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14249 pseudo-terminal nomenclature should reflect POSIX
Change-Id: Ib4a3cef899ff4c71b09cb0dc6878863c5e8357bc
@@ -6,344 +6,344 @@
SYNOPSIS
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
- int open(const char *path, int oflag, /* mode_t mode */);
+ int
+ open(const char *path, int oflag [, mode_t mode]);
+ int
+ openat(int fildes, const char *path, int oflag [, mode_t mode]);
- int openat(int fildes, const char *path, int oflag,
- /* mode_t mode */);
-
-
DESCRIPTION
- The open() 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 path argument points to a pathname naming the file.
+ The open() 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 path argument points to a pathname naming the file.
-
- The openat() function is identical to the open() function except that
- the path argument is interpreted relative to the starting point implied
- by the fildes argument. If the fildes argument has the special value
+ The openat() function is identical to the open() function except that the
+ path argument is interpreted relative to the starting point implied by
+ the fildes argument. If the fildes argument has the special value
AT_FDCWD, a relative path argument will be resolved relative to the
current working directory. If the path argument is absolute, the fildes
argument is ignored.
+ The open() 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 FD_CLOEXEC file descriptor
+ flag associated with the new file descriptor is cleared.
- The open() 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 FD_CLOEXEC file
- descriptor flag associated with the new file descriptor is cleared.
+ The file offset used to mark the current position within the file is set
+ to the beginning of the file.
+ The file status flags and file access modes of the open file description
+ are set according to the value of oflag. The mode argument is used only
+ when O_CREAT is specified (see below).
- The file offset used to mark the current position within the file is
- set to the beginning of the file.
+ Values for oflag are constructed by a bitwise-inclusive-OR of flags from
+ the following list, defined in fcntl.h(3HEAD). Applications must specify
+ exactly one of the first three values (file access modes) below in the
+ value of oflag:
-
- The file status flags and file access modes of the open file
- description are set according to the value of oflag. The mode argument
- is used only when O_CREAT is specified (see below.)
-
-
- Values for oflag are constructed by a bitwise-inclusive-OR of flags
- from the following list, defined in <fcntl.h>. Applications must
- specify exactly one of the first three values (file access modes) below
- in the value of oflag:
-
O_RDONLY
Open for reading only.
-
O_WRONLY
Open for writing only.
+ O_RDWR Open for reading and writing. The result is undefined if this
+ flag is applied to a FIFO.
- O_RDWR
- Open for reading and writing. The result is undefined if
- this flag is applied to a FIFO.
-
-
-
Any combination of the following may be used:
O_APPEND
+ If set, the file offset is set to the end of the file prior to
+ each write.
- If set, the file offset is set to the end of the file prior to each
- write.
-
-
O_CREAT
+ Create the file if it does not exist. This flag requires that
+ the mode argument be specified.
- Create the file if it does not exist. This flag requires that the
- mode argument be specified.
-
If the file exists, this flag has no effect except as noted under
O_EXCL below. Otherwise, the file is created with the user ID of
- the file set to the effective user ID of the process. The group ID
- of the file is set to the effective group IDs of the process, or if
- the S_ISGID bit is set in the directory in which the file is being
- created, the file's group ID is set to the group ID of its parent
- directory. If the group ID of the new file does not match the
- effective group ID or one of the supplementary groups IDs, the
- S_ISGID bit is cleared. The access permission bits (see
- <sys/stat.h>) of the file mode are set to the value of mode,
- modified as follows (see creat(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 umask(2)) are
- correspondingly cleared in the file's permission mask. The "save
- text image after execution bit" of the mode is cleared (see
- chmod(2)). When bits other than the file permission bits are set,
- the effect is unspecified. The mode argument does not affect
- whether the file is open for reading, writing or for both.
+ the file set to the effective user ID of the process. The group
+ ID of the file is set to the effective group IDs of the process,
+ or if the S_ISGID bit is set in the directory in which the file
+ is being created, the file's group ID is set to the group ID of
+ its parent directory. If the group ID of the new file does not
+ match the effective group ID or one of the supplementary groups
+ IDs, the S_ISGID bit is cleared.
