cp: omit unnecessary stat of destination

'cp A B' attempts to open B as a directory, to see whether to
write to B/A instead of to B.  In the common case where the
open fails with ENOENT, do not bother to stat B afterwards
since the stat should also fail with ENOENT.
* src/copy.c (copy_internal, copy): Change bool arg about
nonexistent destination to a 3-way int argument.  All callers changed.
(copy_internal): Do not bother to stat a destination already known
to not exist when following symlinks.

diff --git a/src/copy.c b/src/copy.c
index 9f2cf7e33d9f6cd9546d7dd82806dfc76d954fca..fccb20f95e4bfe33b8bc90ae5cd791f324bf16b1 100644 (file)
--- a/src/copy.c
+++ b/src/copy.c
@@ -127,7 +127,7 @@ struct dir_list
 
 static bool copy_internal (char const *src_name, char const *dst_name,
                            int dst_dirfd, char const *dst_relname,
-                           bool new_dst, struct stat const *parent,
+                           int nonexistent_dst, struct stat const *parent,
                            struct dir_list *ancestors,
                            const struct cp_options *x,
                            bool command_line_arg,
@@ -1978,19 +1978,24 @@ source_is_dst_backup (char const *srcbase, struct stat const *src_st,
 }
 
 /* Copy the file SRC_NAME to the file DST_NAME aka DST_DIRFD+DST_RELNAME.
-   NEW_DST means DST_NAME is known not to exist (e.g., because its
-   parent directory was just created).  A non-null PARENT describes the
-   parent directory.  ANCESTORS points to a linked, null terminated list of
-   devices and inodes of parent directories of SRC_NAME.  COMMAND_LINE_ARG
-   is true iff SRC_NAME was specified on the command line.
+   If NONEXISTENT_DST is positive, DST_NAME does not exist even as a
+   dangling symlink; if negative, it does not exist except possibly
+   as a dangling symlink; if zero, its existence status is unknown.
+   A non-null PARENT describes the parent directory.
+   ANCESTORS points to a linked, null terminated list of
+   devices and inodes of parent directories of SRC_NAME.
+   X summarizes the command-line options.
+   COMMAND_LINE_ARG means SRC_NAME was specified on the command line.
    FIRST_DIR_CREATED_PER_COMMAND_LINE_ARG is both input and output.
    Set *COPY_INTO_SELF if SRC_NAME is a parent of (or the
    same as) DST_NAME; otherwise, clear it.
+   If X->move_mode, set *RENAME_SUCCEEDED according to whether
+   the source was simply renamed to the destination.
    Return true if successful.  */
 static bool
 copy_internal (char const *src_name, char const *dst_name,
                int dst_dirfd, char const *dst_relname,
-               bool new_dst,
+               int nonexistent_dst,
                struct stat const *parent,
                struct dir_list *ancestors,
                const struct cp_options *x,
@@ -2013,6 +2018,12 @@ copy_internal (char const *src_name, char const *dst_name,
   bool dest_is_symlink = false;
   bool have_dst_lstat = false;
 
+  /* Whether the destination is (or was) known to be new, updated as
+     more info comes in.  This may become true if the destination is a
+     dangling symlink, in contexts where dangling symlinks should be
+     treated the same as nonexistent files.  */
+  bool new_dst = 0 < nonexistent_dst;
+
   *copy_into_self = false;
 
   int rename_errno = x->rename_errno;
@@ -2022,9 +2033,7 @@ copy_internal (char const *src_name, char const *dst_name,
         rename_errno = (renameatu (AT_FDCWD, src_name, dst_dirfd, dst_relname,
                                    RENAME_NOREPLACE)
                         ? errno : 0);
-      new_dst = rename_errno == 0;
-      if (rename_succeeded)
-        *rename_succeeded = new_dst;
+      nonexistent_dst = *rename_succeeded = new_dst = rename_errno == 0;
     }
 
   if (rename_errno == 0
@@ -2081,7 +2090,7 @@ copy_internal (char const *src_name, char const *dst_name,
 
   bool dereference = should_dereference (x, command_line_arg);
 
