cgit.c: improve error message when git repo cannot be accessed

The current 'Not a git repository' error message is not very helpful,
since it doesn't state the cause of the problem.

This patch uses errno to provide a hint of the underlying problem. It
would have been even better to give the exact cause (e.g. for ENOENT it
would be nice to know which file/directory is missing), but that would
require reimplementing setup_git_directory_gently() which seems a bit
overkill.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/cgit.c b/cgit.c
index e498030..5259f56 100644
--- a/cgit.c
+++ b/cgit.c
@@ -342,135 +342,139 @@ static void prepare_context(struct cgit_context *ctx)
         ctx->env.path_info = xstrdupn(getenv("PATH_INFO"));
         ctx->env.query_string = xstrdupn(getenv("QUERY_STRING"));
         ctx->env.request_method = xstrdupn(getenv("REQUEST_METHOD"));
         ctx->env.script_name = xstrdupn(getenv("SCRIPT_NAME"));
         ctx->env.server_name = xstrdupn(getenv("SERVER_NAME"));
         ctx->env.server_port = xstrdupn(getenv("SERVER_PORT"));
         ctx->page.mimetype = "text/html";
         ctx->page.charset = PAGE_ENCODING;
         ctx->page.filename = NULL;
         ctx->page.size = 0;
         ctx->page.modified = time(NULL);
         ctx->page.expires = ctx->page.modified;
         ctx->page.etag = NULL;
         memset(&ctx->cfg.mimetypes, 0, sizeof(struct string_list));
         if (ctx->env.script_name)
                 ctx->cfg.script_name = ctx->env.script_name;
         if (ctx->env.query_string)
                 ctx->qry.raw = ctx->env.query_string;
         if (!ctx->env.cgit_config)
                 ctx->env.cgit_config = CGIT_CONFIG;
 }
 
 struct refmatch {
         char *req_ref;
         char *first_ref;
         int match;
 };
 
 int find_current_ref(const char *refname, const unsigned char *sha1,
                      int flags, void *cb_data)
 {
         struct refmatch *info;
 
         info = (struct refmatch *)cb_data;
         if (!strcmp(refname, info->req_ref))
                 info->match = 1;
         if (!info->first_ref)
                 info->first_ref = xstrdup(refname);
         return info->match;
 }
 
 char *find_default_branch(struct cgit_repo *repo)
 {
         struct refmatch info;
         char *ref;
 
         info.req_ref = repo->defbranch;
         info.first_ref = NULL;
         info.match = 0;
         for_each_branch_ref(find_current_ref, &info);
         if (info.match)
                 ref = info.req_ref;
         else
                 ref = info.first_ref;
         if (ref)
                 ref = xstrdup(ref);
         return ref;
 }
 
 static int prepare_repo_cmd(struct cgit_context *ctx)
 {
         char *tmp;
         unsigned char sha1[20];
         int nongit = 0;
+        int rc;
 
         setenv("GIT_DIR", ctx->repo->path, 1);
         setup_git_directory_gently(&nongit);
         if (nongit) {
+                rc = errno;
                 ctx->page.title = fmt("%s - %s", ctx->cfg.root_title,
                                       "config error");
-                tmp = fmt("Not a git repository: '%s'", ctx->repo->path);
+                tmp = fmt("Failed to open %s: %s",
+                          ctx->repo->name,
+                          rc ? strerror(rc) : "Not a valid git repository");
                 ctx->repo = NULL;
                 cgit_print_http_headers(ctx);
                 cgit_print_docstart(ctx);
                 cgit_print_pageheader(ctx);
                 cgit_print_error(tmp);
                 cgit_print_docend();
                 return 1;
         }
         ctx->page.title = fmt("%s - %s", ctx->repo->name, ctx->repo->desc);
 
         if (!ctx->qry.head) {
                 ctx->qry.nohead = 1;
                 ctx->qry.head = find_default_branch(ctx->repo);
                 ctx->repo->defbranch = ctx->qry.head;
         }
 
         if (!ctx->qry.head) {
                 cgit_print_http_headers(ctx);
                 cgit_print_docstart(ctx);
                 cgit_print_pageheader(ctx);
                 cgit_print_error("Repository seems to be empty");
                 cgit_print_docend();
                 return 1;
         }
 
         if (get_sha1(ctx->qry.head, sha1)) {
                 tmp = xstrdup(ctx->qry.head);
                 ctx->qry.head = ctx->repo->defbranch;
                 ctx->page.status = 404;
                 ctx->page.statusmsg = "not found";
                 cgit_print_http_headers(ctx);
                 cgit_print_docstart(ctx);
                 cgit_print_pageheader(ctx);
                 cgit_print_error(fmt("Invalid branch: %s", tmp));
                 cgit_print_docend();
                 return 1;
         }
         return 0;
 }
 
 static void process_request(void *cbdata)
 {
         struct cgit_context *ctx = cbdata;
         struct cgit_cmd *cmd;
 
         cmd = cgit_get_cmd(ctx);
         if (!cmd) {
                 ctx->page.title = "cgit error";
                 cgit_print_http_headers(ctx);
                 cgit_print_docstart(ctx);
                 cgit_print_pageheader(ctx);
                 cgit_print_error("Invalid request");
                 cgit_print_docend();
                 return;
         }
 
         /* If cmd->want_vpath is set, assume ctx->qry.path contains a "virtual"
          * in-project path limit to be made available at ctx->qry.vpath.
          * Otherwise, no path limit is in effect (ctx->qry.vpath = NULL).
          */
         ctx->qry.vpath = cmd->want_vpath ? ctx->qry.path : NULL;
 
         if (cmd->want_repo && !ctx->repo) {
                 cgit_print_http_headers(ctx);