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diff --git a/usr/src/man/man2/open.2 b/usr/src/man/man2/open.2 new file mode 100644 index 0000000000..348b55522a --- /dev/null +++ b/usr/src/man/man2/open.2 @@ -0,0 +1,1001 @@ +'\" te +.\" Copyright (c) 2008, Sun Microsystems, Inc. All Rights Reserved. +.\" Copyright 1989 AT&T +.\" Portions Copyright (c) 1992, X/Open Company Limited. All Rights Reserved. +.\" Sun Microsystems, Inc. gratefully acknowledges The Open Group for permission to reproduce portions of its copyrighted documentation. Original documentation from The Open Group can be obtained online at +.\" http://www.opengroup.org/bookstore/. +.\" The Institute of Electrical and Electronics Engineers and The Open Group, have given us permission to reprint portions of their documentation. In the following statement, the phrase "this text" refers to portions of the system documentation. Portions of this text are reprinted and reproduced in electronic form in the Sun OS Reference Manual, from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2004 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between these versions and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html. +.\" This notice shall appear on any product containing this material. +.\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License"). You may not use this file except in compliance with the License. +.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing. See the License for the specific language governing permissions and limitations under the License. +.\" When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE. If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner] +.TH open 2 "16 Jun 2008" "SunOS 5.11" "System Calls" +.SH NAME +open, openat \- open a file +.SH SYNOPSIS +.LP +.nf +#include <sys/types.h> +#include <sys/stat.h> +#include <fcntl.h> + +\fBint\fR \fBopen\fR(\fBconst char *\fR\fIpath\fR, \fBint\fR \fIoflag\fR, \fB/* mode_t\fR \fImode\fR */); +.fi + +.LP +.nf +\fBint\fR \fBopenat\fR(\fBint\fR \fIfildes\fR, \fBconst char *\fR\fIpath\fR, \fBint\fR \fIoflag\fR, + \fB/* mode_t\fR \fImode\fR */); +.fi + +.SH DESCRIPTION +.sp +.LP +The \fBopen()\fR function establishes the connection between a file and a file +descriptor. It creates an open file description that refers to a file and a +file descriptor that refers to that open file description. The file descriptor +is used by other I/O functions to refer to that file. The \fIpath\fR argument +points to a pathname naming the file. +.sp +.LP +The \fBopenat()\fR function is identical to the \fBopen()\fR function except +that the \fIpath\fR argument is interpreted relative to the starting point +implied by the \fIfildes\fR argument. If the \fIfildes\fR argument has the +special value \fBAT_FDCWD\fR, a relative path argument will be resolved +relative to the current working directory. If the \fIpath\fR argument is +absolute, the \fIfildes\fR argument is ignored. +.sp +.LP +The \fBopen()\fR function returns a file descriptor for the named file that is +the lowest file descriptor not currently open for that process. The open file +description is new, and therefore the file descriptor does not share it with +any other process in the system. The \fBFD_CLOEXEC\fR file descriptor flag +associated with the new file descriptor is cleared. +.sp +.LP +The file offset used to mark the current position within the file is set to the +beginning of the file. +.sp +.LP +The file status flags and file access modes of the open file description are +set according to the value of \fIoflag\fR. The \fImode\fR argument is used only +when \fBO_CREAT\fR is specified (see below.) +.sp +.LP +Values for \fIoflag\fR are constructed by a bitwise-inclusive-OR of flags from +the following list, defined in <\fBfcntl.h\fR>. Applications must specify +exactly one of the first three values (file access modes) below in the value of +\fIoflag\fR: +.sp +.ne 2 +.mk +.na +\fB\fBO_RDONLY\fR\fR +.ad +.RS 12n +.rt +Open for reading only. