rev-parse: check i before using argv[i] against argc

The --prefix, --default, and --resolve-git-dir options to
git-rev-parse require an argument, but when given no argument,
the code uses the NULL read from argv[argc] without checking,
leading to a segfault.

Instead, check first and die() with an error message.

Signed-off-by: David Sharp <dhsharp@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/rev-parse.c b/builtin/rev-parse.c
index c76b89dc5bcccb42f7c2613072b1093a58c7d21c..068fd17ac91be66d831cb22461013bc24f9d1c02 100644 (file)
--- a/builtin/rev-parse.c
+++ b/builtin/rev-parse.c
@@ -523,15 +523,17 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
                                continue;
                        }
                        if (!strcmp(arg, "--default")) {
-                               def = argv[i+1];
-                               i++;
+                               def = argv[++i];
+                               if (!def)
+                                       die("--default requires an argument");
                                continue;
                        }
                        if (!strcmp(arg, "--prefix")) {
-                               prefix = argv[i+1];
+                               prefix = argv[++i];
+                               if (!prefix)
+                                       die("--prefix requires an argument");
                                startup_info->prefix = prefix;
                                output_prefix = 1;
-                               i++;
                                continue;
                        }
                        if (!strcmp(arg, "--revs-only")) {
@@ -703,9 +705,12 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
                                continue;
                        }
                        if (!strcmp(arg, "--resolve-git-dir")) {
-                               const char *gitdir = resolve_gitdir(argv[i+1]);
+                               const char *gitdir = argv[++i];
                                if (!gitdir)
-                                       die("not a gitdir '%s'", argv[i+1]);
+                                       die("--resolve-git-dir requires an argument");
+                               gitdir = resolve_gitdir(gitdir);
+                               if (!gitdir)
+                                       die("not a gitdir '%s'", argv[i]);
                                puts(gitdir);
                                continue;
                        }