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 #include "swap.h"
  30 #include "ctf-endian.h"
  31
  32 #include "elf-bfd.h"
  33
  34 /* Make a new struct ctf_archive_internal wrapper for a ctf_archive or a
  35    ctf_file.  Closes ARC and/or FP on error.  Arrange to free the SYMSECT and
  36    STRSECT interior on close.  */
  37
  38 static struct ctf_archive_internal *
  39 ctf_new_archive_internal (int is_archive, struct ctf_archive *arc,
  40                           ctf_file_t *fp, const ctf_sect_t *symsect,
  41                           const ctf_sect_t *strsect,
  42                           int *errp)
  43 {
  44   struct ctf_archive_internal *arci;
  45
  46   if ((arci = calloc (1, sizeof (struct ctf_archive_internal))) == NULL)
  47     {
  48       if (is_archive)
  49         ctf_arc_close_internal (arc);
  50       else
  51         ctf_file_close (fp);
  52       return (ctf_set_open_errno (errp, errno));
  53     }
  54   arci->ctfi_is_archive = is_archive;
  55   if (is_archive)
  56     arci->ctfi_archive = arc;
  57   else
  58     arci->ctfi_file = fp;
  59   if (symsect)
  60      memcpy (&arci->ctfi_symsect, symsect, sizeof (struct ctf_sect));
  61   if (strsect)
  62      memcpy (&arci->ctfi_strsect, strsect, sizeof (struct ctf_sect));
  63
  64   return arci;
  65 }
  66
  67 /* Free the BFD bits of a CTF file on ctf_file_close().  */
  68
  69 static void
  70 ctf_bfdclose (struct ctf_archive_internal *arci)
  71 {
  72   if (arci->ctfi_abfd != NULL)
  73     if (!bfd_close_all_done (arci->ctfi_abfd))
  74       ctf_dprintf ("Cannot close BFD: %s\n", bfd_errmsg (bfd_get_error()));
  75 }
  76
  77 /* Open a CTF file given the specified BFD.  */
  78
  79 ctf_archive_t *
  80 ctf_bfdopen (struct bfd *abfd, int *errp)
  81 {
  82   ctf_archive_t *arc;
  83   asection *ctf_asect;
  84   bfd_byte *contents;
  85   ctf_sect_t ctfsect;
  86
  87   libctf_init_debug();
  88
  89   if ((ctf_asect = bfd_get_section_by_name (abfd, _CTF_SECTION)) == NULL)
  90     {
  91       return (ctf_set_open_errno (errp, ECTF_NOCTFDATA));
  92     }
  93
  94   if (!bfd_malloc_and_get_section (abfd, ctf_asect, &contents))
  95     {
  96       ctf_dprintf ("ctf_bfdopen(): cannot malloc CTF section: %s\n",
  97                    bfd_errmsg (bfd_get_error()));
  98       return (ctf_set_open_errno (errp, ECTF_FMT));
  99     }
 100
 101   ctfsect.cts_name = _CTF_SECTION;
 102   ctfsect.cts_entsize = 1;
 103   ctfsect.cts_size = bfd_section_size (ctf_asect);
 104   ctfsect.cts_data = contents;
 105
 106   if ((arc = ctf_bfdopen_ctfsect (abfd, &ctfsect, errp)) != NULL)
 107     {
 108       arc->ctfi_data = (void *) ctfsect.cts_data;
 109       return arc;
 110     }
 111
 112   free (contents);
 113   return NULL;                          /* errno is set for us.  */
 114 }
 115
 116 /* Open a CTF file given the specified BFD and CTF section (which may contain a
 117    CTF archive or a file).  Takes ownership of the ctfsect, and frees it
 118    later.  */
 119
 120 ctf_archive_t *
 121 ctf_bfdopen_ctfsect (struct bfd *abfd _libctf_unused_,
 122                      const ctf_sect_t *ctfsect, int *errp)
 123 {
 124   struct ctf_archive *arc = NULL;
 125   ctf_archive_t *arci;
 126   ctf_file_t *fp = NULL;
 127   ctf_sect_t *symsectp = NULL;
 128   ctf_sect_t *strsectp = NULL;
 129   const char *bfderrstr = NULL;
 130   int is_archive;
 131
 132 #ifdef HAVE_BFD_ELF
 133   asection *sym_asect;
 134   ctf_sect_t symsect, strsect;
 135   /* TODO: handle SYMTAB_SHNDX.  */
 136
 137   if ((sym_asect = bfd_section_from_elf_index (abfd,
 138                                                elf_onesymtab (abfd))) != NULL)
 139     {
 140       Elf_Internal_Shdr *symhdr = &elf_symtab_hdr (abfd);
 141       asection *str_asect = NULL;
 142       bfd_byte *contents;
 143
