BSD 4_3_Reno release

[unix-history] / usr / src / lib / libc / sys / write.2

diff --git a/usr/src/lib/libc/sys/write.2 b/usr/src/lib/libc/sys/write.2
index eacf3da..af35a6b 100644 (file)
--- a/usr/src/lib/libc/sys/write.2
+++ b/usr/src/lib/libc/sys/write.2
@@ -2,17 +2,17 @@
 .\" All rights reserved.  The Berkeley software License Agreement
 .\" specifies the terms and conditions for redistribution.
 .\"
 .\" All rights reserved.  The Berkeley software License Agreement
 .\" specifies the terms and conditions for redistribution.
 .\"

-.\"    @(#)write.2     6.1 (Berkeley) %G%
+.\"    @(#)write.2     6.5 (Berkeley) 5/14/86

 .\"
 .\"

-.TH WRITE 2 ""
+.TH WRITE 2 "May 14, 1986"

 .UC 4
 .SH NAME
 .UC 4
 .SH NAME

-write, writev \- write on a file
+write, writev \- write output

 .SH SYNOPSIS
 .nf
 .ft B
 .SH SYNOPSIS
 .nf
 .ft B

-write(d, buf, nbytes)
-int d;
+cc = write(d, buf, nbytes)
+int cc, d;

 char *buf;
 int nbytes;
 .PP
 char *buf;
 int nbytes;
 .PP


@@ -21,10 +21,10 @@ int nbytes;
 #include <sys/uio.h>
 .PP
 .ft B
 #include <sys/uio.h>
 .PP
 .ft B

-writev(d, iov, ioveclen)
-int d;
+cc = writev(d, iov, iovcnt)
+int cc, d;

 struct iovec *iov;
 struct iovec *iov;

-int ioveclen;
+int iovcnt;

 .fi
 .SH DESCRIPTION
 .I Write
 .fi
 .SH DESCRIPTION
 .I Write


@@ -36,8 +36,35 @@ from the buffer pointed to by
 .IR buf .
 .I Writev
 performs the same action, but gathers the output data
 .IR buf .
 .I Writev
 performs the same action, but gathers the output data

-from the \fIiovlen\fP buffers specified by the members
-of the \fIiovec\fP array: iov[0], iov[1], etc.
+from the 
+.I iovcnt
+buffers specified by the members of the
+.I iov
+array: iov[0], iov[1], ..., iov[iovcnt\|\-\|1].
+.PP
+For 
+.IR writev ,
+the 
+.I iovec
+structure is defined as
+.PP
+.nf
+.RS
+.DT
+struct iovec {
+       caddr_t iov_base;
+       int     iov_len;
+};
+.RE
+.fi
+.PP
+Each 
+.I iovec
+entry specifies the base address and length of an area
+in memory from which data should be written.
+.I Writev
+will always write a complete area before proceeding
+to the next.

 .PP
 On objects capable of seeking, the \fIwrite\fP starts at a position
 given by the pointer associated with
 .PP
 On objects capable of seeking, the \fIwrite\fP starts at a position
 given by the pointer associated with


@@ -59,13 +86,24 @@ This prevents penetration of system security
 by a user who
 \*(lqcaptures\*(rq a writable set-user-id file
 owned by the super-user.
 by a user who
 \*(lqcaptures\*(rq a writable set-user-id file
 owned by the super-user.

+.PP
+When using non-blocking I/O on objects such as sockets that are subject
+to flow control,
+.I write
+and
+.I writev
+may write fewer bytes than requested;
+the return value must be noted,
+and the remainder of the operation should be retried when possible.

 .SH "RETURN VALUE
 .SH "RETURN VALUE

-Upon successful completion the number of bytes actually writen
-is returned.  Otherwise a \-1 is returned and
+Upon successful completion the number of bytes actually written
+is returned.  Otherwise a \-1 is returned and the global variable

 .I errno
 is set to indicate the error.
 .SH ERRORS
 .I Write
 .I errno
 is set to indicate the error.
 .SH ERRORS
 .I Write

+and
+.I writev

 will fail and the file pointer will remain unchanged if one or more
 of the following are true:
 .TP 15
 will fail and the file pointer will remain unchanged if one or more
 of the following are true:
 .TP 15


@@ -78,7 +116,7 @@ for reading by any process.
 .TP 15
 [EPIPE]
 An attempt is made to write to a socket of type SOCK_STREAM
 .TP 15
 [EPIPE]
 An attempt is made to write to a socket of type SOCK_STREAM

-which is not connected to a peer socket.
+that is not connected to a peer socket.

 .TP 15
 [EFBIG]
 An attempt was made to write a file that exceeds the process's
 .TP 15
 [EFBIG]
 An attempt was made to write a file that exceeds the process's


@@ -87,5 +125,47 @@ file size limit or the maximum file size.
 [EFAULT]
 Part of \fIiov\fP or data to be written to the file
 points outside the process's allocated address space.
 [EFAULT]
 Part of \fIiov\fP or data to be written to the file
 points outside the process's allocated address space.

+.TP 15
+[EINVAL]
+The pointer associated with
+.I d
+was negative.
+.TP 15
+[ENOSPC]
+There is no free space remaining on the file system
+containing the file.
+.TP 15
+[EDQUOT]
+The user's quota of disk blocks on the file system
+containing the file has been exhausted.
+.TP 15
+[EIO]
+An I/O error occurred while reading from or writing to the file system.
+.TP 15
+[EWOULDBLOCK]
+The file was marked for non-blocking I/O,
+and no data could be written immediately.
+.PP
+In addition, 
+.I writev
+may return one of the following errors:
+.TP 15
+[EINVAL]
+.I Iovcnt
+was less than or equal to 0, or greater than 16.
+.TP 15
+[EINVAL]
+One of the
+.I iov_len
+values in the
+.I iov
+array was negative.
+.TP 15
+[EINVAL]
+The sum of the
+.I iov_len
+values in the
+.I iov
+array overflowed a 32-bit integer.

 .SH "SEE ALSO"
 .SH "SEE ALSO"

-lseek(2), open(2), pipe(2)
+fcntl(2), lseek(2), open(2), pipe(2), select(2)