add support for submodules

XD.c

@@ -61,8 +61,9 @@ static int explain = 0;
 char
 *find_git_repo()
 {
-  char path[PATH_MAX] = ".", *rpath;
+  char path[PATH_MAX] = ".", fstr[PATH_MAX], *rpath, *res;
   struct stat s;
+	FILE *f;
   int i, c;
 
   /* find the number of jumps to the root of the fs */
@@ -83,8 +84,26 @@ char
     strcat(path, "/.git");
 
     /* if there seems to be a git directory return the directory it was found in */
-    if (stat(path, &s) == 0 && S_ISDIR(s.st_mode)) {
+		if (stat(path, &s) == 0) {
+			if (S_ISDIR(s.st_mode)) {
 				return realpath(path, NULL);
+			} else if (S_ISREG(s.st_mode)) {
+				/* we do some special magic here to check if we're in a submodule */
+				f = fopen(path, "r");
+				if (!f) {
+					L("fopen: %s", strerror(errno));
+					return NULL;
+				}
+				res = fgets(fstr, PATH_MAX, f);
+				fclose(f);
+				if (!res) {
+					L("fgets: %s", strerror(errno));
+					return NULL;
+				}
+				if (strncmp(fstr, "gitdir: ", strlen("gitdir: ")) == 0) {
+					return realpath(strndup(fstr + strlen("gitdir: "), strlen(fstr + strlen("gitdir: ")) - 1), NULL);
+				}
+			}
 		}
 
     /* reset contents of gpath, and go up a directory */