fileflags.c

APUE(第二版)的随书源代码,与第一版的代码相比增加了一些章节的代码(详见第二版的说明)

#include	<sys/types.h>
#include	<fcntl.h>
#include	"ourhdr.h"

int
main(int argc, char *argv[])
{
	int		accmode, val;

	if (argc != 2)
		err_quit("usage: a.out <descriptor#>");

	if ( (val = fcntl(atoi(argv[1]), F_GETFL, 0)) < 0)
		err_sys("fcntl error for fd %d", atoi(argv[1]));

	accmode = val & O_ACCMODE;
	if      (accmode == O_RDONLY)	printf("read only");
	else if (accmode == O_WRONLY)	printf("write only");
	else if (accmode == O_RDWR)		printf("read write");
	else err_dump("unknown access mode");

	if (val & O_APPEND)			printf(", append");
	if (val & O_NONBLOCK)		printf(", nonblocking");
#if	!defined(_POSIX_SOURCE) && defined(O_SYNC)
	if (val & O_SYNC)			printf(", synchronous writes");
#endif
	putchar('\n');
	exit(0);
}