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
@@ -278,263 +278,267 @@ static void querystring_cb(const char *name, const char *value)
 	} else if (!strcmp(name, "showmsg")) {
 		ctx.qry.showmsg = atoi(value);
 	} else if (!strcmp(name, "period")) {
 		ctx.qry.period = xstrdup(value);
 	} else if (!strcmp(name, "ss")) {
 		ctx.qry.ssdiff = atoi(value);
 	} else if (!strcmp(name, "all")) {
 		ctx.qry.show_all = atoi(value);
 	} else if (!strcmp(name, "context")) {
 		ctx.qry.context = atoi(value);
 	} else if (!strcmp(name, "ignorews")) {
 		ctx.qry.ignorews = atoi(value);
 	}
 }
 
 char *xstrdupn(const char *str)
 {
 	return (str ? xstrdup(str) : NULL);
 }
 
 static void prepare_context(struct cgit_context *ctx)
 {
 	memset(ctx, 0, sizeof(*ctx));
 	ctx->cfg.agefile = "info/web/last-modified";
 	ctx->cfg.nocache = 0;
 	ctx->cfg.cache_size = 0;
 	ctx->cfg.cache_dynamic_ttl = 5;
 	ctx->cfg.cache_max_create_time = 5;
 	ctx->cfg.cache_repo_ttl = 5;
 	ctx->cfg.cache_root = CGIT_CACHE_ROOT;
 	ctx->cfg.cache_root_ttl = 5;
 	ctx->cfg.cache_scanrc_ttl = 15;
 	ctx->cfg.cache_static_ttl = -1;
 	ctx->cfg.css = "/cgit.css";
 	ctx->cfg.logo = "/cgit.png";
 	ctx->cfg.local_time = 0;
 	ctx->cfg.enable_gitweb_owner = 1;
 	ctx->cfg.enable_tree_linenumbers = 1;
 	ctx->cfg.max_repo_count = 50;
 	ctx->cfg.max_commit_count = 50;
 	ctx->cfg.max_lock_attempts = 5;
 	ctx->cfg.max_msg_len = 80;
 	ctx->cfg.max_repodesc_len = 80;
 	ctx->cfg.max_blob_size = 0;
 	ctx->cfg.max_stats = 0;
 	ctx->cfg.module_link = "./?repo=%s&page=commit&id=%s";
 	ctx->cfg.project_list = NULL;
 	ctx->cfg.renamelimit = -1;
 	ctx->cfg.remove_suffix = 0;
 	ctx->cfg.robots = "index, nofollow";
 	ctx->cfg.root_title = "Git repository browser";
 	ctx->cfg.root_desc = "a fast webinterface for the git dscm";
 	ctx->cfg.scan_hidden_path = 0;
 	ctx->cfg.script_name = CGIT_SCRIPT_NAME;
 	ctx->cfg.section = "";
 	ctx->cfg.summary_branches = 10;
 	ctx->cfg.summary_log = 10;
 	ctx->cfg.summary_tags = 10;
 	ctx->cfg.max_atom_items = 10;
 	ctx->cfg.ssdiff = 0;
 	ctx->env.cgit_config = xstrdupn(getenv("CGIT_CONFIG"));
 	ctx->env.http_host = xstrdupn(getenv("HTTP_HOST"));
 	ctx->env.https = xstrdupn(getenv("HTTPS"));
 	ctx->env.no_http = xstrdupn(getenv("NO_HTTP"));
 	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);
 		cgit_print_docstart(ctx);
 		cgit_print_pageheader(ctx);
 		cgit_print_error(fmt("No repository selected"));
 		cgit_print_docend();
 		return;
 	}
 
 	if (ctx->repo && prepare_repo_cmd(ctx))
 		return;
 
 	if (cmd->want_layout) {
 		cgit_print_http_headers(ctx);
 		cgit_print_docstart(ctx);
 		cgit_print_pageheader(ctx);
 	}
 
 	cmd->fn(ctx);
 
 	if (cmd->want_layout)
 		cgit_print_docend();
 }
 
 int cmp_repos(const void *a, const void *b)
 {
 	const struct cgit_repo *ra = a, *rb = b;
 	return strcmp(ra->url, rb->url);
 }
 
 char *build_snapshot_setting(int bitmap)
 {
 	const struct cgit_snapshot_format *f;
 	char *result = xstrdup("");
 	char *tmp;
 	int len;
 
 	for (f = cgit_snapshot_formats; f->suffix; f++) {
 		if (f->bit & bitmap) {
 			tmp = result;
 			result = xstrdup(fmt("%s%s ", tmp, f->suffix));
 			free(tmp);
 		}
 	}
 	len = strlen(result);
 	if (len)
 		result[len - 1] = '\0';
 	return result;
 }
 
 char *get_first_line(char *txt)
 {
 	char *t = xstrdup(txt);
 	char *p = strchr(t, '\n');
 	if (p)
 		*p = '\0';
 	return t;
 }
 
 void print_repo(FILE *f, struct cgit_repo *repo)
 {
 	fprintf(f, "repo.url=%s\n", repo->url);
 	fprintf(f, "repo.name=%s\n", repo->name);
 	fprintf(f, "repo.path=%s\n", repo->path);
 	if (repo->owner)
 		fprintf(f, "repo.owner=%s\n", repo->owner);