gdb/gdb_bfd.c - gdb

Global variables defined

Data types defined

Functions defined

Macros defined

Source code

  1. /* Definitions for BFD wrappers used by GDB.

  3.    Copyright (C) 2011-2015 Free Software Foundation, Inc.

  5.    This file is part of GDB.

  7.    This program is free software; you can redistribute it and/or modify
  8.    it under the terms of the GNU General Public License as published by
  9.    the Free Software Foundation; either version 3 of the License, or
  10.    (at your option) any later version.

  12.    This program is distributed in the hope that it will be useful,
  13.    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15.    GNU General Public License for more details.

  17.    You should have received a copy of the GNU General Public License
  18.    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

  20. #include "defs.h"
  21. #include "gdb_bfd.h"
  22. #include "ui-out.h"
  23. #include "gdbcmd.h"
  24. #include "hashtab.h"
  25. #include "filestuff.h"
  26. #include "vec.h"
  27. #ifdef HAVE_ZLIB_H
  28. #include <zlib.h>
  29. #endif
  30. #ifdef HAVE_MMAP
  31. #include <sys/mman.h>
  32. #ifndef MAP_FAILED
  33. ‌#define MAP_FAILED ((void *) -1)
  34. #endif
  35. #endif

  37. ‌typedef bfd *bfdp;
  38. ‌DEF_VEC_P (bfdp);

  40. /* An object of this type is stored in the section's user data when
  41.    mapping a section.  */

  43. ‌struct gdb_bfd_section_data
  44. {
  45.   /* Size of the data.  */
  46.   bfd_size_type size;
  47.   /* If the data was mmapped, this is the length of the map.  */
  48.   bfd_size_type map_len;
  49.   /* The data.  If NULL, the section data has not been read.  */
  50.   void *data;
  51.   /* If the data was mmapped, this is the map address.  */
  52.   void *map_addr;
  53. };

  55. /* A hash table holding every BFD that gdb knows about.  This is not
  56.    to be confused with 'gdb_bfd_cache', which is used for sharing
  57.    BFDs; in contrast, this hash is used just to implement
  58.    "maint info bfd".  */

  60. ‌static htab_t all_bfds;

  62. /* An object of this type is stored in each BFD's user data.  */

  64. ‌struct gdb_bfd_data
  65. {
  66.   /* The reference count.  */
  67.   int refc;

  69.   /* The mtime of the BFD at the point the cache entry was made.  */
  70.   time_t mtime;

  72.   /* This is true if we have determined whether this BFD has any
  73.      sections requiring relocation.  */
  74.   unsigned int relocation_computed : 1;

  76.   /* This is true if any section needs relocation.  */
  77.   unsigned int needs_relocations : 1;

  79.   /* This is true if we have successfully computed the file's CRC.  */
  80.   unsigned int crc_computed : 1;

  82.   /* The file's CRC.  */
  83.   unsigned long crc;

  85.   /* If the BFD comes from an archive, this points to the archive's
  86.      BFD.  Otherwise, this is NULL.  */
  87.   bfd *archive_bfd;

  89.   /* Table of all the bfds this bfd has included.  */
  90.   VEC (bfdp) *included_bfds;

  92.   /* The registry.  */
  93.   REGISTRY_FIELDS;
  94. };

  96. ‌#define GDB_BFD_DATA_ACCESSOR(ABFD) \
  97.   ((struct gdb_bfd_data *) bfd_usrdata (ABFD))

  99. DEFINE_REGISTRY (bfd, GDB_BFD_DATA_ACCESSOR)

  101. /* A hash table storing all the BFDs maintained in the cache.  */

  103. ‌static htab_t gdb_bfd_cache;

  105. /* The type of an object being looked up in gdb_bfd_cache.  We use
  106.    htab's capability of storing one kind of object (BFD in this case)
  107.    and using a different sort of object for searching.  */

  109. ‌struct gdb_bfd_cache_search
  110. {
  111.   /* The filename.  */
  112.   const char *filename;
  113.   /* The mtime.  */
  114.   time_t mtime;
  115. };

