  struct gaih_addrtuple local_at[2] = {0};
+  struct gaih_result res = {};
+  struct gaih_addrtuple local_at[2] = {};
 
   res.at = local_at;
 
diff --git a/posix/getopt.c b/posix/getopt.c
index e2951f74601..66aaeb3cc46 100644
--- a/posix/getopt.c
+++ b/posix/getopt.c
@@ -729,7 +729,7 @@ _getopt_internal (int argc, char **argv, const char *optstring,
   NAME (int argc, char *const *argv, const char *optstring)	\
   {								\
     return _getopt_internal (argc, (char **)argv, optstring,	\
-			     0, 0, 0, POSIXLY_CORRECT);		\
+			     NULL, NULL, 0, POSIXLY_CORRECT);	\
   }
 
 #ifdef _LIBC
diff --git a/posix/regcomp.c b/posix/regcomp.c
index 5380d3c7b9d..1f3c6aec8c5 100644
--- a/posix/regcomp.c
+++ b/posix/regcomp.c
@@ -674,7 +674,7 @@ re_comp (const char *s)
     {
       if (!re_comp_buf.buffer)
 	return gettext ("No previous regular expression");
-      return 0;
+      return NULL;
     }
 
   if (re_comp_buf.buffer)
diff --git a/posix/regexec.c b/posix/regexec.c
index 180e3bce40c..99f49bed62f 100644
--- a/posix/regexec.c
+++ b/posix/regexec.c
@@ -2277,7 +2277,7 @@ merge_state_with_log (reg_errcode_t *err, re_match_context_t *mctx,
       mctx->state_log[cur_idx] = next_state;
       mctx->state_log_top = cur_idx;
     }
-  else if (mctx->state_log[cur_idx] == 0)
+  else if (mctx->state_log[cur_idx] == NULL)
     {
       mctx->state_log[cur_idx] = next_state;
     }
diff --git a/resolv/base64.c b/resolv/base64.c
index 6237257bb0c..11463235c8d 100644
--- a/resolv/base64.c
+++ b/resolv/base64.c
@@ -205,7 +205,7 @@ b64_pton (char const *src, u_char *target, size_t targsize)
 			break;
 
 		pos = strchr(Base64, ch);
-		if (pos == 0) 		/* A non-base64 character. */
+		if (pos == NULL) 		/* A non-base64 character. */
 			return (-1);
 
 		switch (state) {
diff --git a/resolv/compat-gethnamaddr.c b/resolv/compat-gethnamaddr.c
index 1c630fcb3d6..eec68d0b23b 100644
--- a/resolv/compat-gethnamaddr.c
+++ b/resolv/compat-gethnamaddr.c
@@ -804,7 +804,7 @@ _gethtbyname2 (const char *name, int af)
 			continue;
 		if (strcasecmp(p->h_name, name) == 0)
 			break;
-		for (cp = p->h_aliases; *cp != 0; cp++)
+		for (cp = p->h_aliases; *cp != NULL; cp++)
 			if (strcasecmp(*cp, name) == 0)
 				goto found;
 	}
diff --git a/resolv/res_debug.c b/resolv/res_debug.c
index 1b1f5233f93..73af0c72fec 100644
--- a/resolv/res_debug.c
+++ b/resolv/res_debug.c
@@ -503,7 +503,7 @@ const struct res_sym __p_rcode_syms[] attribute_hidden = {
 
 int
 sym_ston(const struct res_sym *syms, const char *name, int *success) {
-	for ((void)NULL; syms->name != 0; syms++) {
+	for ((void)NULL; syms->name != NULL; syms++) {
 		if (strcasecmp (name, syms->name) == 0) {
 			if (success)
 				*success = 1;
@@ -519,7 +519,7 @@ const char *
 sym_ntos(const struct res_sym *syms, int number, int *success) {
 	static char unname[20];
 
-	for ((void)NULL; syms->name != 0; syms++) {
+	for ((void)NULL; syms->name != NULL; syms++) {
 		if (number == syms->number) {
 			if (success)
 				*success = 1;
@@ -538,7 +538,7 @@ const char *
 sym_ntop(const struct res_sym *syms, int number, int *success) {
 	static char unname[20];
 
