open (Debugging with GDB)

Synopsis:

int open(const char *pathname, int flags);
int open(const char *pathname, int flags, mode_t mode);

Request:

‘Fopen,pathptr/len,flags,mode’

flags is the bitwise OR of the following values:

O_CREAT: If the file does not exist it will be created. The host rules apply as far as file ownership and time stamps are concerned.
O_EXCL: When used with O_CREAT, if the file already exists it is an error and open() fails.
O_TRUNC: If the file already exists and the open mode allows writing (O_RDWR or O_WRONLY is given) it will be truncated to zero length.
O_APPEND: The file is opened in append mode.
O_RDONLY: The file is opened for reading only.
O_WRONLY: The file is opened for writing only.
O_RDWR: The file is opened for reading and writing.

Other bits are silently ignored.

mode is the bitwise OR of the following values:

Other bits are silently ignored.

Return value:

open returns the new file descriptor or -1 if an error occurred.

Errors:

EEXIST: pathname already exists and O_CREAT and O_EXCL were used.
EISDIR: pathname refers to a directory.
EACCES: The requested access is not allowed.
ENAMETOOLONG: pathname was too long.
ENOENT: A directory component in pathname does not exist.
ENODEV: pathname refers to a device, pipe, named pipe or socket.
EROFS: pathname refers to a file on a read-only filesystem and write access was requested.
EFAULT: pathname is an invalid pointer value.
ENOSPC: No space on device to create the file.
EMFILE: The process already has the maximum number of files open.
ENFILE: The limit on the total number of files open on the system has been reached.
EINTR: The call was interrupted by the user.