[vlc-devel] [PATCH] compat: add pread

[Steve Lhomme]

Oops, missing a file.

On Thu, Jan 7, 2016 at 2:26 PM, Steve Lhomme <robux4 at videolabs.io> wrote:
> ---
>  compat/pread.c   | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>  configure.ac     |  2 +-
>  src/misc/block.c | 21 ---------------------
>  3 files changed, 54 insertions(+), 22 deletions(-)
>  create mode 100644 compat/pread.c
>
> diff --git a/compat/pread.c b/compat/pread.c
> new file mode 100644
> index 0000000..aad1813
> --- /dev/null
> +++ b/compat/pread.c
> @@ -0,0 +1,53 @@
> +/*****************************************************************************
> + * pread.c: POSIX C pread() replacement
> + *****************************************************************************
> + * Copyright © 2016 VLC authors and VideoLAN
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU Lesser General Public License as published by
> + * the Free Software Foundation; either version 2.1 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public License
> + * along with this program; if not, write to the Free Software Foundation,
> + * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
> + *****************************************************************************/
> +
> +#ifdef HAVE_CONFIG_H
> +# include <config.h>
> +#endif
> +
> +#ifdef _WIN32
> +#include <windows.h>
> +
> +ssize_t pread (int fd, void *buf, size_t count, off_t offset)
> +{
> +    HANDLE handle = (HANDLE)(intptr_t)_get_osfhandle (fd);
> +    if (handle == INVALID_HANDLE_VALUE)
> +        return -1;
> +
> +    OVERLAPPED olap; olap.Offset = offset; olap.OffsetHigh = (offset >> 32);
> +    DWORD written;
> +    /* This braindead API will override the file pointer even if we specify
> +     * an explicit read offset... So do not expect this to mix well with
> +     * regular read() calls. */
> +    if (ReadFile (handle, buf, count, &written, &olap))
> +        return written;
> +    return -1;
> +}
> +#else
> +#include <io.h>
> +
> +ssize_t pread (int fd, void *buf, size_t count, off_t offset)
> +{
> +    if ( lseek (fd, offset, SEEK_SET) != offset ) {
> +        return -1;
> +    }
> +    return read( fd, buf, count );
> +}
> +#endif
> diff --git a/configure.ac b/configure.ac
> index 7286e27..b8a674b 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -565,7 +565,7 @@ need_libc=false
>  dnl Check for usual libc functions
>  AC_CHECK_DECLS([nanosleep],,,[#include <time.h>])
>  AC_CHECK_FUNCS([daemon fcntl fstatvfs fork getenv getpwuid_r isatty lstat memalign mkostemp mmap open_memstream openat pread posix_fadvise posix_madvise setlocale stricmp strnicmp strptime uselocale pthread_cond_timedwait_monotonic_np pthread_condattr_setclock])
> -AC_REPLACE_FUNCS([atof atoll dirfd fdopendir ffsll flockfile fsync getdelim getpid lldiv nrand48 poll posix_memalign rewind setenv strcasecmp strcasestr strdup strlcpy strndup strnlen strnstr strsep strtof strtok_r strtoll swab tdestroy timegm timespec_get strverscmp])
> +AC_REPLACE_FUNCS([atof atoll dirfd fdopendir ffsll flockfile fsync getdelim getpid lldiv nrand48 poll posix_memalign pread rewind setenv strcasecmp strcasestr strdup strlcpy strndup strnlen strnstr strsep strtof strtok_r strtoll swab tdestroy timegm timespec_get strverscmp])
>  AC_CHECK_FUNCS(fdatasync,,
>    [AC_DEFINE(fdatasync, fsync, [Alias fdatasync() to fsync() if missing.])
>  ])
> diff --git a/src/misc/block.c b/src/misc/block.c
> index 610659d..6306bf0 100644
> --- a/src/misc/block.c
> +++ b/src/misc/block.c
> @@ -377,27 +377,6 @@ block_t *block_shm_Alloc (void *addr, size_t length)
>  #endif
>
>
> -#ifdef _WIN32
> -# include <io.h>
> -
> -static
> -ssize_t pread (int fd, void *buf, size_t count, off_t offset)
> -{
> -    HANDLE handle = (HANDLE)(intptr_t)_get_osfhandle (fd);
> -    if (handle == INVALID_HANDLE_VALUE)
> -        return -1;
> -
> -    OVERLAPPED olap; olap.Offset = offset; olap.OffsetHigh = (offset >> 32);
> -    DWORD written;
> -    /* This braindead API will override the file pointer even if we specify
> -     * an explicit read offset... So do not expect this to mix well with
> -     * regular read() calls. */
> -    if (ReadFile (handle, buf, count, &written, &olap))
> -        return written;
> -    return -1;
> -}
> -#endif
> -
>  /**
>   * Loads a file into a block of memory through a file descriptor.
>   * If possible a private file mapping is created. Otherwise, the file is read
> --
> 2.6.3
>