[PATCH 0/18] snprintf cleanups

Our code base calls snprintf() into a fixed-size buffer in a bunch of places. Sometimes we check the result, and sometimes we accept a silent truncation. In some cases an overflow is easy given long input. In some cases it's impossible. And in some cases it depends on how big PATH_MAX is on your filesystem, and whether it's actually enforced. :)

This series attempts to give more predictable and consistent results by removing arbitrary buffer limitations. It also tries to make further audits of snprintf() easier by converting to xsnprintf() where appropriate.

There are still some snprintf() calls left after this. A few are in code that's in flux, or is being cleaned up in nearby series (several of my recent cleanup series were split off from this). A few should probably remain (e.g., git-daemon will refuse to consider a repo name larger than PATH_MAX, which may be a reasonable defense against weird memory tricks. I wouldn't be sad to see this turned into a strbuf with an explicit length policy enforced separately, though). And there were a few that I just didn't get around to converting (the dumb-http walker, for example, but I think it may need a pretty involved audit overall).

It's a lot of patches, but hopefully they're all pretty straightforward to read.

  [01/18]: do not check odb_mkstemp return value for errors
  [02/18]: odb_mkstemp: write filename into strbuf
  [03/18]: odb_mkstemp: use git_path_buf
  [04/18]: diff: avoid fixed-size buffer for patch-ids
  [05/18]: tag: use strbuf to format tag header
  [06/18]: fetch: use heap buffer to format reflog
  [07/18]: avoid using fixed PATH_MAX buffers for refs
  [08/18]: avoid using mksnpath for refs
  [09/18]: create_branch: move msg setup closer to point of use
  [10/18]: create_branch: use xstrfmt for reflog message
  [11/18]: name-rev: replace static buffer with strbuf
  [12/18]: receive-pack: print --pack-header directly into argv array
  [13/18]: replace unchecked snprintf calls with heap buffers
  [14/18]: combine-diff: replace malloc/snprintf with xstrfmt
  [15/18]: convert unchecked snprintf into xsnprintf
  [16/18]: transport-helper: replace checked snprintf with xsnprintf
  [17/18]: gc: replace local buffer with git_path
  [18/18]: daemon: use an argv_array to exec children

 bisect.c               |  8 +++++---
 branch.c               | 16 ++++++++--------
 builtin/checkout.c     |  5 ++---
 builtin/fetch.c        |  6 ++++--
 builtin/gc.c           |  8 +-------
 builtin/index-pack.c   | 22 ++++++++++++----------
 builtin/ls-remote.c    | 10 ++++++----
 builtin/name-rev.c     | 21 ++++++++++++---------
 builtin/notes.c        |  9 ++++-----
 builtin/receive-pack.c | 17 ++++++++++-------
 builtin/replace.c      | 50 +++++++++++++++++++++++++++-----------------------
 builtin/rev-parse.c    |  5 +++--
 builtin/tag.c          | 42 ++++++++++++++++++------------------------
 cache.h                |  7 +++++--
 combine-diff.c         |  7 ++++---
 daemon.c               | 38 +++++++++++++++++---------------------
 diff.c                 | 20 +++++++++++++-------
 environment.c          | 14 ++++++--------
 fast-import.c          |  9 +++++----
 grep.c                 |  4 ++--
 http.c                 | 10 +++++-----
 imap-send.c            |  2 +-
 pack-bitmap-write.c    | 14 +++++++-------
 pack-write.c           | 16 ++++++++--------
 refs.c                 | 44 ++++++++++++++++++++++++++------------------
 sha1_file.c            |  4 ++--
 submodule.c            |  2 +-
 transport-helper.c     |  5 +----
 28 files changed, 215 insertions(+), 200 deletions(-)