nativelibc/posix-io/truncate.c

/*	A part of the Native C Library for Windows NT
	Copyright 2007-2015 PC GO Ld.

	This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

	This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
*/

#include <unistd.h>
#include <windows.h>
#include <fcntl.h>
#include <nt.h>
#include <errno.h>

#include <stdio.h>

int ftruncate(int fd, off_t length) {
	if(length < 0) {
		errno = EINVAL;
		return -1;
	}
	if(fd == STDOUT_FILENO || fd == STDERR_FILENO) {
		int real_fd = (fd == STDOUT_FILENO ? _get_stdout_fd : _get_stderr_fd)();
		switch(real_fd) {
			case TTY_FD_INVALID:
				errno = EBADF;
				return -1;
			case TTY_FD_DEFAULT:
				errno = EINVAL;
				return -1;
		}
		fd = real_fd;
	}

	IO_STATUS_BLOCK io_status;
	FILE_END_OF_FILE_INFORMATION feofi = { .EndOfFile.QuadPart = length };
	long int status = NtSetInformationFile((void *)fd, &io_status, &feofi, sizeof feofi, FileEndOfFileInformation);
	printf("nativelibc debug: ftruncate: status = 0x%lx\n", status);
	return __set_errno_from_ntstatus(status) ? -1 : 0;
}

int truncate(const char *path, off_t length) {
	if(!path) {
		errno = EFAULT;
		return -1;
	}
	if(length < 0) {
		errno = EINVAL;
		return -1;
	}
	if(!*path) {
		errno = ENOENT;
		return -1;
	}

	int fd = open(path, O_WRONLY);
	if(fd == -1) return -1;

	int r = ftruncate(fd, length);
	int e = errno;
	if(close(fd) < 0) return -1;
	errno = e;
	return r;
}