-	for ((void)NULL; syms->name != 0; syms++) {
+	for ((void)NULL; syms->name != NULL; syms++) {
 		if (number == syms->number) {
 			if (success)
 				*success = 1;
diff --git a/resolv/res_hconf.c b/resolv/res_hconf.c
index e1158943a94..1737bce2f9d 100644
--- a/resolv/res_hconf.c
+++ b/resolv/res_hconf.c
@@ -118,12 +118,12 @@ arg_trimdomain_list (const char *fname, int line_num, const char *args)
 	  if (__asprintf (&buf, _("\
 %s: line %d: cannot specify more than %d trim domains"),
 			  fname, line_num, TRIMDOMAINS_MAX) < 0)
-	    return 0;
+	    return NULL;
 
 	  __fxprintf (NULL, "%s", buf);
 
 	  free (buf);
-	  return 0;
+	  return NULL;
 	}
       _res_hconf.trimdomain[_res_hconf.num_trimdomains++] =
 	__strndup (start, len);
@@ -139,12 +139,12 @@ arg_trimdomain_list (const char *fname, int line_num, const char *args)
 	      if (__asprintf (&buf, _("\
 %s: line %d: list delimiter not followed by domain"),
 			      fname, line_num) < 0)
-		return 0;
+		return NULL;
 
 	      __fxprintf (NULL, "%s", buf);
 
 	      free (buf);
-	      return 0;
+	      return NULL;
 	    }
 	default:
 	  break;
@@ -175,12 +175,12 @@ arg_bool (const char *fname, int line_num, const char *args, unsigned flag)
       if (__asprintf (&buf,
 		      _("%s: line %d: expected `on' or `off', found `%s'\n"),
 		      fname, line_num, args) < 0)
-	return 0;
+	return NULL;
 
       __fxprintf (NULL, "%s", buf);
 
       free (buf);
-      return 0;
+      return NULL;
     }
   return args;
 }
@@ -190,7 +190,7 @@ static void
 parse_line (const char *fname, int line_num, const char *str)
 {
   const char *start;
-  const struct cmd *c = 0;
+  const struct cmd *c = NULL;
   size_t len;
   size_t i;
 
diff --git a/stdio-common/iovfscanf.c b/stdio-common/iovfscanf.c
index 43b5c70c3f6..68d0a325f79 100644
--- a/stdio-common/iovfscanf.c
+++ b/stdio-common/iovfscanf.c
@@ -29,7 +29,7 @@ attribute_compat_text_section
 __IO_vfscanf (FILE *fp, const char *format, va_list ap, int *errp)
 {
   int rv = __vfscanf_internal (fp, format, ap, 0);
-  if (__glibc_unlikely (errp != 0))
+  if (__glibc_unlikely (errp != NULL))
     *errp = (rv == -1);
   return rv;
 }
diff --git a/string/argz-delete.c b/string/argz-delete.c
index e513e46d586..879daa98212 100644
--- a/string/argz-delete.c
+++ b/string/argz-delete.c
@@ -33,7 +33,7 @@ argz_delete (char **argz, size_t *argz_len, char *entry)
       if (*argz_len == 0)
 	{
 	  free (*argz);
-	  *argz = 0;
+	  *argz = NULL;
 	}
     }
 }
diff --git a/string/argz-extract.c b/string/argz-extract.c
index e685da57957..fd0003965d4 100644
--- a/string/argz-extract.c
+++ b/string/argz-extract.c
@@ -30,6 +30,6 @@ __argz_extract (const char *argz, size_t len, char **argv)
       argz += part_len + 1;
       len -= part_len + 1;
     }
-  *argv = 0;
+  *argv = NULL;
 }
 weak_alias (__argz_extract, argz_extract)
diff --git a/string/argz-replace.c b/string/argz-replace.c
index fdd9a8e1c94..d2add630ff6 100644
--- a/string/argz-replace.c
+++ b/string/argz-replace.c
@@ -38,7 +38,7 @@ str_append (char **to, size_t *to_len, const char *buf, const size_t buf_len)
   else
     {
       free (*to);
-      *to = 0;
+      *to = NULL;
     }
 }
 
@@ -53,10 +53,10 @@ __argz_replace (char **argz, size_t *argz_len, const char *str, const char *with
 
