[Libguestfs] [PATCH libguestfs] guestfish: detect a few more failed syscalls

[Matthew Booth]

On 19/08/09 09:34, Jim Meyering wrote:
> There were a few unchecked syscalls in fish.c
>
>> From ba8b8b0684a03b6e6fbb939ed7e1cbf5e1000092 Mon Sep 17 00:00:00 2001
> From: Jim Meyering<meyering at redhat.com>
> Date: Wed, 19 Aug 2009 10:01:07 +0200
> Subject: [PATCH libguestfs] guestfish: detect a few more failed syscalls
>
> * fish/fish.c (issue_command): Detect/diagnose more failed syscalls.
> ---
>   fish/fish.c |   26 +++++++++++++++++++++-----
>   1 files changed, 21 insertions(+), 5 deletions(-)
>
> diff --git a/fish/fish.c b/fish/fish.c
> index 830617b..e6cd270 100644
> --- a/fish/fish.c
> +++ b/fish/fish.c
> @@ -750,8 +750,14 @@ issue_command (const char *cmd, char *argv[], const char *pipecmd)
>     if (pipecmd) {
>       int fd[2];
>
> -    fflush (stdout);
> -    pipe (fd);
> +    if (fflush (stdout)); {

Looks like a stray semicolon in there. Also, wouldn't it be better form 
to test for test for a return value of EOF?

> +      perror ("failed to flush standard output");
> +      return -1;
> +    }
> +    if (pipe (fd)) {
> +      perror ("pipe failed");
> +      return -1;
> +    }

Again, I'd explicitly test for a return value of -1 for consistency.

>       pid = fork ();
>       if (pid == -1) {
>         perror ("fork");
> @@ -760,7 +766,10 @@ issue_command (const char *cmd, char *argv[], const char *pipecmd)
>
>       if (pid == 0) {		/* Child process. */
>         close (fd[1]);
> -      dup2 (fd[0], 0);
> +      if (dup2 (fd[0], 0)<  0) {
> +        perror ("dup2 of stdin failed");
> +        _exit (1);
> +      }

fd[1] ought to be closed after this call. Not directly relevant to this 
patch, but '0' is a magic number. Use STDIN_FILENO from unistd.h.

>         r = system (pipecmd);
>         if (r == -1) {
> @@ -770,9 +779,16 @@ issue_command (const char *cmd, char *argv[], const char *pipecmd)
>         _exit (WEXITSTATUS (r));
>       }
>
> -    stdout_saved_fd = dup (1);
> +    if ((stdout_saved_fd = dup (1))<  0) {
> +      perror ("failed to dup stdout");
> +      return -1;
> +    }

'1' is a magic number. Use STDOUT_FILENO from unistd.h.

>       close (fd[0]);
> -    dup2 (fd[1], 1);
> +    if (dup2 (fd[1], 1)) {
> +      perror ("failed to dup stdout");
> +      close (stdout_saved_fd);
> +      return -1;
> +    }

Test for return value of -1. '1' is a magic number.

>       close (fd[1]);
>     }
>
> --
> 1.6.4.378.g88f2f

Matt
-- 
Matthew Booth, RHCA, RHCSS
Red Hat Engineering, Virtualisation Team

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