Re: [PATCH] Fix start_command closing cmd->out/in regardless of cmd->close_out/in

[Johannes Sixt <j.sixt@viscovery.net>]

Ping Yin schrieb:
> When 'FILE *fp' is assigned to child_process.out and then start_command or
> run_command is run, the standard output of the child process is expected to
> be outputed to fp. However, sometimes fp is not expected to be closed since
> further IO may be still performmed on fp.
> ---
>  run-command.c |    4 ----
>  1 files changed, 0 insertions(+), 4 deletions(-)
> 
> diff --git a/run-command.c b/run-command.c
> index 476d00c..4e5f58d 100644
> --- a/run-command.c
> +++ b/run-command.c
> @@ -115,13 +115,9 @@ int start_command(struct child_process *cmd)
>  
>  	if (need_in)
>  		close(fdin[0]);
> -	else if (cmd->in)
> -		close(cmd->in);
>  
>  	if (need_out)
>  		close(fdout[1]);
> -	else if (cmd->out > 1)
> -		close(cmd->out);
>  
>  	if (need_err)
>  		close(fderr[1]);

This is dangerous! You have to audit all current callers whether they close 
cmd->in or cmd->out (if they don't need the fd anymore). Otherwise you risk 
to keep a writable pipe end open and then the reader hangs, waiting for 
input that will never arrive.

-- Hannes