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Merge branch 'jk/run-command-capture'

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The run-command interface was easy to abuse and make a pipe for us
to read from the process, wait for the process to finish and then
attempt to read its output, which is a pattern that lead to a
deadlock.  Fix such uses by introducing a helper to do this
correctly (i.e. we need to read first and then wait the process to
finish) and also add code to prevent such abuse in the run-command
helper.

* jk/run-command-capture:
  run-command: forbid using run_command with piped output
  trailer: use capture_command
  submodule: use capture_command
  wt-status: use capture_command
  run-command: introduce capture_command helper
  wt_status: fix signedness mismatch in strbuf_read call
  wt-status: don't flush before running "submodule status"
This commit is contained in:
Junio C Hamano
2015-03-25 12:54:27 -07:00
parent d78374e578 c29b3962af
commit ea1fd481b4
5 changed files with 44 additions and 24 deletions
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23
run-command.c
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@ -557,7 +557,12 @@ int finish_command(struct child_process *cmd)
int run_command(struct child_process *cmd)
{
int code = start_command(cmd);
int code;
if (cmd->out < 0 || cmd->err < 0)
die("BUG: run_command with a pipe can cause deadlock");
code = start_command(cmd);
if (code)
return code;
return finish_command(cmd);
@ -829,3 +834,19 @@ int run_hook_le(const char *const *env, const char *name, ...)
return ret;
}
int capture_command(struct child_process *cmd, struct strbuf *buf, size_t hint)
{
cmd->out = -1;
if (start_command(cmd) < 0)
return -1;
if (strbuf_read(buf, cmd->out, hint) < 0) {
close(cmd->out);
finish_command(cmd); /* throw away exit code */
return -1;
}
close(cmd->out);
return finish_command(cmd);
}