  117. /* A hash function for BFDs.  */

  119. static hashval_t
  120. ‌hash_bfd (const void *b)
  121. {
  122.   const bfd *abfd = b;

  124.   /* It is simplest to just hash the filename.  */
  125.   return htab_hash_string (bfd_get_filename (abfd));
  126. }

  128. /* An equality function for BFDs.  Note that this expects the caller
  129.    to search using struct gdb_bfd_cache_search only, not BFDs.  */

  131. static int
  132. ‌eq_bfd (const void *a, const void *b)
  133. {
  134.   const bfd *abfd = a;
  135.   const struct gdb_bfd_cache_search *s = b;
  136.   struct gdb_bfd_data *gdata = bfd_usrdata (abfd);

  138.   return (gdata->mtime == s->mtime
  139.           && strcmp (bfd_get_filename (abfd), s->filename) == 0);
  140. }

  142. /* See gdb_bfd.h.  */

  144. struct bfd *
  145. ‌gdb_bfd_open (const char *name, const char *target, int fd)
  146. {
  147.   hashval_t hash;
  148.   void **slot;
  149.   bfd *abfd;
  150.   struct gdb_bfd_cache_search search;
  151.   struct stat st;

  153.   if (gdb_bfd_cache == NULL)
  154.     gdb_bfd_cache = htab_create_alloc (1, hash_bfd, eq_bfd, NULL,
  155.                                        xcalloc, xfree);

  157.   if (fd == -1)
  158.     {
  159.       fd = gdb_open_cloexec (name, O_RDONLY | O_BINARY, 0);
  160.       if (fd == -1)
  161.         {
  162.           bfd_set_error (bfd_error_system_call);
  163.           return NULL;
  164.         }
  165.     }

  167.   search.filename = name;
  168.   if (fstat (fd, &st) < 0)
  169.     {
  170.       /* Weird situation here.  */
  171.       search.mtime = 0;
  172.     }
  173.   else
  174.     search.mtime = st.st_mtime;

  176.   /* Note that this must compute the same result as hash_bfd.  */
  177.   hash = htab_hash_string (name);
  178.   /* Note that we cannot use htab_find_slot_with_hash here, because
  179.      opening the BFD may fail; and this would violate hashtab
  180.      invariants.  */
  181.   abfd = htab_find_with_hash (gdb_bfd_cache, &search, hash);
  182.   if (abfd != NULL)
  183.     {
  184.       close (fd);
  185.       gdb_bfd_ref (abfd);
  186.       return abfd;
  187.     }

  189.   abfd = bfd_fopen (name, target, FOPEN_RB, fd);
  190.   if (abfd == NULL)
  191.     return NULL;

  193.   slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash, INSERT);
  194.   gdb_assert (!*slot);
  195.   *slot = abfd;

  197.   gdb_bfd_ref (abfd);
  198.   return abfd;
  199. }

  201. /* A helper function that releases any section data attached to the
  202.    BFD.  */

  204. static void
  205. ‌free_one_bfd_section (bfd *abfd, asection *sectp, void *ignore)
  206. {
  207.   struct gdb_bfd_section_data *sect = bfd_get_section_userdata (abfd, sectp);

  209.   if (sect != NULL && sect->data != NULL)
  210.     {
  211. #ifdef HAVE_MMAP
  212.       if (sect->map_addr != NULL)
  213.         {
  214.           int res;

  216.           res = munmap (sect->map_addr, sect->map_len);
  217.           gdb_assert (res == 0);
  218.         }
  219.       else
  220. #endif
  221.         xfree (sect->data);
  222.     }
  223. }

  225. /* Close ABFD, and warn if that fails.  */

  227. static int
  228. ‌gdb_bfd_close_or_warn (struct bfd *abfd)
  229. {
  230.   int ret;
  231.   char *name = bfd_get_filename (abfd);

  233.   bfd_map_over_sections (abfd, free_one_bfd_section, NULL);

  235.   ret = bfd_close (abfd);

