Re: [PATCH v4 2/6] util: refactor qemu_open_old to split off variadic args handling

[Markus Armbruster]

Daniel P. Berrangé <berrange@redhat.com> writes:

> This simple refactoring prepares for future patches. The variadic args
> handling is split from the main bulk of the open logic. The duplicated
> calls to open() are removed in favour of updating the "flags" variable
> to have O_CLOEXEC.
>
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> ---
>  util/osdep.c | 40 +++++++++++++++++++++++++++-------------
>  1 file changed, 27 insertions(+), 13 deletions(-)
>
> diff --git a/util/osdep.c b/util/osdep.c
> index 9df1b6adec..9ff92551e7 100644
> --- a/util/osdep.c
> +++ b/util/osdep.c
> @@ -22,6 +22,7 @@
>   * THE SOFTWARE.
>   */
>  #include "qemu/osdep.h"
> +#include "qapi/error.h"
>  
>  /* Needed early for CONFIG_BSD etc. */
>  
> @@ -282,10 +283,10 @@ int qemu_lock_fd_test(int fd, int64_t start, int64_t 
> len, bool exclusive)
>  /*
>   * Opens a file with FD_CLOEXEC set
>   */
> -int qemu_open_old(const char *name, int flags, ...)
> +static int
> +qemu_open_internal(const char *name, int flags, mode_t mode)
>  {
>      int ret;
> -    int mode = 0;
>  
>  #ifndef _WIN32
>      const char *fdset_id_str;
> @@ -323,22 +324,35 @@ int qemu_open_old(const char *name, int flags, ...)
>      }
>  #endif
>  
> -    if (flags & O_CREAT) {
> -        va_list ap;
> -
> -        va_start(ap, flags);
> -        mode = va_arg(ap, int);
> -        va_end(ap);
> -    }
> -
>  #ifdef O_CLOEXEC
> -    ret = open(name, flags | O_CLOEXEC, mode);
> -#else
> +    flags |= O_CLOEXEC;
> +#endif /* O_CLOEXEC */
> +
>      ret = open(name, flags, mode);
> +
> +#ifndef O_CLOEXEC
>      if (ret >= 0) {
>          qemu_set_cloexec(ret);
>      }
> -#endif
> +#endif /* ! O_CLOEXEC */

I dislike this part, to be honest.  I find

    #ifdef O_CLOEXEC
        flags |= O_CLOEXEC;
    #endif /* O_CLOEXEC */

        ret = open(name, flags, mode);

    #ifndef O_CLOEXEC
        if (ret >= 0) {
            qemu_set_cloexec(ret);
        }
    #endif /* ! O_CLOEXEC */

harder to read than

    #ifdef O_CLOEXEC
        ret = open(name, flags | O_CLOEXEC, mode);
    #else
        ret = open(name, flags, mode);
        if (ret >= 0) {
            qemu_set_cloexec(ret);
        }
    #endif

> +
> +    return ret;
> +}
> +
> +
> +int qemu_open_old(const char *name, int flags, ...)
> +{
> +    va_list ap;
> +    mode_t mode = 0;
> +    int ret;
> +
> +    va_start(ap, flags);
> +    if (flags & O_CREAT) {
> +        mode = va_arg(ap, int);
> +    }
> +    va_end(ap);
> +
> +    ret = qemu_open_internal(name, flags, mode);
>  
>  #ifdef O_DIRECT
>      if (ret == -1 && errno == EINVAL && (flags & O_DIRECT)) {