ui-snapshot: avoid segfault when no filename is specified

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

1 files changed, 17 insertions, 6 deletions

diff --git a/ui-snapshot.c b/ui-snapshot.c
index f25613e..5372f5d 100644
--- a/ui-snapshot.c
+++ b/ui-snapshot.c
@@ -1,194 +1,205 @@
 /* ui-snapshot.c: generate snapshot of a commit
  *
  * Copyright (C) 2006 Lars Hjemli
  *
  * Licensed under GNU General Public License v2
  *   (see COPYING for full license text)
  */
 
 #include "cgit.h"
 #include "html.h"
 #include "ui-shared.h"
 
 static int write_compressed_tar_archive(struct archiver_args *args,const char *filter)
 {
 	int rw[2];
 	pid_t gzpid;
 	int stdout2;
 	int status;
 	int rv;
 
 	stdout2 = chk_non_negative(dup(STDIN_FILENO), "Preserving STDOUT before compressing");
 	chk_zero(pipe(rw), "Opening pipe from compressor subprocess");
 	gzpid = chk_non_negative(fork(), "Forking compressor subprocess");
 	if(gzpid==0) {
 		/* child */
 		chk_zero(close(rw[1]), "Closing write end of pipe in child");
 		chk_zero(close(STDIN_FILENO), "Closing STDIN");
 		chk_non_negative(dup2(rw[0],STDIN_FILENO), "Redirecting compressor input to stdin");
 		execlp(filter,filter,NULL);
 		_exit(-1);
 	}
 	/* parent */
 	chk_zero(close(rw[0]), "Closing read end of pipe");
 	chk_non_negative(dup2(rw[1],STDOUT_FILENO), "Redirecting output to compressor");
 
 	rv = write_tar_archive(args);
 
 	chk_zero(close(STDOUT_FILENO), "Closing STDOUT redirected to compressor");
 	chk_non_negative(dup2(stdout2,STDOUT_FILENO), "Restoring uncompressed STDOUT");
 	chk_zero(close(stdout2), "Closing uncompressed STDOUT");
 	chk_zero(close(rw[1]), "Closing write end of pipe in parent");
 	chk_positive(waitpid(gzpid,&status,0), "Waiting on compressor process");
 	if(! ( WIFEXITED(status) && WEXITSTATUS(status)==0 ) )
 		cgit_print_error("Failed to compress archive");
 
 	return rv;
 }
 
 static int write_tar_gzip_archive(struct archiver_args *args)
 {
 	return write_compressed_tar_archive(args,"gzip");
 }
 
 static int write_tar_bzip2_archive(struct archiver_args *args)
 {
 	return write_compressed_tar_archive(args,"bzip2");
 }
 
 const struct cgit_snapshot_format cgit_snapshot_formats[] = {
 	{ ".zip", "application/x-zip", write_zip_archive, 0x1 },
 	{ ".tar.gz", "application/x-gzip", write_tar_gzip_archive, 0x2 },
 	{ ".tar.bz2", "application/x-bzip2", write_tar_bzip2_archive, 0x4 },
 	{ ".tar", "application/x-tar", write_tar_archive, 0x8 },
 	{}
 };
 
 static const struct cgit_snapshot_format *get_format(const char *filename)
 {
 	const struct cgit_snapshot_format *fmt;
 	int fl, sl;
 
 	fl = strlen(filename);
 	for(fmt = cgit_snapshot_formats; fmt->suffix; fmt++) {
 		sl = strlen(fmt->suffix);
 		if (sl >= fl)
 			continue;
 		if (!strcmp(fmt->suffix, filename + fl - sl))
 			return fmt;
 	}
 	return NULL;
 }
 
 static int make_snapshot(const struct cgit_snapshot_format *format,
 			 const char *hex, const char *prefix,
 			 const char *filename)
 {
 	struct archiver_args args;
 	struct commit *commit;
 	unsigned char sha1[20];
 
