[ovs-dev] [coverity3 02/13] process: Avoid late failure if /dev/null cannot be opened.

[Ethan Jackson]

Looks Good.

On Wed, Feb 23, 2011 at 1:24 PM, Ben Pfaff <blp at nicira.com> wrote:
> It is (very slightly) risky to open /dev/null every time that we need it,
> because open can fail.  So this commit opens /dev/null in advance instead.
>
> Coverity #10719.
> ---
>  lib/process.c |   24 ++++++++++++++++++------
>  1 files changed, 18 insertions(+), 6 deletions(-)
>
> diff --git a/lib/process.c b/lib/process.c
> index 6e9ea8e..8263437 100644
> --- a/lib/process.c
> +++ b/lib/process.c
> @@ -1,5 +1,5 @@
>  /*
> - * Copyright (c) 2008, 2009, 2010 Nicira Networks.
> + * Copyright (c) 2008, 2009, 2010, 2011 Nicira Networks.
>  *
>  * Licensed under the Apache License, Version 2.0 (the "License");
>  * you may not use this file except in compliance with the License.
> @@ -195,6 +195,7 @@ process_start(char **argv,
>               struct process **pp)
>  {
>     sigset_t oldsigs;
> +    int nullfd;
>     pid_t pid;
>     int error;
>
> @@ -205,6 +206,15 @@ process_start(char **argv,
>         return error;
>     }
>
> +    if (n_null_fds) {
> +        nullfd = get_null_fd();
> +        if (nullfd < 0) {
> +            return -nullfd;
> +        }
> +    } else {
> +        nullfd = -1;
> +    }
> +
>     block_sigchld(&oldsigs);
>     pid = fork();
>     if (pid < 0) {
> @@ -225,15 +235,17 @@ process_start(char **argv,
>         unblock_sigchld(&oldsigs);
>         for (fd = 0; fd < fd_max; fd++) {
>             if (is_member(fd, null_fds, n_null_fds)) {
> -                /* We can't use get_null_fd() here because we might have
> -                 * already closed its fd. */
> -                int nullfd = open("/dev/null", O_RDWR);
>                 dup2(nullfd, fd);
> -                close(nullfd);
> -            } else if (fd >= 3 && !is_member(fd, keep_fds, n_keep_fds)) {
> +            } else if (fd >= 3 && fd != nullfd
> +                       && !is_member(fd, keep_fds, n_keep_fds)) {
>                 close(fd);
>             }
>         }
> +        if (nullfd >= 0
> +            && !is_member(nullfd, keep_fds, n_keep_fds)
> +            && !is_member(nullfd, null_fds, n_null_fds)) {
> +            close(nullfd);
> +        }
>         execvp(argv[0], argv);
>         fprintf(stderr, "execvp(\"%s\") failed: %s\n",
>                 argv[0], strerror(errno));
> --
> 1.7.2.3
>
>
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