BSD 4_4 release

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

diff --git a/usr/src/lib/libc/sys/open.2 b/usr/src/lib/libc/sys/open.2
index e37ab9c..45adf9b 100644 (file)
--- a/usr/src/lib/libc/sys/open.2
+++ b/usr/src/lib/libc/sys/open.2
@@ -1,188 +1,257 @@
-.\" Copyright (c) 1980 Regents of the University of California.
-.\" All rights reserved.  The Berkeley software License Agreement
-.\" specifies the terms and conditions for redistribution.
+.\" Copyright (c) 1980, 1991, 1993
+.\"    The Regents of the University of California.  All rights reserved.

 .\"
 .\"

-.\"    @(#)open.2      6.3 (Berkeley) %G%
+.\" 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.

 .\"
 .\"

-.TH OPEN 2 ""
-.UC 4
-.SH NAME
-open \- open a file for reading or writing, or create a new file
-.SH SYNOPSIS
-.nf
-.ft B
-#include <sys/file.h>
-.PP
-.ft B
-open(path, flags, mode)
-char *path;
-int flags, mode;
-.fi
-.SH DESCRIPTION
-.I Open
-opens the file
-.I path
-for reading and/or writing, as specified by the
-.I flags
-argument and returns a descriptor for that file.
+.\" 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.
+.\"
+.\"     @(#)open.2     8.1 (Berkeley) 6/4/93
+.\"
+.Dd June 4, 1993
+.Dt OPEN 2
+.Os BSD 4
+.Sh NAME
+.Nm open
+.Nd open or create a file for reading or writing
+.Sh SYNOPSIS
+.Fd #include <fcntl.h>
+.Ft int
+.Fn open "const char *path" "int flags" "mode_t mode"
+.Sh DESCRIPTION
+The file name specified by
+.Fa path
+is opened
+for reading and/or writing as specified by the
+argument
+.Fa flags
+and the file descriptor returned to the calling process.

 The
 The

-.I flags
+.Fa flags

 argument may indicate the file is to be
 argument may indicate the file is to be

-created if it does not already exist (by specifying the
-O_CREAT flag), in which case the file is created with mode
-.I mode
+created if it does not exist (by specifying the
+.Dv O_CREAT
+flag), in which case the file is created with mode
+.Fa mode

 as described in
 as described in

-.IR chmod (2)
+.Xr chmod 2

 and modified by the process' umask value (see
 and modified by the process' umask value (see

-.IR umask (2)).
-.PP
-.I Path
-is the address of a string of ASCII characters representing
-a path name, terminated by a null character.
+.Xr umask 2 ) .
+.Pp

 The flags specified are formed by
 The flags specified are formed by

-.IR or 'ing
+.Em or Ap ing

 the following values
 the following values

-.PP
-.RS
- O_RDONLY      open for reading only
- O_WRONLY      open for writing only
- O_RDWR        open for reading and writing
- O_NDELAY      do not block on open
- O_APPEND      append on each write
- O_CREAT       create file if it does not exist
- O_TRUNC       truncate size to 0
- O_EXCL        error if create and file exists
-.RE
-.PP
-Opening a file with O_APPEND set causes each write on the file
-to be appended to the end.  If O_TRUNC is specified and the
+.Pp
+.Bd -literal -offset indent -compact
+O_RDONLY       open for reading only
+O_WRONLY       open for writing only
+O_RDWR         open for reading and writing
+O_NONBLOCK     do not block on open
+O_APPEND       append on each write
+O_CREAT                create file if it does not exist
+O_TRUNC                truncate size to 0
+O_EXCL         error if create and file exists
+O_SHLOCK       atomically obtain a shared lock
+O_EXLOCK       atomically obtain an exclusive lock
+.Ed
+.Pp
+Opening a file with
+.Dv O_APPEND
+set causes each write on the file
+to be appended to the end.  If
+.Dv O_TRUNC
+is specified and the

 file exists, the file is truncated to zero length.
 file exists, the file is truncated to zero length.

-If O_EXCL is set with O_CREAT, then if the file already
-exists, the open returns an error.  This can be used to
+If
+.Dv O_EXCL
+is set with
+.Dv O_CREAT
+and the file already
+exists,
+.Fn open
+returns an error.  This may be used to

 implement a simple exclusive access locking mechanism.
 implement a simple exclusive access locking mechanism.

