GLibclear_fd

staticinlinegboolean
g_clear_fd(
int*fd_ptr,
GError**error
)

If fd_ptr points to a file descriptor, close it and return whether closing it was successful, like g_close(). If fd_ptr points to a negative number, return TRUE without closing anything. In both cases, set fd_ptr to -1 before returning.

Like g_close(), if closing the file descriptor fails, the error is stored in both %errno and error. If this function succeeds, %errno is undefined.

On POSIX platforms, this function is async-signal safe if error is NULL and fd_ptr points to either a negative number or a valid open file descriptor. This makes it safe to call from a signal handler or a GSpawnChildSetupFunc under those conditions. See signal(7) and signal-safety(7) for more details.

It is a programming error for fd_ptr to point to a non-negative number that is not a valid file descriptor.

A typical use of this function is to clean up a file descriptor at the end of its scope, whether it has been set successfully or not:

gboolean
operate_on_fd (GError **error)
{
 gboolean ret = FALSE;
 int fd = -1;
 fd = open_a_fd (error);
 if (fd < 0)
 goto out;
 if (!do_something (fd, error))
 goto out;
 if (!g_clear_fd (&fd, error))
 goto out;
 ret = TRUE;
out:
 // OK to call even if fd was never opened or was already closed
 g_clear_fd (&fd, NULL);
 return ret;
}

This function is also useful in conjunction with #g_autofd.

Available since: 2.76

This function is not directly available to language bindings.

fd_ptr

Type: int*

A pointer to a file descriptor.

The argument will be modified by the function.

error

Type:

The return location for a recoverable error.

The argument can be NULL.

If the return location is not NULL, then you must initialize it to a NULL GError*.

The argument will be left initialized to NULL by the function if there are no errors.

In case of error, the argument will be set to a newly allocated GError; the caller will take ownership of the data, and be responsible for freeing it.