 	if(get_sha1(hex, sha1)) {
 		cgit_print_error(fmt("Bad object id: %s", hex));
 		return 1;
 	}
 	commit = lookup_commit_reference(sha1);
 	if(!commit) {
 		cgit_print_error(fmt("Not a commit reference: %s", hex));
 		return 1;
 	}
 	memset(&args, 0, sizeof(args));
 	if (prefix) {
 		args.base = fmt("%s/", prefix);
 		args.baselen = strlen(prefix) + 1;
 	} else {
 		args.base = "";
 		args.baselen = 0;
 	}
 	args.tree = commit->tree;
 	args.time = commit->date;
 	ctx.page.mimetype = xstrdup(format->mimetype);
 	ctx.page.filename = xstrdup(filename);
 	cgit_print_http_headers(&ctx);
 	format->write_func(&args);
 	return 0;
 }
 
 /* Try to guess the requested revision from the requested snapshot name.
  * First the format extension is stripped, e.g. "cgit-0.7.2.tar.gz" become
  * "cgit-0.7.2". If this is a valid commit object name we've got a winner.
  * Otherwise, if the snapshot name has a prefix matching the result from
  * repo_basename(), we strip the basename and any following '-' and '_'
  * characters ("cgit-0.7.2" -> "0.7.2") and check the resulting name once
  * more. If this still isn't a valid commit object name, we check if pre-
  * pending a 'v' to the remaining snapshot name ("0.7.2" -> "v0.7.2") gives
  * us something valid.
  */
 static const char *get_ref_from_filename(const char *url, const char *filename,
 					 const struct cgit_snapshot_format *format)
 {
 	const char *reponame;
 	unsigned char sha1[20];
 	char *snapshot;
 
 	snapshot = xstrdup(filename);
 	snapshot[strlen(snapshot) - strlen(format->suffix)] = '\0';
 	fprintf(stderr, "snapshot=%s\n", snapshot);
 
 	if (get_sha1(snapshot, sha1) == 0)
 		return snapshot;
 
 	reponame = cgit_repobasename(url);
 	fprintf(stderr, "reponame=%s\n", reponame);
 	if (prefixcmp(snapshot, reponame) == 0) {
 		snapshot += strlen(reponame);
 		while (snapshot && (*snapshot == '-' || *snapshot == '_'))
 			snapshot++;
 	}
 
 	if (get_sha1(snapshot, sha1) == 0)
 		return snapshot;
 
 	snapshot = fmt("v%s", snapshot);
 	if (get_sha1(snapshot, sha1) == 0)
 		return snapshot;
 
 	return NULL;
 }
 
+void show_error(char *msg)
+{
+	ctx.page.mimetype = "text/html";
+	cgit_print_http_headers(&ctx);
+	cgit_print_docstart(&ctx);
+	cgit_print_pageheader(&ctx);
+	cgit_print_error(msg);
+	cgit_print_docend();
+}
+
 void cgit_print_snapshot(const char *head, const char *hex,
 			 const char *filename, int snapshots, int dwim)
 {
 	const struct cgit_snapshot_format* f;
 	char *prefix = NULL;
 
+	if (!filename) {
+		show_error("No snapshot name specified");
+		return;
+	}
+
 	f = get_format(filename);
 	if (!f) {
-		ctx.page.mimetype = "text/html";
-		cgit_print_http_headers(&ctx);
-		cgit_print_docstart(&ctx);
-		cgit_print_pageheader(&ctx);
-		cgit_print_error(fmt("Unsupported snapshot format: %s", filename));
-		cgit_print_docend();
+		show_error(xstrdup(fmt("Unsupported snapshot format: %s",
+				       filename)));
 		return;
 	}
 
 	if (!hex && dwim) {
 		hex = get_ref_from_filename(ctx.repo->url, filename, f);
 		if (hex == NULL) {
 			html_status(404, "Not found", 0);
 			return;
 		}
 		prefix = xstrdup(filename);
 		prefix[strlen(filename) - strlen(f->suffix)] = '\0';
 	}
 
 	if (!hex)
 		hex = head;
 
 	if (!prefix)
 		prefix = xstrdup(cgit_repobasename(ctx.repo->url));
 
 	make_snapshot(f, hex, prefix, filename);
 	free(prefix);
 }