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Re: [libvirt] [PATCH 1/2] Use '-' to read from stdin



On 06/13/2011 09:39 PM, Michael Williams wrote:
> Modify virFileReadAll to open stdin when '-' is given as the filename.
> 
> Signed-off-by: Michael Williams <mspacex gmail com>
> ---
>  src/util/util.c |    8 +++++++-
>  1 files changed, 7 insertions(+), 1 deletions(-)
> 
> diff --git a/src/util/util.c b/src/util/util.c
> index df4dfac..554d68e 100644
> --- a/src/util/util.c
> +++ b/src/util/util.c
> @@ -443,7 +443,13 @@ virFileReadLimFD(int fd, int maxlen, char **buf)
>   int virFileReadAll(const char *path, int maxlen, char **buf)
>  {
> -    int fd = open(path, O_RDONLY);
> +    int fd;
> +
> +    if (strcmp(path,"-") == 0)

s/,"/, "/ - space after comma.

> +    	fd = fileno(stdin);

Micro-optimization: POSIX guarantees that the constant STDIN_FILENO
works here, which is slightly more efficient than fileno(stdin).

Problem: this closes fd 0 after virFileReadLimFD, even though the user
probably wants to keep on using stdin (especially if stdin is a tty, and
EOF was triggered by ^D although the terminal still accepts input).  You
have to avoid closing the fd if "-" was present.

Question: is this sufficient?  That is, do all virsh.c callers that read
file contents eventually call into this function, or do you need to also
hook up some other locations to honor "-"?

-- 
Eric Blake   eblake redhat com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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