branch: fix segfault when resolving an invalid HEAD

diff --git a/builtin-fmt-merge-msg.c b/builtin-fmt-merge-msg.c
index 3d3097d299d4c964e1acfff7a365501a8bd53587..5c145d2165027adc5e5d44c6dda969e1ed86be57 100644 (file)
--- a/builtin-fmt-merge-msg.c
+++ b/builtin-fmt-merge-msg.c
@@ -81,7 +81,7 @@ static int handle_line(char *line)
        if (len < 43 || line[40] != '\t')
                return 1;
 
-       if (!strncmp(line + 41, "not-for-merge", 13))
+       if (!prefixcmp(line + 41, "not-for-merge"))
                return 0;
 
        if (line[41] != '\t')
@@ -119,15 +119,15 @@ static int handle_line(char *line)
        if (pulling_head) {
                origin = xstrdup(src);
                src_data->head_status |= 1;
-       } else if (!strncmp(line, "branch ", 7)) {
+       } else if (!prefixcmp(line, "branch ")) {
                origin = xstrdup(line + 7);
                append_to_list(&src_data->branch, origin, NULL);
                src_data->head_status |= 2;
-       } else if (!strncmp(line, "tag ", 4)) {
+       } else if (!prefixcmp(line, "tag ")) {
                origin = line;
                append_to_list(&src_data->tag, xstrdup(origin + 4), NULL);
                src_data->head_status |= 2;
-       } else if (!strncmp(line, "remote branch ", 14)) {
+       } else if (!prefixcmp(line, "remote branch ")) {
                origin = xstrdup(line + 14);
                append_to_list(&src_data->r_branch, origin, NULL);
                src_data->head_status |= 2;
@@ -259,13 +259,15 @@ int cmd_fmt_merge_msg(int argc, const char **argv, const char *prefix)
                else if (!strcmp(argv[1], "--no-summary"))
                        merge_summary = 0;
                else if (!strcmp(argv[1], "-F") || !strcmp(argv[1], "--file")) {
-                       if (argc < 2)
+                       if (argc < 3)
                                die ("Which file?");
                        if (!strcmp(argv[2], "-"))
                                in = stdin;
                        else {
                                fclose(in);
                                in = fopen(argv[2], "r");
+                               if (!in)
+                                       die("cannot open %s", argv[2]);
                        }
                        argc--; argv++;
                } else
@@ -278,7 +280,9 @@ int cmd_fmt_merge_msg(int argc, const char **argv, const char *prefix)
 
        /* get current branch */
        current_branch = resolve_ref("HEAD", head_sha1, 1, NULL);
-       if (!strncmp(current_branch, "refs/heads/", 11))
+       if (!current_branch)
+               die("No current branch");
+       if (!prefixcmp(current_branch, "refs/heads/"))
                current_branch += 11;
 
        while (fgets(line, sizeof(line), in)) {