484 lines
13 KiB
C
484 lines
13 KiB
C
/* Definitions for BFD wrappers used by GDB.
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Copyright (C) 2011, 2012
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Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "defs.h"
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#include "gdb_bfd.h"
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#include "gdb_assert.h"
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#include "gdb_string.h"
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#include "hashtab.h"
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#ifdef HAVE_ZLIB_H
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#include <zlib.h>
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#endif
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#ifdef HAVE_MMAP
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#include <sys/mman.h>
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#ifndef MAP_FAILED
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#define MAP_FAILED ((void *) -1)
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#endif
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#endif
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/* An object of this type is stored in the section's user data when
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mapping a section. */
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struct gdb_bfd_section_data
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{
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/* Size of the data. */
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bfd_size_type size;
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/* If the data was mmapped, this is the length of the map. */
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bfd_size_type map_len;
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/* The data. If NULL, the section data has not been read. */
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void *data;
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/* If the data was mmapped, this is the map address. */
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void *map_addr;
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};
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/* See gdb_bfd.h. */
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void
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gdb_bfd_stash_filename (struct bfd *abfd)
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{
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char *name = bfd_get_filename (abfd);
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char *data;
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data = bfd_alloc (abfd, strlen (name) + 1);
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strcpy (data, name);
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/* Unwarranted chumminess with BFD. */
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abfd->filename = data;
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}
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/* An object of this type is stored in each BFD's user data. */
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struct gdb_bfd_data
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{
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/* The reference count. */
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int refc;
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/* The mtime of the BFD at the point the cache entry was made. */
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time_t mtime;
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};
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/* A hash table storing all the BFDs maintained in the cache. */
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static htab_t gdb_bfd_cache;
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/* The type of an object being looked up in gdb_bfd_cache. We use
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htab's capability of storing one kind of object (BFD in this case)
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and using a different sort of object for searching. */
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struct gdb_bfd_cache_search
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{
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/* The filename. */
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const char *filename;
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/* The mtime. */
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time_t mtime;
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};
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/* A hash function for BFDs. */
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static hashval_t
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hash_bfd (const void *b)
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{
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const bfd *abfd = b;
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/* It is simplest to just hash the filename. */
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return htab_hash_string (bfd_get_filename (abfd));
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}
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/* An equality function for BFDs. Note that this expects the caller
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to search using struct gdb_bfd_cache_search only, not BFDs. */
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static int
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eq_bfd (const void *a, const void *b)
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{
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const bfd *abfd = a;
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const struct gdb_bfd_cache_search *s = b;
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struct gdb_bfd_data *gdata = bfd_usrdata (abfd);
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return (gdata->mtime == s->mtime
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&& strcmp (bfd_get_filename (abfd), s->filename) == 0);
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}
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/* See gdb_bfd.h. */
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struct bfd *
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gdb_bfd_open (const char *name, const char *target, int fd)
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{
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hashval_t hash;
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void **slot;
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bfd *abfd;
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struct gdb_bfd_cache_search search;
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struct stat st;
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if (gdb_bfd_cache == NULL)
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gdb_bfd_cache = htab_create_alloc (1, hash_bfd, eq_bfd, NULL,
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xcalloc, xfree);
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if (fd == -1)
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{
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fd = open (name, O_RDONLY | O_BINARY);
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if (fd == -1)
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{
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bfd_set_error (bfd_error_system_call);
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return NULL;
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}
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}
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search.filename = name;
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if (fstat (fd, &st) < 0)
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{
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/* Weird situation here. */
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search.mtime = 0;
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}
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else
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search.mtime = st.st_mtime;
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/* Note that this must compute the same result as hash_bfd. */
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hash = htab_hash_string (name);
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/* Note that we cannot use htab_find_slot_with_hash here, because
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opening the BFD may fail; and this would violate hashtab
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invariants. */
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abfd = htab_find_with_hash (gdb_bfd_cache, &search, hash);
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if (abfd != NULL)
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{
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close (fd);
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return gdb_bfd_ref (abfd);
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}
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abfd = bfd_fopen (name, target, FOPEN_RB, fd);
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if (abfd == NULL)
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return NULL;
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slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash, INSERT);
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gdb_assert (!*slot);
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*slot = abfd;
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gdb_bfd_stash_filename (abfd);
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return gdb_bfd_ref (abfd);
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}
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/* A helper function that releases any section data attached to the
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BFD. */
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static void
