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Re: [PATCH] preadv2/pwritev2: Handle offset == -1 [BZ #22753]
- From: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
- To: libc-alpha at sourceware dot org
- Date: Mon, 29 Jan 2018 11:48:45 -0200
- Subject: Re: [PATCH] preadv2/pwritev2: Handle offset == -1 [BZ #22753]
- Authentication-results: sourceware.org; auth=none
- References: <20180129125318.6E52940104B9E@oldenburg.str.redhat.com>
On 29/01/2018 10:53, Florian Weimer wrote:
> 2018-01-29 Florian Weimer <fweimer@redhat.com>
>
> [BZ #22753]
> * sysdeps/posix/preadv2.c (preadv2): Handle offset == -1.
> * sysdeps/posix/preadv64v2.c (preadv64v2): Likewise.
> * sysdeps/posix/pwritev2.c (pwritev2): Likewise.
> * sysdeps/posix/pwritev64v2.c (pwritev64v2): Likweise.
> * sysdeps/unix/sysv/linux/preadv2.c (preadv2): Likewise.
> * sysdeps/unix/sysv/linux/preadv64v2.c (preadv64v2): Likewise.
> * sysdeps/unix/sysv/linux/pwritev2.c (pwritev2): Likewise.
> * sysdeps/unix/sysv/linux/pwritev64v2.c (pwritev64v2): Likweise.
> * manual/llio.texi (Scatter-Gather): Mention offset -1.
> * misc/tst-preadvwritev-common.c (do_test_without_offset): New.
> * misc/tst-preadvwritev2.c (do_test): Call it.
> * misc/tst-preadvwritev64v2.c (do_test): Likewise.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
>
> diff --git a/manual/llio.texi b/manual/llio.texi
> index 642e56e710..b4fd5e1d91 100644
> --- a/manual/llio.texi
> +++ b/manual/llio.texi
> @@ -1251,9 +1251,13 @@ When the source file is compiled using @code{_FILE_OFFSET_BITS == 64} on a
> @c This is a syscall for Linux v4.6. The sysdeps/posix fallback emulation
> @c is also MT-Safe since it calls preadv.
>
> -This function is similar to the @code{preadv} function, with the difference
> -it adds an extra @var{flags} parameter of type @code{int}. The supported
> -@var{flags} are dependent of the underlying system. For Linux it supports:
> +This function is similar to the @code{preadv} function, with the
> +difference it adds an extra @var{flags} parameter of type @code{int}.
> +Additionally, if @var{offset} is @math{-1}, the current file position
> +is used and updated (like the @code{readv} function).
> +
> +The supported @var{flags} are dependent of the underlying system. For
> +Linux it supports:
>
> @vtable @code
> @item RWF_HIPRI
> @@ -1320,10 +1324,13 @@ When the source file is compiled using @code{_FILE_OFFSET_BITS == 64} on a
> @c This is a syscall for Linux v4.6. The sysdeps/posix fallback emulation
> @c is also MT-Safe since it calls pwritev.
>
> -This function is similar to the @code{pwritev} function, with the difference
> -it adds an extra @var{flags} parameter of type @code{int}. The supported
> -@var{flags} are dependent of the underlying system and for Linux it supports
> -the same ones as for @code{preadv2}.
> +This function is similar to the @code{pwritev} function, with the
> +difference it adds an extra @var{flags} parameter of type @code{int}.
> +Additionally, if @var{offset} is @math{-1}, the current file position
> +should is used and updated (like the @code{writev} function).
> +
> +The supported @var{flags} are dependent of the underlying system. For
> +Linux, the supported flags are the same as those for @code{preadv2}.