   if (str && *str)
     {
-      char *arg = 0;
+      char *arg = NULL;
       char *src = *argz;
       size_t src_len = *argz_len;
-      char *dst = 0;
+      char *dst = NULL;
       size_t dst_len = 0;
       int delayed_copy = 1;	/* True while we've avoided copying anything.  */
       size_t str_len = strlen (str), with_len = strlen (with);
@@ -84,7 +84,7 @@ __argz_replace (char **argz, size_t *argz_len, const char *str, const char *with
 		      else
 			{
 			  str_append (&to, &to_len, from, strlen (from));
-			  from = 0;
+			  from = NULL;
 			}
 		    }
 		}
diff --git a/string/argz.h b/string/argz.h
index 49e85a09ec9..b2dd9941322 100644
--- a/string/argz.h
+++ b/string/argz.h
@@ -141,7 +141,7 @@ __NTH (__argz_next (const char *__argz, size_t __argz_len,
       return __entry >= __argz + __argz_len ? (char *) NULL : (char *) __entry;
     }
   else
-    return __argz_len > 0 ? (char *) __argz : 0;
+    return __argz_len > 0 ? (char *) __argz : NULL;
 }
 __extern_inline char *
 __NTH (argz_next (const char *__argz, size_t __argz_len,
diff --git a/string/envz.c b/string/envz.c
index cb02b4b338c..4f53dcb2e75 100644
--- a/string/envz.c
+++ b/string/envz.c
@@ -50,7 +50,7 @@ envz_entry (const char *envz, size_t envz_len, const char *name)
 	envz++, envz_len--;	/* skip '\0' */
     }
 
-  return 0;
+  return NULL;
 }
 libc_hidden_def (envz_entry)
 
@@ -67,7 +67,7 @@ envz_get (const char *envz, size_t envz_len, const char *name)
       if (*entry)
 	entry++;
       else
-	entry = 0;		/* A null entry.  */
+	entry = NULL;		/* A null entry.  */
     }
   return entry;
 }
diff --git a/sunrpc/clnt_raw.c b/sunrpc/clnt_raw.c
index 5b9bd482478..79c0964e7bb 100644
--- a/sunrpc/clnt_raw.c
+++ b/sunrpc/clnt_raw.c
@@ -90,11 +90,11 @@ clntraw_create (u_long prog, u_long vers)
   XDR *xdrs;
   CLIENT *client;
 
-  if (clp == 0)
+  if (clp == NULL)
     {
       clp = (struct clntraw_private_s *) calloc (1, sizeof (*clp));
-      if (clp == 0)
-	return (0);
+      if (clp == NULL)
+	return NULL;
       clntraw_private = clp;
     }
   xdrs = &clp->xdr_stream;
diff --git a/sunrpc/clnt_simp.c b/sunrpc/clnt_simp.c
index fab61d21700..ee77af9cbcf 100644
--- a/sunrpc/clnt_simp.c
+++ b/sunrpc/clnt_simp.c
@@ -60,10 +60,10 @@ callrpc (const char *host, u_long prognum, u_long versnum, u_long procnum,
   enum clnt_stat clnt_stat;
   struct timeval timeout, tottimeout;
 
-  if (crp == 0)
+  if (crp == NULL)
     {
       crp = (struct callrpc_private_s *) calloc (1, sizeof (*crp));
-      if (crp == 0)
+      if (crp == NULL)
 	return 0;
       callrpc_private = crp;
     }
diff --git a/sunrpc/key_call.c b/sunrpc/key_call.c
index b0b29e09a7f..c8e414b1df2 100644
--- a/sunrpc/key_call.c
+++ b/sunrpc/key_call.c
@@ -542,7 +542,7 @@ key_call (u_long proc, xdrproc_t xdr_arg, char *arg,
   else if (proc == KEY_GEN && __key_gendes_LOCAL)
     {
       des_block *res;
-      res = (*__key_gendes_LOCAL) (__geteuid (), 0);
+      res = (*__key_gendes_LOCAL) (__geteuid (), NULL);
       *(des_block *) rslt = *res;
       return 1;
     }
diff --git a/sunrpc/svc_raw.c b/sunrpc/svc_raw.c
index f0176311d5c..2879ce6f84a 100644
--- a/sunrpc/svc_raw.c
+++ b/sunrpc/svc_raw.c
@@ -72,10 +72,10 @@ svcraw_create (void)
 {
   struct svcraw_private_s *srp = svcraw_private;
 
-  if (srp == 0)
+  if (srp == NULL)
     {
       srp = (struct svcraw_private_s *) calloc (1, sizeof (*srp));
-      if (srp == 0)
+      if (srp == NULL)
 	return NULL;
     }
   srp->server.xp_sock = 0;
@@ -99,7 +99,7 @@ svcraw_recv (SVCXPRT *xprt, struct rpc_msg *msg)
   struct svcraw_private_s *srp = svcraw_private;
   XDR *xdrs;
 
