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Support custom debug dirs #100

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Support custom debug dirs #100

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d518d40
libbacktrace: Allow configuring debug dir
jtojnar Dec 24, 2022
48addfb
libbacktrace: Support multiple build id directories
jtojnar Dec 24, 2022
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13 changes: 7 additions & 6 deletions Makefile.am
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Original file line number Diff line number Diff line change
Expand Up @@ -33,7 +33,8 @@ ACLOCAL_AMFLAGS = -I config

AM_CPPFLAGS =

AM_CFLAGS = $(EXTRA_FLAGS) $(WARN_FLAGS) $(PIC_FLAG)
AM_CFLAGS = $(EXTRA_FLAGS) $(WARN_FLAGS) $(PIC_FLAG) \
-DSYSTEM_DEBUG_DIR=\"$(SEPARATE_DEBUG_DIR)\"

include_HEADERS = backtrace.h backtrace-supported.h

Expand Down Expand Up @@ -132,7 +133,7 @@ libbacktrace_noformat_la_DEPENDENCIES = $(libbacktrace_noformat_la_LIBADD)
if HAVE_ELF
if HAVE_OBJCOPY_DEBUGLINK

TEST_BUILD_ID_DIR=$(abs_builddir)/usr/lib/debug/.build-id/
TEST_DEBUG_DIR=$(abs_builddir)/usr/lib/debug

check_LTLIBRARIES += libbacktrace_elf_for_test.la

Expand All @@ -141,8 +142,8 @@ libbacktrace_elf_for_test_la_LIBADD = $(BACKTRACE_FILE) elf_for_test.lo \
$(VIEW_FILE) $(ALLOC_FILE)

elf_for_test.c: elf.c
SEARCH='^#define SYSTEM_BUILD_ID_DIR.*$$'; \
REPLACE="#define SYSTEM_BUILD_ID_DIR \"$(TEST_BUILD_ID_DIR)\""; \
SEARCH='^#define BUILD_ID_DIR.*$$'; \
REPLACE='\0\n#undef SYSTEM_DEBUG_DIR\n#define SYSTEM_DEBUG_DIR "$(TEST_DEBUG_DIR)"'; \
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@jtojnar jtojnar Dec 24, 2022 •
edited
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Ideally, we would be able to just use -D flag here but I tried the following

--- a/Makefile.am
+++ b/Makefile.am
@@ -144,12 +144,9 @@ libbacktrace_elf_for_test_la_LIBADD = $(BACKTRACE_FILE) elf_for_test.lo \
 	$(VIEW_FILE) $(ALLOC_FILE)
 
 elf_for_test.c: elf.c
-	SEARCH='^#define BUILD_ID_DIR.*$$'; \
-	REPLACE='\0\n#undef SYSTEM_DEBUG_DIR\n#define SYSTEM_DEBUG_DIR "$(TEST_DEBUG_DIR)"'; \
-	$(SED) "s%$$SEARCH%$$REPLACE%" \
-		$< \
-		> [email protected]
-	mv [email protected] $@
+	cp $< $@
+
+libbacktrace_elf_for_test_la_CFLAGS = -USYSTEM_DEBUG_DIR -DSYSTEM_DEBUG_DIR=\"$(TEST_DEBUG_DIR)\"
 
 endif HAVE_OBJCOPY_DEBUGLINK
 endif HAVE_ELF

without success and autotools are just too confusing to me.

libbacktrace_elf_for_test_la_CFLAGS does not seem to affect the compilation of elf_for_test.lo (it still gets -DSYSTEM_DEBUG_DIR from AM_CFLAGS) and it only appears when linking the objects into libbacktrace_elf_for_test.la:

cp elf.c elf_for_test.c
/nix/store/4xw8n979xpivdc46a9ndcvyhwgif00hz-bash-5.1-p16/bin/bash ./libtool  --tag=CC   --mode=compile gcc -DHAVE_CONFIG_H -I.    -funwind-tables -frandom-seed=elf_for_test.lo -W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition -Wmissing-format-attribute -Wcast-qual  -DSYSTEM_DEBUG_DIR=\"/nix/store/dkpyi2cxvjxk74l2pjighshbzncy2hmy-libbacktrace-unstable-2022-12-16/lib/debug\" -g -O2 -c -o elf_for_test.lo elf_for_test.c
libtool: compile:  gcc -DHAVE_CONFIG_H -I. -funwind-tables -frandom-seed=elf_for_test.lo -W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition -Wmissing-format-attribute -Wcast-qual -DSYSTEM_DEBUG_DIR=\"/nix/store/dkpyi2cxvjxk74l2pjighshbzncy2hmy-libbacktrace-unstable-2022-12-16/lib/debug\" -g -O2 -c elf_for_test.c  -fPIC -DPIC -o .libs/elf_for_test.o
/nix/store/4xw8n979xpivdc46a9ndcvyhwgif00hz-bash-5.1-p16/bin/bash ./libtool  --tag=CC   --mode=link gcc -USYSTEM_DEBUG_DIR -DSYSTEM_DEBUG_DIR=\"/build/libbacktrace/usr/lib/debug\" -g -O2   -o libbacktrace_elf_for_test.la  libbacktrace_elf_for_test_la-atomic.lo libbacktrace_elf_for_test_la-dwarf.lo libbacktrace_elf_for_test_la-fileline.lo libbacktrace_elf_for_test_la-posix.lo libbacktrace_elf_for_test_la-print.lo libbacktrace_elf_for_test_la-sort.lo libbacktrace_elf_for_test_la-state.lo backtrace.lo simple.lo elf_for_test.lo mmapio.lo mmap.lo 
libtool: link: ar cr .libs/libbacktrace_elf_for_test.a .libs/libbacktrace_elf_for_test_la-atomic.o .libs/libbacktrace_elf_for_test_la-dwarf.o .libs/libbacktrace_elf_for_test_la-fileline.o .libs/libbacktrace_elf_for_test_la-posix.o .libs/libbacktrace_elf_for_test_la-print.o .libs/libbacktrace_elf_for_test_la-sort.o .libs/libbacktrace_elf_for_test_la-state.o .libs/backtrace.o .libs/simple.o .libs/elf_for_test.o .libs/mmapio.o .libs/mmap.o 
libtool: link: ranlib .libs/libbacktrace_elf_for_test.a

