Validate symbol file using build-id

Consumer part of the "build-id" attribute.

gdb/ChangeLog
2015-07-15  Aleksandar Ristovski  <aristovski@qnx.com
	    Jan Kratochvil  <jan.kratochvil@redhat.com>

	Validate symbol file using build-id.
	* NEWS (Changes since GDB 7.10): Add 'set validate-build-id'
	and 'show validate-build-id'.  Add build-id attribute.
	* solib-darwin.c (_initialize_darwin_solib): Assign validate value.
	* solib-dsbt.c (_initialize_dsbt_solib): Ditto.
	* solib-frv.c (_initialize_frv_solib): Ditto.
	* solib-spu.c (set_spu_solib_ops): Ditto.
	* solib-svr4.c: Include rsp-low.h.
	(NOTE_GNU_BUILD_ID_NAME): New define.
	(svr4_validate): New function.
	(svr4_copy_library_list): Duplicate field build_id.
	(library_list_start_library): Parse 'build-id' attribute.
	(svr4_library_attributes): Add 'build-id' attribute.
	(_initialize_svr4_solib): Assign validate value.
	* solib-target.c (solib.h): Include.
	(_initialize_solib_target): Assign validate value.
	* solib.c (validate_build_id, show_validate_build_id): New.
	(solib_map_sections): Use ops->validate.
	(clear_so): Free build_id.
	(default_solib_validate): New function.
	(_initialize_solib): Add "validate-build-id".
	* solib.h (default_solib_validate): New declaration.
	* solist.h (struct so_list): New fields 'build_idsz' and 'build_id'.
	(target_so_ops): New field 'validate'.

gdb/doc/ChangeLog
2015-07-15  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.texinfo (Files): Add 'set validate-build-id'
	and 'show validate-build-id'.

2 files changed, 43 insertions, 0 deletions

diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index 5b90cb4..fc66f0c 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,8 @@
+2015-07-15  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
+	* gdb.texinfo (Files): Add 'set validate-build-id'
+	and 'show validate-build-id'.
+
 2015-07-15  Aleksandar Ristovski  <aristovski@qnx.com
 	    Jan Kratochvil  <jan.kratochvil@redhat.com>
 
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 932c38d..513c08e 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -17950,6 +17950,44 @@ libraries that were loaded by explicit user requests are not
 discarded.
 @end table
 
+@table @code
+@kindex set validate-build-id
+@cindex override @value{GDBN} build-id check
+@item set validate-build-id @var{mode}
+Setting to override @value{GDBN} build-id check.
+
+Inferior shared libraries and symbol files may contain unique build-id.
+By default @value{GDBN} will ignore symbol files with non-matching build-id
+while printing:
+
+@smallexample
+  warning: Shared object "libfoo.so.1" could not be validated (remote
+  build ID 2bc1745e does not match local build ID a08f8767) and will be
+  ignored; or use 'set validate-build-id off'.
+@end smallexample
+
+Turning off this setting would load such symbol file while still printing:
+
+@smallexample
+  warning: Shared object "libfoo.so.1" could not be validated (remote
+  build ID 2bc1745e does not match local build ID a08f8767) but it is
+  being loaded due to 'set validate-build-id off'.
+@end smallexample
+
+If remote build-id is present but it does not match local build-id (or local
+build-id is not present) then this setting enables (@var{mode} is @code{off}) or
+disables (@var{mode} is @code{on}) loading of such symbol file.  On systems
+where build-id is not present in the remote system this setting has no effect.
+The default value is @code{on}.
+
+Loading non-matching symbol file may confuse debugging including breakage
+of backtrace output.
+
+@kindex show validate-build-id
+@item show validate-build-id
+Display the current mode of build-id check override.
+@end table
+
 Sometimes you may wish that @value{GDBN} stops and gives you control
 when any of shared library events happen.  The best way to do this is
 to use @code{catch load} and @code{catch unload} (@pxref{Set