-  if (srp == 0)
+  if (srp == NULL)
     return FALSE;
   xdrs = &srp->xdr_stream;
   xdrs->x_op = XDR_DECODE;
@@ -115,7 +115,7 @@ svcraw_reply (SVCXPRT *xprt, struct rpc_msg *msg)
   struct svcraw_private_s *srp = svcraw_private;
   XDR *xdrs;
 
-  if (srp == 0)
+  if (srp == NULL)
     return FALSE;
   xdrs = &srp->xdr_stream;
   xdrs->x_op = XDR_ENCODE;
@@ -131,7 +131,7 @@ svcraw_getargs (SVCXPRT *xprt, xdrproc_t xdr_args, caddr_t args_ptr)
 {
   struct svcraw_private_s *srp = svcraw_private;
 
-  if (srp == 0)
+  if (srp == NULL)
     return FALSE;
   return (*xdr_args) (&srp->xdr_stream, args_ptr);
 }
@@ -142,7 +142,7 @@ svcraw_freeargs (SVCXPRT *xprt, xdrproc_t xdr_args, caddr_t args_ptr)
   struct svcraw_private_s *srp = svcraw_private;
   XDR *xdrs;
 
-  if (srp == 0)
+  if (srp == NULL)
     return FALSE;
   xdrs = &srp->xdr_stream;
   xdrs->x_op = XDR_FREE;
diff --git a/sunrpc/svc_simple.c b/sunrpc/svc_simple.c
index 2f2595c0ffe..5a6dd1fce64 100644
--- a/sunrpc/svc_simple.c
+++ b/sunrpc/svc_simple.c
@@ -74,7 +74,7 @@ __registerrpc (u_long prognum, u_long versnum, u_long procnum,
 	buf = NULL;
       goto err_out;
     }
-  if (transp == 0)
+  if (transp == NULL)
     {
       transp = svcudp_create (RPC_ANYSOCK);
       if (transp == NULL)
diff --git a/sunrpc/xdr_mem.c b/sunrpc/xdr_mem.c
index 46a1f6f1903..a5aa93f4378 100644
--- a/sunrpc/xdr_mem.c
+++ b/sunrpc/xdr_mem.c
@@ -195,7 +195,7 @@ xdrmem_setpos (XDR *xdrs, u_int pos)
 static int32_t *
 xdrmem_inline (XDR *xdrs, u_int len)
 {
-  int32_t *buf = 0;
+  int32_t *buf = NULL;
 
   if (xdrs->x_handy >= len)
     {
diff --git a/sunrpc/xdr_sizeof.c b/sunrpc/xdr_sizeof.c
index 1592406d646..03c23cd42b0 100644
--- a/sunrpc/xdr_sizeof.c
+++ b/sunrpc/xdr_sizeof.c
@@ -89,7 +89,7 @@ x_inline (XDR *xdrs, u_int len)
       free (xdrs->x_private);
       if ((xdrs->x_private = (caddr_t) malloc (len)) == NULL)
 	{
-	  xdrs->x_base = 0;
+	  xdrs->x_base = NULL;
 	  return NULL;
 	}
       xdrs->x_base = (void *) (long) len;
@@ -109,7 +109,7 @@ static void
 x_destroy (XDR *xdrs)
 {
   xdrs->x_handy = 0;
-  xdrs->x_base = 0;
+  xdrs->x_base = NULL;
   if (xdrs->x_private)
     {
       free (xdrs->x_private);
diff --git a/sunrpc/xdr_stdio.c b/sunrpc/xdr_stdio.c
index 0c2cbb78ded..204ed599ae2 100644
--- a/sunrpc/xdr_stdio.c
+++ b/sunrpc/xdr_stdio.c
@@ -89,7 +89,7 @@ xdrstdio_create (XDR *xdrs, FILE *file, enum xdr_op op)
   xdrs->x_ops = (struct xdr_ops *) &xdrstdio_ops;
   xdrs->x_private = (caddr_t) file;
   xdrs->x_handy = 0;
-  xdrs->x_base = 0;
+  xdrs->x_base = NULL;
 }
 
 /*
diff --git a/support/blob_repeat.c b/support/blob_repeat.c
index 693956f436c..19c9aaf4446 100644
--- a/support/blob_repeat.c
+++ b/support/blob_repeat.c
@@ -92,7 +92,7 @@ allocate_malloc (size_t total_size, const void *element, size_t element_size,
 {
   void *buffer = malloc (total_size);
   if (buffer == NULL)
-    return (struct support_blob_repeat) { 0 };
+    return (struct support_blob_repeat) {};
   fill (buffer, element, element_size, count);
   return (struct support_blob_repeat)
     {
@@ -136,7 +136,7 @@ allocate_big (size_t total_size, const void *element, size_t element_size,
   if (stride_size == 0)
     {
       errno = EOVERFLOW;
-      return (struct support_blob_repeat) { 0 };
+      return (struct support_blob_repeat) {};
     }
 