  237.   if (!ret)
  238.     warning (_("cannot close \"%s\": %s"),
  239.              name, bfd_errmsg (bfd_get_error ()));

  241.   return ret;
  242. }

  244. /* See gdb_bfd.h.  */

  246. void
  247. ‌gdb_bfd_ref (struct bfd *abfd)
  248. {
  249.   struct gdb_bfd_data *gdata;
  250.   void **slot;

  252.   if (abfd == NULL)
  253.     return;

  255.   gdata = bfd_usrdata (abfd);

  257.   if (gdata != NULL)
  258.     {
  259.       gdata->refc += 1;
  260.       return;
  261.     }

  263.   /* Ask BFD to decompress sections in bfd_get_full_section_contents.  */
  264.   abfd->flags |= BFD_DECOMPRESS;

  266.   gdata = bfd_zalloc (abfd, sizeof (struct gdb_bfd_data));
  267.   gdata->refc = 1;
  268.   gdata->mtime = bfd_get_mtime (abfd);
  269.   gdata->archive_bfd = NULL;
  270.   bfd_usrdata (abfd) = gdata;

  272.   bfd_alloc_data (abfd);

  274.   /* This is the first we've seen it, so add it to the hash table.  */
  275.   slot = htab_find_slot (all_bfds, abfd, INSERT);
  276.   gdb_assert (slot && !*slot);
  277.   *slot = abfd;
  278. }

  280. /* See gdb_bfd.h.  */

  282. void
  283. ‌gdb_bfd_unref (struct bfd *abfd)
  284. {
  285.   int ix;
  286.   struct gdb_bfd_data *gdata;
  287.   struct gdb_bfd_cache_search search;
  288.   bfd *archive_bfd, *included_bfd;

  290.   if (abfd == NULL)
  291.     return;

  293.   gdata = bfd_usrdata (abfd);
  294.   gdb_assert (gdata->refc >= 1);

  296.   gdata->refc -= 1;
  297.   if (gdata->refc > 0)
  298.     return;

  300.   archive_bfd = gdata->archive_bfd;
  301.   search.filename = bfd_get_filename (abfd);

  303.   if (gdb_bfd_cache && search.filename)
  304.     {
  305.       hashval_t hash = htab_hash_string (search.filename);
  306.       void **slot;

  308.       search.mtime = gdata->mtime;
  309.       slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash,
  310.                                        NO_INSERT);

  312.       if (slot && *slot)
  313.         htab_clear_slot (gdb_bfd_cache, slot);
  314.     }

  316.   for (ix = 0;
  317.        VEC_iterate (bfdp, gdata->included_bfds, ix, included_bfd);
  318.        ++ix)
  319.     gdb_bfd_unref (included_bfd);
  320.   VEC_free (bfdp, gdata->included_bfds);

  322.   bfd_free_data (abfd);
  323.   bfd_usrdata (abfd) = NULL;  /* Paranoia.  */

  325.   htab_remove_elt (all_bfds, abfd);

  327.   gdb_bfd_close_or_warn (abfd);

  329.   gdb_bfd_unref (archive_bfd);
  330. }

  332. /* A helper function that returns the section data descriptor
  333.    associated with SECTION.  If no such descriptor exists, a new one
  334.    is allocated and cleared.  */

  336. static struct gdb_bfd_section_data *
  337. ‌get_section_descriptor (asection *section)
  338. {
  339.   struct gdb_bfd_section_data *result;

  341.   result = bfd_get_section_userdata (section->owner, section);

  343.   if (result == NULL)
  344.     {
  345.       result = bfd_zalloc (section->owner, sizeof (*result));
  346.       bfd_set_section_userdata (section->owner, section, result);
  347.     }

  349.   return result;
  350. }

  352. /* See gdb_bfd.h.  */

  354. const gdb_byte *
  355. ‌gdb_bfd_map_section (asection *sectp, bfd_size_type *size)
  356. {
  357.   bfd *abfd;
  358.   struct gdb_bfd_section_data *descriptor;
  359.   bfd_byte *data;