+ The access permission bits (see stat.h(3HEAD)) of the file mode
+ are set to the value of mode, modified as follows (see creat(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 umask(2)) are correspondingly cleared in the
+ file's permission mask. The "save text image after execution
+ bit" of the mode is cleared (see chmod(2)). When bits other than
+ the file permission bits are set, the effect is unspecified. The
+ mode argument does not affect whether the file is open for
+ reading, writing or for both.
O_DIRECT
+ Indicates that the file data is not going to be reused in the
+ near future. When possible, data is read or written directly
+ between the application's memory and the device when the data is
+ accessed with read(2) and write(2) operations. See directio(3C)
+ for more details.
- Indicates that the file data is not going to be reused in the near
- future. When possible, data is read or written directly between
- the application's memory and the device when the data is accessed
- with read(2) and write(2) operations. See directio(3C) for more
- details.
-
-
O_DIRECTORY
-
Indicates that attempts to open path should fail unless path is a
- directory. If both O_CREAT and O_DIRECTORY are specified then the
- call will fail if it would result in a file being created. If a
- directory already exists at path then it will behave as if the
- O_DIRECTORY flag had not been present. If the O_EXCL and O_CREAT
- flags are specified, then the call will always fail as they imply a
- file should always be created.
+ directory. If both O_CREAT and O_DIRECTORY are specified then
+ the call will fail if it would result in a file being created.
+ If a directory already exists at path then it will behave as if
+ the O_DIRECTORY flag had not been present. If the O_EXCL and
+ O_CREAT flags are specified, then the call will always fail as
+ they imply a file should always be created.
-
O_DSYNC
+ Write I/O operations on the file descriptor complete as defined
+ by synchronized I/O data integrity completion.
- Write I/O operations on the file descriptor complete as defined by
- synchronized I/O data integrity completion.
+ O_EXCL If O_CREAT and O_EXCL are set, open() 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 open() naming the same filename in the same directory
+ with O_EXCL and O_CREAT set. If O_EXCL and O_CREAT are set, and
+ path names a symbolic link, open() fails and sets errno to
+ EEXIST, regardless of the contents of the symbolic link. If
+ O_EXCL is set and O_CREAT is not set, the result is undefined.
+ O_EXEC If set, indicates that the file should be opened for execute
+ permission. This option is only valid for regular files; an
+ error will be returned if the target is not a regular file.
- O_EXCL
-
- If O_CREAT and O_EXCL are set, open() 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
- open() naming the same filename in the same directory with O_EXCL
- and O_CREAT set. If O_EXCL and O_CREAT are set, and path names a
- symbolic link, open() fails and sets errno to EEXIST, regardless of
- the contents of the symbolic link. If O_EXCL is set and O_CREAT is
- not set, the result is undefined.
-
-
- O_EXEC
-
- If set, indicates that the file should be opened for execute
- permission. This option is only valid for regular files, an error
- will be returned if it is not.
-
-
O_LARGEFILE
-
If set, the offset maximum in the open file description is the
largest value that can be represented correctly in an object of
type off64_t.
-
O_NOCTTY
+ If set and path identifies a terminal device, open() does not
+ cause the terminal device to become the controlling terminal for
+ the process.
- If set and path identifies a terminal device, open() does not cause
- the terminal device to become the controlling terminal for the
- process.
-
-
O_NOFOLLOW
-
If the path names a symbolic link, open() fails and sets errno to
ELOOP.
-
O_NOLINKS
+ If the link count of the named file is greater than 1, open()
+ fails and sets errno to EMLINK.
- If the link count of the named file is greater than 1, open() fails
- and sets errno to EMLINK.
-
-
O_CLOEXEC
-
If set, the file descriptor returned will be closed prior to any
- future exec() calls.
+ future exec(2) calls.
+ O_NONBLOCK O_NDELAY
+ These flags can affect subsequent reads and writes (see read(2)
+ and write(2)). If both O_NDELAY and O_NONBLOCK are set,
+ O_NONBLOCK takes precedence.
- O_NONBLOCK or O_NDELAY
-
- These flags can affect subsequent reads and writes (see read(2) and
- write(2)). If both O_NDELAY and O_NONBLOCK are set, O_NONBLOCK
- takes precedence.
