[PATCH 0/4] Detect exec errors in start_command early

From: Johannes Sixt <j6t@kdbg.org>
Date: Jan 10, 2010, 13:04 UTC
Message-ID: <201001101404.22258.j6t@kdbg.org>
In-Reply-To: <1263044757-12560-2-git-send-email-ilari.liusvaara@elisanet.fi>

On Samstag, 9. Januar 2010, Ilari Liusvaara wrote:

>  6 files changed, 282 insertions(+), 13 deletions(-)

IMHO, you are going completely overboard with your patch.

You check every single possible and unlikely error condition in the new code that you introde, but ignore that there are quite a number of calls in the existing code whose error conditions go checked.

And as a result, you "only" report errno values of some calls, and ignore that there is at least one potential die() call hidden in execv_git_cmd(). IOW, your code is not a catch-all and only an isolated solution.

I hope I can do better.

I developed this series on top of il/vcs-helper. But patches 1-3/4 are actually an independent topic and also suitable to be merged into jk/run-command-use-shell to implement improved DWIM whether a shell is needed.

Patch 4/4 is to address your problem of weak error reporting with transport helpers. I think I understand now what your problem is -- namely that previously no error was reported if a transport helper program did not exist. The reason for the missing error message is IMO a design weakness in the protocol: It requires that the parent talks first - and by talking to an early-died child process it dies from SIGPIPE. I experimented with signal(SIGPIPE, SIG_IGN) to get around this, but it didn't work (the SIGPIPE arrived anyway).

Anyway, patch 4/4 goes on top of il/vcs-helper after merging the topic consisting of 1-3/4.

Ilari Liusvaara (1):
  Improve error message when a transport helper was not found

Johannes Sixt (3):
  start_command: report child process setup errors to the parent's
    stderr
  run-command: move wait_or_whine earlier
  start_command: detect execvp failures early

 Makefile               |    1 +
 run-command.c          |  177 
+++++++++++++++++++++++++++++++++++-------------
 t/t0061-run-command.sh |   14 ++++
 test-run-command.c     |   35 ++++++++++
 transport-helper.c     |   14 +++-
 5 files changed, 191 insertions(+), 50 deletions(-)
 create mode 100755 t/t0061-run-command.sh
 create mode 100644 test-run-command.c