Re: [PATCH 2/2] A loose object is not corrupt if it cannot be read due to EMFILE

[Jonathan Nieder <jrnieder@gmail.com>]

Erik Faye-Lund wrote:

> We also seem to depend quite heavily on errno being preserved on
> non-errors some places around in the code.

Hmm, sounds worrying.

- builtin/fetch.c::s_update_ref appears to have some of this kind of
  bogosity.
- safe_create_leading_directories_const and git_config_set_multivar let
  free() touch errno.  Probably not a problem.
- lock_file ought to preserve or set errno on failure.
- daemon::run_service sometimes sets errno on failure and sometimes not.
  This is confusing even if callers don't seem to care.
- fast-import::dump_marks_helper ought to do its own error reporting.
- resolve_ref seems to rely on get_packed_refs not to clobber errno.
- sha1_file::open_packed_git_1 seems to rely on unuse_one_window not to
  clobber errno.

Aside from that:

The following does not take into account correctness of error
messages.  (That is probably a good reason to fix compat/mingw's
opendir.  Sorry, I forgot to take that into account before.)

Builtins
--------
apply.c:
	checks errno following lstat() failure.
	checks errno following try_create_file() return from
	 mkdir(), symlink(), or open() failure.
clone.c:	checks errno following mkdir() and unlink() failure.
commit.c:	saves errno following strbuf_read_file() failure.
fetch.c:
	checks errno following write_in_full(), close(), fopen() failure.
	see above for the s_update_ref() checks.
for-each-ref.c:	checks errno following strtol() failure.
grep.c:	checks errno following open() and lstat() failure.
index-pack.c:
	checks errno following open() failure.
	checks errno following odb_pack_keep() [= open()] failure.
init-db.c:	checks errno following mkdir(), lstat() failure.
log.c:	checks errno following mkdir() failure.
mailsplit.c:	checks errno following opendir() failure.
pack-objects.c:	checks errno following fgets() failure.
rm.c:	checks errno following lstat() failure.
update-index.c:
	checks errno following lstat() failure.
	relies on strtoul() not to clobber errno on success.
	checks errno following hold_locked_index() return from
	 lock_file() failure (see above).
upload-archive.c:
	checks errno following read(), pipe(), fork(), and poll() failure.

Compatibility routines
----------------------
cygwin.c, inet_ntop.c, mingw.c, and mmap.c use errno in
noncosmetic ways.  I haven't checked them.

git wrapper
-----------
git.c:	checks errno following run_command_v_opt() failure.

libgit
------
config.c:	checks errno following open() failure, with intervening free().
connect.c:	checks errno following connect(), socket() failure.
copy.c:	saves errno following xread(), xwrite() failure.
daemon.c:	checks errno following poll(), accept() failure.
diff-lib.c:	checks errno following lstat() failure.
diff.c:	checks errno following lstat() failure.
dir.c:	checks errno following unlink() failure.
entry.c:	checks errno following mkdir() failure.
fast-import.c:
	saves errno following fdopen(), fprintf(), fclose() failure.
	saves errno following commit_lock_file [=close() or rename()] failure.
	relies on strtoul() not to clobber errno on success.
git-compat-util.h:
	relies on strtoul(), strtol() not to clobber errno on success.
http.c:	checks errno following open() failure.
lockfile.c:	checks errno following open() failure.
merge-recursive.c:
	checks errno following write_in_full(), unlink() failure.
path.c:	checks errno following snprintf() failure.
read-cache.c:	checks errno following lstat(), open() failure.
refs.c:	see above for resolve_ref() worries.
rerere.c:	checks errno following fwrite(), unlink() failure.
run-command.c:
	checks errno following waitpid, pipe, fork, execv, failure.
	wait_or_whine() does not set errno when child died by signal.
setup.c:	checks errno following lstat() failure.
sha1_file.c:
	checks errno following open(), opendir() failure.
	see above re unuse_one_window() failure.
sha1_name.c:	checks errno following lstat() failure.
strbuf.c:	checks errno following readlink() failure.
symlinks.c:	checks errno following stat(), lstat() failure.
transport-helper.c:	checks errno following start_command() failure.
unpack-trees.c:	checks errno following lstat() failure.
upload-pack.c:	checks errno following poll() failure.
utf8.c:	checks errno following iconv() failure.
wrapper.c:
	checks errno following read(), write(), unlink(), rmdir() failure.
write_or_die.c:	checks errno following fflush(), write() failures.

Test helpers
------------
test-run-command.c:	checks errno following start_command() failure.