-
When opening a FIFO with O_RDONLY or O_WRONLY set:
- o If O_NONBLOCK or O_NDELAY is set, an open() for reading
- only returns without delay. An open() for writing only
- returns an error if no process currently has the file
- open for reading.
+ o If O_NONBLOCK or O_NDELAY is set, an open() for reading only
+ returns without delay. An open() for writing only returns an
+ error if no process currently has the file open for reading.
- o If O_NONBLOCK and O_NDELAY are clear, an open() for
- reading only blocks until a thread opens the file for
- writing. An open() for writing only blocks the calling
- thread until a thread opens the file for reading.
- After both ends of a FIFO have been opened, there is no guarantee
- that further calls to open() O_RDONLY (O_WRONLY) will synchronize
- with later calls to open() O_WRONLY (O_RDONLY) until both ends of
- the FIFO have been closed by all readers and writers. Any data
- written into a FIFO will be lost if both ends of the FIFO are
- closed before the data is read.
+ o If O_NONBLOCK and O_NDELAY are clear, an open() for reading
+ only blocks until a thread opens the file for writing. An
+ open() for writing only blocks the calling thread until a
+ thread opens the file for reading.
+ After both ends of a FIFO have been opened once, there is no
+ guarantee that further calls to open() O_RDONLY (O_WRONLY) will
+ synchronize with later calls to open() O_WRONLY (O_RDONLY) until
+ both ends of the FIFO have been closed by all readers and
+ writers. Any data written into a FIFO will be lost if both ends
+ of the FIFO are closed before the data is read.
+
When opening a block special or character special file that
supports non-blocking opens:
- o If O_NONBLOCK or O_NDELAY is set, the open() function
- returns without blocking for the device to be ready or
- available. Subsequent behavior of the device is device-
- specific.
+ o If O_NONBLOCK or O_NDELAY is set, the open() function returns
+ without blocking for the device to be ready or available.
+ Subsequent behavior of the device is device-specific.
- o If O_NONBLOCK and O_NDELAY are clear, the open()
- function blocks the calling thread until the device is
- ready or available before returning.
- Otherwise, the behavior of O_NONBLOCK and O_NDELAY is unspecified.
+ o If O_NONBLOCK and O_NDELAY are clear, the open() function
+ blocks the calling thread until the device is ready or
+ available before returning.
+ Otherwise, the behavior of O_NONBLOCK and O_NDELAY is
+ unspecified.
O_RSYNC
-
Read I/O operations on the file descriptor complete at the same
- level of integrity as specified by the O_DSYNC and O_SYNC flags. If
- both O_DSYNC and O_RSYNC are set in oflag, all I/O operations on
- the file descriptor complete as defined by synchronized I/O data
- integrity completion. If both O_SYNC and O_RSYNC are set in oflag,
- all I/O operations on the file descriptor complete as defined by
- synchronized I/O file integrity completion.
+ level of integrity as specified by the O_DSYNC and O_SYNC flags.
+ If both O_DSYNC and O_RSYNC are set in oflag, all I/O operations
+ on the file descriptor complete as defined by synchronized I/O
+ data integrity completion. If both O_SYNC and O_RSYNC are set in
+ oflag, all I/O operations on the file descriptor complete as
+ defined by synchronized I/O file integrity completion.
-
O_SEARCH
-
If set, indicates that the directory should be opened for
- searching. This option is only valid for a directory, an error
- will be returned if it is not.
+ searching. This option is only valid for a directory; an error
+ will be returned if the target is not a directory.
+ O_SYNC Write I/O operations on the file descriptor complete as defined
+ by synchronized I/O file integrity completion (see
+ fcntl.h(3HEAD)) definition of O_SYNC.
- O_SYNC
-
- Write I/O operations on the file descriptor complete as defined by
- synchronized I/O file integrity completion (see fcntl.h(3HEAD)
- definition of O_SYNC).
-
-
O_TRUNC
-
If the file exists and is a regular file, and the file is
- successfully opened O_RDWR or O_WRONLY, its length is truncated to
- 0 and the mode and owner are unchanged. It has no effect on FIFO
- special files or terminal device files. Its effect on other file
- types is implementation-dependent. The result of using O_TRUNC with
- O_RDONLY is undefined.
