PR gdb/27570: missing support for debuginfod in core_target::build_file_mappings

Add debuginfod support to core_target::build_file_mappings and
locate_exec_from_corefile_build_id to enable the downloading of
missing executables and shared libraries referenced in core files.

Also add debuginfod support to solib_map_sections so that previously
downloaded shared libraries can be retrieved from the local debuginfod
cache.

When core file shared libraries are found locally, verify that their
build-ids match the corresponding build-ids found in the core file.
If there is a mismatch, attempt to query debuginfod for the correct
build and print a warning if unsuccessful:

  warning: Build-id of /lib64/libc.so.6 does not match core file.

Also disable debuginfod when gcore invokes gdb.  Debuginfo is not
needed for core file generation so debuginfod queries will slow down
gcore unnecessarily.

1 files changed, 17 insertions, 0 deletions

diff --git a/gdb/debuginfod-support.h b/gdb/debuginfod-support.h
index 29e361b..5b1c1cb 100644
--- a/gdb/debuginfod-support.h
+++ b/gdb/debuginfod-support.h
@@ -61,4 +61,21 @@ debuginfod_debuginfo_query (const unsigned char *build_id,
 			    const char *filename,
 			    gdb::unique_xmalloc_ptr<char> *destname);
 
+/* Query debuginfod servers for an executable file with BUILD_ID.
+   BUILD_ID can be given as a binary blob or a null-terminated string.
+   If given as a binary blob, BUILD_ID_LEN should be the number of bytes.
+   If given as a null-terminated string, BUILD_ID_LEN should be 0.
+
+   FILENAME should be the name or path associated with the executable.
+   It is used for printing messages to the user.
+
+   If the file is successfully retrieved, its path on the local machine
+   is stored in DESTNAME.  If GDB is not built with debuginfod, this
+   function returns -ENOSYS.  */
+
+extern scoped_fd debuginfod_exec_query (const unsigned char *build_id,
+					int build_id_len,
+					const char *filename,
+					gdb::unique_xmalloc_ptr<char>
+					  *destname);
 #endif /* DEBUGINFOD_SUPPORT_H */