git/fetch: ensure we clean packfiles on failure

When pulling into a git repository that is group
writable as a non-owner, the pack file is left
in place because we do not have permission to
remove it.

We also leave it behind if we bail out early due
to an error, or due to only listing the changes.

This pushes down the creation of the file, and
cleans it up on error.

thanks to Anthony Martin for spotting the bug.
git/fetch: ensure we clean packfiles on failure

When pulling into a git repository that is group
writable as a non-owner, the pack file is left
in place because we do not have permission to
remove it.

We also leave it behind if we bail out early due
to an error, or due to only listing the changes.

This pushes down the creation of the file, and
cleans it up on error.

Also, while we're here, clean up index caching,
and ensure we close the fd in all cases.

thanks to Anthony Martin for spotting the bug.

sys/src/cmd/git/fetch.c

@@ -5,7 +5,6 @@
 
 char *fetchbranch;
 char *upstream = "origin";
-char *packtmp = ".git/objects/pack/fetch.tmp";
 int listonly;
 
 int
@@ -111,7 +110,7 @@ mkoutpath(char *path)
 	for(p=strchr(s+1, '/'); p; p=strchr(p+1, '/')){
 		*p = 0;
 		if(access(s, AEXIST) != 0){
-			fd = create(s, OREAD, DMDIR | 0755);
+			fd = create(s, OREAD, DMDIR | 0775);
 			if(fd == -1)
 				return -1;
 			close(fd);
@@ -162,13 +161,30 @@ handlecaps(char *caps)
 	}
 }
 
-int
-fetchpack(Conn *c, int pfd, char *packtmp)
+void
+fail(char *pack, char *idx, char *msg, ...)
 {
-	char buf[Pktmax], idxtmp[256], *sp[3];
+	char buf[ERRMAX];
+	va_list ap;
+
+	va_start(ap, msg);
+	snprint(buf, sizeof(buf), msg, ap);
+	va_end(ap);
+
+	remove(pack);
+	remove(idx);
+	fprint(2, "%s", buf);
+	exits(buf);
+}
+
+int
+fetchpack(Conn *c)
+{
+	char buf[Pktmax], *sp[3];
+	char *packtmp, *idxtmp;
 	Hash h, *have, *want;
 	int nref, refsz, first;
-	int i, n, req;
+	int i, n, req, pfd;
 	vlong packsz;
 	Object *o;
 
@@ -249,6 +265,15 @@ fetchpack(Conn *c, int pfd, char *packtmp)
 		sysfatal("read: %r");
 	buf[n] = 0;
 
+	if((packtmp = smprint(".git/objects/pack/fetch.%d.pack", getpid())) == nil)
+		sysfatal("smprint: %r");
+	if((idxtmp = smprint(".git/objects/idx/fetch.%d.idx", getpid())) == nil)
+		sysfatal("smprint: %r");
+	if(mkoutpath(packtmp) == -1)
+		sysfatal("could not create %s: %r", packtmp);
+	if((pfd = create(packtmp, ORDWR, 0664)) == -1)
+		sysfatal("could not create %s: %r", packtmp);
+
 	fprint(2, "fetching...\n");
 	packsz = 0;
 	while(1){
@@ -259,19 +284,17 @@ fetchpack(Conn *c, int pfd, char *packtmp)
 			sysfatal("fetch packfile: %r");
 		packsz += n;
 	}
+
 	closeconn(c);
 	if(seek(pfd, 0, 0) == -1)
-		sysfatal("packfile seek: %r");
+		fail(packtmp, idxtmp, "packfile seek: %r");
 	if(checkhash(pfd, packsz, &h) == -1)
-		sysfatal("corrupt packfile: %r");
+		fail(packtmp, idxtmp, "corrupt packfile: %r");
 	close(pfd);
-	n = strlen(packtmp) - strlen(".tmp");
-	memcpy(idxtmp, packtmp, n);
-	memcpy(idxtmp + n, ".idx", strlen(".idx") + 1);
 	if(indexpack(packtmp, idxtmp, h) == -1)
-		sysfatal("could not index fetched pack: %r");
+		fail(packtmp, idxtmp, "could not index fetched pack: %r");
 	if(rename(packtmp, idxtmp, h) == -1)
-		sysfatal("could not rename indexed pack: %r");
+		fail(packtmp, idxtmp, "could not rename indexed pack: %r");
 	return 0;
 }
 
@@ -287,7 +310,6 @@ usage(void)
 void
 main(int argc, char **argv)
 {
-	int pfd;
 	Conn c;
 
 	ARGBEGIN{
@@ -302,14 +324,9 @@ main(int argc, char **argv)
 	if(argc != 1)
 		usage();
 
-	if(mkoutpath(packtmp) == -1)
-		sysfatal("could not create %s: %r", packtmp);
-	if((pfd = create(packtmp, ORDWR, 0644)) == -1)
-		sysfatal("could not create %s: %r", packtmp);
-
 	if(gitconnect(&c, argv[0], "upload") == -1)
 		sysfatal("could not dial %s: %r", argv[0]);
-	if(fetchpack(&c, pfd, packtmp) == -1)
+	if(fetchpack(&c) == -1)
 		sysfatal("fetch failed: %r");
 	closeconn(&c);
 	exits(nil);

sys/src/cmd/git/pack.c

@@ -197,23 +197,22 @@ loadpack(Packf *pf, char *name)
 		}
 	}
 	if((ifd = open(buf, OREAD)) == -1)
-		goto error;
-	if((d = dirfstat(ifd)) == nil)
-		goto error;
+		return -1;
+	if((d = dirfstat(ifd)) == nil){
+		close(ifd);
+		return -1;
+	}
 	pf->nidx = d->length;
 	pf->idx = emalloc(pf->nidx);
 	if(readn(ifd, pf->idx, pf->nidx) != pf->nidx){
+		close(ifd);
 		free(pf->idx);
 		free(d);
-		goto error;
+		return -1;
 	}
+	close(ifd);
 	free(d);
 	return 0;
-
-error:
-	if(ifd != -1)
-		close(ifd);
-	return -1;	
 }
 
 static void