>
> When the source file is compiled with @code{_FILE_OFFSET_BITS == 64} the
> @code{pwritev2} function is in fact @code{pwritev64v2} and the type
> diff --git a/misc/tst-preadvwritev-common.c b/misc/tst-preadvwritev-common.c
> index 560c8f89b6..b59a3de465 100644
> --- a/misc/tst-preadvwritev-common.c
> +++ b/misc/tst-preadvwritev-common.c
> @@ -16,6 +16,7 @@
> License along with the GNU C Library; if not, see
> <http://www.gnu.org/licenses/>. */
>
> +#include <array_length.h>
> #include <stdio.h>
> #include <stdint.h>
> #include <errno.h>
> @@ -25,6 +26,7 @@
>
> #include <support/check.h>
> #include <support/temp_file.h>
> +#include <support/xunistd.h>
>
> static char *temp_filename;
> static int temp_fd;
> @@ -50,6 +52,42 @@ do_prepare (int argc, char **argv)
> pwritev (__fd, __iov, __iovcnt, __offset)
> #endif
>
> +static __attribute__ ((unused)) void
> +do_test_without_offset (void)
> +{
> + xftruncate (temp_fd, 0);
> +
> + xwrite (temp_fd, "123", 3);
> + xlseek (temp_fd, 2, SEEK_SET);
> + {
> + struct iovec iov[] =
> + {
> + { (void *) "abc", 3 },
> + { (void *) "xyzt", 4 },
> + };
> + TEST_COMPARE (PWRITEV (temp_fd, iov, array_length (iov), -1), 7);
> + }
> + TEST_COMPARE (xlseek (temp_fd, 0, SEEK_CUR), 9);
> +
> + xlseek (temp_fd, 1, SEEK_SET);
> + char buf1[3];
> + char buf2[2];
> + {
> + struct iovec iov[] =
> + {
> + { buf1, sizeof (buf1) },
> + { buf2, sizeof (buf2) },
> + };
> + TEST_COMPARE (PREADV (temp_fd, iov, array_length (iov), -1),
> + sizeof (buf1) + sizeof (buf2));
> + TEST_COMPARE (memcmp ("2ab", buf1, sizeof (buf1)), 0);
> + TEST_COMPARE (memcmp ("cx", buf2, sizeof (buf2)), 0);
> + TEST_COMPARE (xlseek (temp_fd, 0, SEEK_CUR), 6);
> + }
> +
> + xftruncate (temp_fd, 0);
> +}
> +
> static int
> do_test_with_offset (off_t offset)
> {
> diff --git a/misc/tst-preadvwritev2.c b/misc/tst-preadvwritev2.c
> index d8a9daf66a..be22802dbe 100644
> --- a/misc/tst-preadvwritev2.c
> +++ b/misc/tst-preadvwritev2.c
> @@ -29,6 +29,7 @@ static int
> do_test (void)
> {
> do_test_with_invalid_flags ();
> + do_test_without_offset ();
>
> return do_test_with_offset (0);
> }
> diff --git a/misc/tst-preadvwritev64v2.c b/misc/tst-preadvwritev64v2.c
> index 2c656ae3d7..8d3cc32b28 100644
> --- a/misc/tst-preadvwritev64v2.c
> +++ b/misc/tst-preadvwritev64v2.c
> @@ -31,6 +31,7 @@ static int
> do_test (void)
> {
> do_test_with_invalid_flags ();
> + do_test_without_offset ();
>
> return do_test_with_offset (0);
> }
> diff --git a/sysdeps/posix/preadv2.c b/sysdeps/posix/preadv2.c
> index d29147608f..4f8557ac83 100644
> --- a/sysdeps/posix/preadv2.c
> +++ b/sysdeps/posix/preadv2.c
> @@ -33,7 +33,10 @@ preadv2 (int fd, const struct iovec *vector, int count, off_t offset,
> return -1;
> }
>
> - return preadv (fd, vector, count, offset);
> + if (offset == -1)
> + return __readv (fd, vector, count);
> + else
> + return preadv (fd, vector, count, offset);
> }
>
> #endif
> diff --git a/sysdeps/posix/preadv64v2.c b/sysdeps/posix/preadv64v2.c
> index a4844b145c..f89ad08c54 100644
> --- a/sysdeps/posix/preadv64v2.c
> +++ b/sysdeps/posix/preadv64v2.c
> @@ -30,7 +30,10 @@ preadv64v2 (int fd, const struct iovec *vector, int count, off64_t offset,
> return -1;
> }
>
> - return preadv64 (fd, vector, count, offset);
> + if (offset == -1)
