Re: [PATCH 0/3] Be more careful when prunning

On Thu, Oct 06, 2011 at 22:19:42 +0200, Carlos Martín Nieto wrote:

The first patch is not that big a deal, but it's better if we're
freeing the refspecs, we might as well free all of them.

The second patch teaches get_stale_heads to use the user-provided
refspecs instead of the ones in the config. For example, running

    git fetch --prune origin refs/heads/master:refs/heads/master

doesn't remove the other branches anymore. For a more interesting (and
believable) example, let's take

    git fetch --prune origin refs/heads/b/*:refs/heads/b/*

because you want to prune the refs inside the b/ namespace
only. Currently git will delete all the refs that aren't under that
namespace. With the second patch applied, git won't remove any refs
outside the b/ namespace.

What is probably the most usual case is covered by the third patch,
which pretends that a "refs/tags/*:refs/tags/*" refspec was given on
the command-line.

I applied the patches to current master (7f41b6b) and got a segfault
with:

    git fetch -p -t origin master

It does not happen with master.

Backtrace:

(gdb) bt
#0  0x00007ffff7395d18 in __strchr_sse42 () from /lib64/libc.so.6
#1  0x00000000004b2d39 in find_in_refs (query=0x7fffffffdb90, ref_count=2, refs=<optimized out>) at remote.c:1709
#2  get_stale_heads_cb (refname=0x7a8f31 "refs/heads/a/branch/name", sha1=0x7a8f09 "\367\343\375C٩\223u\305OG\233)z\347X\370\333\325", <incomplete sequence \335>, flags=0, cb_data=0x7fffffffdc50) at remote.c:1740
#3  0x00000000004adf19 in do_for_each_ref (submodule=<optimized out>, base=0x4ea1c2 "", fn=0x4b2ca0 <get_stale_heads_cb>, trim=0, flags=0, cb_data=0x7fffffffdc50) at refs.c:684
#4  0x00000000004b4249 in get_stale_heads (remote=<optimized out>, fetch_map=<optimized out>, refs=<optimized out>, ref_count=<optimized out>) at remote.c:1777
#5  0x0000000000426cfb in prune_refs (ref_map=<optimized out>, n=<optimized out>, refs=<optimized out>, transport=0x78e040) at builtin/fetch.c:511
#6  do_fetch (ref_count=<optimized out>, refs=<optimized out>, transport=0x78e040) at builtin/fetch.c:711
#7  fetch_one (remote=<optimized out>, argc=<optimized out>, argv=<optimized out>) at builtin/fetch.c:894
#8  0x0000000000427550 in cmd_fetch (argc=2, argv=0x7fffffffe070, prefix=0x0) at builtin/fetch.c:955
#9  0x0000000000405084 in run_builtin (argv=0x7fffffffe070, argc=5, p=0x731b08) at git.c:308
#10 handle_internal_command (argc=5, argv=0x7fffffffe070) at git.c:466
#11 0x000000000040448b in run_argv (argv=0x7fffffffdf10, argcp=0x7fffffffdf1c) at git.c:512
#12 main (argc=5, argv=0x7fffffffe070) at git.c:585

--Ben