[PATCH] Fix pwritev

[PATCH] Fix pwritev

[Jakub Jelinek]

Hi!

sysdeps/posix/pwritev.c looks copied from preadv.c, with only half of the
things changed that actually need changing.

Fixed thusly, ok to commit?

2009-04-23  Jakub Jelinek  <jakub@redhat.com>

	* sysdeps/posix/pwritev.c (PWRITEV): Fix up comment.  Copy
	data from vector to temporary buffer and call PWRITEV after it
	instead of vice versa.
	* sysdeps/posix/preadv.c: Fix up comment.
	* misc/preadv.c: Likewise.
	* misc/preadv64.c: Likewise.
	* misc/pwritev.c: Likewise.
	* misc/pwritev64.c: Likewise.
	* misc/sys/uio.h (preadv, pwritev, preadv64, pwritev64): Likewise.

--- libc/sysdeps/posix/pwritev.c.jj	2009-04-03 21:52:46.000000000 +0200
+++ libc/sysdeps/posix/pwritev.c	2009-04-23 23:10:52.000000000 +0200
@@ -44,12 +44,12 @@ ifree (char **ptrp)
 }
 
 
-/* Read data from file descriptor FD at the given position OFFSET
-   without change the file pointer, and put the result in the buffers
-   described by VECTOR, which is a vector of COUNT 'struct iovec's.
-   The buffers are filled in the order specified.  Operates just like
-   'read' (see <unistd.h>) except that data are put in VECTOR instead
-   of a contiguous buffer.  */
+/* Write data pointed by the buffers described by IOVEC, which is a
+   vector of COUNT 'struct iovec's, to file descriptor FD at the given
+   position OFFSET without change the file pointer.  The data is
+   written in the order specified.  Operates just like 'write' (see
+   <unistd.h>) except that the data are taken from IOVEC instead of a
+   contiguous buffer.  */
 ssize_t
 PWRITEV (int fd, const struct iovec *vector, int count, OFF_T offset)
 {
@@ -81,26 +81,14 @@ PWRITEV (int fd, const struct iovec *vec
 	return -1;
     }
 
-  /* Read the data.  */
-  ssize_t bytes_read = PWRITE (fd, buffer, bytes, offset);
-  if (bytes_read <= 0)
-    return -1;
-
   /* Copy the data from BUFFER into the memory specified by VECTOR.  */
-  bytes = bytes_read;
+  char *ptr = buffer;
   for (int i = 0; i < count; ++i)
-    {
-      size_t copy = MIN (vector[i].iov_len, bytes);
-
-      (void) memcpy ((void *) vector[i].iov_base, (void *) buffer, copy);
-
-      buffer += copy;
-      bytes -= copy;
-      if (bytes == 0)
-	break;
-    }
+    ptr = __mempcpy ((void *) ptr, (void *) vector[i].iov_base,
+		     vector[i].iov_len);
 
-  return bytes_read;
+  /* Write the data.  */
+  return PWRITE (fd, buffer, bytes, offset);
 }
 #if __WORDSIZE == 64 && defined pwritev64
 # undef pwritev64
--- libc/misc/sys/uio.h.jj	2009-04-07 07:56:51.000000000 +0200
+++ libc/misc/sys/uio.h	2009-04-23 23:13:20.000000000 +0200
@@ -58,7 +58,7 @@ extern ssize_t writev (int __fd, __const
    without change the file pointer, and put the result in the buffers
    described by IOVEC, which is a vector of COUNT 'struct iovec's.
    The buffers are filled in the order specified.  Operates just like
-   'read' (see <unistd.h>) except that data are put in IOVEC instead
+   'pread' (see <unistd.h>) except that data are put in IOVEC instead
    of a contiguous buffer.
 
    This function is a cancellation point and therefore not marked with
@@ -69,7 +69,7 @@ extern ssize_t preadv (int __fd, __const
 /* Write data pointed by the buffers described by IOVEC, which is a
    vector of COUNT 'struct iovec's, to file descriptor FD at the given
    position OFFSET without change the file pointer.  The data is
-   written in the order specified.  Operates just like 'write' (see
+   written in the order specified.  Operates just like 'pwrite' (see
    <unistd.h>) except that the data are taken from IOVEC instead of a
    contiguous buffer.
 
