Print this page
14249 pseudo-terminal nomenclature should reflect POSIX
Change-Id: Ib4a3cef899ff4c71b09cb0dc6878863c5e8357bc
@@ -4,42 +4,37 @@
close - close a file descriptor
SYNOPSIS
#include <unistd.h>
- int close(int fildes);
+ int
+ close(int fildes);
-
DESCRIPTION
- The close() function deallocates the file descriptor indicated by
- fildes. To deallocate means to make the file descriptor available for
- return by subsequent calls to open(2) or other functions that allocate
- file descriptors. All outstanding record locks owned by the process on
- the file associated with the file descriptor will be removed (that is,
+ The close() function deallocates the file descriptor indicated by fildes.
+ To deallocate means to make the file descriptor available for return by
+ subsequent calls to open(2) or other functions that allocate file
+ descriptors. All outstanding record locks owned by the process on the
+ file associated with the file descriptor will be removed (that is,
unlocked).
-
If close() is interrupted by a signal that is to be caught, it will
- return -1 with errno set to EINTR and the state of fildes is
- unspecified. If an I/O error occurred while reading from or writing to
- the file system during close(), it returns -1, sets errno to EIO, and
- the state of fildes is unspecified.
+ return -1 with errno set to EINTR and the state of fildes is unspecified.
+ If an I/O error occurred while reading from or writing to the file system
+ during close(), it returns -1, sets errno to EIO, and the state of fildes
+ is unspecified.
+ When all file descriptors associated with a pipe or FIFO special file are
+ closed, any data remaining in the pipe or FIFO will be discarded.
- When all file descriptors associated with a pipe or FIFO special file
- are closed, any data remaining in the pipe or FIFO will be discarded.
-
-
When all file descriptors associated with an open file description have
been closed the open file description will be freed.
+ If the link count of the file is 0, when all file descriptors associated
+ with the file are closed, the space occupied by the file will be freed
+ and the file will no longer be accessible.
- If the link count of the file is 0, when all file descriptors
- associated with the file are closed, the space occupied by the file
- will be freed and the file will no longer be accessible.
-
-
If a streams-based (see Intro(2)) fildes is closed and the calling
process was previously registered to receive a SIGPOLL signal (see
signal(3C)) for events associated with that stream (see I_SETSIG in
streamio(7I)), the calling process will be unregistered for events
associated with the stream. The last close() for a stream causes the
@@ -50,122 +45,80 @@
before dismantling the stream. The time delay can be changed via an
I_SETCLTIME ioctl(2) request (see streamio(7I)). If the O_NONBLOCK or
O_NDELAY flag is set, or if there are any pending signals, close() does
not wait for output to drain, and dismantles the stream immediately.
+ If fildes is associated with one end of a pipe, the last close() causes a
+ hangup to occur on the other end of the pipe. In addition, if the other
+ end of the pipe has been named by fattach(3C), then the last close()
+ forces the named end to be detached by fdetach(3C). If the named end has
+ no open file descriptors associated with it and gets detached, the stream
+ associated with that end is also dismantled.
- If fildes is associated with one end of a pipe, the last close() causes
- a hangup to occur on the other end of the pipe. In addition, if the
- other end of the pipe has been named by fattach(3C), then the last
- close() forces the named end to be detached by fdetach(3C). If the
- named end has no open file descriptors associated with it and gets
- detached, the stream associated with that end is also dismantled.
+ If fildes refers to the manager side of a pseudo-terminal, a SIGHUP
+ signal is sent to the session leader, if any, for which the subsidiary
+ side of the pseudo-terminal is the controlling terminal. It is
+ unspecified whether closing the manager side of the pseudo-terminal
+ flushes all queued input and output.
+ If fildes refers to the subsidiary side of a streams-based pseudo-
+ terminal, a zero-length message may be sent to the manager.
- If fildes refers to the master side of a pseudo-terminal, a SIGHUP
- signal is sent to the session leader, if any, for which the slave side
- of the pseudo-terminal is the controlling terminal. It is unspecified
- whether closing the master side of the pseudo-terminal flushes all
- queued input and output.
-
-
- If fildes refers to the slave side of a streams-based pseudo-terminal,
- a zero-length message may be sent to the master.
-
-
When there is an outstanding cancelable asynchronous I/O operation
against fildes when close() is called, that I/O operation is canceled.
An I/O operation that is not canceled completes as if the close()
operation had not yet occurred. All operations that are not canceled
will complete as if the close() blocked until the operations completed.