  361.   gdb_assert ((sectp->flags & SEC_RELOC) == 0);
  362.   gdb_assert (size != NULL);

  364.   abfd = sectp->owner;

  366.   descriptor = get_section_descriptor (sectp);

  368.   /* If the data was already read for this BFD, just reuse it.  */
  369.   if (descriptor->data != NULL)
  370.     goto done;

  372. #ifdef HAVE_MMAP
  373.   if (!bfd_is_section_compressed (abfd, sectp))
  374.     {
  375.       /* The page size, used when mmapping.  */
  376.       static int pagesize;

  378.       if (pagesize == 0)
  379.         pagesize = getpagesize ();

  381.       /* Only try to mmap sections which are large enough: we don't want
  382.          to waste space due to fragmentation.  */

  384.       if (bfd_get_section_size (sectp) > 4 * pagesize)
  385.         {
  386.           descriptor->size = bfd_get_section_size (sectp);
  387.           descriptor->data = bfd_mmap (abfd, 0, descriptor->size, PROT_READ,
  388.                                        MAP_PRIVATE, sectp->filepos,
  389.                                        &descriptor->map_addr,
  390.                                        &descriptor->map_len);

  392.           if ((caddr_t)descriptor->data != MAP_FAILED)
  393.             {
  394. #if HAVE_POSIX_MADVISE
  395.               posix_madvise (descriptor->map_addr, descriptor->map_len,
  396.                              POSIX_MADV_WILLNEED);
  397. #endif
  398.               goto done;
  399.             }

  401.           /* On failure, clear out the section data and try again.  */
  402.           memset (descriptor, 0, sizeof (*descriptor));
  403.         }
  404.     }
  405. #endif /* HAVE_MMAP */

  407.   /* Handle compressed sections, or ordinary uncompressed sections in
  408.      the no-mmap case.  */

  410.   descriptor->size = bfd_get_section_size (sectp);
  411.   descriptor->data = NULL;

  413.   data = NULL;
  414.   if (!bfd_get_full_section_contents (abfd, sectp, &data))
  415.     error (_("Can't read data for section '%s' in file '%s'"),
  416.            bfd_get_section_name (abfd, sectp),
  417.            bfd_get_filename (abfd));
  418.   descriptor->data = data;

  420. done:
  421.   gdb_assert (descriptor->data != NULL);
  422.   *size = descriptor->size;
  423.   return descriptor->data;
  424. }

  426. /* Return 32-bit CRC for ABFD.  If successful store it to *FILE_CRC_RETURN and
  427.    return 1.  Otherwise print a warning and return 0.  ABFD seek position is
  428.    not preserved.  */

  430. static int
  431. ‌get_file_crc (bfd *abfd, unsigned long *file_crc_return)
  432. {
  433.   unsigned long file_crc = 0;

  435.   if (bfd_seek (abfd, 0, SEEK_SET) != 0)
  436.     {
  437.       warning (_("Problem reading \"%s\" for CRC: %s"),
  438.                bfd_get_filename (abfd), bfd_errmsg (bfd_get_error ()));
  439.       return 0;
  440.     }

  442.   for (;;)
  443.     {
  444.       gdb_byte buffer[8 * 1024];
  445.       bfd_size_type count;

  447.       count = bfd_bread (buffer, sizeof (buffer), abfd);
  448.       if (count == (bfd_size_type) -1)
  449.         {
  450.           warning (_("Problem reading \"%s\" for CRC: %s"),
  451.                    bfd_get_filename (abfd), bfd_errmsg (bfd_get_error ()));
  452.           return 0;
  453.         }
  454.       if (count == 0)
  455.         break;
  456.       file_crc = bfd_calc_gnu_debuglink_crc32 (file_crc, buffer, count);
  457.     }

  459.   *file_crc_return = file_crc;
  460.   return 1;
  461. }

  463. /* See gdb_bfd.h.  */

  465. int
  466. ‌gdb_bfd_crc (struct bfd *abfd, unsigned long *crc_out)
  467. {
  468.   struct gdb_bfd_data *gdata = bfd_usrdata (abfd);

