__FSEXT_alloc_fd

Syntax

#include <sys/fsext.h> int __FSEXT_alloc_fd(__FSEXT_Function *_function);

Description

This function is part of the File System Extensions. It is used by extensions that fully emulate the I/O functions, and thus don't have a corresponding DOS file handle. Upon the first call, this function opens DOS's `NUL' device, so as to allocate a handle that DOS won't then reuse. Upon subsequent calls, that handle is duplicated by calling the DOS dup function; this makes all of the handles use a single entry in the System File Table, and thus be independent of what the `FILES=' parameter of `CONFIG.SYS' says. __FSEXT_alloc_fd also assigns the handler function for the handle it returns.

The module is responsible for calling _close on the descriptor after setting the handler function to zero in the extended close handler.

Return Value

If successful, a new file descriptor is returned. On error, a negative number is returned and errno is set to indicate the error.

Portability

ANSI/ISO C	No
POSIX	No

Example

int socket() { int fd = __FSEXT_alloc_fd(socket_handler); init_socket(fd); return fd; }