-If O_EXCL is set and the last component of the pathname is
-a symbolic link, the open will fail even if the symbolic
+If
+.Dv O_EXCL
+is set and the last component of the pathname is
+a symbolic link,
+.Fn open
+will fail even if the symbolic

 link points to a non-existent name.
 link points to a non-existent name.

-If the O_NDELAY flag is specified and the open call would result
-in the process being blocked for some reason (e.g. waiting for
-carrier on a dialup line), the open returns immediately. 
-The first time the process attempts to perform i/o on the open
+If the
+.Dv O_NONBLOCK
+flag is specified and the
+.Fn open
+call would result
+in the process being blocked for some reason (e.g., waiting for
+carrier on a dialup line),
+.Fn open
+returns immediately.
+The first time the process attempts to perform I/O on the open

 file it will block (not currently implemented).
 file it will block (not currently implemented).

-.PP
-Upon successful completion a non-negative integer termed a
-file descriptor is returned.
+.Pp
+When opening a file, a lock with
+.Xr flock 2
+semantics can be obtained by setting
+.Dv O_SHLOCK
+for a shared lock, or
+.Dv O_EXLOCK
+for an exclusive lock.
+If creating a file with
+.Dv O_CREAT ,
+the request for the lock will never fail
+(provided that the underlying filesystem supports locking).
+.Pp
+If successful,
+.Fn open
+returns a non-negative integer, termed a file descriptor.
+It returns -1 on failure.

 The file pointer used to mark the current position within the
 file is set to the beginning of the file.
 The file pointer used to mark the current position within the
 file is set to the beginning of the file.

-.PP
+.Pp
+When a new file is created it is given the group of the directory
+which contains it.
+.Pp

 The new descriptor is set to remain open across
 The new descriptor is set to remain open across

-.IR execve
+.Xr execve

 system calls; see
 system calls; see

-.IR close (2).
-.PP
-No process may have more than {OPEN_MAX} file descriptors open
-simultaneously.
-.SH "ERRORS
-The named file is opened unless one or more of the
-following are true:
-.TP 15
-[ENOTDIR]
+.Xr close 2
+and
+.Xr fcntl 2 .
+.Pp
+The system imposes a limit on the number of file descriptors
+open simultaneously by one process.
+.Xr Getdtablesize 2
+returns the current system limit.
+.Sh ERRORS
+The named file is opened unless:
+.Bl -tag -width Er
+.It Bq Er ENOTDIR

 A component of the path prefix is not a directory.
 A component of the path prefix is not a directory.

-.TP 15
-[EINVAL]
-The pathname contains a character with the high-order bit set.
-.TP 15
-[ENAMETOOLONG]
+.It Bq Er ENAMETOOLONG

 A component of a pathname exceeded 255 characters,
 or an entire path name exceeded 1023 characters.
 A component of a pathname exceeded 255 characters,
 or an entire path name exceeded 1023 characters.

-.TP 15
-[ENOENT]
-O_CREAT is not set and the named file does not exist.
-.TP 15
-[ENOENT]
+.It Bq Er ENOENT
+.Dv O_CREAT
+is not set and the named file does not exist.
+.It Bq Er ENOENT

 A component of the path name that must exist does not exist.
 A component of the path name that must exist does not exist.

-.TP 15
-[EACCES]
+.It Bq Er EACCES

 Search permission is denied for a component of the path prefix.
 Search permission is denied for a component of the path prefix.

-.TP 15
-[EACCES]
+.It Bq Er EACCES

 The required permissions (for reading and/or writing)
 The required permissions (for reading and/or writing)

-are denied for the named flag.
-.TP 15
-[EACCES]
-O_CREAT is specified,
+are denied for the given flags.
+.It Bq Er EACCES
+.Dv O_CREAT
+is specified,

 the file does not exist,
 and the directory in which it is to be created
 does not permit writing.
 the file does not exist,
 and the directory in which it is to be created
 does not permit writing.

-.TP 15
-[ELOOP]
+.It Bq Er ELOOP

 Too many symbolic links were encountered in translating the pathname.
 Too many symbolic links were encountered in translating the pathname.

-.TP 15
-[EISDIR]
+.It Bq Er EISDIR

 The named file is a directory, and the arguments specify
 The named file is a directory, and the arguments specify

-it is to be opened for writting.
-.TP 15
-[EROFS]
+it is to be opened for writing.
+.It Bq Er EROFS

 The named file resides on a read-only file system,
 and the file is to be modified.
 The named file resides on a read-only file system,
 and the file is to be modified.

