[PATCH v3 bpf-next 3/4] selftests/bpf: add get_lib_path() helper

[Alan Maguire <alan.maguire@oracle.com>]

get_lib_path(path_substr) returns full path to a library
containing path_substr (such as "libc-") found via
/proc/self/maps.  Caller is responsible for freeing
the returned string.

Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
---
 tools/testing/selftests/bpf/trace_helpers.c | 17 +++++++++++++++++
 tools/testing/selftests/bpf/trace_helpers.h |  2 ++
 2 files changed, 19 insertions(+)

diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c
index ca6abae..49e5f0d 100644
--- a/tools/testing/selftests/bpf/trace_helpers.c
+++ b/tools/testing/selftests/bpf/trace_helpers.c
@@ -216,3 +216,20 @@ ssize_t get_rel_offset(uintptr_t addr)
 	fclose(f);
 	return -EINVAL;
 }
+
+char *get_lib_path(const char *path_substr)
+{
+	char *found = NULL;
+	char lib_path[512];
+	FILE *f;
+
+	f = fopen("/proc/self/maps", "r");
+	while (fscanf(f, "%*s %*s %*s %*s %*s %[^\n]", lib_path) == 1) {
+		if (strstr(lib_path, path_substr) == NULL)
+			continue;
+		found = strdup(lib_path);
+		break;
+	}
+	fclose(f);
+	return found;
+}
diff --git a/tools/testing/selftests/bpf/trace_helpers.h b/tools/testing/selftests/bpf/trace_helpers.h
index 238a9c9..ff379f6 100644
--- a/tools/testing/selftests/bpf/trace_helpers.h
+++ b/tools/testing/selftests/bpf/trace_helpers.h
@@ -20,5 +20,7 @@ struct ksym {
 
 ssize_t get_uprobe_offset(const void *addr);
 ssize_t get_rel_offset(uintptr_t addr);
+/* Return allocated string path to library that contains path_substr. */
+char *get_lib_path(const char *path_substr);
 
 #endif
-- 
1.8.3.1