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBO_WRONLY\fR\fR +.ad +.RS 12n +.rt +Open for writing only. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBO_RDWR\fR\fR +.ad +.RS 12n +.rt +Open for reading and writing. The result is undefined if this flag is applied +to a FIFO. +.RE + +.sp +.LP +Any combination of the following may be used: +.sp +.ne 2 +.mk +.na +\fB\fBO_APPEND\fR\fR +.ad +.sp .6 +.RS 4n +If set, the file offset is set to the end of the file prior to each write. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBO_CREAT\fR\fR +.ad +.sp .6 +.RS 4n +Create the file if it does not exist. This flag requires that the \fImode\fR +argument be specified. +.sp +If the file exists, this flag has no effect except as noted under \fBO_EXCL\fR +below. Otherwise, the file is created with the user \fBID\fR of the file set +to the effective user \fBID\fR of the process. The group \fBID\fR of the file +is set to the effective group \fBIDs\fR of the process, or if the \fBS_ISGID\fR +bit is set in the directory in which the file is being created, the file's +group \fBID\fR is set to the group \fBID\fR of its parent directory. If the +group \fBID\fR of the new file does not match the effective group \fBID\fR or +one of the supplementary groups IDs, the \fBS_ISGID\fR bit is cleared. The +access permission bits (see \fB<sys/stat.h>\fR) of the file mode are set to the +value of \fImode\fR, modified as follows (see \fBcreat\fR(2)): a bitwise-AND is +performed on the file-mode bits and the corresponding bits in the complement of +the process's file mode creation mask. Thus, all bits set in the process's file +mode creation mask (see \fBumask\fR(2)) are correspondingly cleared in the +file's permission mask. The "save text image after execution bit" of the mode +is cleared (see \fBchmod\fR(2)). \fBO_SYNC\fR Write I/O operations on the file +descriptor complete as defined by synchronized I/O file integrity completion +(see \fBfcntl.h\fR(3HEAD) definition of \fBO_SYNC\fR.) When bits other than the +file permission bits are set, the effect is unspecified. The \fImode\fR +argument does not affect whether the file is open for reading, writing or for +both. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBO_DSYNC\fR\fR +.ad +.sp .6 +.RS 4n +Write I/O operations on the file descriptor complete as defined by synchronized +I/O data integrity completion. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBO_EXCL\fR\fR +.ad +.sp .6 +.RS 4n +If \fBO_CREAT\fR and \fBO_EXCL\fR are set, \fBopen()\fR fails if the file +exists. The check for the existence of the file and the creation of the file if +it does not exist is atomic with respect to other threads executing +\fBopen()\fR naming the same filename in the same directory with \fBO_EXCL\fR +and \fBO_CREAT\fR set. If \fBO_EXCL\fR and \fBO_CREAT\fR are set, and path +names a symbolic link, \fBopen()\fR fails and sets \fBerrno\fR to \fBEEXIST\fR, +regardless of the contents of the symbolic link. If \fBO_EXCL\fR is set and +\fBO_CREAT\fR is not set, the result is undefined. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBO_LARGEFILE\fR\fR +.ad +.sp .6 +.RS 4n +If set, the offset maximum in the open file description is the largest value +that can be represented correctly in an object of type \fBoff64_t\fR. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBO_NOCTTY\fR\fR +.ad +.sp .6 +.RS 4n +If set and \fIpath\fR identifies a terminal device, \fBopen()\fR does not cause +the terminal device to become the controlling terminal for the process. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBO_NOFOLLOW\fR\fR +.ad +.sp .6 +.RS 4n +If the path names a symbolic link, \fBopen()\fR fails and sets \fBerrno\fR to +\fBELOOP\fR. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBO_NOLINKS\fR\fR +.ad +.sp .6 +.RS 4n +If the link count of the named file is greater than 1, \fBopen()\fR fails and +sets \fBerrno\fR to \fBEMLINK\fR. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBO_NONBLOCK\fR or \fBO_NDELAY\fR\fR +.ad +.sp .6 +.RS 4n +These flags can affect subsequent reads and writes (see \fBread\fR(2) and +\fBwrite\fR(2)). If both \fBO_NDELAY\fR and \fBO_NONBLOCK\fR are set, +\fBO_NONBLOCK\fR takes precedence. +.sp +When opening a \fBFIFO\fR with \fBO_RDONLY\fR or \fBO_WRONLY\fR set: +.RS +4 +.TP +.ie t \(bu +.el o +If \fBO_NONBLOCK\fR or \fBO_NDELAY\fR is set, an \fBopen()\fR for reading only +returns without delay. An \fBopen()\fR for writing only returns an error if no +process currently has the file open for reading. +.RE +.RS +4 +.TP +.ie t \(bu +.el o +If \fBO_NONBLOCK\fR and \fBO_NDELAY\fR are clear, an \fBopen()\fR for reading +only blocks until a thread opens the file for writing. An \fBopen()\fR for +writing only blocks the calling thread until a thread opens the file for +reading. +.RE +After both ends of a \fBFIFO\fR have been opened, there is no guarantee that +further calls to \fBopen()\fR \fBO_RDONLY\fR (\fBO_WRONLY\fR) will synchronize +with later calls to \fBopen()\fR \fBO_WRONLY\fR (\fBO_RDONLY\fR) until both +ends of the \fBFIFO\fR have been closed by all readers and writers. Any data +written into a \fBFIFO\fR will be lost if both ends of the \fBFIFO\fR are +closed before the data is read. +.sp +When opening a block special or character special file that supports +non-blocking opens: +.RS +4 +.TP +.ie t \(bu +.el o +If \fBO_NONBLOCK\fR or \fBO_NDELAY\fR is set, the \fBopen()\fR function returns +without blocking for the device to be ready or available. Subsequent behavior +of the device is device-specific. +.RE +.RS +4 +.TP +.ie t \(bu +.el o +If \fBO_NONBLOCK\fR and \fBO_NDELAY\fR are clear, the \fBopen()\fR function +blocks the calling thread until the device is ready or available before +returning. +.RE +Otherwise, the behavior of \fBO_NONBLOCK\fR and \fBO_NDELAY\fR is unspecified. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBO_RSYNC\fR\fR +.ad +.sp .6 +.RS 4n +Read I/O operations on the file descriptor complete at the same level of +integrity as specified by the \fBO_DSYNC\fR and \fBO_SYNC\fR flags. If both +\fBO_DSYNC\fR and \fBO_RSYNC\fR are set in \fIoflag\fR, all I/O operations on +the file descriptor complete as defined by synchronized I/O data integrity +completion. If both \fBO_SYNC\fR and \fBO_RSYNC\fR are set in \fIoflag\fR, all +I/O operations on the file descriptor complete as defined by synchronized I/O +file integrity completion. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBO_SYNC\fR\fR +.ad +.sp .6 +.RS 4n +Write I/O operations on the file descriptor complete as defined by synchronized +I/O file integrity completion. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBO_TRUNC\fR\fR +.ad +.sp .6 +.RS 4n +If the file exists and is a regular file, and the file is successfully opened +\fBO_RDWR\fR or \fBO_WRONLY\fR, its length is truncated to 0 and the mode and +owner are unchanged. It has no effect on \fBFIFO\fR special files or terminal +device files. Its effect on other file types is implementation-dependent. The +result of using \fBO_TRUNC\fR with \fBO_RDONLY\fR is undefined. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBO_XATTR\fR\fR +.ad +.sp .6 +.RS 4n +If set in \fBopenat()\fR, a relative path argument is interpreted as a +reference to an extended attribute of the file associated with the supplied +file descriptor. This flag therefore requires the presence of a legal +\fIfildes\fR argument. If set in \fBopen()\fR, the implied file descriptor is +that for the current working directory. Extended attributes must be referenced +with a relative path; providing an absolute path results in a normal file +reference. +.RE + +.sp +.LP +If \fBO_CREAT\fR is set and the file did not previously exist, upon successful +completion, \fBopen()\fR marks for update the \fBst_atime\fR, \fBst_ctime\fR, +and \fBst_mtime\fR fields of the file and the \fBst_ctime\fR and \fBst_mtime\fR +fields of the parent directory. +.sp +.LP +If \fBO_TRUNC\fR is set and the file did previously exist, upon successful +completion, \fBopen()\fR marks for update the \fBst_ctime\fR and \fBst_mtime\fR +fields of the file. +.sp +.LP +If both the \fBO_SYNC\fR and \fBO_DSYNC\fR flags are set, the effect is as if +only the \fBO_SYNC\fR flag was set. +.sp +.LP +If \fIpath\fR refers to a \fBSTREAMS\fR file, \fIoflag\fR may be constructed +from \fBO_NONBLOCK\fR or \fBO_NODELAY\fR OR-ed with either \fBO_RDONLY\fR, +\fBO_WRONLY\fR, or \fBO_RDWR\fR. Other flag values are not applicable to +\fBSTREAMS\fR devices and have no effect on them. The values \fBO_NONBLOCK\fR +and \fBO_NODELAY\fR affect the operation of \fBSTREAMS\fR drivers and certain +functions (see \fBread\fR(2), \fBgetmsg\fR(2), \fBputmsg\fR(2), and +\fBwrite\fR(2)) applied to file descriptors associated with \fBSTREAMS\fR +files. For \fBSTREAMS\fR drivers, the implementation of \fBO_NONBLOCK\fR and +\fBO_NODELAY\fR is device-specific. +.sp +.LP +When \fBopen()\fR is invoked to open a named stream, and the \fBconnld\fR +module (see \fBconnld\fR(7M)) has been pushed on the pipe, \fBopen()\fR blocks +until the server process has issued an \fBI_RECVFD\fR \fBioctl()\fR (see +\fBstreamio\fR(7I)) to receive the file descriptor. +.sp +.LP +If \fIpath\fR names the master side of a pseudo-terminal device, then it is +unspecified whether \fBopen()\fR locks the slave side so that it cannot be +opened. Portable applications must call \fBunlockpt\fR(3C) before opening the +slave side. +.sp +.LP +If the file is a regular file and the local file system is mounted with the +\fBnbmand\fR mount option, then a mandatory share reservation is automatically +obtained on the file. The share reservation is obtained as if \fBfcntl\fR(2) +were called with \fIcmd\fR \fBF_SHARE_NBMAND\fR and the \fBfshare_t\fR values +set as follows: +.sp +.ne 2 +.mk +.na +\fB\fBf_access\fR\fR +.ad +.RS 12n +.rt +Set to the type of read/write access for which the file is opened. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBf_deny\fR\fR +.ad +.RS 12n +.rt +\fBF_NODNY\fR +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBf_id\fR\fR +.ad +.RS 12n +.rt +The file descriptor value returned from \fBopen()\fR. +.RE + +.sp +.LP +If \fIpath\fR is a symbolic link and \fBO_CREAT\fR and \fBO_EXCL\fR are set, +the link is not followed. +.sp +.LP +Certain flag values can be set following \fBopen()\fR as described in +\fBfcntl\fR(2). +.sp +.LP +The largest value that can be represented correctly in an object of type +\fBoff_t\fR is established as the offset maximum in the open file description. +.SH RETURN VALUES +.sp +.LP +Upon successful completion, the \fBopen()\fR function opens the file and return +a non-negative integer representing the lowest numbered unused file descriptor. +Otherwise, \fB\(mi1\fR is returned, \fBerrno\fR is set to indicate the error, +and no files are created or modified. +.SH ERRORS +.sp +.LP +The \fBopen()\fR and \fBopenat()\fR functions will fail if: +.sp +.ne 2 +.mk +.na +\fB\fBEACCES\fR\fR +.ad +.RS 16n +.rt +Search permission is denied on a component of the path prefix. +.sp +The file exists and the permissions specified by \fIoflag\fR are denied. +.sp +The file does not exist and write permission is denied for the parent directory +of the file to be created. +.sp +\fBO_TRUNC\fR is specified and write permission is denied. +.sp +The {\fBPRIV_FILE_DAC_SEARCH\fR} privilege allows processes to search +directories regardless of permission bits. The {\fBPRIV_FILE_DAC_WRITE\fR} +privilege allows processes to open files for writing regardless of permission +bits. See \fBprivileges\fR(5) for special considerations when opening files +owned by UID 0 for writing. The {\fBPRIV_FILE_DAC_READ\fR} privilege allows +processes to open files for reading regardless of permission bits. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBEAGAIN\fR\fR +.ad +.RS 16n +.rt +A mandatory share reservation could not be obtained because the desired access +conflicts with an existing \fBf_deny\fR share reservation. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBEBADF\fR\fR +.ad +.RS 16n +.rt +The file descriptor provided to \fBopenat()\fR is invalid. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBEDQUOT\fR\fR +.ad +.RS 16n +.rt +The file does not exist, \fBO_CREAT\fR is specified, and either the directory +where the new file entry is being placed cannot be extended because the user's +quota of disk blocks on that file system has been exhausted, or the user's +quota of inodes on the file system where the file is being created has been +exhausted. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBEEXIST\fR\fR +.ad +.RS 16n +.rt +The \fBO_CREAT\fR and \fBO_EXCL\fR flags are set and the named file exists. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBEILSEQ\fR\fR +.ad +.RS 16n +.rt +The \fIpath\fR argument includes non-UTF8 characters and the file system +accepts only file names where all characters are part of the UTF-8 character +codeset. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBEINTR\fR\fR +.ad +.RS 16n +.rt +A signal was caught during \fBopen()\fR. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBEFAULT\fR\fR +.ad +.RS 16n +.rt +The \fIpath\fR argument points to an illegal address. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBEINVAL\fR\fR +.ad +.RS 16n +.rt +The system does not support synchronized I/O for this file, or the +\fBO_XATTR\fR flag was supplied and the underlying file system does not support +extended file attributes. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBEIO\fR\fR +.ad +.RS 16n +.rt +The \fIpath\fR argument names a \fBSTREAMS\fR file and a hangup or error +occurred during the \fBopen()\fR. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBEISDIR\fR\fR +.ad +.RS 16n +.rt +The named file is a directory and \fIoflag\fR includes \fBO_WRONLY\fR or +\fBO_RDWR\fR. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBELOOP\fR\fR +.ad +.RS 16n +.rt +Too many symbolic links were encountered in resolving \fIpath\fR. +.sp +A loop exists in symbolic links encountered during resolution of the \fIpath\fR +argument. +.sp +The \fBO_NOFOLLOW\fR flag is set and the final component of path is a symbolic +link. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBEMFILE\fR\fR +.ad +.RS 16n +.rt +There are currently {\fBOPEN_MAX\fR} file descriptors open in the calling +process. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBEMLINK\fR\fR +.ad +.RS 16n +.rt +The \fBO_NOLINKS\fR flag is set and the named file has a link count greater +than 1. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBEMULTIHOP\fR\fR +.ad +.RS 16n +.rt +Components of \fIpath\fR require hopping to multiple remote machines and the +file system does not allow it. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBENAMETOOLONG\fR\fR +.ad +.RS 16n +.rt +The length of the \fIpath\fR argument exceeds {\fBPATH_MAX\fR} or a pathname +component is longer than {\fBNAME_MAX\fR}. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBENFILE\fR\fR +.ad +.RS 16n +.rt +The maximum allowable number of files is currently open in the system. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBENOENT\fR\fR +.ad +.RS 16n +.rt +The \fBO_CREAT\fR flag is not set and the named file does not exist; or the +\fBO_CREAT\fR flag is set and either the path prefix does not exist or the +\fIpath\fR argument points to an empty string. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBENOLINK\fR\fR +.ad +.RS 16n +.rt +The \fIpath\fR argument points to a remote machine, and the link to that +machine is no longer active. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBENOSR\fR\fR +.ad +.RS 16n +.rt +The \fIpath\fR argument names a STREAMS-based file and the system is unable to +allocate a STREAM. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBENOSPC\fR\fR +.ad +.RS 16n +.rt +The directory or file system that would contain the new file cannot be +expanded, the file does not exist, and \fBO_CREAT\fR is specified. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBENOSYS\fR\fR +.ad +.RS 16n +.rt +The device specified by \fIpath\fR does not support the open operation. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBENOTDIR\fR\fR +.ad +.RS 16n +.rt +A component of the path prefix is not a directory or a relative path was +supplied to \fBopenat()\fR, the \fBO_XATTR\fR flag was not supplied, and the +file descriptor does not refer to a directory. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBENXIO\fR\fR +.ad +.RS 16n +.rt +The \fBO_NONBLOCK\fR flag is set, the named file is a FIFO, the \fBO_WRONLY\fR +flag is set, and no process has the file open for reading; or the named file is +a character special or block special file and the device associated with this +special file does not exist or has been retired by the fault management +framework . +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBEOPNOTSUPP\fR\fR +.ad +.RS 16n +.rt +An attempt was made to open a path that corresponds to a \fBAF_UNIX\fR socket. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBEOVERFLOW\fR\fR +.ad +.RS 16n +.rt +The named file is a regular file and either \fBO_LARGEFILE\fR is not set and +the size of the file cannot be represented correctly in an object of type +\fBoff_t\fR or \fBO_LARGEFILE\fR is set and the size of the file cannot be +represented correctly in an object of type \fBoff64_t\fR. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBEROFS\fR\fR +.ad +.RS 16n +.rt +The named file resides on a read-only file system and either \fBO_WRONLY\fR, +\fBO_RDWR\fR, \fBO_CREAT\fR (if file does not exist), or \fBO_TRUNC\fR is set +in the \fIoflag\fR argument. +.RE + +.sp +.LP +The \fBopenat()\fR function will fail if: +.sp +.ne 2 +.mk +.na +\fB\fBEBADF\fR\fR +.ad +.RS 9n +.rt +The \fIfildes\fR argument is not a valid open file descriptor or is not +\fBAT_FTCWD\fR. +.RE + +.sp +.LP +The \fBopen()\fR function may fail if: +.sp +.ne 2 +.mk +.na +\fB\fBEAGAIN\fR\fR +.ad +.RS 16n +.rt +The \fIpath\fR argument names the slave side of a pseudo-terminal device that +is locked. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBEINVAL\fR\fR +.ad +.RS 16n +.rt +The value of the \fIoflag\fR argument is not valid. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBENAMETOOLONG\fR\fR +.ad +.RS 16n +.rt +Pathname resolution of a symbolic link produced an intermediate result whose +length exceeds {\fBPATH_MAX\fR}. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBENOMEM\fR\fR +.ad +.RS 16n +.rt +The \fIpath\fR argument names a \fBSTREAMS\fR file and the system is unable to +allocate resources. +.RE + +.sp +.ne 2 +.mk +.na +\fB\fBETXTBSY\fR\fR +.ad +.RS 16n +.rt +The file is a pure procedure (shared text) file that is being executed and +\fIoflag\fR is \fBO_WRONLY\fR or \fBO_RDWR\fR. +.RE + +.SH EXAMPLES +.LP +\fBExample 1 \fROpen a file for writing by the owner. +.sp +.LP +The following example opens the file \fB/tmp/file\fR, either by creating it if +it does not already exist, or by truncating its length to 0 if it does exist. +If the call creates a new file, the access permission bits in the file mode of +the file are set to permit reading and writing by the owner, and to permit +reading only by group members and others. + +.sp +.LP +If the call to \fBopen()\fR is successful, the file is opened for writing. + +.sp +.in +2 +.nf +#include <fcntl.h> +\&... +int fd; +mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH; +char *filename = "/tmp/file"; +\&... +fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, mode); +\&... +.fi +.in -2 + +.LP +\fBExample 2 \fROpen a file using an existence check. +.sp +.LP +The following example uses the \fBopen()\fR function to try to create the +\fBLOCKFILE\fR file and open it for writing. Since the \fBopen()\fR function +specifies the \fBO_EXCL\fR flag, the call fails if the file already exists. In +that case, the application assumes that someone else is updating the password +file and exits. + +.sp +.in +2 +.nf +#include <fcntl.h> +#include <stdio.h> +#include <stdlib.h> +#define LOCKFILE "/etc/ptmp" +\&... +int pfd; /* Integer for file descriptor returned by open() call. */ +\&... +if ((pfd = open(LOCKFILE, O_WRONLY | O_CREAT | O_EXCL, + S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)) == -1) +{ + fprintf(stderr, "Cannot open /etc/ptmp. Try again later.\en"); + exit(1); +} +\&... +.fi +.in -2 + +.LP +\fBExample 3 \fROpen a file for writing. +.sp +.LP +The following example opens a file for writing, creating the file if it does +not already exist. If the file does exist, the system truncates the file to +zero bytes. + +.sp +.in +2 +.nf +#include <fcntl.h> +#include <stdio.h> +#include <stdlib.h> +#define LOCKFILE "/etc/ptmp" +\&... +int pfd; +char filename[PATH_MAX+1]; +\&... +if ((pfd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, + S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)) == -1) +{ + perror("Cannot open output file\en"); exit(1); +} +\&... +.fi +.in -2 + +.SH USAGE +.sp +.LP +The \fBopen()\fR function has a transitional interface for 64-bit file offsets. +See \fBlf64\fR(5). Note that using \fBopen64()\fR is equivalent to using +\fBopen()\fR with \fBO_LARGEFILE\fR set in \fIoflag\fR. +.SH ATTRIBUTES +.sp +.LP +See \fBattributes\fR(5) for descriptions of the following attributes: +.sp + +.sp +.TS +tab() box; +cw(2.75i) |cw(2.75i) +lw(2.75i) |lw(2.75i) +. +ATTRIBUTE TYPEATTRIBUTE VALUE +_ +Interface StabilityCommitted +_ +MT-LevelAsync-Signal-Safe +_ +StandardFor \fBopen()\fR, see \fBstandards\fR(5). +.TE + +.SH SEE ALSO +.sp +.LP +\fBIntro\fR(2), \fBchmod\fR(2), \fBclose\fR(2), \fBcreat\fR(2), \fBdup\fR(2), +\fBexec\fR(2), \fBfcntl\fR(2), \fBgetmsg\fR(2), \fBgetrlimit\fR(2), +\fBlseek\fR(2), \fBputmsg\fR(2), \fBread\fR(2), \fBstat\fR(2), \fBumask\fR(2), +\fBwrite\fR(2), \fBattropen\fR(3C), \fBfcntl.h\fR(3HEAD), \fBstat.h\fR(3HEAD), +\fBunlockpt\fR(3C), \fBattributes\fR(5), \fBlf64\fR(5), \fBprivileges\fR(5), +\fBstandards\fR(5), \fBconnld\fR(7M), \fBstreamio\fR(7I) +.SH NOTES +.sp +.LP +Hierarchical Storage Management (HSM) file systems can sometimes cause long +delays when opening a file, since HSM files must be recalled from secondary +storage. |