forked from Imagelibrary/binutils-gdb
fix PR symtab/15597
This patch fixes gdb PR symtab/15597. The bug is that the .gnu_debugaltlink section includes the build-id of the alt file, but gdb does not use it. This patch fixes the problem by changing gdb to do what it ought to always have done: verify the build id of the file found using the filename in .gnu_debugaltlink; and if that does not match, try to find the correct debug file using the build-id and debug-file-directory. This patch touches BFD. Previously, gdb had its own code for parsing .gnu_debugaltlink; I changed it to use the BFD functions after those were introduced. However, the BFD functions are incorrect -- they assume that .gnu_debugaltlink is formatted like .gnu_debuglink. However, it it is not. Instead, it consists of a file name followed by the build-id -- no alignment, and the build-id is not a CRC. Fixing this properly is a bit of a pain. But, because separate_alt_debug_file_exists just has a FIXME for the build-id case, I did not fix it properly. Instead I introduced a hack. This leaves BFD working just as well as it did before my patch. I'm willing to do something better here but I could use some guidance as to what. It seems that the build-id code in BFD is largely punted on. FWIW gdb is the only user of bfd_get_alt_debug_link_info outside of BFD itself. I moved the build-id logic out of elfread.c and into a new file. This seemed cleanest to me. Writing a test case was a bit of a pain. I added a couple new features to the DWARF assembler to handle this. Built and regtested on x86-64 Fedora 18. * bfd-in2.h: Rebuild. * opncls.c (bfd_get_alt_debug_link_info): Add buildid_len parameter. Change type of buildid_out. Update. (get_alt_debug_link_info_shim): New function. (bfd_follow_gnu_debuglink): Use it. * Makefile.in (SFILES): Add build-id.c. (HFILES_NO_SRCDIR): Add build-id.h. * build-id.c: New file, largely from elfread.c. Modified most functions. * build-id.h: New file. * dwarf2read.c (dwarf2_get_dwz_file): Update for change to bfd_get_alt_debug_link_info. Verify dwz file's build-id. Search for dwz file using build-id. * elfread.c (build_id_bfd_get, build_id_verify) (build_id_to_debug_filename, find_separate_debug_file): Remove. * gdb.dwarf2/dwzbuildid.exp: New file. * lib/dwarf.exp (Dwarf::_section): Add "flags" and "type" parameters. (Dwarf::_defer_output): Change "section" parameter to "section_spec"; update. (Dwarf::gnu_debugaltlink, Dwarf::_note, Dwarf::build_id): New procs.
This commit is contained in:
Tom Tromey
126
gdb/elfread.c
126
gdb/elfread.c
@@ -45,6 +45,7 @@
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#include "regcache.h"
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#include "bcache.h"
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#include "gdb_bfd.h"
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#include "build-id.h"
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extern void _initialize_elfread (void);
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@@ -1087,131 +1088,6 @@ elf_gnu_ifunc_resolver_return_stop (struct breakpoint *b)
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update_breakpoint_locations (b, sals, sals_end);
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}
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/* Locate NT_GNU_BUILD_ID from ABFD and return its content. */
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static const struct elf_build_id *
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build_id_bfd_get (bfd *abfd)
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{
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if (!bfd_check_format (abfd, bfd_object)
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|| bfd_get_flavour (abfd) != bfd_target_elf_flavour
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|| elf_tdata (abfd)->build_id == NULL)
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return NULL;
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return elf_tdata (abfd)->build_id;
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}
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/* Return if FILENAME has NT_GNU_BUILD_ID matching the CHECK value. */
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static int
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build_id_verify (const char *filename, const struct elf_build_id *check)
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{
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bfd *abfd;
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const struct elf_build_id *found;
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int retval = 0;
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/* We expect to be silent on the non-existing files. */
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abfd = gdb_bfd_open_maybe_remote (filename);
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if (abfd == NULL)
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return 0;
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found = build_id_bfd_get (abfd);
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if (found == NULL)
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warning (_("File \"%s\" has no build-id, file skipped"), filename);
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else if (found->size != check->size
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|| memcmp (found->data, check->data, found->size) != 0)
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warning (_("File \"%s\" has a different build-id, file skipped"),
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filename);
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else
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retval = 1;
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gdb_bfd_unref (abfd);
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return retval;
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}
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static char *
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build_id_to_debug_filename (const struct elf_build_id *build_id)
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{
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char *link, *debugdir, *retval = NULL;
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VEC (char_ptr) *debugdir_vec;
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struct cleanup *back_to;
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int ix;
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/* DEBUG_FILE_DIRECTORY/.build-id/ab/cdef */
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link = alloca (strlen (debug_file_directory) + (sizeof "/.build-id/" - 1) + 1
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+ 2 * build_id->size + (sizeof ".debug" - 1) + 1);
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/* Keep backward compatibility so that DEBUG_FILE_DIRECTORY being "" will
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cause "/.build-id/..." lookups. */
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debugdir_vec = dirnames_to_char_ptr_vec (debug_file_directory);
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back_to = make_cleanup_free_char_ptr_vec (debugdir_vec);
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for (ix = 0; VEC_iterate (char_ptr, debugdir_vec, ix, debugdir); ++ix)
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{
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size_t debugdir_len = strlen (debugdir);
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const gdb_byte *data = build_id->data;
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size_t size = build_id->size;
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char *s;
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memcpy (link, debugdir, debugdir_len);
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s = &link[debugdir_len];
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s += sprintf (s, "/.build-id/");
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if (size > 0)
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{
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size--;
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s += sprintf (s, "%02x", (unsigned) *data++);
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}
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if (size > 0)
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*s++ = '/';
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while (size-- > 0)
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s += sprintf (s, "%02x", (unsigned) *data++);
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strcpy (s, ".debug");
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/* lrealpath() is expensive even for the usually non-existent files. */
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if (access (link, F_OK) == 0)
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retval = lrealpath (link);
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if (retval != NULL && !build_id_verify (retval, build_id))
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{
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xfree (retval);
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retval = NULL;
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}
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if (retval != NULL)
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break;
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}
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do_cleanups (back_to);
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return retval;
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}
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static char *
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find_separate_debug_file_by_buildid (struct objfile *objfile)
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{
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const struct elf_build_id *build_id;
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build_id = build_id_bfd_get (objfile->obfd);
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if (build_id != NULL)
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{
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char *build_id_name;
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build_id_name = build_id_to_debug_filename (build_id);
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/* Prevent looping on a stripped .debug file. */
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if (build_id_name != NULL
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&& filename_cmp (build_id_name, objfile_name (objfile)) == 0)
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{
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warning (_("\"%s\": separate debug info file has no debug info"),
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build_id_name);
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xfree (build_id_name);
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}
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else if (build_id_name != NULL)
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return build_id_name;
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}
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return NULL;
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}
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/* Scan and build partial symbols for a symbol file.
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We have been initialized by a call to elf_symfile_init, which
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currently does nothing.
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