   /* Ensure that the stride size is at least maximum_small_size.  This
@@ -154,7 +154,7 @@ allocate_big (size_t total_size, const void *element, size_t element_size,
   void *target = mmap (NULL, total_size, PROT_NONE,
                        MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
   if (target == MAP_FAILED)
-    return (struct support_blob_repeat) { 0 };
+    return (struct support_blob_repeat) {};
 
   /* Create the backing file for the repeated mapping.  Call mkstemp
      directly to remove the resources backing the temporary file
@@ -191,7 +191,7 @@ allocate_big (size_t total_size, const void *element, size_t element_size,
         xmunmap (target, total_size);
         xclose (fd);
         errno = saved_errno;
-        return (struct support_blob_repeat) { 0 };
+        return (struct support_blob_repeat) {};
       }
     if (ptr != target)
       FAIL_EXIT1 ("mapping of %zu bytes moved from %p to %p",
@@ -235,7 +235,7 @@ allocate_big (size_t total_size, const void *element, size_t element_size,
             xmunmap (target, total_size);
             xclose (fd);
             errno = saved_errno;
-            return (struct support_blob_repeat) { 0 };
+            return (struct support_blob_repeat) {};
           }
         if (ptr != current)
           FAIL_EXIT1 ("MAP_PRIVATE mapping of %zu bytes moved from %p to %p",
@@ -263,7 +263,7 @@ repeat_allocate (const void *element, size_t element_size,
   if (__builtin_mul_overflow (element_size, count, &total_size))
     {
       errno = EOVERFLOW;
-      return (struct support_blob_repeat) { 0 };
+      return (struct support_blob_repeat) {};
     }
   if (total_size <= maximum_small_size)
     return allocate_malloc (total_size, element, element_size, count);
@@ -297,5 +297,5 @@ support_blob_repeat_free (struct support_blob_repeat *blob)
         xmunmap (blob->start, blob->size);
       errno = saved_errno;
     }
-  *blob = (struct support_blob_repeat) { 0 };
+  *blob = (struct support_blob_repeat) {};
 }
diff --git a/support/shell-container.c b/support/shell-container.c
index ca833791d5f..86f43ab23fb 100644
--- a/support/shell-container.c
+++ b/support/shell-container.c
@@ -119,7 +119,7 @@ copy_func (char **argv)
       goto out;
     }
 
-  if (support_copy_file_range (sfd, 0, dfd, 0, st.st_size, 0) != st.st_size)
+  if (support_copy_file_range (sfd, NULL, dfd, NULL, st.st_size, 0) != st.st_size)
     {
       fprintf (stderr, "cp: cannot copy file %s to %s: %s\n",
 	       sname, dname, strerror (errno));
@@ -145,7 +145,7 @@ exit_func (char **argv)
 {
   int exit_val = 0;
 
-  if (argv[0] != 0)
+  if (argv[0] != NULL)
     exit_val = atoi (argv[0]) & 0xff;
   exit (exit_val);
   return 0;
diff --git a/support/support_openpty.c b/support/support_openpty.c
index fbf9f71e738..1d154a9d0ae 100644
--- a/support/support_openpty.c
+++ b/support/support_openpty.c
@@ -57,7 +57,7 @@ support_openpty (int *a_outer, int *a_inner, char **a_name,
                  const struct winsize *winp)
 {
   int outer = -1, inner = -1;
-  char *namebuf = 0;
+  char *namebuf = NULL;
 
   outer = posix_openpt (O_RDWR | O_NOCTTY);
   if (outer == -1)
diff --git a/support/support_set_vma_name_supported.c b/support/support_set_vma_name_supported.c
index 2de066fbe83..99350663456 100644
--- a/support/support_set_vma_name_supported.c
+++ b/support/support_set_vma_name_supported.c
@@ -32,7 +32,7 @@ support_set_vma_name_supported (void)
   if (size == -1)
     FAIL_EXIT1 ("sysconf (_SC_PAGESIZE): %m\n");
 