  470.   if (!gdata->crc_computed)
  471.     gdata->crc_computed = get_file_crc (abfd, &gdata->crc);

  473.   if (gdata->crc_computed)
  474.     *crc_out = gdata->crc;
  475.   return gdata->crc_computed;
  476. }



  480. /* See gdb_bfd.h.  */

  482. bfd *
  483. ‌gdb_bfd_fopen (const char *filename, const char *target, const char *mode,
  484.                int fd)
  485. {
  486.   bfd *result = bfd_fopen (filename, target, mode, fd);

  488.   if (result)
  489.     gdb_bfd_ref (result);

  491.   return result;
  492. }

  494. /* See gdb_bfd.h.  */

  496. bfd *
  497. ‌gdb_bfd_openr (const char *filename, const char *target)
  498. {
  499.   bfd *result = bfd_openr (filename, target);

  501.   if (result)
  502.     gdb_bfd_ref (result);

  504.   return result;
  505. }

  507. /* See gdb_bfd.h.  */

  509. bfd *
  510. ‌gdb_bfd_openw (const char *filename, const char *target)
  511. {
  512.   bfd *result = bfd_openw (filename, target);

  514.   if (result)
  515.     gdb_bfd_ref (result);

  517.   return result;
  518. }

  520. /* See gdb_bfd.h.  */

  522. bfd *
  523. ‌gdb_bfd_openr_iovec (const char *filename, const char *target,
  524.                      void *(*open_func) (struct bfd *nbfd,
  525.                                          void *open_closure),
  526.                      void *open_closure,
  527.                      file_ptr (*pread_func) (struct bfd *nbfd,
  528.                                              void *stream,
  529.                                              void *buf,
  530.                                              file_ptr nbytes,
  531.                                              file_ptr offset),
  532.                      int (*close_func) (struct bfd *nbfd,
  533.                                         void *stream),
  534.                      int (*stat_func) (struct bfd *abfd,
  535.                                        void *stream,
  536.                                        struct stat *sb))
  537. {
  538.   bfd *result = bfd_openr_iovec (filename, target,
  539.                                  open_func, open_closure,
  540.                                  pread_func, close_func, stat_func);

  542.   if (result)
  543.     gdb_bfd_ref (result);

  545.   return result;
  546. }

  548. /* See gdb_bfd.h.  */

  550. void
  551. ‌gdb_bfd_mark_parent (bfd *child, bfd *parent)
  552. {
  553.   struct gdb_bfd_data *gdata;

  555.   gdb_bfd_ref (child);
  556.   /* No need to stash the filename here, because we also keep a
  557.      reference on the parent archive.  */

  559.   gdata = bfd_usrdata (child);
  560.   if (gdata->archive_bfd == NULL)
  561.     {
  562.       gdata->archive_bfd = parent;
  563.       gdb_bfd_ref (parent);
  564.     }
  565.   else
  566.     gdb_assert (gdata->archive_bfd == parent);
  567. }

  569. /* See gdb_bfd.h.  */

  571. bfd *
  572. ‌gdb_bfd_openr_next_archived_file (bfd *archive, bfd *previous)
  573. {
  574.   bfd *result = bfd_openr_next_archived_file (archive, previous);

  576.   if (result)
  577.     gdb_bfd_mark_parent (result, archive);

  579.   return result;
  580. }

  582. /* See gdb_bfd.h.  */

  584. void
  585. ‌gdb_bfd_record_inclusion (bfd *includer, bfd *includee)
  586. {
  587.   struct gdb_bfd_data *gdata;

  589.   gdb_bfd_ref (includee);
  590.   gdata = bfd_usrdata (includer);
  591.   VEC_safe_push (bfdp, gdata->included_bfds, includee);
  592. }

  594. /* See gdb_bfd.h.  */

  596. bfd *
  597. ‌gdb_bfd_fdopenr (const char *filename, const char *target, int fd)
  598. {
  599.   bfd *result = bfd_fdopenr (filename, target, fd);

