open(), openat(), and creat() can fail with the following errors:
EACCES The requested access to the file is not allowed, or search
permission is denied for one of the directories in the
path prefix of pathname, or the file did not exist yet and
write access to the parent directory is not allowed. (See
also path_resolution(7).)
EACCES Where O_CREAT is specified, the protected_fifos or
protected_regular sysctl is enabled, the file already
exists and is a FIFO or regular file, the owner of the
file is neither the current user nor the owner of the
containing directory, and the containing directory is both
world- or group-writable and sticky. For details, see the
descriptions of /proc/sys/fs/protected_fifos and
/proc/sys/fs/protected_regular in proc(5).
EBADF (openat()) pathname is relative but dirfd is neither
AT_FDCWD nor a valid file descriptor.
EBUSY O_EXCL was specified in flags and pathname refers to a
block device that is in use by the system (e.g., it is
mounted).
EDQUOT Where O_CREAT is specified, the file does not exist, and
the user's quota of disk blocks or inodes on the
filesystem has been exhausted.
EEXIST pathname already exists and O_CREAT and O_EXCL were used.
EFAULT pathname points outside your accessible address space.
EFBIG See EOVERFLOW.
EINTR While blocked waiting to complete an open of a slow device
(e.g., a FIFO; see fifo(7)), the call was interrupted by a
signal handler; see signal(7).
EINVAL The filesystem does not support the O_DIRECT flag. See
NOTES for more information.
EINVAL Invalid value in flags.
EINVAL O_TMPFILE was specified in flags, but neither O_WRONLY nor
O_RDWR was specified.
EINVAL O_CREAT was specified in flags and the final component
("basename") of the new file's pathname is invalid (e.g.,
it contains characters not permitted by the underlying
filesystem).
EINVAL The final component ("basename") of pathname is invalid
(e.g., it contains characters not permitted by the
underlying filesystem).
EISDIR pathname refers to a directory and the access requested
involved writing (that is, O_WRONLY or O_RDWR is set).
EISDIR pathname refers to an existing directory, O_TMPFILE and
one of O_WRONLY or O_RDWR were specified in flags, but
this kernel version does not provide the O_TMPFILE
functionality.
ELOOP Too many symbolic links were encountered in resolving
pathname.
ELOOP pathname was a symbolic link, and flags specified
O_NOFOLLOW but not O_PATH.
EMFILE The per-process limit on the number of open file
descriptors has been reached (see the description of
RLIMIT_NOFILE in getrlimit(2)).
ENAMETOOLONG
pathname was too long.
ENFILE The system-wide limit on the total number of open files
has been reached.
ENODEV pathname refers to a device special file and no
corresponding device exists. (This is a Linux kernel bug;
in this situation ENXIO must be returned.)
ENOENT O_CREAT is not set and the named file does not exist.
ENOENT A directory component in pathname does not exist or is a
dangling symbolic link.
ENOENT pathname refers to a nonexistent directory, O_TMPFILE and
one of O_WRONLY or O_RDWR were specified in flags, but
this kernel version does not provide the O_TMPFILE
functionality.
ENOMEM The named file is a FIFO, but memory for the FIFO buffer
can't be allocated because the per-user hard limit on
memory allocation for pipes has been reached and the
caller is not privileged; see pipe(7).
ENOMEM Insufficient kernel memory was available.
ENOSPC pathname was to be created but the device containing
pathname has no room for the new file.
ENOTDIR
A component used as a directory in pathname is not, in
fact, a directory, or O_DIRECTORY was specified and
pathname was not a directory.
ENOTDIR
(openat()) pathname is a relative pathname and dirfd is a
file descriptor referring to a file other than a
directory.
ENXIO O_NONBLOCK | O_WRONLY is set, the named file is a FIFO,
and no process has the FIFO open for reading.
ENXIO The file is a device special file and no corresponding
device exists.
ENXIO The file is a UNIX domain socket.
EOPNOTSUPP
The filesystem containing pathname does not support
O_TMPFILE.
EOVERFLOW
pathname refers to a regular file that is too large to be
opened. The usual scenario here is that an application
compiled on a 32-bit platform without
-D_FILE_OFFSET_BITS=64 tried to open a file whose size
exceeds (1<<31)-1 bytes; see also O_LARGEFILE above. This
is the error specified by POSIX.1; in kernels before
2.6.24, Linux gave the error EFBIG for this case.
EPERM The O_NOATIME flag was specified, but the effective user
ID of the caller did not match the owner of the file and
the caller was not privileged.
EPERM The operation was prevented by a file seal; see fcntl(2).
EROFS pathname refers to a file on a read-only filesystem and
write access was requested.
ETXTBSY
pathname refers to an executable image which is currently
being executed and write access was requested.
ETXTBSY
pathname refers to a file that is currently in use as a
swap file, and the O_TRUNC flag was specified.
ETXTBSY
pathname refers to a file that is currently being read by
the kernel (e.g., for module/firmware loading), and write
access was requested.
EWOULDBLOCK
The O_NONBLOCK flag was specified, and an incompatible
lease was held on the file (see fcntl(2)).