+ successfully opened O_RDWR or O_WRONLY, its length is truncated
+ to 0 and the mode and owner are unchanged. It has no effect on
+ FIFO special files or terminal device files. Its effect on other
+ file types is implementation-dependent. The result of using
+ O_TRUNC with O_RDONLY is undefined.
-
O_XATTR
-
If set in openat(), 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 fildes argument. If set in open(), 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.
+ reference to an extended attribute of the file associated with
+ the supplied file descriptor. This flag therefore requires the
+ presence of a legal fildes argument. If set in open(), 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.
+ If O_CREAT is set and the file did not previously exist, upon successful
+ completion, open() marks for update the st_atime, st_ctime, and st_mtime
+ fields of the file and the st_ctime and st_mtime fields of the parent
+ directory.
-
- If O_CREAT is set and the file did not previously exist, upon
- successful completion, open() marks for update the st_atime, st_ctime,
- and st_mtime fields of the file and the st_ctime and st_mtime fields of
- the parent directory.
-
-
If O_TRUNC is set and the file did previously exist, upon successful
completion, open() marks for update the st_ctime and st_mtime fields of
the file.
-
If both the O_SYNC and O_DSYNC flags are set, the effect is as if only
the O_SYNC flag was set.
-
If path refers to a STREAMS file, oflag may be constructed from
- O_NONBLOCK or O_NODELAY OR-ed with either O_RDONLY, O_WRONLY, or
- O_RDWR. Other flag values are not applicable to STREAMS devices and
- have no effect on them. The values O_NONBLOCK and O_NODELAY affect the
- operation of STREAMS drivers and certain functions (see read(2),
- getmsg(2), putmsg(2), and write(2)) applied to file descriptors
- associated with STREAMS files. For STREAMS drivers, the implementation
- of O_NONBLOCK and O_NODELAY is device-specific.
+ O_NONBLOCK or O_NODELAY OR-ed with either O_RDONLY, O_WRONLY, or O_RDWR.
+ Other flag values are not applicable to STREAMS devices and have no
+ effect on them. The values O_NONBLOCK and O_NODELAY affect the operation
+ of STREAMS drivers and certain functions (see read(2), getmsg(2),
+ putmsg(2), and write(2)) applied to file descriptors associated with
+ STREAMS files. For STREAMS drivers, the implementation of O_NONBLOCK and
+ O_NODELAY is device-specific.
+ When open() is invoked to open a named stream, and the connld(7M) module
+ has been pushed on the pipe, open() blocks until the server process has
+ issued an I_RECVFD ioctl(2) (see streamio(7I)) to receive the file
+ descriptor.
- When open() is invoked to open a named stream, and the connld module
- (see connld(7M)) has been pushed on the pipe, open() blocks until the
- server process has issued an I_RECVFD ioctl() (see streamio(7I)) to
- receive the file descriptor.
+ If path names the manager side of a pseudo-terminal device, then it is
+ unspecified whether open() locks the subsidiary side so that it cannot be
+ opened. Portable applications must call unlockpt(3C) before opening the
+ subsidiary side.
-
- If path names the master side of a pseudo-terminal device, then it is
- unspecified whether open() locks the slave side so that it cannot be
- opened. Portable applications must call unlockpt(3C) before opening
- the slave side.
-
-
If the file is a regular file and the local file system is mounted with
the nbmand mount option, then a mandatory share reservation is
- automatically obtained on the file. The share reservation is obtained
- as if fcntl(2) were called with cmd F_SHARE_NBMAND and the fshare_t
- values set as follows:
+ automatically obtained on the file. The share reservation is obtained as
+ if fcntl(2) were called with cmd F_SHARE_NBMAND and the fshare_t values
+ set as follows:
f_access
Set to the type of read/write access for which the file is
opened.
+ f_deny F_NODNY
- f_deny
- F_NODNY
+ f_id The file descriptor value returned from open().
+ If path is a symbolic link and O_CREAT and O_EXCL are set, the link is
+ not followed.
- f_id
- The file descriptor value returned from open().
+ Certain flag values can be set following open() as described in fcntl(2).
+ The largest value that can be represented correctly in an object of type
+ off_t is established as the offset maximum in the open file description.