$(SED) "s%$$SEARCH%$$REPLACE%" \
$< \
> [email protected]
Expand Down Expand Up @@ -458,13 +459,13 @@ endif HAVE_OBJCOPY_DEBUGLINK

%_buildid: %
./install-debuginfo-for-buildid.sh \
"$(TEST_BUILD_ID_DIR)" \
"$(TEST_DEBUG_DIR)/.build-id" \
$<
$(OBJCOPY) --strip-debug $< $@

%_buildidfull: %
./install-debuginfo-for-buildid.sh \
"$(TEST_BUILD_ID_DIR)" \
"$(TEST_DEBUG_DIR)/.build-id" \
$<
$(OBJCOPY) --strip-all $< $@

Expand Down
8 changes: 8 additions & 0 deletions configure.ac
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Expand Up @@ -67,6 +67,14 @@ AM_MAINTAINER_MODE
AC_ARG_WITH(target-subdir,
[ --with-target-subdir=SUBDIR Configuring in a subdirectory for target])

AC_ARG_WITH(separate-debug-dir,
[ --with-separate-debug-dir=DEBUGDIR Look for global separate debug info in this path @<:@LIBDIR/debug@:>@],
[separate_debug_dir=$withval],
[separate_debug_dir=$libdir/debug])

SEPARATE_DEBUG_DIR=$separate_debug_dir
AC_SUBST(SEPARATE_DEBUG_DIR)

# We must force CC to /not/ be precious variables; otherwise
# the wrong, non-multilib-adjusted value will be used in multilibs.
# As a side effect, we have to subst CFLAGS ourselves.
Expand Down
59 changes: 37 additions & 22 deletions elf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -856,7 +856,7 @@ elf_readlink (struct backtrace_state *state, const char *filename,
}
}

#define SYSTEM_BUILD_ID_DIR "/usr/lib/debug/.build-id/"
#define BUILD_ID_DIR "/.build-id/"

/* Open a separate debug info file, using the build ID to find it.
Returns an open file descriptor, or -1.
Expand All @@ -865,12 +865,12 @@ elf_readlink (struct backtrace_state *state, const char *filename,
when the build ID is known is in /usr/lib/debug/.build-id. */

static int
elf_open_debugfile_by_buildid (struct backtrace_state *state,
elf_open_debugfile_by_buildid (const char * const prefix,
struct backtrace_state *state,
const char *buildid_data, size_t buildid_size,
backtrace_error_callback error_callback,
void *data)
{
const char * const prefix = SYSTEM_BUILD_ID_DIR;
const size_t prefix_len = strlen (prefix);
const char * const suffix = ".debug";
const size_t suffix_len = strlen (suffix);
Expand Down Expand Up @@ -6947,27 +6947,42 @@ elf_add (struct backtrace_state *state, const char *filename, int descriptor,
if (buildid_data != NULL)
{
int d;
char debug_directories[strlen(SYSTEM_DEBUG_DIR) + 1];
char *debug_dir;

d = elf_open_debugfile_by_buildid (state, buildid_data, buildid_size,
error_callback, data);
if (d >= 0)
{
int ret;
strcpy(debug_directories, SYSTEM_DEBUG_DIR);

elf_release_view (state, &buildid_view, error_callback, data);
if (debuglink_view_valid)
elf_release_view (state, &debuglink_view, error_callback, data);
if (debugaltlink_view_valid)
elf_release_view (state, &debugaltlink_view, error_callback, data);
ret = elf_add (state, "", d, NULL, 0, base_address, opd,
error_callback, data, fileline_fn, found_sym,
found_dwarf, NULL, 0, 1, NULL, 0);
if (ret < 0)
backtrace_close (d, error_callback, data);
else if (descriptor >= 0)
backtrace_close (descriptor, error_callback, data);
return ret;
}
debug_dir = strtok (debug_directories, ":");
while (debug_dir != NULL)
{
char prefix[strlen(debug_dir) + strlen(BUILD_ID_DIR) + 1];
strcpy(prefix, debug_dir);
strcat(prefix, BUILD_ID_DIR);

d = elf_open_debugfile_by_buildid (prefix, state, buildid_data, buildid_size,
error_callback, data);

if (d >= 0)
{
int ret;

elf_release_view (state, &buildid_view, error_callback, data);
if (debuglink_view_valid)
elf_release_view (state, &debuglink_view, error_callback, data);
if (debugaltlink_view_valid)
elf_release_view (state, &debugaltlink_view, error_callback, data);
ret = elf_add (state, "", d, NULL, 0, base_address, opd,
error_callback, data, fileline_fn, found_sym,
found_dwarf, NULL, 0, 1, NULL, 0);
if (ret < 0)
backtrace_close (d, error_callback, data);
else if (descriptor >= 0)
backtrace_close (descriptor, error_callback, data);
return ret;
}

debug_dir = strtok (NULL, ":");
}
}

if (buildid_view_valid)
Expand Down