-  void *vma = xmmap (0,
+  void *vma = xmmap (NULL,
 		     size,
 		     PROT_NONE,
 		     MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE,
diff --git a/support/support_stack_alloc.c b/support/support_stack_alloc.c
index edf3dbfc210..346a46aa2a6 100644
--- a/support/support_stack_alloc.c
+++ b/support/support_stack_alloc.c
@@ -58,7 +58,7 @@ support_stack_alloc (size_t size)
   /* Use MAP_NORESERVE so that RAM will not be wasted on the guard
      bands; touch all the pages of the actual stack before returning,
      so we know they are allocated.  */
-  void *alloc_base = xmmap (0,
+  void *alloc_base = xmmap (NULL,
                             alloc_size,
                             PROT_NONE,
                             MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE|MAP_STACK,
diff --git a/support/test-container.c b/support/test-container.c
index ebcc722da58..54896280a20 100644
--- a/support/test-container.c
+++ b/support/test-container.c
@@ -440,7 +440,7 @@ copy_one_file (const char *sname, const char *dname)
   if (dfd < 0)
     FAIL_EXIT1 ("unable to open %s for writing\n", dname);
 
-  xcopy_file_range (sfd, 0, dfd, 0, st.st_size, 0);
+  xcopy_file_range (sfd, NULL, dfd, NULL, st.st_size, 0);
 
   xclose (sfd);
   xclose (dfd);
diff --git a/support/xsigstack.c b/support/xsigstack.c
index 415e65976cc..59512a2148e 100644
--- a/support/xsigstack.c
+++ b/support/xsigstack.c
@@ -64,7 +64,7 @@ xfree_sigstack (void *stack)
 {
   struct sigstack_desc *desc = stack;
 
-  if (sigaltstack (&desc->old_stack, 0))
+  if (sigaltstack (&desc->old_stack, NULL))
     FAIL_EXIT1 ("sigaltstack (restore old stack: sp=%p, size=%zu, flags=%u): "
                 "%m\n", desc->old_stack.ss_sp, desc->old_stack.ss_size,
                 desc->old_stack.ss_flags);
diff --git a/sysdeps/posix/system.c b/sysdeps/posix/system.c
index 01e8bc45215..be327042809 100644
--- a/sysdeps/posix/system.c
+++ b/sysdeps/posix/system.c
@@ -144,7 +144,7 @@ do_system (const char *line)
   __posix_spawnattr_setflags (&spawn_attr,
 			      POSIX_SPAWN_SETSIGDEF | POSIX_SPAWN_SETSIGMASK);
 
-  ret = __posix_spawn (&pid, SHELL_PATH, 0, &spawn_attr,
+  ret = __posix_spawn (&pid, SHELL_PATH, NULL, &spawn_attr,
 		       (char *const[]){ (char *) SHELL_NAME,
 					(char *) "-c",
 					(char *) "--",
diff --git a/sysdeps/unix/sysv/linux/brk.c b/sysdeps/unix/sysv/linux/brk.c
index a0be43e4f99..dbdb8ddd7da 100644
--- a/sysdeps/unix/sysv/linux/brk.c
+++ b/sysdeps/unix/sysv/linux/brk.c
@@ -22,7 +22,7 @@
 #include <brk_call.h>
 
 /* This must be initialized data because commons can't have aliases.  */
-void *__curbrk = 0;
+void *__curbrk = NULL;
 
 #if HAVE_INTERNAL_BRK_ADDR_SYMBOL
 /* Old braindamage in GCC's crtstuff.c requires this symbol in an attempt
diff --git a/sysdeps/unix/sysv/linux/dl-early_allocate.c b/sysdeps/unix/sysv/linux/dl-early_allocate.c
index 4d98076ab39..ce5c6b55ffd 100644
--- a/sysdeps/unix/sysv/linux/dl-early_allocate.c
+++ b/sysdeps/unix/sysv/linux/dl-early_allocate.c
@@ -51,7 +51,7 @@ _dl_early_allocate (size_t size)
     {
       /* If brk has not been invoked, there is no need to update
          __curbrk.  The first call to brk will take care of that.  */
-      void *previous = __brk_call (0);
+      void *previous = __brk_call (NULL);
       result = __brk_call (previous + size);
       if (result == previous)
         result = NULL;
diff --git a/sysdeps/unix/sysv/linux/dl-sysdep.c b/sysdeps/unix/sysv/linux/dl-sysdep.c
index 4352549f013..d1170a1d000 100644
--- a/sysdeps/unix/sysv/linux/dl-sysdep.c
+++ b/sysdeps/unix/sysv/linux/dl-sysdep.c
@@ -113,7 +113,7 @@ _dl_sysdep_start (void **start_argptr,
   /* Initialize DSO sorting algorithm after tunables.  */
   _dl_sort_maps_init ();
 
