libctf/ctf-open-bfd.c

   1 /* Opening CTF files with BFD.
   2    Copyright (C) 2019 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 <stddef.h>
  22 #include <sys/types.h>
  23 #include <sys/stat.h>
  24 #include <errno.h>
  25 #include <string.h>
  26 #include <fcntl.h>
  27 #include <elf.h>
  28 #include <bfd.h>
  29
  30 #include "elf-bfd.h"
  31
  32 /* Make a new struct ctf_archive_internal wrapper for a ctf_archive or a
  33    ctf_file.  Closes ARC and/or FP on error.  Arrange to free the SYMSECT and
  34    STRSECT interior on close.  */
  35
  36 static struct ctf_archive_internal *
  37 ctf_new_archive_internal (int is_archive, struct ctf_archive *arc,
  38                           ctf_file_t *fp, const ctf_sect_t *symsect,
  39                           const ctf_sect_t *strsect,
  40                           int *errp)
  41 {
  42   struct ctf_archive_internal *arci;
  43
  44   if ((arci = calloc (1, sizeof (struct ctf_archive_internal))) == NULL)
  45     {
  46       if (is_archive)
  47         ctf_arc_close_internal (arc);
  48       else
  49         ctf_file_close (fp);
  50       return (ctf_set_open_errno (errp, errno));
  51     }
  52   arci->ctfi_is_archive = is_archive;
  53   if (is_archive)
  54     arci->ctfi_archive = arc;
  55   else
  56     arci->ctfi_file = fp;
  57   if (symsect)
  58      memcpy (&arci->ctfi_symsect, symsect, sizeof (struct ctf_sect));
  59   if (strsect)
  60      memcpy (&arci->ctfi_strsect, strsect, sizeof (struct ctf_sect));
  61
  62   return arci;
  63 }
  64
  65 /* Free the BFD bits of a CTF file on ctf_file_close().  */
  66
  67 static void
  68 ctf_bfdclose (struct ctf_archive_internal *arci)
  69 {
  70   if (arci->ctfi_abfd != NULL)
  71     if (!bfd_close_all_done (arci->ctfi_abfd))
  72       ctf_dprintf ("Cannot close BFD: %s\n", bfd_errmsg (bfd_get_error()));
  73 }
  74
  75 /* Open a CTF file given the specified BFD.  */
  76
  77 ctf_archive_t *
  78 ctf_bfdopen (struct bfd *abfd, int *errp)
  79 {
  80   ctf_archive_t *arc;
  81   asection *ctf_asect;
  82   bfd_byte *contents;
  83   ctf_sect_t ctfsect;
  84
  85   libctf_init_debug();
  86
  87   if ((ctf_asect = bfd_get_section_by_name (abfd, _CTF_SECTION)) == NULL)
  88     {
  89       return (ctf_set_open_errno (errp, ECTF_NOCTFDATA));
  90     }
  91
  92   if (!bfd_malloc_and_get_section (abfd, ctf_asect, &contents))
  93     {
  94       ctf_dprintf ("ctf_bfdopen(): cannot malloc CTF section: %s\n",
  95                    bfd_errmsg (bfd_get_error()));
  96       return (ctf_set_open_errno (errp, ECTF_FMT));
  97     }
  98
  99   ctfsect.cts_name = _CTF_SECTION;
 100   ctfsect.cts_entsize = 1;
 101   ctfsect.cts_size = bfd_section_size (abfd, ctf_asect);
 102   ctfsect.cts_data = contents;
 103
 104   if ((arc = ctf_bfdopen_ctfsect (abfd, &ctfsect, errp)) != NULL)
 105     {
 106       arc->ctfi_data = (void *) ctfsect.cts_data;
 107       return arc;
 108     }
 109
 110   free (contents);
 111   return NULL;                          /* errno is set for us.  */
 112 }
 113
 114 /* Open a CTF file given the specified BFD and CTF section (which may contain a
 115    CTF archive or a file).  Takes ownership of the ctfsect, and frees it
 116    later.  */
 117
 118 ctf_archive_t *
 119 ctf_bfdopen_ctfsect (struct bfd *abfd _libctf_unused_,
 120                      const ctf_sect_t *ctfsect, int *errp)
 121 {
 122   struct ctf_archive *arc = NULL;
 123   ctf_archive_t *arci;
 124   ctf_file_t *fp = NULL;
 125   ctf_sect_t *symsectp = NULL;
 126   ctf_sect_t *strsectp = NULL;
 127   const char *bfderrstr = NULL;
 128   int is_archive;
 129
 130 #ifdef HAVE_BFD_ELF
 131   asection *sym_asect;
 132   ctf_sect_t symsect, strsect;
 133   /* TODO: handle SYMTAB_SHNDX.  */
 134
 135   if ((sym_asect = bfd_section_from_elf_index (abfd,
 136                                                elf_onesymtab (abfd))) != NULL)