  601.   if (result)
  602.     gdb_bfd_ref (result);

  604.   return result;
  605. }



  609. gdb_static_assert (ARRAY_SIZE (_bfd_std_section) == 4);

  611. /* See gdb_bfd.h.  */

  613. int
  614. ‌gdb_bfd_section_index (bfd *abfd, asection *section)
  615. {
  616.   if (section == NULL)
  617.     return -1;
  618.   else if (section == bfd_com_section_ptr)
  619.     return bfd_count_sections (abfd) + 1;
  620.   else if (section == bfd_und_section_ptr)
  621.     return bfd_count_sections (abfd) + 2;
  622.   else if (section == bfd_abs_section_ptr)
  623.     return bfd_count_sections (abfd) + 3;
  624.   else if (section == bfd_ind_section_ptr)
  625.     return bfd_count_sections (abfd) + 4;
  626.   return section->index;
  627. }

  629. /* See gdb_bfd.h.  */

  631. int
  632. ‌gdb_bfd_count_sections (bfd *abfd)
  633. {
  634.   return bfd_count_sections (abfd) + 4;
  635. }

  637. /* See gdb_bfd.h.  */

  639. int
  640. ‌gdb_bfd_requires_relocations (bfd *abfd)
  641. {
  642.   struct gdb_bfd_data *gdata = bfd_usrdata (abfd);

  644.   if (gdata->relocation_computed == 0)
  645.     {
  646.       asection *sect;

  648.       for (sect = abfd->sections; sect != NULL; sect = sect->next)
  649.         if ((sect->flags & SEC_RELOC) != 0)
  650.           {
  651.             gdata->needs_relocations = 1;
  652.             break;
  653.           }

  655.       gdata->relocation_computed = 1;
  656.     }

  658.   return gdata->needs_relocations;
  659. }



  663. /* A callback for htab_traverse that prints a single BFD.  */

  665. static int
  666. ‌print_one_bfd (void **slot, void *data)
  667. {
  668.   bfd *abfd = *slot;
  669.   struct gdb_bfd_data *gdata = bfd_usrdata (abfd);
  670.   struct ui_out *uiout = data;
  671.   struct cleanup *inner;

  673.   inner = make_cleanup_ui_out_tuple_begin_end (uiout, NULL);
  674.   ui_out_field_int (uiout, "refcount", gdata->refc);
  675.   ui_out_field_string (uiout, "addr", host_address_to_string (abfd));
  676.   ui_out_field_string (uiout, "filename", bfd_get_filename (abfd));
  677.   ui_out_text (uiout, "\n");
  678.   do_cleanups (inner);

  680.   return 1;
  681. }

  683. /* Implement the 'maint info bfd' command.  */

  685. static void
  686. ‌maintenance_info_bfds (char *arg, int from_tty)
  687. {
  688.   struct cleanup *cleanup;
  689.   struct ui_out *uiout = current_uiout;

  691.   cleanup = make_cleanup_ui_out_table_begin_end (uiout, 3, -1, "bfds");
  692.   ui_out_table_header (uiout, 10, ui_left, "refcount", "Refcount");
  693.   ui_out_table_header (uiout, 18, ui_left, "addr", "Address");
  694.   ui_out_table_header (uiout, 40, ui_left, "filename", "Filename");

  696.   ui_out_table_body (uiout);
  697.   htab_traverse (all_bfds, print_one_bfd, uiout);

  699.   do_cleanups (cleanup);
  700. }

  702. /* -Wmissing-prototypes */
  703. extern initialize_file_ftype _initialize_gdb_bfd;

  705. void
  706. ‌_initialize_gdb_bfd (void)
  707. {
  708.   all_bfds = htab_create_alloc (10, htab_hash_pointer, htab_eq_pointer,
  709.                                 NULL, xcalloc, xfree);

  711.   add_cmd ("bfds", class_maintenance, maintenance_info_bfds, _("\
  712. List the BFDs that are currently open."),
  713.            &maintenanceinfolist);
  714. }