[libvirt RFCv6 05/27] virfile: change virFileDiskCopy arguments to extend beyond stdin, stdout

[Daniel P. Berrangé]

On Thu, May 05, 2022 at 02:52:19PM +0200, Claudio Fontana wrote:
> Signed-off-by: Claudio Fontana <cfontana at suse.de>
> ---
>  src/util/iohelper.c | 17 +---------
>  src/util/virfile.c  | 82 ++++++++++++++++++++++++++++++++++-----------
>  src/util/virfile.h  |  2 +-
>  3 files changed, 64 insertions(+), 37 deletions(-)
> 
> diff --git a/src/util/iohelper.c b/src/util/iohelper.c
> index ce10ccb905..055540c8c4 100644
> --- a/src/util/iohelper.c
> +++ b/src/util/iohelper.c
> @@ -58,7 +58,6 @@ int
>  main(int argc, char **argv)
>  {
>      const char *path;
> -    int oflags = -1;
>      int fd = -1;
>  
>      program_name = argv[0];
> @@ -79,25 +78,11 @@ main(int argc, char **argv)
>                      program_name, argv[3]);
>              exit(EXIT_FAILURE);
>          }
> -#ifdef F_GETFL
> -        oflags = fcntl(fd, F_GETFL);
> -#else
> -        /* Stupid mingw.  */
> -        if (fd == STDIN_FILENO)
> -            oflags = O_RDONLY;
> -        else if (fd == STDOUT_FILENO)
> -            oflags = O_WRONLY;
> -#endif
> -        if (oflags < 0) {
> -            fprintf(stderr, _("%s: unable to determine access mode of fd %d"),
> -                    program_name, fd);
> -            exit(EXIT_FAILURE);
> -        }
>      } else { /* unknown argc pattern */
>          usage(EXIT_FAILURE);
>      }
>  
> -    if (fd < 0 || virFileDiskCopy(path, fd, oflags) < 0)
> +    if (fd < 0 || virFileDiskCopy(fd, path, -1, "stdio") < 0)
>          goto error;
>  
>      return 0;
> diff --git a/src/util/virfile.c b/src/util/virfile.c
> index 30b0eee074..87d3e53819 100644
> --- a/src/util/virfile.c
> +++ b/src/util/virfile.c
> @@ -4669,19 +4669,64 @@ runIOCopy(const struct runIOParams p)
>      return total;
>  }
>  
> +/**
> + * virFileDiskCopy: run IO to copy data between storage and a pipe or socket.
> + *
> + * @disk_fd:     the already open regular file or block device
> + * @disk_path:   the pathname corresponding to disk_fd (for error reporting)
> + * @remote_fd:   the pipe or socket
> + *               Use -1 to auto-choose between STDIN or STDOUT.
> + * @remote_path: the pathname corresponding to remote_fd (for error reporting)
> + *
> + * Note that the direction of the transfer is detected based on the @disk_fd
> + * file access mode (man 2 open). Therefore @disk_fd must be opened with
> + * O_RDONLY or O_WRONLY. O_RDWR is not supported.
> + *
> + * virFileDiskCopy always closes the file descriptor disk_fd,
> + * and any error during close(2) is reported and considered a failure.
> + *
> + * Returns: bytes transferred or < 0 on failure.
> + */
>  
>  off_t
> -virFileDiskCopy(const char *path, int fd, int oflags)
> +virFileDiskCopy(int disk_fd, const char *disk_path, int remote_fd, const char *remote_path)
>  {
>      int ret = -1;
>      off_t total = 0;
>      struct stat sb;
>      struct runIOParams p;
> +    int oflags = -1;
> +
> +#ifdef F_GETFL
> +    oflags = fcntl(disk_fd, F_GETFL);
> +#else /* !F_GETFL */
> +    /*
> +     * mingw still does not support F_GETFL, and does not seem willing to
> +     * support it in the future. So we need a hack to get iohelper working,
> +     * specifically possible only when using stdio.
> +     */
> +    if (disk_fd == STDIN_FILENO) {
> +        oflags = O_RDONLY;
> +    } else if (disk_fd == STDOUT_FILENO) {
> +        oflags = O_WRONLY;
> +    } else {
> +        virReportError(VIR_ERR_OPERATION_UNSUPPORTED,
> +                       _("%s: disk_fd must be stdin or stdout, due to lack of F_GETFL (mingw)"),
> +                       __FUNCTION__);
> +        goto cleanup;
> +    }
> +#endif /* !F_GETFL */

With this issue, and the posix_memalign issue, I'm inclined to say we
should just take the easy way out and hide virFileDiskCopy behind
#ifndef WIN32, since we don't even need it on WIN32.


With regards,
Daniel
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