diff options
Diffstat (limited to 'lib/libc/sys/write.2')
-rw-r--r-- | lib/libc/sys/write.2 | 252 |
1 files changed, 0 insertions, 252 deletions
diff --git a/lib/libc/sys/write.2 b/lib/libc/sys/write.2 deleted file mode 100644 index f8d8063..0000000 --- a/lib/libc/sys/write.2 +++ /dev/null @@ -1,252 +0,0 @@ -.\" Copyright (c) 1980, 1991, 1993 -.\" The Regents of the University of California. All rights reserved. -.\" -.\" Redistribution and use in source and binary forms, with or without -.\" modification, are permitted provided that the following conditions -.\" are met: -.\" 1. Redistributions of source code must retain the above copyright -.\" notice, this list of conditions and the following disclaimer. -.\" 2. Redistributions in binary form must reproduce the above copyright -.\" notice, this list of conditions and the following disclaimer in the -.\" documentation and/or other materials provided with the distribution. -.\" 3. All advertising materials mentioning features or use of this software -.\" must display the following acknowledgement: -.\" This product includes software developed by the University of -.\" California, Berkeley and its contributors. -.\" 4. Neither the name of the University nor the names of its contributors -.\" may be used to endorse or promote products derived from this software -.\" without specific prior written permission. -.\" -.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND -.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE -.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE -.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE -.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL -.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS -.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) -.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT -.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY -.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF -.\" SUCH DAMAGE. -.\" -.\" @(#)write.2 8.5 (Berkeley) 4/2/94 -.\" -.Dd April 2, 1994 -.Dt WRITE 2 -.Os BSD 4 -.Sh NAME -.Nm write , -.Nm writev -.Nd write output -.Sh SYNOPSIS -.Fd #include <sys/types.h> -.Fd #include <sys/uio.h> -.Fd #include <unistd.h> -.Ft ssize_t -.Fn write "int d" "const void *buf" "size_t nbytes" -.Ft ssize_t -.Fn writev "int d" "const struct iovec *iov" "int iovcnt" -.Sh DESCRIPTION -.Fn Write -attempts to write -.Fa nbytes -of data to the object referenced by the descriptor -.Fa d -from the buffer pointed to by -.Fa buf . -.Fn Writev -performs the same action, but gathers the output data -from the -.Fa iovcnt -buffers specified by the members of the -.Fa iov -array: iov[0], iov[1], ..., iov[iovcnt\|-\|1]. -.Pp -For -.Fn writev , -the -.Fa iovec -structure is defined as: -.Pp -.Bd -literal -offset indent -compact -struct iovec { - char *iov_base; /* Base address. */ - size_t iov_len; /* Length. */ -}; -.Ed -.Pp -Each -.Fa iovec -entry specifies the base address and length of an area -in memory from which data should be written. -.Fn Writev -will always write a complete area before proceeding -to the next. -.Pp -On objects capable of seeking, the -.Fn write -starts at a position -given by the pointer associated with -.Fa d , -see -.Xr lseek 2 . -Upon return from -.Fn write , -the pointer is incremented by the number of bytes which were written. -.Pp -Objects that are not capable of seeking always write from the current -position. The value of the pointer associated with such an object -is undefined. -.Pp -If the real user is not the super-user, then -.Fn write -clears the set-user-id bit on a file. -This prevents penetration of system security -by a user who -.Dq captures -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, -.Fn write -and -.Fn 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 IMPLEMENTATION NOTES -.Pp -In the non-threaded library -.Fn write -is implemented as the -.Va write -syscall. -.Pp -In the threaded library, the -.Va write -syscall is assembled to -.Fn _thread_sys_write -and -.Fn write -is implemented as a function which locks -.Va d -for read and write, then calls -.Fn _thread_sys_write . -If the call to -.Fn _thread_sys_write -would block, a context switch is performed. Before returning, -.Fn write -unlocks -.Va d . -.Pp -In the non-threaded library -.Fn writev -is implemented as the -.Va writev -syscall. -.Pp -In the threaded library, the -.Va writev -syscall is assembled to -.Fn _thread_sys_writev -and -.Fn writev -is implemented as a function which locks -.Va d -for read and write, then calls -.Fn _thread_sys_writev . -If the call to -.Fn _thread_sys_writev -would block, a context switch is performed. Before returning, -.Fn writev -unlocks -.Va d . -.Sh RETURN VALUES -Upon successful completion the number of bytes which were written -is returned. Otherwise a -1 is returned and the global variable -.Va errno -is set to indicate the error. -.Sh ERRORS -.Fn Write -and -.Fn writev -will fail and the file pointer will remain unchanged if: -.Bl -tag -width Er -.It Bq Er EBADF -.Fa D -is not a valid descriptor open for writing. -.It Bq Er EPIPE -An attempt is made to write to a pipe that is not open -for reading by any process. -.It Bq Er EPIPE -An attempt is made to write to a socket of type -.Dv SOCK_STREAM -that is not connected to a peer socket. -.It Bq Er EFBIG -An attempt was made to write a file that exceeds the process's -file size limit or the maximum file size. -.It Bq Er EFAULT -Part of -.Fa iov -or data to be written to the file -points outside the process's allocated address space. -.It Bq Er EINVAL -The pointer associated with -.Fa d -was negative. -.It Bq Er ENOSPC -There is no free space remaining on the file system -containing the file. -.It Bq Er EDQUOT -The user's quota of disk blocks on the file system -containing the file has been exhausted. -.It Bq Er EIO -An I/O error occurred while reading from or writing to the file system. -.It Bq Er EAGAIN -The file was marked for non-blocking I/O, -and no data could be written immediately. -.El -.Pp -In addition, -.Fn writev -may return one of the following errors: -.Bl -tag -width Er -.It Bq Er EINVAL -.Fa Iovcnt -was less than or equal to 0, or greater than -.Dv UIO_MAXIOV . -.It Bq Er EINVAL -One of the -.Fa iov_len -values in the -.Fa iov -array was negative. -.It Bq Er EINVAL -The sum of the -.Fa iov_len -values in the -.Fa iov -array overflowed a 32-bit integer. -.El -.Sh SEE ALSO -.Xr fcntl 2 , -.Xr lseek 2 , -.Xr open 2 , -.Xr pipe 2 , -.Xr select 2 -.Sh STANDARDS -The -.Fn write -function call is expected to conform to -.St -p1003.1-90 . -.Sh HISTORY -The -.Fn writev -function call -appeared in -.Bx 4.2 . -A -.Fn write -function call appeared in -.At v6 . |