Re: [Qemu-block] [PATCH v7 11/35] util: introduce qemu_file_getlength()

[Eduardo Habkost]

On Mon, Nov 09, 2015 at 12:44:55PM +0800, Xiao Guangrong wrote:
> On 11/06/2015 11:50 PM, Eduardo Habkost wrote:
> >As this patch affects raw_getlength(), CCing the raw block driver
> >maintainer and the qemu-block mailing list.
> 
> Eduardo, thanks for your reminder. I will keep CCing Kevin and qemu-block mail
> list for future version.
> 
> >
> >On Mon, Nov 02, 2015 at 05:13:13PM +0800, Xiao Guangrong wrote:
> >>It is used to get the size of the specified file, also qemu_fd_getlength()
> >>is introduced to unify the code with raw_getlength() in block/raw-posix.c
> >>
> >>Signed-off-by: Xiao Guangrong 
> >>---
> >>  block/raw-posix.c|  7 +--
> >>  include/qemu/osdep.h |  2 ++
> >>  util/osdep.c | 31 +++
> >
> >I know I was the one who suggested osdep.c, but maybe oslib-posix.c is a
> >more appropriate place for the new function?
> >
> 
> Since the function we introduced here can work on both windows and posix, so
> i thing osdep.c is the right place. Otherwise we should implement it for 
> multiple
> platforms.

I didn't notice it was going to be used by a platform-independent
qemu_file_getlength() function in addition to the posix-specific
raw_getlength(). Have you tested it on Windows, though?

If you didn't test it on Windows, what about keeping
qemu_file_getlength() available only on posix, by now? The only
users are raw-posix.c and hostmem-file.c, currently. If in the
future somebody need it on Windows, they can decide between
moving the SEEK_END code to osdep.c (after testing it), or moving
the existing raw-win32.c:raw_getlength() code to a
oslib-win32.c:qemu_file_getlength() function.

-- 
Eduardo

Re: [Qemu-block] [PATCH v7 11/35] util: introduce qemu_file_getlength()

[Eduardo Habkost]

As this patch affects raw_getlength(), CCing the raw block driver
maintainer and the qemu-block mailing list.

On Mon, Nov 02, 2015 at 05:13:13PM +0800, Xiao Guangrong wrote:
> It is used to get the size of the specified file, also qemu_fd_getlength()
> is introduced to unify the code with raw_getlength() in block/raw-posix.c
> 
> Signed-off-by: Xiao Guangrong 
> ---
>  block/raw-posix.c|  7 +--
>  include/qemu/osdep.h |  2 ++
>  util/osdep.c | 31 +++

I know I was the one who suggested osdep.c, but maybe oslib-posix.c is a
more appropriate place for the new function?


>  3 files changed, 34 insertions(+), 6 deletions(-)
> 
> diff --git a/block/raw-posix.c b/block/raw-posix.c
> index 918c756..734e6dd 100644
> --- a/block/raw-posix.c
> +++ b/block/raw-posix.c
> @@ -1592,18 +1592,13 @@ static int64_t raw_getlength(BlockDriverState *bs)
>  {
>  BDRVRawState *s = bs->opaque;
>  int ret;
> -int64_t size;
>  
>  ret = fd_open(bs);
>  if (ret < 0) {
>  return ret;
>  }
>  
> -size = lseek(s->fd, 0, SEEK_END);
> -if (size < 0) {
> -return -errno;
> -}
> -return size;
> +return qemu_fd_getlength(s->fd);
>  }
>  #endif
>  
> diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
> index dbc17dc..ca4c3fa 100644
> --- a/include/qemu/osdep.h
> +++ b/include/qemu/osdep.h
> @@ -303,4 +303,6 @@ int qemu_read_password(char *buf, int buf_size);
>  pid_t qemu_fork(Error **errp);
>  
>  size_t qemu_file_get_page_size(const char *mem_path, Error **errp);
> +int64_t qemu_fd_getlength(int fd);
> +size_t qemu_file_getlength(const char *file, Error **errp);
>  #endif
> diff --git a/util/osdep.c b/util/osdep.c
> index 0092bb6..5a61e19 100644
> --- a/util/osdep.c
> +++ b/util/osdep.c
> @@ -428,3 +428,34 @@ writev(int fd, const struct iovec *iov, int iov_cnt)
>  return readv_writev(fd, iov, iov_cnt, true);
>  }
>  #endif
> +
> +int64_t qemu_fd_getlength(int fd)
> +{
> +int64_t size;
> +
> +size = lseek(fd, 0, SEEK_END);
> +if (size < 0) {
> +return -errno;
> +}
> +return size;
> +}
> +
> +size_t qemu_file_getlength(const char *file, Error **errp)
> +{
> +int64_t size;
> +int fd = qemu_open(file, O_RDONLY);
> +
> +if (fd < 0) {
> +error_setg_file_open(errp, errno, file);
> +return 0;
> +}
> +
> +size = qemu_fd_getlength(fd);
> +if (size < 0) {
> +error_setg_errno(errp, -size, "can't get size of file %s", file);
> +size = 0;
> +}
> +
> +qemu_close(fd);
> +return size;
> +}
> -- 
> 1.8.3.1
> 

-- 
Eduardo