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free_one_bfd_section (bfd *abfd, asection *sectp, void *ignore)
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{
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struct gdb_bfd_section_data *sect = bfd_get_section_userdata (abfd, sectp);
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if (sect != NULL && sect->data != NULL)
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{
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#ifdef HAVE_MMAP
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if (sect->map_addr != NULL)
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{
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int res;
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res = munmap (sect->map_addr, sect->map_len);
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gdb_assert (res == 0);
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}
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else
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#endif
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xfree (sect->data);
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}
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}
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/* Close ABFD, and warn if that fails. */
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static int
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gdb_bfd_close_or_warn (struct bfd *abfd)
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{
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int ret;
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char *name = bfd_get_filename (abfd);
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bfd_map_over_sections (abfd, free_one_bfd_section, NULL);
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ret = bfd_close (abfd);
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if (!ret)
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warning (_("cannot close \"%s\": %s"),
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name, bfd_errmsg (bfd_get_error ()));
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return ret;
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}
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/* Add reference to ABFD. Returns ABFD. */
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struct bfd *
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gdb_bfd_ref (struct bfd *abfd)
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{
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struct gdb_bfd_data *gdata;
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if (abfd == NULL)
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return NULL;
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gdata = bfd_usrdata (abfd);
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if (gdata != NULL)
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{
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gdata->refc += 1;
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return abfd;
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}
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gdata = bfd_zalloc (abfd, sizeof (struct gdb_bfd_data));
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gdata->refc = 1;
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gdata->mtime = bfd_get_mtime (abfd);
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bfd_usrdata (abfd) = gdata;
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return abfd;
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}
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/* Unreference and possibly close ABFD. */
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void
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gdb_bfd_unref (struct bfd *abfd)
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{
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struct gdb_bfd_data *gdata;
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struct gdb_bfd_cache_search search;
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if (abfd == NULL)
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return;
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gdata = bfd_usrdata (abfd);
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gdb_assert (gdata->refc >= 1);
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gdata->refc -= 1;
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if (gdata->refc > 0)
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return;
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search.filename = bfd_get_filename (abfd);
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if (gdb_bfd_cache && search.filename)
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{
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hashval_t hash = htab_hash_string (search.filename);
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void **slot;
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search.mtime = gdata->mtime;
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slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash,
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NO_INSERT);
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if (slot && *slot)
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htab_clear_slot (gdb_bfd_cache, slot);
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}
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bfd_usrdata (abfd) = NULL; /* Paranoia. */
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gdb_bfd_close_or_warn (abfd);
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}
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/* A helper function that returns the section data descriptor
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associated with SECTION. If no such descriptor exists, a new one
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is allocated and cleared. */
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static struct gdb_bfd_section_data *
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get_section_descriptor (asection *section)
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{
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struct gdb_bfd_section_data *result;
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result = bfd_get_section_userdata (section->owner, section);
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if (result == NULL)
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{
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result = bfd_zalloc (section->owner, sizeof (*result));
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bfd_set_section_userdata (section->owner, section, result);
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}
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return result;
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}
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/* Decompress a section that was compressed using zlib. Store the
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decompressed buffer, and its size, in DESCRIPTOR. */
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static void
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zlib_decompress_section (asection *sectp,
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struct gdb_bfd_section_data *descriptor)
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{
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bfd *abfd = sectp->owner;
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#ifndef HAVE_ZLIB_H
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error (_("Support for zlib-compressed data (from '%s', section '%s') "
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"is disabled in this copy of GDB"),
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bfd_get_filename (abfd),
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bfd_get_section_name (sectp));
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#else
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bfd_size_type compressed_size = bfd_get_section_size (sectp);
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gdb_byte *compressed_buffer = xmalloc (compressed_size);
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struct cleanup *cleanup = make_cleanup (xfree, compressed_buffer);
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struct cleanup *inner_cleanup;
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bfd_size_type uncompressed_size;
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gdb_byte *uncompressed_buffer;
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z_stream strm;
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int rc;
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int header_size = 12;
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struct dwarf2_per_bfd_section *section_data;
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if (bfd_seek (abfd, sectp->filepos, SEEK_SET) != 0
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|| bfd_bread (compressed_buffer,
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compressed_size, abfd) != compressed_size)
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error (_("can't read data from '%s', section '%s'"),
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bfd_get_filename (abfd),
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bfd_get_section_name (abfd, sectp));
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/* Read the zlib header. In this case, it should be "ZLIB" followed
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by the uncompressed section size, 8 bytes in big-endian order. */
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if (compressed_size < header_size
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|| strncmp (compressed_buffer, "ZLIB", 4) != 0)
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error (_("corrupt ZLIB header from '%s', section '%s'"),
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bfd_get_filename (abfd),
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bfd_get_section_name (abfd, sectp));
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uncompressed_size = compressed_buffer[4]; uncompressed_size <<= 8;