 144       if (symhdr->sh_link != SHN_UNDEF &&
 145           symhdr->sh_link <= elf_numsections (abfd))
 146         str_asect = bfd_section_from_elf_index (abfd, symhdr->sh_link);
 147
 148       Elf_Internal_Shdr *strhdr = elf_elfsections (abfd)[symhdr->sh_link];
 149
 150       if (sym_asect && str_asect)
 151         {
 152           if (!bfd_malloc_and_get_section (abfd, str_asect, &contents))
 153             {
 154               bfderrstr = "Cannot malloc string table";
 155               free (contents);
 156               goto err;
 157             }
 158           strsect.cts_data = contents;
 159           strsect.cts_name = (char *) strsect.cts_data + strhdr->sh_name;
 160           strsect.cts_size = bfd_section_size (str_asect);
 161           strsect.cts_entsize = strhdr->sh_size;
 162           strsectp = &strsect;
 163
 164           if (!bfd_malloc_and_get_section (abfd, sym_asect, &contents))
 165             {
 166               bfderrstr = "Cannot malloc symbol table";
 167               free (contents);
 168               goto err_free_str;
 169             }
 170
 171           symsect.cts_name = (char *) strsect.cts_data + symhdr->sh_name;
 172           symsect.cts_entsize = symhdr->sh_size;
 173           symsect.cts_size = bfd_section_size (sym_asect);
 174           symsect.cts_data = contents;
 175           symsectp = &symsect;
 176         }
 177     }
 178 #endif
 179
 180   if (ctfsect->cts_size > sizeof (uint64_t) &&
 181       ((*(uint64_t *) ctfsect->cts_data) == CTFA_MAGIC))
 182     {
 183       is_archive = 1;
 184       if ((arc = ctf_arc_bufopen ((void *) ctfsect->cts_data,
 185                                   ctfsect->cts_size, errp)) == NULL)
 186         goto err_free_sym;
 187     }
 188   else
 189     {
 190       is_archive = 0;
 191       if ((fp = ctf_bufopen (ctfsect, symsectp, strsectp, errp)) == NULL)
 192         {
 193           ctf_dprintf ("ctf_internal_open(): cannot open CTF: %s\n",
 194                        ctf_errmsg (*errp));
 195           goto err_free_sym;
 196         }
 197     }
 198   arci = ctf_new_archive_internal (is_archive, arc, fp, symsectp, strsectp,
 199                                    errp);
 200
 201   if (arci)
 202     return arci;
 203  err_free_sym:
 204 #ifdef HAVE_BFD_ELF
 205   free ((void *) symsect.cts_data);
 206 err_free_str:
 207   free ((void *) strsect.cts_data);
 208 #endif
 209 err: _libctf_unused_;
 210   if (bfderrstr)
 211     {
 212       ctf_dprintf ("ctf_bfdopen(): %s: %s\n", bfderrstr,
 213                    bfd_errmsg (bfd_get_error()));
 214       ctf_set_open_errno (errp, ECTF_FMT);
 215     }
 216   return NULL;
 217 }
 218
 219 /* Open the specified file descriptor and return a pointer to a CTF archive that
 220    contains one or more CTF containers.  The file can be an ELF file, a raw CTF
 221    file, or a CTF archive.  The caller is responsible for closing the file
 222    descriptor when it is no longer needed.  If this is an ELF file, TARGET, if
 223    non-NULL, should be the name of a suitable BFD target.  */
 224
 225 ctf_archive_t *
 226 ctf_fdopen (int fd, const char *filename, const char *target, int *errp)
 227 {
 228   ctf_archive_t *arci;
 229   bfd *abfd;
 230   int nfd;
 231
 232   struct stat st;
 233   ssize_t nbytes;
 234
 235   ctf_preamble_t ctfhdr;
 236   uint64_t arc_magic;
 237
 238   memset (&ctfhdr, 0, sizeof (ctfhdr));
 239
 240   libctf_init_debug();
 241
 242   if (fstat (fd, &st) == -1)
 243     return (ctf_set_open_errno (errp, errno));
 244
 245   if ((nbytes = ctf_pread (fd, &ctfhdr, sizeof (ctfhdr), 0)) <= 0)
 246     return (ctf_set_open_errno (errp, nbytes < 0 ? errno : ECTF_FMT));
 247
 248   /* If we have read enough bytes to form a CTF header and the magic string
 249      matches, in either endianness, attempt to interpret the file as raw
