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- /* Read MiniDebugInfo data from an objfile.
- Copyright (C) 2012-2022 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 "symfile.h"
- #include "objfiles.h"
- #include "gdbcore.h"
- #include <algorithm>
- #ifdef HAVE_LIBLZMA
- /* We stash a reference to the .gnu_debugdata BFD on the enclosing
- BFD. */
- static const bfd_key<gdb_bfd_ref_ptr> gnu_debug_key;
- #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 gdb_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 gdb_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 = (asection *) open_closure;
- bfd_size_type size, offset;
- lzma_stream_flags options;
- gdb_byte footer[LZMA_STREAM_HEADER_SIZE];
- gdb_byte *indexdata;
- lzma_index *index;
- uint64_t memlimit = UINT64_MAX;
- struct gdb_lzma_stream *lstream;
- size_t pos;
- size = bfd_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 = (gdb_byte *) 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 = XCNEW (struct gdb_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 gdb_lzma_stream *'. */
- static file_ptr
- lzma_pread (struct bfd *nbfd, void *stream, void *buf, file_ptr nbytes,
- file_ptr offset)
- {
- struct gdb_lzma_stream *lstream = (struct gdb_lzma_stream *) 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 = (gdb_byte *) 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 = (gdb_byte *) 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 = std::min (nbytes, (file_ptr) 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 gdb_lzma_stream *'. */
- static int
- lzma_close (struct bfd *nbfd,
- void *stream)
- {
- struct gdb_lzma_stream *lstream = (struct gdb_lzma_stream *) stream;
- lzma_index_end (lstream->index, &gdb_lzma_allocator);
- xfree (lstream->data);
- xfree (lstream);
- /* Zero means success. */
- return 0;
- }
- /* bfd_openr_iovec STAT_P implementation for
- find_separate_debug_file_in_section. Passed STREAM
- is 'struct gdb_lzma_stream *'. */
- static int
- lzma_stat (struct bfd *abfd,
- void *stream,
- struct stat *sb)
- {
- struct gdb_lzma_stream *lstream = (struct gdb_lzma_stream *) stream;
- memset (sb, 0, sizeof (struct stat));
- 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. */
- gdb_bfd_ref_ptr
- find_separate_debug_file_in_section (struct objfile *objfile)
- {
- asection *section;
- gdb_bfd_ref_ptr 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
- gdb_bfd_ref_ptr *shared = gnu_debug_key.get (objfile->obfd);
- if (shared != nullptr)
- return *shared;
- std::string filename = string_printf (_(".gnu_debugdata for %s"),
- objfile_name (objfile));
- abfd = gdb_bfd_openr_iovec (filename.c_str (), gnutarget, lzma_open,
- section, lzma_pread, lzma_close, lzma_stat);
- if (abfd == NULL)
- return NULL;
- if (!bfd_check_format (abfd.get (), bfd_object))
- {
- warning (_("Cannot parse .gnu_debugdata section; not a BFD object"));
- return NULL;
- }
- gnu_debug_key.emplace (objfile->obfd, abfd);
- #else
- warning (_("Cannot parse .gnu_debugdata section; LZMA support was "
- "disabled at compile time"));
- #endif /* !HAVE_LIBLZMA */
- return abfd;
- }
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