+RETURN VALUES
+ The open() and openat() functions open the file and, if successful,
+ return a non-negative integer representing the lowest numbered unused
+ file descriptor; otherwise the value -1 is returned and the global
+ variable errno is set to indicate the error and no files are created or
+ modified.
- If path is a symbolic link and O_CREAT and O_EXCL are set, the link is
- not followed.
+EXAMPLES
+ Example 1 Open a file for writing by the owner.
+ The following example opens the file /tmp/file, 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.
- Certain flag values can be set following open() as described in
- fcntl(2).
+ If the call to open() is successful, the file is opened for writing.
+ #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);
+ ...
- The largest value that can be represented correctly in an object of
- type off_t is established as the offset maximum in the open file
- description.
+ Example 2 Open a file using an existence check.
-RETURN VALUES
- Upon successful completion, both open() and openat() functions open the
- file and return a non-negative integer representing the lowest numbered
- unused file descriptor. Otherwise, -1 is returned, errno is set to
- indicate the error, and no files are created or modified.
+ The following example uses the open() function to try to create the
+ LOCKFILE file and open it for writing. Since the open() function
+ specifies the O_EXCL 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.
+ #include <fcntl.h>
+ #include <stdio.h>
+ #include <stdlib.h>
+ #include <err.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)) < 0) {
+ err(1, "Cannot open %s. Try again later.", LOCKFILE);
+ }
+ ...
+
+ Example 3 Open a file for writing.
+
+ 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.
+
+ #include <fcntl.h>
+ #include <stdio.h>
+ #include <stdlib.h>
+ #include <err.h>
+ ...
+ 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)) < 0) {
+ err(1, "Cannot open output file");
+ }
+ ...
+
ERRORS
The open() and openat() functions will fail if:
- EACCES
- Search permission is denied on a component of the path
+ EACCES Search permission is denied on a component of the path
prefix.
The file exists and the permissions specified by oflag
are denied.
@@ -352,319 +352,168 @@
O_TRUNC is specified and write permission is denied.
The {PRIV_FILE_DAC_SEARCH} privilege allows processes
to search directories regardless of permission bits.
- The {PRIV_FILE_DAC_WRITE} privilege allows processes to
- open files for writing regardless of permission bits.
- See privileges(5) for special considerations when
- opening files owned by UID 0 for writing. The
- {PRIV_FILE_DAC_READ} privilege allows processes to open
- files for reading regardless of permission bits.
+ The {PRIV_FILE_DAC_WRITE} privilege allows processes
+ to open files for writing regardless of permission
+ bits. See privileges(5) for special considerations
+ when opening files owned by user ID 0 for writing.
+ The {PRIV_FILE_DAC_READ} privilege allows processes to
+ open files for reading regardless of permission bits.
-
- EAGAIN
- A mandatory share reservation could not be obtained
+ EAGAIN A mandatory share reservation could not be obtained
because the desired access conflicts with an existing
- f_deny share reservation.
+ f_deny share reservation (see fcntl(2)).
-
- EDQUOT
- The file does not exist, O_CREAT is specified, and
+ EDQUOT The file does not exist, O_CREAT 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.
+ the user's quota of inodes on the file system where
+ the file is being created has been exhausted.
+ EEXIST The O_CREAT and O_EXCL flags are set and the named
+ file already exists.
- EEXIST
- The O_CREAT and O_EXCL flags are set and the named file
- exists.
+ EILSEQ The path argument includes bytes that are not valid
+ UTF-8 characters, and the file system accepts only
+ file names where all characters are part of the UTF-8
+ character codeset.
+ EINTR A signal was caught during open().
- EILSEQ
- The path argument includes non-UTF8 characters and the
- file system accepts only file names where all
- characters are part of the UTF-8 character codeset.
+ EFAULT The path argument points to an illegal address.
+ EINVAL Either the system does not support synchronized or
+ direct I/O for this file, or the O_XATTR flag was
+ supplied and the underlying file system does not
+ support extended file attributes.
- EINTR
- A signal was caught during open().
-
-
- EFAULT
- The path argument points to an illegal address.
-
-
- EINVAL
- The system does not support synchronized or direct I/O
- for this file, or the O_XATTR flag was supplied and the
- underlying file system does not support extended file
- attributes.
