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