-  if (!new_dst)
+  if (nonexistent_dst <= 0)
     {
       if (! (rename_errno == EEXIST && x->interactive == I_ALWAYS_NO))
         {
@@ -2099,8 +2108,11 @@ copy_internal (char const *src_name, char const *dst_name,
                || x->backup_type != no_backups
                || x->unlink_dest_before_opening);
           int fstatat_flags = use_lstat ? AT_SYMLINK_NOFOLLOW : 0;
-          if (follow_fstatat (dst_dirfd, dst_relname, &dst_sb, fstatat_flags)
-              == 0)
+          if (!use_lstat && nonexistent_dst < 0)
+            new_dst = true;
+          else if (follow_fstatat (dst_dirfd, dst_relname, &dst_sb,
+                                   fstatat_flags)
+                   == 0)
             {
               have_dst_lstat = use_lstat;
               rename_errno = EEXIST;
@@ -3139,17 +3151,20 @@ valid_options (const struct cp_options *co)
 }
 
 /* Copy the file SRC_NAME to the file DST_NAME aka DST_DIRFD+DST_RELNAME.
-   NONEXISTENT_DST means the file DST_NAME is known not to exist
-   (e.g., because its parent directory was just created).
-   OPTIONS is ... FIXME-describe
+   If NONEXISTENT_DST is positive, DST_NAME does not exist even as a
+   dangling symlink; if negative, it does not exist except possibly
+   as a dangling symlink; if zero, its existence status is unknown.
+   OPTIONS summarizes the command-line options.
    Set *COPY_INTO_SELF if SRC_NAME is a parent of (or the
    same as) DST_NAME; otherwise, set clear it.
+   If X->move_mode, set *RENAME_SUCCEEDED according to whether
+   the source was simply renamed to the destination.
    Return true if successful.  */
 
 extern bool
 copy (char const *src_name, char const *dst_name,
       int dst_dirfd, char const *dst_relname,
-      bool nonexistent_dst, const struct cp_options *options,
+      int nonexistent_dst, const struct cp_options *options,
       bool *copy_into_self, bool *rename_succeeded)
 {
   assert (valid_options (options));

diff --git a/src/copy.h b/src/copy.h
index ea5541471f7287daeeee091be7622344102c2ea9..1f1de86735c932d363e3a87781c4b681832fae37 100644 (file)
--- a/src/copy.h
+++ b/src/copy.h
@@ -289,7 +289,7 @@ int rpl_rename (char const *, char const *);
 
 bool copy (char const *src_name, char const *dst_name,
            int dst_dirfd, char const *dst_relname,
-           bool nonexistent_dst, const struct cp_options *options,
+           int nonexistent_dst, const struct cp_options *options,
            bool *copy_into_self, bool *rename_succeeded)
   _GL_ATTRIBUTE_NONNULL ((1, 2, 4, 6, 7));
 

diff --git a/src/cp.c b/src/cp.c
index 9d337802f9577e113ef5abb916e34fb6c812370f..db15f0d3bde52dec2f76341459ffe75fade89890 100644 (file)
--- a/src/cp.c
+++ b/src/cp.c
@@ -836,7 +836,7 @@ do_copy (int n_files, char **file, char const *target_directory,
           x = &x_tmp;
         }
 
-      ok = copy (source, dest, AT_FDCWD, dest, false, x, &unused, NULL);
+      ok = copy (source, dest, AT_FDCWD, dest, -new_dst, x, &unused, NULL);
     }
 
   return ok;

diff --git a/src/install.c b/src/install.c
index c0d0c3223db9667d15fd48d9576fa0e6c13652fe..b157f59d28282004cae8ceee86b34b4269467826 100644 (file)
--- a/src/install.c
+++ b/src/install.c
@@ -448,7 +448,7 @@ copy_file (char const *from, char const *to, const struct cp_options *x)
      However, since !x->recursive, the call to "copy" will fail if FROM
      is a directory.  */
 
-  return copy (from, to, AT_FDCWD, to, false, x, &copy_into_self, NULL);
+  return copy (from, to, AT_FDCWD, to, 0, x, &copy_into_self, NULL);
 }
 
 /* Set the attributes of file or directory NAME.

diff --git a/src/mv.c b/src/mv.c
index 27f223f8a36a46eb7e575b32ea837c8e38250063..b5eb169f380b8bc94d849d84dcb042ee0177bac0 100644 (file)
--- a/src/mv.c
+++ b/src/mv.c
@@ -170,7 +170,7 @@ do_move (char const *source, char const *dest, const struct cp_options *x)
 {
   bool copy_into_self;
   bool rename_succeeded;
-  bool ok = copy (source, dest, AT_FDCWD, dest, false, x,
+  bool ok = copy (source, dest, AT_FDCWD, dest, 0, x,
                   &copy_into_self, &rename_succeeded);
 
   if (ok)