-
-
- EIO
- The path argument names a STREAMS file and a hangup or
+ EIO The path argument names a STREAMS file and a hangup or
error occurred during the open().
-
- EISDIR
- The named file is a directory and oflag includes
+ EISDIR The named file is a directory and oflag includes
O_WRONLY or O_RDWR.
-
- ELOOP
- Too many symbolic links were encountered in resolving
+ ELOOP Too many symbolic links were encountered in resolving
path.
A loop exists in symbolic links encountered during
resolution of the path argument.
The O_NOFOLLOW flag is set and the final component of
path is a symbolic link.
+ EMFILE There are currently {OPEN_MAX} file descriptors open
+ in the calling process.
- EMFILE
- There are currently {OPEN_MAX} file descriptors open in
- the calling process.
+ EMLINK The O_NOLINKS flag is set and the named file has a
+ link count greater than 1.
-
- EMLINK
- The O_NOLINKS flag is set and the named file has a link
- count greater than 1.
-
-
- EMULTIHOP
- Components of path require hopping to multiple remote
+ EMULTIHOP Components of path require hopping to multiple remote
machines and the file system does not allow it.
+ ENAMETOOLONG The length of the path argument exceeds {PATH_MAX} or
+ a pathname component is longer than {NAME_MAX}.
- ENAMETOOLONG
- The length of the path argument exceeds {PATH_MAX} or a
- pathname component is longer than {NAME_MAX}.
+ ENFILE The maximum allowable number of files is currently
+ open in the system.
+ ENOENT The O_CREAT flag is not set and the named file does
+ not exist; or the O_CREAT flag is set and either the
+ path prefix does not exist or the path argument points
+ to an empty string.
- ENFILE
- The maximum allowable number of files is currently open
- in the system.
-
-
- ENOENT
- The O_CREAT flag is not set and the named file does not
- exist; or the O_CREAT flag is set and either the path
- prefix does not exist or the path argument points to an
- empty string.
-
The O_CREAT and O_DIRECTORY flags were both set and
path did not point to a file.
-
- ENOEXEC
- The O_EXEC flag is set and path does not point to a
+ ENOEXEC The O_EXEC flag is set and path does not point to a
regular file.
-
- ENOLINK
- The path argument points to a remote machine, and the
+ ENOLINK The path argument points to a remote machine, and the
link to that machine is no longer active.
-
- ENOSR
- The path argument names a STREAMS-based file and the
+ ENOSR Th path argument names a STREAMS-based file and the
system is unable to allocate a STREAM.
+ ENOSPC The directory or file system that would contain the
+ new file cannot be expanded, the file does not exist,
+ and O_CREAT is specified.
- ENOSPC
- The directory or file system that would contain the new
- file cannot be expanded, the file does not exist, and
- O_CREAT is specified.
-
-
- ENOSYS
- The device specified by path does not support the open
+ ENOSYS The device specified by path does not support the open
operation.
-
- ENOTDIR
- A component of the path prefix is not a directory or a
+ ENOTDIR A component of the path prefix is not a directory or a
relative path was supplied to openat(), the O_XATTR
- flag was not supplied, and the file descriptor does not
- refer to a directory. The O_SEARCH flag was passed and
- path does not refer to a directory.
+ flag was not supplied, and the file descriptor does
+ not refer to a directory. The O_SEARCH flag was
+ passed and path does not refer to a directory.
The O_DIRECTORY flag was set and the file was not a
directory.
-
- ENXIO
- The O_NONBLOCK flag is set, the named file is a FIFO,
+ ENXIO The O_NONBLOCK flag is set, the named file is a FIFO,
the O_WRONLY 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 .
+ 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.
+ EOPNOTSUPP An attempt was made to open a path that corresponds to
+ an AF_UNIX socket.
- EOPNOTSUPP
- An attempt was made to open a path that corresponds to
- a AF_UNIX socket.
-
-
- EOVERFLOW
- The named file is a regular file and either O_LARGEFILE
- is not set and the size of the file cannot be
- represented correctly in an object of type off_t or
+ EOVERFLOW The named file is a regular file and either
+ O_LARGEFILE is not set and the size of the file cannot
+ be represented correctly in an object of type off_t or
O_LARGEFILE is set and the size of the file cannot be
represented correctly in an object of type off64_t.