-  __brk (0);			/* Initialize the break.  */
+  __brk (NULL);			/* Initialize the break.  */
 
 #ifdef DL_PLATFORM_INIT
   DL_PLATFORM_INIT;
diff --git a/sysdeps/unix/sysv/linux/gettimeofday.c b/sysdeps/unix/sysv/linux/gettimeofday.c
index 5ca89166110..3c97da05be9 100644
--- a/sysdeps/unix/sysv/linux/gettimeofday.c
+++ b/sysdeps/unix/sysv/linux/gettimeofday.c
@@ -31,7 +31,7 @@
 static int
 __gettimeofday_syscall (struct timeval *restrict tv, void *restrict tz)
 {
-  if (__glibc_unlikely (tz != 0))
+  if (__glibc_unlikely (tz != NULL))
     memset (tz, 0, sizeof *tz);
   return INLINE_SYSCALL_CALL (gettimeofday, tv, tz);
 }
@@ -47,7 +47,7 @@ libc_ifunc (__gettimeofday,
 int
 __gettimeofday (struct timeval *restrict tv, void *restrict tz)
 {
-  if (__glibc_unlikely (tz != 0))
+  if (__glibc_unlikely (tz != NULL))
     memset (tz, 0, sizeof *tz);
 
   return INLINE_VSYSCALL (gettimeofday, 2, tv, tz);
diff --git a/sysdeps/unix/sysv/linux/settimeofday.c b/sysdeps/unix/sysv/linux/settimeofday.c
index 4235dc83e66..4fa1d660153 100644
--- a/sysdeps/unix/sysv/linux/settimeofday.c
+++ b/sysdeps/unix/sysv/linux/settimeofday.c
@@ -26,9 +26,9 @@ int
 __settimeofday64 (const struct __timeval64 *tv, const struct timezone *tz)
 {
   /* Backwards compatibility for setting the UTC offset.  */
-  if (__glibc_unlikely (tz != 0))
+  if (__glibc_unlikely (tz != NULL))
     {
-      if (tv != 0)
+      if (tv != NULL)
 	{
 	  __set_errno (EINVAL);
 	  return -1;
diff --git a/sysdeps/unix/sysv/linux/sigwait.c b/sysdeps/unix/sysv/linux/sigwait.c
index 37de8db0dcf..f0dff83dab1 100644
--- a/sysdeps/unix/sysv/linux/sigwait.c
+++ b/sysdeps/unix/sysv/linux/sigwait.c
@@ -25,7 +25,7 @@ __sigwait (const sigset_t *set, int *sig)
   siginfo_t si;
   int ret;
   do
-    ret = __sigtimedwait (set, &si, 0);
+    ret = __sigtimedwait (set, &si, NULL);
   /* Applications do not expect sigwait to return with EINTR, and the
      error code is not specified by POSIX.  */
   while (ret < 0 && errno == EINTR);
diff --git a/sysdeps/unix/sysv/linux/sigwaitinfo.c b/sysdeps/unix/sysv/linux/sigwaitinfo.c
index dba25bdc3b6..1d48b11b57e 100644
--- a/sysdeps/unix/sysv/linux/sigwaitinfo.c
+++ b/sysdeps/unix/sysv/linux/sigwaitinfo.c
@@ -22,7 +22,7 @@
 int
 __sigwaitinfo (const sigset_t *set, siginfo_t *info)
 {
-  return __sigtimedwait (set, info, 0);
+  return __sigtimedwait (set, info, NULL);
 }
 
 libc_hidden_def (__sigwaitinfo)
diff --git a/sysdeps/unix/sysv/linux/spawni.c b/sysdeps/unix/sysv/linux/spawni.c
index 1edf62c6d7b..85796c68c2e 100644
--- a/sysdeps/unix/sysv/linux/spawni.c
+++ b/sysdeps/unix/sysv/linux/spawni.c
@@ -115,7 +115,7 @@ __spawni_child (void *arguments)
   memset (&sa, '\0', sizeof (sa));
 
   sigset_t hset;
-  __sigprocmask (SIG_BLOCK, 0, &hset);
+  __sigprocmask (SIG_BLOCK, NULL, &hset);
   for (int sig = 1; sig < _NSIG; ++sig)
     {
       if ((attr->__flags & POSIX_SPAWN_SETSIGDEF)
@@ -129,7 +129,7 @@ __spawni_child (void *arguments)
 	    sa.sa_handler = SIG_IGN;
 	  else
 	    {
-	      __libc_sigaction (sig, 0, &sa);
+	      __libc_sigaction (sig, NULL, &sa);
 	      if (sa.sa_handler == SIG_IGN || sa.sa_handler == SIG_DFL)
 		continue;
 	      sa.sa_handler = SIG_DFL;
@@ -138,7 +138,7 @@ __spawni_child (void *arguments)
       else
 	continue;
 
