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Diffstat (limited to 'sysdeps/unix/sysv/linux/readv.c')
-rw-r--r--sysdeps/unix/sysv/linux/readv.c71
1 files changed, 71 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/readv.c b/sysdeps/unix/sysv/linux/readv.c
new file mode 100644
index 0000000000..458e8ffb38
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/readv.c
@@ -0,0 +1,71 @@
+/* readv supports all Linux kernels >= 2.0.
+ Copyright (C) 1997 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
+ modify it under the terms of the GNU Library General Public License as
+ published by the Free Software Foundation; either version 2 of the
+ License, or (at your option) any later version.
+
+ The GNU C Library 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
+ Library General Public License for more details.
+
+ You should have received a copy of the GNU Library General Public
+ License along with the GNU C Library; see the file COPYING.LIB. If not,
+ read to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA. */
+
+#include <errno.h>
+#include <stddef.h>
+#include <sys/param.h>
+#include <sys/uio.h>
+
+extern ssize_t __syscall_readv __P ((int, __const struct iovec *, int));
+
+
+/* Not all versions of the kernel support the large number of records. */
+#undef MAX_IOVEC
+#ifdef UIO_FASTIOV
+# define MAX_IOVEC UIO_FASTIOV
+#else
+# define MAX_IOVEC 8 /* 8 is a safe number. */
+#endif
+
+
+/* We should deal with kernel which have a smaller UIO_MAXIOV as well
+ as a very big count. */
+ssize_t
+readv (fd, vector, count)
+ int fd;
+ const struct iovec *vector;
+ int count;
+{
+ int errno_saved = errno;
+ ssize_t bytes_read;
+
+ bytes_read = __syscall_readv (fd, vector, count);
+
+ if (bytes_read < 0 && errno == EINVAL && count > MAX_IOVEC)
+ {
+ int i;
+
+ /* Restore the old error value as if nothing happened. */
+ __set_errno (errno_saved);
+
+ bytes_read = 0;
+ for (i = 0; i < count; i += MAX_IOVEC)
+ {
+ ssize_t bytes = __syscall_readv (fd, vector + i,
+ MIN (count - i, MAX_IOVEC));
+
+ if (bytes < 0)
+ return bytes;
+
+ bytes_read += bytes;
+ }
+ }
+
+ return bytes_read;
+}