GDB 7.6.50

gdb/minidebug.c

+/* 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 <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);
+
+  /* Zero means success.  */
+  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 (objfile), 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;
+}