perf buildid-cache: Don't skip 16-byte build-ids

lsdir_bid_tail_filter() ignored any build-id that wasn't exactly 20
bytes. This worked only for SHA-1 build-ids. The build-id for a PE file
is always a 16-byte GUID and ELF files can also have MD5 or UUID
build-ids.

This fix changes the filter to allow build-ids between 16 and 20 bytes.

Signed-off-by: Nicholas Fraser <[e-mail]>
Acked-by: Jiri Olsa <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Frank Ch. Eigler <[e-mail]>
Cc: Huw Davies <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Kim Phillips <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Remi Bernon <[e-mail]>
Cc: Song Liu <[e-mail]>
Cc: Tommi Rantala <[e-mail]>
Cc: Ulrich Czekalla <[e-mail]>
Link: http://lore.kernel.org/lkml/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/build-id.c

···
 	int i = 0;
 	while (isxdigit(d->d_name[i]) && i < SBUILD_ID_SIZE - 3)
 		i++;
-	return (i == SBUILD_ID_SIZE - 3) && (d->d_name[i] == '\0');
+	return (i >= SBUILD_ID_MIN_SIZE - 3) && (i <= SBUILD_ID_SIZE - 3) &&
+		(d->d_name[i] == '\0');
 }
 
 struct strlist *build_id_cache__list_all(bool validonly)
···
 		}
 		strlist__for_each_entry(nd2, linklist) {
 			if (snprintf(sbuild_id, SBUILD_ID_SIZE, "%s%s",
-				     nd->s, nd2->s) != SBUILD_ID_SIZE - 1)
+				     nd->s, nd2->s) > SBUILD_ID_SIZE - 1)
 				goto err_out;
 			if (validonly && !build_id_cache__valid_id(sbuild_id))
 				continue;

tools/perf/util/build-id.h

···
 #ifndef PERF_BUILD_ID_H_
 #define PERF_BUILD_ID_H_ 1
 
-#define BUILD_ID_SIZE	20
+#define BUILD_ID_SIZE	20 /* SHA-1 length in bytes */
+#define BUILD_ID_MIN_SIZE	16 /* MD5/UUID/GUID length in bytes */
 #define SBUILD_ID_SIZE	(BUILD_ID_SIZE * 2 + 1)
+#define SBUILD_ID_MIN_SIZE	(BUILD_ID_MIN_SIZE * 2 + 1)
 
 #include "machine.h"
 #include "tool.h"