libctf/ctf-util.c

   1 /* Miscellaneous utilities.
   2    Copyright (C) 2019-2021 Free Software Foundation, Inc.
   3
   4    This file is part of libctf.
   5
   6    libctf is free software; you can redistribute it and/or modify it under
   7    the terms of the GNU General Public License as published by the Free
   8    Software Foundation; either version 3, or (at your option) any later
   9    version.
  10
  11    This program is distributed in the hope that it will be useful, but
  12    WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  14    See the GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; see the file COPYING.  If not see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <ctf-impl.h>
  21 #include <string.h>
  22 #include "ctf-endian.h"
  23
  24 /* Simple doubly-linked list append routine.  This implementation assumes that
  25    each list element contains an embedded ctf_list_t as the first member.
  26    An additional ctf_list_t is used to store the head (l_next) and tail
  27    (l_prev) pointers.  The current head and tail list elements have their
  28    previous and next pointers set to NULL, respectively.  */
  29
  30 void
  31 ctf_list_append (ctf_list_t *lp, void *newp)
  32 {
  33   ctf_list_t *p = lp->l_prev;   /* p = tail list element.  */
  34   ctf_list_t *q = newp;         /* q = new list element.  */
  35
  36   lp->l_prev = q;
  37   q->l_prev = p;
  38   q->l_next = NULL;
  39
  40   if (p != NULL)
  41     p->l_next = q;
  42   else
  43     lp->l_next = q;
  44 }
  45
  46 /* Prepend the specified existing element to the given ctf_list_t.  The
  47    existing pointer should be pointing at a struct with embedded ctf_list_t.  */
  48
  49 void
  50 ctf_list_prepend (ctf_list_t * lp, void *newp)
  51 {
  52   ctf_list_t *p = newp;         /* p = new list element.  */
  53   ctf_list_t *q = lp->l_next;   /* q = head list element.  */
  54
  55   lp->l_next = p;
  56   p->l_prev = NULL;
  57   p->l_next = q;
  58
  59   if (q != NULL)
  60     q->l_prev = p;
  61   else
  62     lp->l_prev = p;
  63 }
  64
  65 /* Delete the specified existing element from the given ctf_list_t.  The
  66    existing pointer should be pointing at a struct with embedded ctf_list_t.  */
  67
  68 void
  69 ctf_list_delete (ctf_list_t *lp, void *existing)
  70 {
  71   ctf_list_t *p = existing;
  72
  73   if (p->l_prev != NULL)
  74     p->l_prev->l_next = p->l_next;
  75   else
  76     lp->l_next = p->l_next;
  77
  78   if (p->l_next != NULL)
  79     p->l_next->l_prev = p->l_prev;
  80   else
  81     lp->l_prev = p->l_prev;
  82 }
  83
  84 /* Return 1 if the list is empty.  */
  85
  86 int
  87 ctf_list_empty_p (ctf_list_t *lp)
  88 {
  89   return (lp->l_next == NULL && lp->l_prev == NULL);
  90 }
  91
  92 /* Splice one entire list onto the end of another one.  The existing list is
  93    emptied.  */
  94
  95 void
  96 ctf_list_splice (ctf_list_t *lp, ctf_list_t *append)
  97 {
  98   if (ctf_list_empty_p (append))
  99     return;
 100
 101   if (lp->l_prev != NULL)
 102     lp->l_prev->l_next = append->l_next;
 103   else
 104     lp->l_next = append->l_next;
 105
 106   append->l_next->l_prev = lp->l_prev;
 107   lp->l_prev = append->l_prev;
 108   append->l_next = NULL;
 109   append->l_prev = NULL;
 110 }
 111
 112 /* Convert a 32-bit ELF symbol to a ctf_link_sym_t.  */
 113
 114 ctf_link_sym_t *
 115 ctf_elf32_to_link_sym (ctf_dict_t *fp, ctf_link_sym_t *dst, const Elf32_Sym *src,
 116                        uint32_t symidx)
 117 {
 118   Elf32_Sym tmp;
 119   int needs_flipping = 0;
 120
 121 #ifdef WORDS_BIGENDIAN
 122   if (fp->ctf_symsect_little_endian)
 123     needs_flipping = 1;
 124 #else
 125   if (!fp->ctf_symsect_little_endian)
 126     needs_flipping = 1;
 127 #endif
 128
 129   memcpy (&tmp, src, sizeof (Elf32_Sym));
 130   if (needs_flipping)
 131     {
 132       swap_thing (tmp.st_name);
 133       swap_thing (tmp.st_size);
 134       swap_thing (tmp.st_shndx);
 135       swap_thing (tmp.st_value);
 136     }
 137   /* The name must be in the external string table.  */
 138   if (tmp.st_name < fp->ctf_str[CTF_STRTAB_1].cts_len)
 139     dst->st_name = (const char *) fp->ctf_str[CTF_STRTAB_1].cts_strs + tmp.st_name;
 140   else
 141     dst->st_name = _CTF_NULLSTR;
 142   dst->st_nameidx_set = 0;
 143   dst->st_symidx = symidx;
 144   dst->st_shndx = tmp.st_shndx;
 145   dst->st_type = ELF32_ST_TYPE (tmp.st_info);
 146   dst->st_value = tmp.st_value;
 147
 148   return dst;
 149 }
 150
 151 /* Convert a 64-bit ELF symbol to a ctf_link_sym_t.  */