-.TP 15
-[EMFILE]
-{OPEN_MAX} file descriptors are currently open.
-.TP 15
-[ENFILE]
+.It Bq Er EMFILE
+The process has already reached its limit for open file descriptors.
+.It Bq Er ENFILE

 The system file table is full.
 The system file table is full.

-.TP 15
-[ENXIO]
+.It Bq Er ENXIO

 The named file is a character special or block
 special file, and the device associated with this special file
 does not exist.
 The named file is a character special or block
 special file, and the device associated with this special file
 does not exist.

-.TP 15
-[ENXIO]
-The O_NDELAY flag is given, and the file is a communications device
-on which their is no carrier present.
-.TP 15
-[ENOSPC]
-O_CREAT is specified,
+.It Bq Er EINTR
+The
+.Nm
+operation was interrupted by a signal.
+.It Bq Er EOPNOTSUPP
+.Dv O_SHLOCK
+or
+.Dv O_EXLOCK
+is specified but the underlying filesystem does not support locking.
+.It Bq Er ENOSPC
+.Dv O_CREAT
+is specified,

 the file does not exist,
 and the directory in which the entry for the new file is being placed
 cannot be extended because there is no space left on the file
 system containing the directory.
 the file does not exist,
 and the directory in which the entry for the new file is being placed
 cannot be extended because there is no space left on the file
 system containing the directory.

-.TP 15
-[ENOSPC]
-O_CREAT is specified,
+.It Bq Er ENOSPC
+.Dv O_CREAT
+is specified,

 the file does not exist,
 and there are no free inodes on the file system on which the
 file is being created.
 the file does not exist,
 and there are no free inodes on the file system on which the
 file is being created.

-.TP 15
-[EDQUOT]
-O_CREAT is specified,
+.It Bq Er EDQUOT
+.Dv O_CREAT
+is specified,

 the file does not exist,
 the file does not exist,

-and the directory in which the entry for the new fie
+and the directory in which the entry for the new file

 is being placed cannot be extended because the
 user's quota of disk blocks on the file system
 containing the directory has been exhausted.
 is being placed cannot be extended because the
 user's quota of disk blocks on the file system
 containing the directory has been exhausted.

-.TP 15
-[EDQUOT]
-O_CREAT is specified,
+.It Bq Er EDQUOT
+.Dv O_CREAT
+is specified,

 the file does not exist,
 and the user's quota of inodes on the file system on
 which the file is being created has been exhausted.
 the file does not exist,
 and the user's quota of inodes on the file system on
 which the file is being created has been exhausted.

-.TP 15
-[EIO]
+.It Bq Er EIO

 An I/O error occurred while making the directory entry or
 An I/O error occurred while making the directory entry or

-allocating the inode for O_CREAT.
-.TP 15
-[ETXTBSY]
+allocating the inode for
+.Dv O_CREAT .
+.It Bq Er ETXTBSY

 The file is a pure procedure (shared text) file that is being
 The file is a pure procedure (shared text) file that is being

-executed and the \fIopen\fP call requests write access.
-.TP 15
-[EFAULT]
-.I Path
+executed and the
+.Fn open
+call requests write access.
+.It Bq Er EFAULT
+.Fa Path

 points outside the process's allocated address space.
 points outside the process's allocated address space.

-.TP 15
-[EEXIST]
-O_CREAT and O_EXCL were specified and the file exists.
-.TP 15
-[EOPNOTSUPP]
+.It Bq Er EEXIST
+.Dv O_CREAT
+and
+.Dv O_EXCL
+were specified and the file exists.
+.It Bq Er EOPNOTSUPP

 An attempt was made to open a socket (not currently implemented).
 An attempt was made to open a socket (not currently implemented).

-.SH "SEE ALSO"
-chmod(2), close(2), dup(2), lseek(2), read(2), write(2), umask(2)
+.El
+.Sh SEE ALSO
+.Xr chmod 2 ,
+.Xr close 2 ,
+.Xr dup 2 ,
+.Xr getdtablesize 2 ,
+.Xr lseek 2 ,
+.Xr read 2 ,
+.Xr write 2 ,
+.Xr umask 2
+.Sh HISTORY
+An
+.Nm
+function call appeared in Version 6 AT&T UNIX.