@@ -96,7 +96,7 @@ extern ssize_t __REDIRECT (pwritev, (int
    without change the file pointer, and put the result in the buffers
    described by IOVEC, which is a vector of COUNT 'struct iovec's.
    The buffers are filled in the order specified.  Operates just like
-   'read' (see <unistd.h>) except that data are put in IOVEC instead
+   'pread' (see <unistd.h>) except that data are put in IOVEC instead
    of a contiguous buffer.
 
    This function is a cancellation point and therefore not marked with
@@ -107,7 +107,7 @@ extern ssize_t preadv64 (int __fd, __con
 /* Write data pointed by the buffers described by IOVEC, which is a
    vector of COUNT 'struct iovec's, to file descriptor FD at the given
    position OFFSET without change the file pointer.  The data is
-   written in the order specified.  Operates just like 'write' (see
+   written in the order specified.  Operates just like 'pwrite' (see
    <unistd.h>) except that the data are taken from IOVEC instead of a
    contiguous buffer.
 
--- libc/misc/preadv64.c.jj	2009-04-03 21:52:00.000000000 +0200
+++ libc/misc/preadv64.c	2009-04-23 23:15:44.000000000 +0200
@@ -24,7 +24,7 @@
    without change the file pointer, and put the result in the buffers
    described by VECTOR, which is a vector of COUNT 'struct iovec's.
    The buffers are filled in the order specified.  Operates just like
-   'read' (see <unistd.h>) except that data are put in VECTOR instead
+   'pread' (see <unistd.h>) except that data are put in VECTOR instead
    of a contiguous buffer.  */
 ssize_t
 preadv64 (fd, vector, count, offset)
--- libc/misc/preadv.c.jj	2009-04-03 21:51:53.000000000 +0200
+++ libc/misc/preadv.c	2009-04-23 23:15:37.000000000 +0200
@@ -24,7 +24,7 @@
    without change the file pointer, and put the result in the buffers
    described by VECTOR, which is a vector of COUNT 'struct iovec's.
    The buffers are filled in the order specified.  Operates just like
-   'read' (see <unistd.h>) except that data are put in VECTOR instead
+   'pread' (see <unistd.h>) except that data are put in VECTOR instead
    of a contiguous buffer.  */
 ssize_t
 preadv (fd, vector, count, offset)
--- libc/misc/pwritev.c.jj	2009-04-03 21:52:10.000000000 +0200
+++ libc/misc/pwritev.c	2009-04-23 23:15:52.000000000 +0200
@@ -23,7 +23,7 @@
 /* Write data pointed by the buffers described by VECTOR, which is a
    vector of COUNT 'struct iovec's, to file descriptor FD at the given
    position OFFSET without change the file pointer.  The data is
-   written in the order specified.  Operates just like 'write' (see
+   written in the order specified.  Operates just like 'pwrite' (see
    <unistd.h>) except that the data are taken from VECTOR instead of a
    contiguous buffer.  */
 ssize_t
--- libc/misc/pwritev64.c.jj	2009-04-03 21:52:16.000000000 +0200
+++ libc/misc/pwritev64.c	2009-04-23 23:16:01.000000000 +0200
@@ -23,7 +23,7 @@
 /* Write data pointed by the buffers described by VECTOR, which is a
    vector of COUNT 'struct iovec's, to file descriptor FD at the given
    position OFFSET without change the file pointer.  The data is
-   written in the order specified.  Operates just like 'write' (see
+   written in the order specified.  Operates just like 'pwrite' (see
    <unistd.h>) except that the data are taken from VECTOR instead of a
    contiguous buffer.  */
 ssize_t
--- libc/sysdeps/posix/preadv.c.jj	2009-04-22 15:07:09.000000000 +0200
+++ libc/sysdeps/posix/preadv.c	2009-04-23 23:11:10.000000000 +0200
@@ -48,7 +48,7 @@ ifree (char **ptrp)
    without change the file pointer, and put the result in the buffers
    described by VECTOR, which is a vector of COUNT 'struct iovec's.
    The buffers are filled in the order specified.  Operates just like
-   'read' (see <unistd.h>) except that data are put in VECTOR instead
+   'pread' (see <unistd.h>) except that data are put in VECTOR instead
    of a contiguous buffer.  */
 ssize_t
 PREADV (int fd, const struct iovec *vector, int count, OFF_T offset)

	Jakub