-      __libc_sigaction (sig, &sa, 0);
+      __libc_sigaction (sig, &sa, NULL);
     }
 
 #ifdef _POSIX_PRIORITY_SCHEDULING
@@ -172,7 +172,7 @@ __spawni_child (void *arguments)
     goto fail;
 
   /* Execute the file actions.  */
-  if (file_actions != 0)
+  if (file_actions != NULL)
     {
       int cnt;
       struct rlimit64 fdlimit;
diff --git a/sysdeps/x86/nptl/bits/struct_mutex.h b/sysdeps/x86/nptl/bits/struct_mutex.h
index b6bb9aa34af..7a1b8a14b62 100644
--- a/sysdeps/x86/nptl/bits/struct_mutex.h
+++ b/sysdeps/x86/nptl/bits/struct_mutex.h
@@ -54,7 +54,7 @@ struct __pthread_mutex_s
 
 #ifdef __x86_64__
 # define __PTHREAD_MUTEX_INITIALIZER(__kind) \
-  0, 0, 0, 0, __kind, 0, 0, { 0, 0 }
+  0, 0, 0, 0, __kind, 0, 0, { NULL, NULL }
 #else
 # define __PTHREAD_MUTEX_INITIALIZER(__kind) \
   0, 0, 0, __kind, 0, { { 0, 0 } }
diff --git a/timezone/zic.c b/timezone/zic.c
index cf8e79dff46..d5d30163b09 100644
--- a/timezone/zic.c
+++ b/timezone/zic.c
@@ -1950,7 +1950,7 @@ inzsub(char **fields, int nfields, bool iscont)
 	z.z_filenum = filenum;
 	z.z_linenum = linenum;
 	z.z_stdoff = gethms(fields[i_stdoff], _("invalid UT offset"));
-	if ((cp = strchr(fields[i_format], '%')) != 0) {
+	if ((cp = strchr(fields[i_format], '%')) != NULL) {
 		if ((*++cp != 's' && *cp != 'z') || strchr(cp, '%')
 		    || strchr(fields[i_format], '/')) {
 			error(_("invalid abbreviation format"));
@@ -2238,9 +2238,9 @@ rulesub(struct rule *rp, const char *loyearp, const char *hiyearp,
 		rp->r_wday = lp->l_value;
 		rp->r_dayofmonth = len_months[1][rp->r_month];
 	} else {
-		if ((ep = strchr(dp, '<')) != 0)
+		if ((ep = strchr(dp, '<')) != NULL)
 			rp->r_dycode = DC_DOWLEQ;
-		else if ((ep = strchr(dp, '>')) != 0)
+		else if ((ep = strchr(dp, '>')) != NULL)
 			rp->r_dycode = DC_DOWGEQ;
 		else {
 			ep = dp;
diff --git a/wctype/wctrans.c b/wctype/wctrans.c
index 9444ed08d81..4c484c01b5b 100644
--- a/wctype/wctrans.c
+++ b/wctype/wctrans.c
@@ -39,7 +39,7 @@ __wctrans (const char *property)
     }
 
   if (names[0] == '\0')
-    return 0;
+    return NULL;
 
   i = _NL_CURRENT_WORD (LC_CTYPE, _NL_CTYPE_MAP_OFFSET) + cnt;
   return (wctrans_t) _NL_CURRENT_DATA (LC_CTYPE)->values[i].string;
diff --git a/wctype/wctrans_l.c b/wctype/wctrans_l.c
index 96fde935ffb..1a34168b3f8 100644
--- a/wctype/wctrans_l.c
+++ b/wctype/wctrans_l.c
@@ -39,7 +39,7 @@ __wctrans_l (const char *property, locale_t locale)
     }
 
   if (names[0] == '\0')
-    return 0;
+    return NULL;
 
   i = locale->__locales[LC_CTYPE]->values[_NL_ITEM_INDEX (_NL_CTYPE_MAP_OFFSET)].word + cnt;
   return (wctrans_t) locale->__locales[LC_CTYPE]->values[i].string;