binutils-gdb/gdb/minidebug.c

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/* Read MiniDebugInfo data from an objfile.
Copyright (C) 2012-2013 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_string.h"
#include "symfile.h"
#include "objfiles.h"
#include "gdbcore.h"
#ifdef HAVE_LIBLZMA
#include <lzma.h>
/* Allocator function for LZMA. */
static void *
alloc_lzma (void *opaque, size_t nmemb, size_t size)
{
return xmalloc (nmemb * size);
}
/* Free function for LZMA. */
static void
free_lzma (void *opaque, void *ptr)
{
xfree (ptr);
}
/* The allocator object for LZMA. Note that 'gdb_lzma_allocator'
cannot be const due to the lzma library function prototypes. */
static lzma_allocator gdb_lzma_allocator = { alloc_lzma, free_lzma, NULL };
/* Custom bfd_openr_iovec implementation to read compressed data from
a section. This keeps only the last decompressed block in memory
to allow larger data without using to much memory. */
struct lzma_stream
{
/* Section of input BFD from which we are decoding data. */
asection *section;
/* lzma library decompression state. */
lzma_index *index;
/* Currently decoded block. */
bfd_size_type data_start;
bfd_size_type data_end;
gdb_byte *data;
};
/* bfd_openr_iovec OPEN_P implementation for
find_separate_debug_file_in_section. OPEN_CLOSURE is 'asection *'
of the section to decompress.
Return 'struct lzma_stream *' must be freed by caller by xfree, together
with its INDEX lzma data. */
static void *
lzma_open (struct bfd *nbfd, void *open_closure)
{
asection *section = open_closure;
bfd_size_type size, offset;
lzma_stream_flags options;
gdb_byte footer[LZMA_STREAM_HEADER_SIZE];
gdb_byte *indexdata;
lzma_index *index;
int ret;
uint64_t memlimit = UINT64_MAX;
struct lzma_stream *lstream;
size_t pos;
size = bfd_get_section_size (section);
offset = section->filepos + size - LZMA_STREAM_HEADER_SIZE;
if (size < LZMA_STREAM_HEADER_SIZE
|| bfd_seek (section->owner, offset, SEEK_SET) != 0
|| bfd_bread (footer, LZMA_STREAM_HEADER_SIZE, section->owner)
!= LZMA_STREAM_HEADER_SIZE
|| lzma_stream_footer_decode (&options, footer) != LZMA_OK
|| offset < options.backward_size)
{
bfd_set_error (bfd_error_wrong_format);
return NULL;
}
offset -= options.backward_size;
indexdata = xmalloc (options.backward_size);
index = NULL;
pos = 0;
if (bfd_seek (section->owner, offset, SEEK_SET) != 0
|| bfd_bread (indexdata, options.backward_size, section->owner)
!= options.backward_size
|| lzma_index_buffer_decode (&index, &memlimit, &gdb_lzma_allocator,
indexdata, &pos, options.backward_size)
!= LZMA_OK
|| lzma_index_size (index) != options.backward_size)
{
xfree (indexdata);
bfd_set_error (bfd_error_wrong_format);
return NULL;
}
xfree (indexdata);
lstream = xzalloc (sizeof (struct lzma_stream));
lstream->section = section;
lstream->index = index;
return lstream;
}
/* bfd_openr_iovec PREAD_P implementation for
find_separate_debug_file_in_section. Passed STREAM
is 'struct lzma_stream *'. */
static file_ptr
lzma_pread (struct bfd *nbfd, void *stream, void *buf, file_ptr nbytes,
file_ptr offset)
{
struct lzma_stream *lstream = stream;
bfd_size_type chunk_size;
lzma_index_iter iter;
gdb_byte *compressed, *uncompressed;
file_ptr block_offset;
lzma_filter filters[LZMA_FILTERS_MAX + 1];
lzma_block block;
size_t compressed_pos, uncompressed_pos;
file_ptr res;
res = 0;
while (nbytes > 0)