 152
 153 ctf_link_sym_t *
 154 ctf_elf64_to_link_sym (ctf_dict_t *fp, ctf_link_sym_t *dst, const Elf64_Sym *src,
 155                        uint32_t symidx)
 156 {
 157   Elf64_Sym tmp;
 158   int needs_flipping = 0;
 159
 160 #ifdef WORDS_BIGENDIAN
 161   if (fp->ctf_symsect_little_endian)
 162     needs_flipping = 1;
 163 #else
 164   if (!fp->ctf_symsect_little_endian)
 165     needs_flipping = 1;
 166 #endif
 167
 168   memcpy (&tmp, src, sizeof (Elf64_Sym));
 169   if (needs_flipping)
 170     {
 171       swap_thing (tmp.st_name);
 172       swap_thing (tmp.st_size);
 173       swap_thing (tmp.st_shndx);
 174       swap_thing (tmp.st_value);
 175     }
 176
 177   /* The name must be in the external string table.  */
 178   if (tmp.st_name < fp->ctf_str[CTF_STRTAB_1].cts_len)
 179     dst->st_name = (const char *) fp->ctf_str[CTF_STRTAB_1].cts_strs + tmp.st_name;
 180   else
 181     dst->st_name = _CTF_NULLSTR;
 182   dst->st_nameidx_set = 0;
 183   dst->st_symidx = symidx;
 184   dst->st_shndx = tmp.st_shndx;
 185   dst->st_type = ELF32_ST_TYPE (tmp.st_info);
 186
 187   /* We only care if the value is zero, so avoid nonzeroes turning into
 188      zeroes.  */
 189   if (_libctf_unlikely_ (tmp.st_value != 0 && ((uint32_t) tmp.st_value == 0)))
 190     dst->st_value = 1;
 191   else
 192     dst->st_value = (uint32_t) tmp.st_value;
 193
 194   return dst;
 195 }
 196
 197 /* A string appender working on dynamic strings.  Returns NULL on OOM.  */
 198
 199 char *
 200 ctf_str_append (char *s, const char *append)
 201 {
 202   size_t s_len = 0;
 203
 204   if (append == NULL)
 205     return s;
 206
 207   if (s != NULL)
 208     s_len = strlen (s);
 209
 210   size_t append_len = strlen (append);
 211
 212   if ((s = realloc (s, s_len + append_len + 1)) == NULL)
 213     return NULL;
 214
 215   memcpy (s + s_len, append, append_len);
 216   s[s_len + append_len] = '\0';
 217
 218   return s;
 219 }
 220
 221 /* A version of ctf_str_append that returns the old string on OOM.  */
 222
 223 char *
 224 ctf_str_append_noerr (char *s, const char *append)
 225 {
 226   char *new_s;
 227
 228   new_s = ctf_str_append (s, append);
 229   if (!new_s)
 230     return s;
 231   return new_s;
 232 }
 233
 234 /* A realloc() that fails noisily if called with any ctf_str_num_users.  */
 235 void *
 236 ctf_realloc (ctf_dict_t *fp, void *ptr, size_t size)
 237 {
 238   if (fp->ctf_str_num_refs > 0)
 239     {
 240       ctf_dprintf ("%p: attempt to realloc() string table with %lu active refs\n",
 241                    (void *) fp, (unsigned long) fp->ctf_str_num_refs);
 242       return NULL;
 243     }
 244   return realloc (ptr, size);
 245 }
 246
 247 /* Store the specified error code into errp if it is non-NULL, and then
 248    return NULL for the benefit of the caller.  */
 249
 250 void *
 251 ctf_set_open_errno (int *errp, int error)
 252 {
 253   if (errp != NULL)
 254     *errp = error;
 255   return NULL;
 256 }
 257
 258 /* Store the specified error code into the CTF dict, and then return CTF_ERR /
 259    -1 for the benefit of the caller. */
 260
 261 unsigned long
 262 ctf_set_errno (ctf_dict_t *fp, int err)
 263 {
 264   fp->ctf_errno = err;
 265   return CTF_ERR;
 266 }
 267
 268 /* Create a ctf_next_t.  */
 269
 270 ctf_next_t *
 271 ctf_next_create (void)
 272 {
 273   return calloc (1, sizeof (struct ctf_next));
 274 }
 275
 276 /* Destroy a ctf_next_t, for early exit from iterators.  */
 277
 278 void
 279 ctf_next_destroy (ctf_next_t *i)
 280 {
 281   if (i == NULL)
 282     return;
 283
 284   if (i->ctn_iter_fun == (void (*) (void)) ctf_dynhash_next_sorted)
 285     free (i->u.ctn_sorted_hkv);
 286   if (i->ctn_iter_fun == (void (*) (void)) ctf_symbol_next
 287       && i->cu.ctn_fp->ctf_flags & LCTF_RDWR)
 288     ctf_next_destroy (i->u.ctn_next);
 289   free (i);
 290 }
 291
 292 /* Copy a ctf_next_t.  */
 293
 294 ctf_next_t *
 295 ctf_next_copy (ctf_next_t *i)
 296 {
 297   ctf_next_t *i2;
 298
 299   if ((i2 = ctf_next_create()) == NULL)
 300     return NULL;
 301   memcpy (i2, i, sizeof (struct ctf_next));
 302
 303   if (i2->ctn_iter_fun == (void (*) (void)) ctf_dynhash_next_sorted)
 304     {
 305       size_t els = ctf_dynhash_elements ((ctf_dynhash_t *) i->cu.ctn_h);
 306       if ((i2->u.ctn_sorted_hkv = calloc (els, sizeof (ctf_next_hkv_t))) == NULL)
 307         {
 308           free (i2);
 309           return NULL;
 310         }
 311       memcpy (i2->u.ctn_sorted_hkv, i->u.ctn_sorted_hkv,
 312               els * sizeof (ctf_next_hkv_t));
 313     }
 314   return i2;
 315 }