-
If a shared memory object or a memory mapped file remains referenced at
the last close (that is, a process has it mapped), then the entire
contents of the memory object will persist until the memory object
becomes unreferenced. If this is the last close of a shared memory
- object or a memory mapped file and the close results in the memory
- object becoming unreferenced, and the memory object has been unlinked,
- then the memory object will be removed.
+ object or a memory mapped file and the close results in the memory object
+ becoming unreferenced, and the memory object has been unlinked, then the
+ memory object will be removed.
+ If fildes refers to a socket, close() causes the socket to be destroyed.
+ If the socket is connection-mode, and the SO_LINGER option is set for the
+ socket with non-zero linger time, and the socket has untransmitted data,
+ then close() will block for up to the current linger interval until all
+ data is transmitted.
- If fildes refers to a socket, close() causes the socket to be
- destroyed. If the socket is connection-mode, and the SO_LINGER option
- is set for the socket with non-zero linger time, and the socket has
- untransmitted data, then close() will block for up to the current
- linger interval until all data is transmitted.
-
RETURN VALUES
- Upon successful completion, 0 is returned. Otherwise, -1 is returned
- and errno is set to indicate the error.
+ The close() function returns the value 0 if successful; otherwise the
+ value -1 is returned and the global variable errno is set to indicate the
+ error.
-ERRORS
- The close() function will fail if:
-
- EBADF
- The fildes argument is not a valid file descriptor.
-
-
- EINTR
- The close() function was interrupted by a signal.
-
-
- ENOLINK
- The fildes argument is on a remote machine and the link to
- that machine is no longer active.
-
-
- ENOSPC
- There was no free space remaining on the device containing
- the file.
-
-
-
- The close() function may fail if:
-
- EIO
- An I/O error occurred while reading from or writing to the file
- system.
-
-
EXAMPLES
Example 1 Reassign a file descriptor.
+ The following example closes the file descriptor associated with standard
+ output for the current process, re-assigns standard output to a new file
+ descriptor, and closes the original file descriptor to clean up. This
+ example assumes that the file descriptor 0, which is the descriptor for
+ standard input, is not closed.
- The following example closes the file descriptor associated with
- standard output for the current process, re-assigns standard output to
- a new file descriptor, and closes the original file descriptor to clean
- up. This example assumes that the file descriptor 0, which is the
- descriptor for standard input, is not closed.
-
-
#include <unistd.h>
...
int pfd;
...
close(1);
dup(pfd);
close(pfd);
...
-
-
Incidentally, this is exactly what could be achieved using:
-
dup2(pfd, 1);
close(pfd);
-
Example 2 Close a file descriptor.
-
In the following example, close() is used to close a file descriptor
after an unsuccessful attempt is made to associate that file descriptor
with a stream.
-
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#define LOCKFILE "/etc/ptmp"
@@ -178,30 +131,39 @@
unlink(LOCKFILE);
exit(1);
}
...
+ERRORS
+ The close() function will fail if:
-USAGE
- An application that used the stdio function fopen(3C) to open a file
- should use the corresponding fclose(3C) function rather than close().
+ EBADF The fildes argument is not a valid file descriptor.
-ATTRIBUTES
- See attributes(5) for descriptions of the following attributes:
+ EINTR The close() function was interrupted by a signal.
+ ENOLINK The fildes argument is on a remote machine and the
+ link to that machine is no longer active.
+ ENOSPC There was no free space remaining on the device
+ containing the file.
+ The close() function may fail if:
- +--------------------+-------------------+
- | ATTRIBUTE TYPE | ATTRIBUTE VALUE |
- +--------------------+-------------------+
- |Interface Stability | Standard |
- +--------------------+-------------------+
- |MT-Level | Async-Signal-Safe |
- +--------------------+-------------------+
+ EIO An I/O error occurred while reading from or writing to
+ the file system.
+USAGE
+ An application that used the stdio(3C) function fopen(3C) to open a file
+ should use the corresponding fclose(3C) function rather than close().
+
+INTERFACE STABILITY
+ Committed
+
+MT-LEVEL
+ Async-Signal-Safe
+
SEE ALSO
- Intro(2), creat(2), dup(2), exec(2), fcntl(2), ioctl(2), open(2)
+ creat(2), dup(2), exec(2), fcntl(2), Intro(2), ioctl(2), open(2),
pipe(2), fattach(3C), fclose(3C), fdetach(3C), fopen(3C), signal(3C),
signal.h(3HEAD), attributes(5), standards(5), streamio(7I)
- October 18, 2005 CLOSE(2)
+illumos February 5, 2022 illumos