{
if (lstream->data == NULL
|| lstream->data_start > offset || offset >= lstream->data_end)
{
asection *section = lstream->section;
lzma_index_iter_init (&iter, lstream->index);
if (lzma_index_iter_locate (&iter, offset))
break;
compressed = xmalloc (iter.block.total_size);
block_offset = section->filepos + iter.block.compressed_file_offset;
if (bfd_seek (section->owner, block_offset, SEEK_SET) != 0
|| bfd_bread (compressed, iter.block.total_size, section->owner)
!= iter.block.total_size)
{
xfree (compressed);
break;
}
uncompressed = xmalloc (iter.block.uncompressed_size);
memset (&block, 0, sizeof (block));
block.filters = filters;
block.header_size = lzma_block_header_size_decode (compressed[0]);
if (lzma_block_header_decode (&block, &gdb_lzma_allocator, compressed)
!= LZMA_OK)
{
xfree (compressed);
xfree (uncompressed);
break;
}
compressed_pos = block.header_size;
uncompressed_pos = 0;
if (lzma_block_buffer_decode (&block, &gdb_lzma_allocator,
compressed, &compressed_pos,
iter.block.total_size,
uncompressed, &uncompressed_pos,
iter.block.uncompressed_size)
!= LZMA_OK)
{
xfree (compressed);
xfree (uncompressed);
break;
}
xfree (compressed);
xfree (lstream->data);
lstream->data = uncompressed;
lstream->data_start = iter.block.uncompressed_file_offset;
lstream->data_end = (iter.block.uncompressed_file_offset
+ iter.block.uncompressed_size);
}
chunk_size = min (nbytes, lstream->data_end - offset);
memcpy (buf, lstream->data + offset - lstream->data_start, chunk_size);
buf = (gdb_byte *) buf + chunk_size;
offset += chunk_size;
nbytes -= chunk_size;
res += chunk_size;
}
return res;
}
/* bfd_openr_iovec CLOSE_P implementation for
find_separate_debug_file_in_section. Passed STREAM
is 'struct lzma_stream *'. */
static int
lzma_close (struct bfd *nbfd,
void *stream)
{
struct lzma_stream *lstream = stream;
lzma_index_end (lstream->index, &gdb_lzma_allocator);
xfree (lstream->data);
xfree (lstream);
return 0;
}
/* bfd_openr_iovec STAT_P implementation for
find_separate_debug_file_in_section. Passed STREAM
is 'struct lzma_stream *'. */
static int
lzma_stat (struct bfd *abfd,
void *stream,
struct stat *sb)
{
struct lzma_stream *lstream = stream;
sb->st_size = lzma_index_uncompressed_size (lstream->index);
return 0;
}
#endif /* HAVE_LIBLZMA */
/* This looks for a xz compressed separate debug info object file embedded
in a section called .gnu_debugdata. See
http://fedoraproject.org/wiki/Features/MiniDebugInfo
or the "Separate Debug Sections" of the manual for details.
If we find one we create a iovec based bfd that decompresses the
object data on demand. If we don't find one, return NULL. */
bfd *
find_separate_debug_file_in_section (struct objfile *objfile)
{
asection *section;
bfd *abfd;
if (objfile->obfd == NULL)
return NULL;
section = bfd_get_section_by_name (objfile->obfd, ".gnu_debugdata");
if (section == NULL)
return NULL;
#ifdef HAVE_LIBLZMA
abfd = gdb_bfd_openr_iovec (objfile->name, gnutarget, lzma_open, section,
lzma_pread, lzma_close, lzma_stat);
if (abfd == NULL)
return NULL;
if (!bfd_check_format (abfd, bfd_object))
{
warning (_("Cannot parse .gnu_debugdata section; not a BFD object"));
gdb_bfd_unref (abfd);
return NULL;
}
#else
warning (_("Cannot parse .gnu_debugdata section; LZMA support was "
"disabled at compile time"));
abfd = NULL;
#endif /* !HAVE_LIBLZMA */
return abfd;
}