libbacktrace: Add support for NIX_DEBUG_INFO_DIRS

Also fix tests.

pkgs/development/libraries/libbacktrace/0002-libbacktrace-Allow-configuring-debug-dir.patch

@@ -0,0 +1,108 @@
+From f409ee343fe6cdc059bb411746f27a515aec66a8 Mon Sep 17 00:00:00 2001
+From: Jan Tojnar <jtojnar@gmail.com>
+Date: Sat, 24 Dec 2022 16:46:18 +0100
+Subject: [PATCH 2/4] libbacktrace: Allow configuring debug dir
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+On platforms that do not use FHS like NixOS or GNU Guix,
+the build-id directories are not under `/usr/lib/debug`.
+
+Let’s add `--with-separate-debug-dir` configure flag so that
+the path can be changed. The same flag is supported by gdb:
+
+https://github.com/bminor/binutils-gdb/blob/095f84c7e3cf85cd68c657c46b80be078f336bc9/gdb/configure.ac#L113-L115
+---
+ Makefile.am  | 11 ++++++-----
+ configure.ac |  8 ++++++++
+ elf.c        |  4 ++--
+ 3 files changed, 16 insertions(+), 7 deletions(-)
+
+diff --git a/Makefile.am b/Makefile.am
+index 6eab991..da443c1 100644
+--- a/Makefile.am
++++ b/Makefile.am
+@@ -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
+ 
+@@ -134,7 +135,7 @@ 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
+ 
+@@ -143,8 +144,8 @@ 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)"'; \
+ 	$(SED) "s%$$SEARCH%$$REPLACE%" \
+ 		$< \
+ 		> $@.tmp
+@@ -468,7 +469,7 @@ endif HAVE_OBJCOPY_DEBUGLINK
+ 
+ %_buildid: %
+ 	./install-debuginfo-for-buildid.sh \
+-	  "$(TEST_BUILD_ID_DIR)" \
++	  "$(TEST_DEBUG_DIR)/.build-id" \
+ 	  $<
+ 	$(OBJCOPY) --strip-debug $< $@
+ 
+diff --git a/configure.ac b/configure.ac
+index 7f122cb..bb590ab 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -67,6 +67,14 @@ AM_MAINTAINER_MODE
+ AC_ARG_WITH(target-subdir,
+ [  --with-target-subdir=SUBDIR      Configuring in a subdirectory for target])
+ 
++AC_ARG_WITH(separate-debug-dir,
++[  --with-separate-debug-dir=DEBUGDIR      Look for global separate debug info in this path @<:@LIBDIR/debug@:>@],
++[separate_debug_dir=$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.
+diff --git a/elf.c b/elf.c
+index e82ecc5..8b1189c 100644
+--- a/elf.c
++++ b/elf.c
+@@ -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.
+@@ -870,7 +870,7 @@ elf_open_debugfile_by_buildid (struct backtrace_state *state,
+ 			       backtrace_error_callback error_callback,
+ 			       void *data)
+ {
+-  const char * const prefix = SYSTEM_BUILD_ID_DIR;
++  const char * const prefix = SYSTEM_DEBUG_DIR BUILD_ID_DIR;
+   const size_t prefix_len = strlen (prefix);
+   const char * const suffix = ".debug";
+   const size_t suffix_len = strlen (suffix);
+-- 
+2.38.1
+

pkgs/development/libraries/libbacktrace/0003-libbacktrace-Support-multiple-build-id-directories.patch

@@ -0,0 +1,101 @@
+From de122af5382d8017cae63bdee946206c6c6c23ab Mon Sep 17 00:00:00 2001
+From: Jan Tojnar <jtojnar@gmail.com>
+Date: Sat, 24 Dec 2022 20:19:27 +0100
+Subject: [PATCH 3/4] libbacktrace: Support multiple build id directories
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+gdb supports multiple debug directories separated by colons:
+https://github.com/bminor/binutils-gdb/blob/fcbfb25dcca625a7f999ec51d48b6fc3a32123c3/gdb/build-id.c#L136-L142
+
+This is useful for example when using dwarffs in addition
+to debug data installed using distribution’s package manager.
+---
+ elf.c | 57 ++++++++++++++++++++++++++++++++++++---------------------
+ 1 file changed, 36 insertions(+), 21 deletions(-)
+
+diff --git a/elf.c b/elf.c
+index 8b1189c..65c647a 100644
+--- a/elf.c
++++ b/elf.c
+@@ -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_DEBUG_DIR BUILD_ID_DIR;
+   const size_t prefix_len = strlen (prefix);
+   const char * const suffix = ".debug";
+   const size_t suffix_len = strlen (suffix);
+@@ -6936,27 +6936,42 @@ 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, 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, 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)
+-- 
+2.38.1
+

pkgs/development/libraries/libbacktrace/0004-libbacktrace-Support-NIX_DEBUG_INFO_DIRS-environment.patch

@@ -0,0 +1,42 @@
+From a3b7510e4c9e7201a4301f2a45d8569b06354607 Mon Sep 17 00:00:00 2001
+From: Jan Tojnar <jtojnar@gmail.com>
+Date: Sat, 24 Dec 2022 20:30:22 +0100
+Subject: [PATCH 4/4] libbacktrace: Support NIX_DEBUG_INFO_DIRS environment
+ variable
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Let’s make debug data lookup work on NixOS just like in gdb.
+---
+ elf.c | 11 +++++++++--
+ 1 file changed, 9 insertions(+), 2 deletions(-)
+
+diff --git a/elf.c b/elf.c
+index 65c647a..5c8abc0 100644
+--- a/elf.c
++++ b/elf.c
+@@ -6935,11 +6935,18 @@ elf_add (struct backtrace_state *state, const char *filename, int descriptor,
+ 
+   if (buildid_data != NULL)
+     {
++      const char *debug_directories_immutable;
++      const char *nix_debug = getenv ("NIX_DEBUG_INFO_DIRS");
++      if (nix_debug != NULL)
++        debug_directories_immutable = nix_debug;
++      else
++        debug_directories_immutable = SYSTEM_DEBUG_DIR;
++
+       int d;
+-      char debug_directories[strlen(SYSTEM_DEBUG_DIR) + 1];
++      char debug_directories[strlen(debug_directories_immutable) + 1];
+       char *debug_dir;
+ 
+-      strcpy(debug_directories, SYSTEM_DEBUG_DIR);
++      strcpy(debug_directories, debug_directories_immutable);
+ 
+       debug_dir = strtok (debug_directories, ":");
+       while (debug_dir != NULL)
+-- 
+2.38.1
+

pkgs/development/libraries/libbacktrace/default.nix

@@ -22,6 +22,14 @@ stdenv.mkDerivation {
     # Fix tests with shared library.
     # https://github.com/ianlancetaylor/libbacktrace/pull/99
     ./0001-libbacktrace-avoid-libtool-wrapping-tests.patch
+
+    # Support multiple debug dirs.
+    # https://github.com/ianlancetaylor/libbacktrace/pull/100
+    ./0002-libbacktrace-Allow-configuring-debug-dir.patch
+    ./0003-libbacktrace-Support-multiple-build-id-directories.patch
+
+    # Support NIX_DEBUG_INFO_DIRS environment variable.
+    ./0004-libbacktrace-Support-NIX_DEBUG_INFO_DIRS-environment.patch
   ];
 
   nativeBuildInputs = [