Tolerate a missing or empty repository URL

`trim_end()` returns NULL when a repo url is empty or all slashes and
the later newline trim dereferenced it. The legacy `r=` and `p=about`
path also read the last byte of the url without checking it was set.

2 files changed, 4 insertions, 2 deletions

diff --git a/source/cmd.c b/source/cmd.c
index 7eb642c..aaf5fe5 100644
--- a/source/cmd.c
+++ b/source/cmd.c
@@ -42,7 +42,8 @@ static void about_fn(void)
 	if (ctx.repo) {
 		size_t path_info_len = ctx.env.path_info ? strlen(ctx.env.path_info) : 0;
 		if (!ctx.qry.path &&
-		    ctx.qry.url[strlen(ctx.qry.url) - 1] != '/' &&
+		    (!ctx.qry.url || !*ctx.qry.url ||
+		     ctx.qry.url[strlen(ctx.qry.url) - 1] != '/') &&
 		    (!path_info_len || ctx.env.path_info[path_info_len - 1] != '/')) {
 			char *currenturl = cgit_currenturl();
 			char *redirect = fmtalloc("%s/", currenturl);
diff --git a/source/shared.c b/source/shared.c
index a39394d..c509aa1 100644
--- a/source/shared.c
+++ b/source/shared.c
@@ -52,7 +52,8 @@ struct cgit_repo *cgit_add_repo(const char *url)
 	ret = &cgit_repolist.repos[cgit_repolist.count-1];
 	memset(ret, 0, sizeof(struct cgit_repo));
 	ret->url = trim_end(url, '/');
-	*strchrnul(ret->url, '\n') = '\0';
+	if (ret->url)
+		*strchrnul(ret->url, '\n') = '\0';
 	ret->name = ret->url;
 	ret->path = NULL;
 	ret->desc = cgit_default_repo_desc;