libbacktrace patch committed: Read symbol table of debuginfo file

[Ian Lance Taylor]

This patch to libbacktrace reads symbol tables from debuginfo files.
These become another symbol table to search.  This is needed if people
use --strip-all rather than --strip-debug when adding a debuglink
section.  This fixes
https://github.com/ianlancetaylor/libbacktrace/issues/113.
Bootstrapped and ran libbacktrace and libgo tests on
x86_64-pc-linux-gnu.  Committed to mainline.

Ian

* elf.c (elf_add): Add the symbol table from a debuginfo file.
* Makefile.am (MAKETESTS): Add buildidfull and gnudebuglinkfull
variants of buildid and gnudebuglink tests.
(%_gnudebuglinkfull, %_buildidfull): New patterns.
* Makefile.in: Regenerate.

24810fbf7b0ce274dfa46cc362305ac77ee5a72c
diff --git a/libbacktrace/Makefile.am b/libbacktrace/Makefile.am
index 16a72d2abf7..750ed80ed05 100644
--- a/libbacktrace/Makefile.am
+++ b/libbacktrace/Makefile.am
@@ -257,7 +257,7 @@ b2test_LDFLAGS = -Wl,--build-id
 b2test_LDADD = libbacktrace_elf_for_test.la
 
 check_PROGRAMS += b2test
-MAKETESTS += b2test_buildid
+MAKETESTS += b2test_buildid b2test_buildidfull
 
 if HAVE_DWZ
 
@@ -267,7 +267,7 @@ b3test_LDFLAGS = -Wl,--build-id
 b3test_LDADD = libbacktrace_elf_for_test.la
 
 check_PROGRAMS += b3test
-MAKETESTS += b3test_dwz_buildid
+MAKETESTS += b3test_dwz_buildid b3test_dwz_buildidfull
 
 endif HAVE_DWZ
 
@@ -443,12 +443,16 @@ endif HAVE_PTHREAD
 
 if HAVE_OBJCOPY_DEBUGLINK
 
-MAKETESTS += btest_gnudebuglink
+MAKETESTS += btest_gnudebuglink btest_gnudebuglinkfull
 
 %_gnudebuglink: %
        $(OBJCOPY) --only-keep-debug $< $@.debug
        $(OBJCOPY) --strip-debug --add-gnu-debuglink=$@.debug $< $@
 
+%_gnudebuglinkfull: %
+       $(OBJCOPY) --only-keep-debug $< $@.debug
+       $(OBJCOPY) --strip-all --add-gnu-debuglink=$@.debug $< $@
+
 endif HAVE_OBJCOPY_DEBUGLINK
 
 %_buildid: %
@@ -457,6 +461,12 @@ endif HAVE_OBJCOPY_DEBUGLINK
          $<
        $(OBJCOPY) --strip-debug $< $@
 
+%_buildidfull: %
+       ./install-debuginfo-for-buildid.sh \
+         "$(TEST_BUILD_ID_DIR)" \
+         $<
+       $(OBJCOPY) --strip-all $< $@
+
 if HAVE_COMPRESSED_DEBUG
 
 ctestg_SOURCES = btest.c testlib.c
diff --git a/libbacktrace/elf.c b/libbacktrace/elf.c
index c506cc29fe1..664937e1438 100644
--- a/libbacktrace/elf.c
+++ b/libbacktrace/elf.c
@@ -6872,7 +6872,7 @@ elf_add (struct backtrace_state *state, const char 
*filename, int descriptor,
 
   if (symtab_shndx == 0)
     symtab_shndx = dynsym_shndx;
-  if (symtab_shndx != 0 && !debuginfo)
+  if (symtab_shndx != 0)
     {
       const b_elf_shdr *symtab_shdr;
       unsigned int strtab_shndx;