 137     {
 138       Elf_Internal_Shdr *symhdr = &elf_symtab_hdr (abfd);
 139       asection *str_asect = NULL;
 140       bfd_byte *contents;
 141
 142       if (symhdr->sh_link != SHN_UNDEF &&
 143           symhdr->sh_link <= elf_numsections (abfd))
 144         str_asect = bfd_section_from_elf_index (abfd, symhdr->sh_link);
 145
 146       Elf_Internal_Shdr *strhdr = elf_elfsections (abfd)[symhdr->sh_link];
 147
 148       if (sym_asect && str_asect)
 149         {
 150           if (!bfd_malloc_and_get_section (abfd, str_asect, &contents))
 151             {
 152               bfderrstr = "Cannot malloc string table";
 153               free (contents);
 154               goto err;
 155             }
 156           strsect.cts_data = contents;
 157           strsect.cts_name = (char *) strsect.cts_data + strhdr->sh_name;
 158           strsect.cts_size = bfd_section_size (abfd, str_asect);
 159           strsect.cts_entsize = strhdr->sh_size;
 160           strsectp = &strsect;
 161
 162           if (!bfd_malloc_and_get_section (abfd, sym_asect, &contents))
 163             {
 164               bfderrstr = "Cannot malloc symbol table";
 165               free (contents);
 166               goto err_free_str;
 167             }
 168
 169           symsect.cts_name = (char *) strsect.cts_data + symhdr->sh_name;
 170           symsect.cts_entsize = symhdr->sh_size;
 171           symsect.cts_size = bfd_section_size (abfd, sym_asect);
 172           symsect.cts_data = contents;
 173           symsectp = &symsect;
 174         }
 175     }
 176 #endif
 177
 178   if (ctfsect->cts_size > sizeof (uint64_t) &&
 179       ((*(uint64_t *) ctfsect->cts_data) == CTFA_MAGIC))
 180     {
 181       is_archive = 1;
 182       if ((arc = ctf_arc_bufopen ((void *) ctfsect->cts_data,
 183                                   ctfsect->cts_size, errp)) == NULL)
 184         goto err_free_sym;
 185     }
 186   else
 187     {
 188       is_archive = 0;
 189       if ((fp = ctf_bufopen (ctfsect, symsectp, strsectp, errp)) == NULL)
 190         {
 191           ctf_dprintf ("ctf_internal_open(): cannot open CTF: %s\n",
 192                        ctf_errmsg (*errp));
 193           goto err_free_sym;
 194         }
 195     }
 196   arci = ctf_new_archive_internal (is_archive, arc, fp, symsectp, strsectp,
 197                                    errp);
 198
 199   if (arci)
 200     return arci;
 201  err_free_sym:
 202 #ifdef HAVE_BFD_ELF
 203   free ((void *) symsect.cts_data);
 204 err_free_str:
 205   free ((void *) strsect.cts_data);
 206 #endif
 207 err: _libctf_unused_;
 208   if (bfderrstr)
 209     {
 210       ctf_dprintf ("ctf_bfdopen(): %s: %s\n", bfderrstr,
 211                    bfd_errmsg (bfd_get_error()));
 212       ctf_set_open_errno (errp, ECTF_FMT);
 213     }
 214   return NULL;
 215 }
 216
 217 /* Open the specified file descriptor and return a pointer to a CTF archive that
 218    contains one or more CTF containers.  The file can be an ELF file, a raw CTF
 219    file, or a CTF archive.  The caller is responsible for closing the file
 220    descriptor when it is no longer needed.  If this is an ELF file, TARGET, if
 221    non-NULL, should be the name of a suitable BFD target.  */
 222
 223 ctf_archive_t *
 224 ctf_fdopen (int fd, const char *filename, const char *target, int *errp)
 225 {
 226   ctf_archive_t *arci;
 227   bfd *abfd;
 228   int nfd;
 229
 230   struct stat st;
 231   ssize_t nbytes;
 232
 233   ctf_preamble_t ctfhdr;
 234   uint64_t arc_magic;
 235
 236   memset (&ctfhdr, 0, sizeof (ctfhdr));
 237
 238   libctf_init_debug();
 239
 240   if (fstat (fd, &st) == -1)
 241     return (ctf_set_open_errno (errp, errno));
 242
 243   if ((nbytes = ctf_pread (fd, &ctfhdr, sizeof (ctfhdr), 0)) <= 0)
 244     return (ctf_set_open_errno (errp, nbytes < 0 ? errno : ECTF_FMT));
 245