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uncompressed_size += compressed_buffer[5]; uncompressed_size <<= 8;
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uncompressed_size += compressed_buffer[6]; uncompressed_size <<= 8;
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uncompressed_size += compressed_buffer[7]; uncompressed_size <<= 8;
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uncompressed_size += compressed_buffer[8]; uncompressed_size <<= 8;
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uncompressed_size += compressed_buffer[9]; uncompressed_size <<= 8;
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uncompressed_size += compressed_buffer[10]; uncompressed_size <<= 8;
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uncompressed_size += compressed_buffer[11];
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/* It is possible the section consists of several compressed
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buffers concatenated together, so we uncompress in a loop. */
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strm.zalloc = NULL;
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strm.zfree = NULL;
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strm.opaque = NULL;
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strm.avail_in = compressed_size - header_size;
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strm.next_in = (Bytef*) compressed_buffer + header_size;
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strm.avail_out = uncompressed_size;
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uncompressed_buffer = xmalloc (uncompressed_size);
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inner_cleanup = make_cleanup (xfree, uncompressed_buffer);
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rc = inflateInit (&strm);
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while (strm.avail_in > 0)
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{
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if (rc != Z_OK)
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error (_("setting up uncompression in '%s', section '%s': %d"),
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bfd_get_filename (abfd),
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bfd_get_section_name (abfd, sectp),
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rc);
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strm.next_out = ((Bytef*) uncompressed_buffer
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+ (uncompressed_size - strm.avail_out));
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rc = inflate (&strm, Z_FINISH);
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if (rc != Z_STREAM_END)
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error (_("zlib error uncompressing from '%s', section '%s': %d"),
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bfd_get_filename (abfd),
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bfd_get_section_name (abfd, sectp),
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rc);
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rc = inflateReset (&strm);
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}
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rc = inflateEnd (&strm);
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if (rc != Z_OK
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|| strm.avail_out != 0)
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error (_("concluding uncompression in '%s', section '%s': %d"),
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bfd_get_filename (abfd),
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bfd_get_section_name (abfd, sectp),
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rc);
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discard_cleanups (inner_cleanup);
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do_cleanups (cleanup);
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/* Attach the data to the BFD section. */
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descriptor->data = uncompressed_buffer;
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descriptor->size = uncompressed_size;
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#endif
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}
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/* See gdb_bfd.h. */
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const gdb_byte *
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gdb_bfd_map_section (asection *sectp, bfd_size_type *size)
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{
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bfd *abfd;
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gdb_byte *buf, *retbuf;
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unsigned char header[4];
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struct gdb_bfd_section_data *descriptor;
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gdb_assert ((sectp->flags & SEC_RELOC) == 0);
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gdb_assert (size != NULL);
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abfd = sectp->owner;
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descriptor = get_section_descriptor (sectp);
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/* If the data was already read for this BFD, just reuse it. */
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if (descriptor->data != NULL)
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goto done;
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/* Check if the file has a 4-byte header indicating compression. */
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if (bfd_get_section_size (sectp) > sizeof (header)
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&& bfd_seek (abfd, sectp->filepos, SEEK_SET) == 0
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&& bfd_bread (header, sizeof (header), abfd) == sizeof (header))
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{
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/* Upon decompression, update the buffer and its size. */
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if (strncmp (header, "ZLIB", sizeof (header)) == 0)
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{
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zlib_decompress_section (sectp, descriptor);
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goto done;
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}
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}
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#ifdef HAVE_MMAP
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{
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/* The page size, used when mmapping. */
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static int pagesize;
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if (pagesize == 0)
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pagesize = getpagesize ();
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/* Only try to mmap sections which are large enough: we don't want
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to waste space due to fragmentation. */
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if (bfd_get_section_size (sectp) > 4 * pagesize)
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{
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descriptor->size = bfd_get_section_size (sectp);
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descriptor->data = bfd_mmap (abfd, 0, descriptor->size, PROT_READ,
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MAP_PRIVATE, sectp->filepos,
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&descriptor->map_addr,
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&descriptor->map_len);
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if ((caddr_t)descriptor->data != MAP_FAILED)
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{
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#if HAVE_POSIX_MADVISE
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posix_madvise (descriptor->map_addr, descriptor->map_len,
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POSIX_MADV_WILLNEED);
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#endif
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goto done;
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}
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/* On failure, clear out the section data and try again. */
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memset (descriptor, 0, sizeof (*descriptor));
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}
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}
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#endif /* HAVE_MMAP */
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/* If we get here, we are a normal, not-compressed section. */
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descriptor->size = bfd_get_section_size (sectp);
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descriptor->data = xmalloc (descriptor->size);
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if (bfd_seek (abfd, sectp->filepos, SEEK_SET) != 0
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|| bfd_bread (descriptor->data, bfd_get_section_size (sectp),
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abfd) != bfd_get_section_size (sectp))
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{
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xfree (descriptor->data);
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descriptor->data = NULL;
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error (_("Can't read data for section '%s'"),
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bfd_get_filename (abfd));
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}
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done:
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gdb_assert (descriptor->data != NULL);
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*size = descriptor->size;
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return descriptor->data;
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}
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