Re: [PATCH 2/3] prune_object_dir(): verify that path fits in the temporary buffer

[Junio C Hamano <gitster@pobox.com>]

Jeff King <peff@peff.net> writes:

> On Wed, Dec 18, 2013 at 12:07:02PM -0800, Junio C Hamano wrote:
>
>> Jeff King <peff@peff.net> writes:
>> 
>> >> > +			prune_object(path->buf, sha1);
>> >> > +			path->len = baselen;
>> >> 
>> >> This is minor, but I prefer using strbuf_setlen() for this.
>> >
>> > Good catch. I do not think it is minor at all; my version is buggy.
>> > After the loop ends, path->len does not match the NUL in path->buf. That
>> > is OK if the next caller is strbuf-aware, but if it were to pass
>> > path->buf straight to a system call, that would be rather...confusing.
>> 
>> Hmph, rmdir(path->buf) at the end of prune_dir() may have that exact
>> issue.
>> 
>> Will squash in the following.
>
> Thanks. Are you picking this up with a commit message, or did you want
> me to re-send with the usual message/signoff?

I think this should be sufficient ;-)

-- >8 --
From: Jeff King <peff@peff.net>
Date: Tue, 17 Dec 2013 18:22:31 -0500
Subject: [PATCH] builtin/prune.c: use strbuf to avoid having to worry about PATH_MAX

While at it, rename prune_tmp_object(), which used to be a helper to
remove temporary files that were created to become loose object
files, to prune_tmp_file(), as the function is also used to remove
any random cruft whose name begins with tmp_ directly in .git/object
or .git/object/pack directories these days.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/prune.c | 38 ++++++++++++++++++++++++--------------
 1 file changed, 24 insertions(+), 14 deletions(-)

diff --git a/builtin/prune.c b/builtin/prune.c
index 6366917..99f3f35 100644
--- a/builtin/prune.c
+++ b/builtin/prune.c
@@ -17,9 +17,8 @@ static int verbose;
 static unsigned long expire;
 static int show_progress = -1;
 
-static int prune_tmp_object(const char *path, const char *filename)
+static int prune_tmp_file(const char *fullpath)
 {
-	const char *fullpath = mkpath("%s/%s", path, filename);
 	struct stat st;
 	if (lstat(fullpath, &st))
 		return error("Could not stat '%s'", fullpath);
@@ -32,9 +31,8 @@ static int prune_tmp_object(const char *path, const char *filename)
 	return 0;
 }
 
-static int prune_object(char *path, const char *filename, const unsigned char *sha1)
+static int prune_object(const char *fullpath, const unsigned char *sha1)
 {
-	const char *fullpath = mkpath("%s/%s", path, filename);
 	struct stat st;
 	if (lstat(fullpath, &st))
 		return error("Could not stat '%s'", fullpath);
@@ -50,9 +48,10 @@ static int prune_object(char *path, const char *filename, const unsigned char *s
 	return 0;
 }
 
-static int prune_dir(int i, char *path)
+static int prune_dir(int i, struct strbuf *path)
 {
-	DIR *dir = opendir(path);
+	size_t baselen = path->len;
+	DIR *dir = opendir(path->buf);
 	struct dirent *de;
 
 	if (!dir)
@@ -77,28 +76,39 @@ static int prune_dir(int i, char *path)
 			if (lookup_object(sha1))
 				continue;
 
-			prune_object(path, de->d_name, sha1);
+			strbuf_addf(path, "/%s", de->d_name);
+			prune_object(path->buf, sha1);
+			strbuf_setlen(&path, baselen);
 			continue;
 		}
 		if (!prefixcmp(de->d_name, "tmp_obj_")) {
-			prune_tmp_object(path, de->d_name);
+			strbuf_addf(path, "/%s", de->d_name);
+			prune_tmp_file(path->buf);
+			strbuf_setlen(&path, baselen);
 			continue;
 		}
-		fprintf(stderr, "bad sha1 file: %s/%s\n", path, de->d_name);
+		fprintf(stderr, "bad sha1 file: %s/%s\n", path->buf, de->d_name);
 	}
 	closedir(dir);
 	if (!show_only)
-		rmdir(path);
+		rmdir(path->buf);
 	return 0;
 }
 
 static void prune_object_dir(const char *path)
 {
+	struct strbuf buf = STRBUF_INIT;
+	size_t baselen;
 	int i;
+
+	strbuf_addstr(&buf, path);
+	strbuf_addch(&buf, '/');
+	baselen = buf.len;
+
 	for (i = 0; i < 256; i++) {
-		static char dir[4096];
-		sprintf(dir, "%s/%02x", path, i);
-		prune_dir(i, dir);
+		strbuf_addf(&buf, "%02x", i);
+		prune_dir(i, &buf);
+		strbuf_setlen(&buf, baselen);
 	}
 }
 
@@ -120,7 +130,7 @@ static void remove_temporary_files(const char *path)
 	}
 	while ((de = readdir(dir)) != NULL)
 		if (!prefixcmp(de->d_name, "tmp_"))
-			prune_tmp_object(path, de->d_name);
+			prune_tmp_file(mkpath("%s/%s", path, de->d_name));
 	closedir(dir);
 }
 
-- 
1.8.5.2-297-g3e57c29