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-rw-r--r--sysdeps/posix/writev.c45
1 files changed, 38 insertions, 7 deletions
diff --git a/sysdeps/posix/writev.c b/sysdeps/posix/writev.c
index f92ff1c19d..dc2c806d66 100644
--- a/sysdeps/posix/writev.c
+++ b/sysdeps/posix/writev.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 1991, 1992, 1996, 1997 Free Software Foundation, Inc.
+/* Copyright (C) 1991, 1992, 1996, 1997, 2002 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
@@ -19,6 +19,9 @@
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <sys/param.h>
#include <sys/uio.h>
/* Write data pointed by the buffers described by VECTOR, which
@@ -35,23 +38,46 @@ __writev (fd, vector, count)
char *buffer;
register char *bp;
size_t bytes, to_copy;
+ ssize_t bytes_written;
int i;
+ bool use_malloc = false;
/* Find the total number of bytes to be written. */
bytes = 0;
for (i = 0; i < count; ++i)
- bytes += vector[i].iov_len;
+ {
+ /* Check for ssize_t overflow. */
+ if (SSIZE_MAX - bytes < vector[i].iov_len)
+ {
+ errno = EINVAL;
+ return -1;
+ }
+ bytes += vector[i].iov_len;
+ }
- /* Allocate a temporary buffer to hold the data. */
- buffer = (char *) __alloca (bytes);
+ /* Allocate a temporary buffer to hold the data. We should normally
+ use alloca since it's faster and does not require synchronization
+ with other threads. But we cannot if the amount of memory
+ required is too large. Use 512k as the limit. */
+ if (bytes < 512 * 1024)
+ buffer = (char *) __alloca (bytes);
+ else
+ {
+ buffer = (char *) malloc (bytes);
+ if (buffer == NULL)
+ /* XXX I don't know whether it is acceptable to try writing
+ the data in chunks. Probably not so we just fail here. */
+ return -1;
+
+ use_malloc = true;
+ }
/* Copy the data into BUFFER. */
to_copy = bytes;
bp = buffer;
for (i = 0; i < count; ++i)
{
-#define min(a, b) ((a) > (b) ? (b) : (a))
- size_t copy = min (vector[i].iov_len, to_copy);
+ size_t copy = MIN (vector[i].iov_len, to_copy);
bp = __mempcpy ((void *) bp, (void *) vector[i].iov_base, copy);
@@ -60,7 +86,12 @@ __writev (fd, vector, count)
break;
}
- return __write (fd, buffer, bytes);
+ bytes_written = __write (fd, buffer, bytes);
+
+ if (use_malloc)
+ free (buffer);
+
+ return bytes_written;
}
#ifndef __writev
weak_alias (__writev, writev)