> + return __readv (fd, vector, count);
> + else
> + return preadv64 (fd, vector, count, offset);
> }
>
> #ifdef __OFF_T_MATCHES_OFF64_T
> diff --git a/sysdeps/posix/pwritev2.c b/sysdeps/posix/pwritev2.c
> index 3abf37a810..a39304d9d9 100644
> --- a/sysdeps/posix/pwritev2.c
> +++ b/sysdeps/posix/pwritev2.c
> @@ -33,7 +33,10 @@ pwritev2 (int fd, const struct iovec *vector, int count, off_t offset,
> return -1;
> }
>
> - return pwritev (fd, vector, count, offset);
> + if (offset == -1)
> + return __writev (fd, vector, count);
> + else
> + return pwritev (fd, vector, count, offset);
> }
>
> #endif
> diff --git a/sysdeps/posix/pwritev64v2.c b/sysdeps/posix/pwritev64v2.c
> index 374d2ad8a9..7a3a3239d7 100644
> --- a/sysdeps/posix/pwritev64v2.c
> +++ b/sysdeps/posix/pwritev64v2.c
> @@ -31,7 +31,10 @@ pwritev64v2 (int fd, const struct iovec *vector, int count, off64_t offset,
> return -1;
> }
>
> - return pwritev64 (fd, vector, count, offset);
> + if (offset == -1)
> + return __writev (fd, vector, count);
> + else
> + return pwritev64 (fd, vector, count, offset);
> }
>
> #ifdef __OFF_T_MATCHES_OFF64_T
> diff --git a/sysdeps/unix/sysv/linux/preadv2.c b/sysdeps/unix/sysv/linux/preadv2.c
> index 06d29b1322..c8bf0764ef 100644
> --- a/sysdeps/unix/sysv/linux/preadv2.c
> +++ b/sysdeps/unix/sysv/linux/preadv2.c
> @@ -49,7 +49,10 @@ preadv2 (int fd, const struct iovec *vector, int count, off_t offset,
> __set_errno (ENOTSUP);
> return -1;
> }
> - return preadv (fd, vector, count, offset);
> + if (offset == -1)
> + return __readv (fd, vector, count);
> + else
> + return preadv (fd, vector, count, offset);
> }
>
> #endif
> diff --git a/sysdeps/unix/sysv/linux/preadv64v2.c b/sysdeps/unix/sysv/linux/preadv64v2.c
> index 58f7848352..d7400a0252 100644
> --- a/sysdeps/unix/sysv/linux/preadv64v2.c
> +++ b/sysdeps/unix/sysv/linux/preadv64v2.c
> @@ -47,7 +47,11 @@ preadv64v2 (int fd, const struct iovec *vector, int count, off64_t offset,
> __set_errno (ENOTSUP);
> return -1;
> }
> - return preadv64 (fd, vector, count, offset);
> +
> + if (offset == -1)
> + return __readv (fd, vector, count);
> + else
> + return preadv64 (fd, vector, count, offset);
> }
>
> #ifdef __OFF_T_MATCHES_OFF64_T
> diff --git a/sysdeps/unix/sysv/linux/pwritev2.c b/sysdeps/unix/sysv/linux/pwritev2.c
> index d50d9f51f9..29c2264c8f 100644
> --- a/sysdeps/unix/sysv/linux/pwritev2.c
> +++ b/sysdeps/unix/sysv/linux/pwritev2.c
> @@ -45,7 +45,10 @@ pwritev2 (int fd, const struct iovec *vector, int count, off_t offset,
> __set_errno (ENOTSUP);
> return -1;
> }
> - return pwritev (fd, vector, count, offset);
> + if (offset == -1)
> + return __writev (fd, vector, count);
> + else
> + return pwritev (fd, vector, count, offset);
> }
>
> #endif
> diff --git a/sysdeps/unix/sysv/linux/pwritev64v2.c b/sysdeps/unix/sysv/linux/pwritev64v2.c
> index 40c2387690..42da321149 100644
> --- a/sysdeps/unix/sysv/linux/pwritev64v2.c
> +++ b/sysdeps/unix/sysv/linux/pwritev64v2.c
> @@ -47,7 +47,10 @@ pwritev64v2 (int fd, const struct iovec *vector, int count, off64_t offset,
> __set_errno (ENOTSUP);
> return -1;
> }
> - return pwritev64 (fd, vector, count, offset);
> + if (offset == -1)
> + return __writev (fd, vector, count);
> + else
> + return pwritev64 (fd, vector, count, offset);
> }
>
> #ifdef __OFF_T_MATCHES_OFF64_T
>