-
- EROFS
- The named file resides on a read-only file system and
+ EROFS The named file resides on a read-only file system and
either O_WRONLY, O_RDWR, O_CREAT (if file does not
exist), or O_TRUNC is set in the oflag argument.
-
-
The openat() function will fail if:
- EBADF
- The fildes argument is not a valid open file descriptor or is
- not AT_FTCWD.
+ EBADF The fildes argument is not a valid open file
+ descriptor or is not AT_FTCWD.
-
-
The open() function may fail if:
- EAGAIN
- The path argument names the slave side of a pseudo-
- terminal device that is locked.
+ EAGAIN The path argument names the subsidiary side of a
+ pseudo-terminal device that is locked.
+ EINVAL The value of the oflag argument is not valid.
- EINVAL
- The value of the oflag argument is not valid.
-
-
- ENAMETOOLONG
- Pathname resolution of a symbolic link produced an
+ ENAMETOOLONG Pathname resolution of a symbolic link produced an
intermediate result whose length exceeds {PATH_MAX}.
-
- ENOMEM
- The path argument names a STREAMS file and the system
+ ENOMEM The path argument names a STREAMS file and the system
is unable to allocate resources.
+ ETXTBSY The file is a pure procedure (shared text) file that
+ is being executed and oflag is O_WRONLY or O_RDWR.
- ETXTBSY
- The file is a pure procedure (shared text) file that is
- being executed and oflag is O_WRONLY or O_RDWR.
-
-
-EXAMPLES
- Example 1 Open a file for writing by the owner.
-
-
- The following example opens the file /tmp/file, 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.
-
-
-
- If the call to open() is successful, the file is opened for writing.
-
-
- #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);
- ...
-
-
- Example 2 Open a file using an existence check.
-
-
- The following example uses the open() function to try to create the
- LOCKFILE file and open it for writing. Since the open() function
- specifies the O_EXCL 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.
-
-
- #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.\n");
- exit(1);
- }
- ...
-
-
- Example 3 Open a file for writing.
-
-
- 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.
-
-
- #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\n"); exit(1);
- }
- ...
-
-
USAGE
- The open() function has a transitional interface for 64-bit file
- offsets. See lf64(5). Note that using open64() is equivalent to using
- open() with O_LARGEFILE set in oflag.
+ The open() function has a transitional interface for 64-bit file offsets.
+ See lf64(5). Note that using open64() is equivalent to using open(with)
+ O_LARGEFILE set in oflag.
-ATTRIBUTES
- See attributes(5) for descriptions of the following attributes:
+INTERFACE STABILITY
+ Committed
+MT LEVEL
+ Async-Signal-Safe
-
-
- +--------------------+-------------------------------+
- | ATTRIBUTE TYPE | ATTRIBUTE VALUE |
- +--------------------+-------------------------------+
- |Interface Stability | Committed |
- +--------------------+-------------------------------+
- |MT-Level | Async-Signal-Safe |
- +--------------------+-------------------------------+
- |Standard | For open(), see standards(5). |
- +--------------------+-------------------------------+
-
SEE ALSO
- Intro(2), chmod(2), close(2), creat(2), dup(2), exec(2), fcntl(2),
- getmsg(2), getrlimit(2), lseek(2), putmsg(2), read(2), stat(2),
- umask(2), write(2), attropen(3C), directio(3C), fcntl.h(3HEAD),
- stat.h(3HEAD), unlockpt(3C), attributes(5), lf64(5), privileges(5),
- standards(5), connld(7M), streamio(7I)
+ chmod(2), close(2), creat(2), dup(2), exec(2), fcntl(2), getmsg(2),
+ getrlimit(2), Intro(2), lseek(2), putmsg(2), read(2), stat(2), umask(2),
+ write(2), attropen(3C), directio(3C), unlockpt(3C), fcntl.h(3HEAD),
+ stat.h(3HEAD), attributes(5), lf64(5), privileges(5), standards(5),
+ streamio(7I), connld(7M)
NOTES
Hierarchical Storage Management (HSM) file systems can sometimes cause
long delays when opening a file, since HSM files must be recalled from
secondary storage.
- March 10, 2020 OPEN(2)
+illumos February 5, 2022 illumos