[PATCH 2/2] libselinux: propagate selabel_subs_init() errors

[Nicolas Iooss <nicolas.iooss@xxxxxxx>]

Memory allocation failures in selabel_subs_init() should be fatal,
contrary to failures which come from the non-existence of the
substitution files (subs or subs_dist).

Modify selabel_subs_init()'s prototype in order to return the error
state. This forces the pointer to the created substitution list to be
moved to an output function argument.

Signed-off-by: Nicolas Iooss <nicolas.iooss@xxxxxxx>
---
 libselinux/src/label.c          | 18 ++++++++++++------
 libselinux/src/label_file.c     | 24 +++++++++++++++++-------
 libselinux/src/label_internal.h |  4 ++--
 3 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/libselinux/src/label.c b/libselinux/src/label.c
index 70f6809ead2f..b27c103a95fc 100644
--- a/libselinux/src/label.c
+++ b/libselinux/src/label.c
@@ -91,16 +91,20 @@ static char *selabel_sub(struct selabel_sub *ptr, const char *src)
 	return NULL;
 }
 
-struct selabel_sub *selabel_subs_init(const char *path,
-				      struct selabel_digest *digest)
+int selabel_subs_init(const char *path, struct selabel_digest *digest,
+		       struct selabel_sub **out_subs)
 {
 	char buf[1024];
 	FILE *cfg = fopen(path, "re");
 	struct selabel_sub *list = NULL, *sub = NULL;
 	struct stat sb;
+	int status = -1;
 
-	if (!cfg)
-		return list;
+	*out_subs = NULL;
+	if (!cfg) {
+		/* If the file does not exist, it is not fatal */
+		return (errno == ENOENT) ? 0 : -1;
+	}
 
 	if (fstat(fileno(cfg), &sb) < 0)
 		goto out;
@@ -151,9 +155,12 @@ struct selabel_sub *selabel_subs_init(const char *path,
 	if (digest_add_specfile(digest, cfg, NULL, sb.st_size, path) < 0)
 		goto err;
 
+	*out_subs = list;
+	status = 0;
+
 out:
 	fclose(cfg);
-	return list;
+	return status;
 err:
 	if (sub)
 		free(sub->src);
@@ -165,7 +172,6 @@ err:
 		free(list);
 		list = sub;
 	}
-	list = NULL;
 	goto out;
 }
 
diff --git a/libselinux/src/label_file.c b/libselinux/src/label_file.c
index 3ff759032cc1..c05b37a56efe 100644
--- a/libselinux/src/label_file.c
+++ b/libselinux/src/label_file.c
@@ -587,17 +587,27 @@ static int init(struct selabel_handle *rec, const struct selinux_opt *opts,
 	char subs_file[PATH_MAX + 1];
 	/* Process local and distribution substitution files */
 	if (!path) {
-		rec->dist_subs =
-		    selabel_subs_init(selinux_file_context_subs_dist_path(),
-		    rec->digest);
-		rec->subs = selabel_subs_init(selinux_file_context_subs_path(),
-		    rec->digest);
+		status = selabel_subs_init(
+			selinux_file_context_subs_dist_path(),
+			rec->digest, &rec->dist_subs);
+		if (status)
+			goto finish;
+		status = selabel_subs_init(selinux_file_context_subs_path(),
+			rec->digest, &rec->subs);
+		if (status)
+			goto finish;
 		path = selinux_file_context_path();
 	} else {
 		snprintf(subs_file, sizeof(subs_file), "%s.subs_dist", path);
-		rec->dist_subs = selabel_subs_init(subs_file, rec->digest);
+		status = selabel_subs_init(subs_file, rec->digest,
+					   &rec->dist_subs);
+		if (status)
+			goto finish;
 		snprintf(subs_file, sizeof(subs_file), "%s.subs", path);
-		rec->subs = selabel_subs_init(subs_file, rec->digest);
+		status = selabel_subs_init(subs_file, rec->digest,
+					   &rec->subs);
+		if (status)
+			goto finish;
 	}
 
 #endif
diff --git a/libselinux/src/label_internal.h b/libselinux/src/label_internal.h
index b03652ebc477..10f1e57850e1 100644
--- a/libselinux/src/label_internal.h
+++ b/libselinux/src/label_internal.h
@@ -75,8 +75,8 @@ extern int digest_add_specfile(struct selabel_digest *digest, FILE *fp,
 						    const char *path);
 extern void digest_gen_hash(struct selabel_digest *digest);
 
-extern struct selabel_sub *selabel_subs_init(const char *path,
-				    struct selabel_digest *digest);
+extern int selabel_subs_init(const char *path, struct selabel_digest *digest,
+			     struct selabel_sub **out_subs);
 
 struct selabel_lookup_rec {
 	char * ctx_raw;
-- 
2.13.0