 250      CTF.  */
 251
 252   if ((size_t) nbytes >= sizeof (ctf_preamble_t)
 253       && (ctfhdr.ctp_magic == CTF_MAGIC
 254           || ctfhdr.ctp_magic == bswap_16 (CTF_MAGIC)))
 255     {
 256       ctf_file_t *fp = NULL;
 257       void *data;
 258
 259       if ((data = ctf_mmap (st.st_size, 0, fd)) == NULL)
 260         return (ctf_set_open_errno (errp, errno));
 261
 262       if ((fp = ctf_simple_open (data, (size_t) st.st_size, NULL, 0, 0,
 263                                  NULL, 0, errp)) == NULL)
 264         {
 265           ctf_munmap (data, (size_t) st.st_size);
 266           return NULL;                  /* errno is set for us.  */
 267         }
 268
 269       fp->ctf_data_mmapped = data;
 270       fp->ctf_data_mmapped_len = (size_t) st.st_size;
 271
 272       return ctf_new_archive_internal (0, NULL, fp, NULL, NULL, errp);
 273     }
 274
 275   if ((nbytes = ctf_pread (fd, &arc_magic, sizeof (arc_magic), 0)) <= 0)
 276     return (ctf_set_open_errno (errp, nbytes < 0 ? errno : ECTF_FMT));
 277
 278   if ((size_t) nbytes >= sizeof (uint64_t) && le64toh (arc_magic) == CTFA_MAGIC)
 279     {
 280       struct ctf_archive *arc;
 281
 282       if ((arc = ctf_arc_open_internal (filename, errp)) == NULL)
 283         return NULL;                    /* errno is set for us.  */
 284
 285       return ctf_new_archive_internal (1, arc, NULL, NULL, NULL, errp);
 286     }
 287
 288   /* Attempt to open the file with BFD.  We must dup the fd first, since bfd
 289      takes ownership of the passed fd.  */
 290
 291   if ((nfd = dup (fd)) < 0)
 292       return (ctf_set_open_errno (errp, errno));
 293
 294   if ((abfd = bfd_fdopenr (filename, target, nfd)) == NULL)
 295     {
 296       ctf_dprintf ("Cannot open BFD from %s: %s\n",
 297                    filename ? filename : "(unknown file)",
 298                    bfd_errmsg (bfd_get_error()));
 299       return (ctf_set_open_errno (errp, ECTF_FMT));
 300     }
 301
 302   if (!bfd_check_format (abfd, bfd_object))
 303     {
 304       ctf_dprintf ("BFD format problem in %s: %s\n",
 305                    filename ? filename : "(unknown file)",
 306                    bfd_errmsg (bfd_get_error()));
 307       if (bfd_get_error() == bfd_error_file_ambiguously_recognized)
 308         return (ctf_set_open_errno (errp, ECTF_BFD_AMBIGUOUS));
 309       else
 310         return (ctf_set_open_errno (errp, ECTF_FMT));
 311     }
 312
 313   if ((arci = ctf_bfdopen (abfd, errp)) == NULL)
 314     {
 315       if (!bfd_close_all_done (abfd))
 316         ctf_dprintf ("Cannot close BFD: %s\n", bfd_errmsg (bfd_get_error()));
 317       return NULL;                      /* errno is set for us.  */
 318     }
 319   arci->ctfi_bfd_close = ctf_bfdclose;
 320   arci->ctfi_abfd = abfd;
 321
 322   return arci;
 323 }
 324
 325 /* Open the specified file and return a pointer to a CTF container.  The file
 326    can be either an ELF file or raw CTF file.  This is just a convenient
 327    wrapper around ctf_fdopen() for callers.  */
 328
 329 ctf_archive_t *
 330 ctf_open (const char *filename, const char *target, int *errp)
 331 {
 332   ctf_archive_t *arc;
 333   int fd;
 334
 335   if ((fd = open (filename, O_RDONLY)) == -1)
 336     {
 337       if (errp != NULL)
 338         *errp = errno;
 339       return NULL;
 340     }
 341
 342   arc = ctf_fdopen (fd, filename, target, errp);
 343   (void) close (fd);
 344   return arc;
 345 }
 346
 347 /* Public entry point: open a CTF archive, or CTF file.  Returns the archive, or
 348    NULL and an error in *err.  Despite the fact that this uses CTF archives, it
 349    must be in this file to avoid dragging in BFD into non-BFD-using programs.  */
 350 ctf_archive_t *
 351 ctf_arc_open (const char *filename, int *errp)
 352 {
 353   return ctf_open (filename, NULL, errp);
 354 }