Re: [PATCH 0/2] friendlier handling of overflows in archive-tar

[Jeff King <peff@peff.net>]

On Thu, Jun 16, 2016 at 12:35:23AM -0400, Jeff King wrote:

> The ustar format has some fixed-length numeric fields, and it's possible
> to generate a git tree that can't be represented (namely file size and
> mtime). Since f2f0267 (archive-tar: use xsnprintf for trivial
> formatting, 2015-09-24), we detect and die() in these cases. But we can
> actually do the friendly (and POSIX-approved) thing, and add extended
> pax headers to represent the correct values.
> 
>   [1/2]: archive-tar: write extended headers for file sizes >= 8GB
>   [2/2]: archive-tar: write extended headers for far-future mtime

And here's a v2 that addresses the smaller comments from René. I punted
on doing something fancy with tests. I'm not opposed to it, but I'm also
not convinced it's all that useful. Either way, I think it can come on
top if we want it.

Junio, this is the jk/big-and-old-archive-tar topic.

The interdiff is:

diff --git a/archive-tar.c b/archive-tar.c
index c7b85fd..ed562d4 100644
--- a/archive-tar.c
+++ b/archive-tar.c
@@ -179,7 +179,7 @@ static size_t get_path_prefix(const char *path, size_t pathlen, size_t maxlen)
 
 static inline unsigned long ustar_size(uintmax_t size)
 {
-	if (size < 077777777777UL)
+	if (size <= 077777777777UL)
 		return size;
 	else
 		return 0;
@@ -187,7 +187,7 @@ static inline unsigned long ustar_size(uintmax_t size)
 
 static inline unsigned long ustar_mtime(time_t mtime)
 {
-	if (mtime < 077777777777UL)
+	if (mtime <= 077777777777UL)
 		return mtime;
 	else
 		return 0;
@@ -299,7 +299,7 @@ static int write_tar_entry(struct archiver_args *args,
 			memcpy(header.linkname, buffer, size);
 	}
 
-	if (ustar_size(size) != size)
+	if (S_ISREG(mode) && ustar_size(size) != size)
 		strbuf_append_ext_header_uint(&ext_header, "size", size);
 	if (ustar_mtime(args->time) != args->time)
 		strbuf_append_ext_header_uint(&ext_header, "mtime", args->time);