 246   /* If we have read enough bytes to form a CTF header and the magic
 247      string matches, attempt to interpret the file as raw CTF.  */
 248
 249   if ((size_t) nbytes >= sizeof (ctf_preamble_t) &&
 250       ctfhdr.ctp_magic == CTF_MAGIC)
 251     {
 252       ctf_file_t *fp = NULL;
 253       void *data;
 254
 255       if (ctfhdr.ctp_version > CTF_VERSION)
 256         return (ctf_set_open_errno (errp, ECTF_CTFVERS));
 257
 258       if ((data = ctf_mmap (st.st_size, 0, fd)) == NULL)
 259         return (ctf_set_open_errno (errp, errno));
 260
 261       if ((fp = ctf_simple_open (data, (size_t) st.st_size, NULL, 0, 0,
 262                                  NULL, 0, errp)) == NULL)
 263         ctf_munmap (data, (size_t) st.st_size);
 264       fp->ctf_data_mmapped = data;
 265       fp->ctf_data_mmapped_len = (size_t) st.st_size;
 266
 267       return ctf_new_archive_internal (0, NULL, fp, NULL, NULL, errp);
 268     }
 269
 270   if ((nbytes = ctf_pread (fd, &arc_magic, sizeof (arc_magic), 0)) <= 0)
 271     return (ctf_set_open_errno (errp, nbytes < 0 ? errno : ECTF_FMT));
 272
 273   if ((size_t) nbytes >= sizeof (uint64_t) && arc_magic == CTFA_MAGIC)
 274     {
 275       struct ctf_archive *arc;
 276
 277       if ((arc = ctf_arc_open_internal (filename, errp)) == NULL)
 278         return NULL;                    /* errno is set for us.  */
 279
 280       return ctf_new_archive_internal (1, arc, NULL, NULL, NULL, errp);
 281     }
 282
 283   /* Attempt to open the file with BFD.  We must dup the fd first, since bfd
 284      takes ownership of the passed fd.  */
 285
 286   if ((nfd = dup (fd)) < 0)
 287       return (ctf_set_open_errno (errp, errno));
 288
 289   if ((abfd = bfd_fdopenr (filename, target, nfd)) == NULL)
 290     {
 291       ctf_dprintf ("Cannot open BFD from %s: %s\n",
 292                    filename ? filename : "(unknown file)",
 293                    bfd_errmsg (bfd_get_error()));
 294       return (ctf_set_open_errno (errp, ECTF_FMT));
 295     }
 296
 297   if (!bfd_check_format (abfd, bfd_object))
 298     {
 299       ctf_dprintf ("BFD format problem in %s: %s\n",
 300                    filename ? filename : "(unknown file)",
 301                    bfd_errmsg (bfd_get_error()));
 302       if (bfd_get_error() == bfd_error_file_ambiguously_recognized)
 303         return (ctf_set_open_errno (errp, ECTF_BFD_AMBIGUOUS));
 304       else
 305         return (ctf_set_open_errno (errp, ECTF_FMT));
 306     }
 307
 308   if ((arci = ctf_bfdopen (abfd, errp)) == NULL)
 309     {
 310       if (!bfd_close_all_done (abfd))
 311         ctf_dprintf ("Cannot close BFD: %s\n", bfd_errmsg (bfd_get_error()));
 312       return NULL;                      /* errno is set for us.  */
 313     }
 314   arci->ctfi_bfd_close = ctf_bfdclose;
 315   arci->ctfi_abfd = abfd;
 316
 317   return arci;
 318 }
 319
 320 /* Open the specified file and return a pointer to a CTF container.  The file
 321    can be either an ELF file or raw CTF file.  This is just a convenient
 322    wrapper around ctf_fdopen() for callers.  */
 323
 324 ctf_archive_t *
 325 ctf_open (const char *filename, const char *target, int *errp)
 326 {
 327   ctf_archive_t *arc;
 328   int fd;
 329
 330   if ((fd = open (filename, O_RDONLY)) == -1)
 331     {
 332       if (errp != NULL)
 333         *errp = errno;
 334       return NULL;
 335     }
 336
 337   arc = ctf_fdopen (fd, filename, target, errp);
 338   (void) close (fd);
 339   return arc;
 340 }
 341
 342 /* Public entry point: open a CTF archive, or CTF file.  Returns the archive, or
 343    NULL and an error in *err.  Despite the fact that this uses CTF archives, it
 344    must be in this file to avoid dragging in BFD into non-BFD-using programs.  */
 345 ctf_archive_t *
 346 ctf_arc_open (const char *filename, int *errp)
 347 {
 348   return ctf_open (filename, NULL, errp);
 349 }