read_fifo.c

源码包中是我在学习Linux进程间通信时所写的关于五种通信方式（管道

#include "fifo.h"

/* read data from FIFO */

int main(int argc, char **argv )
{
	int	fd;
	char 	buffer[BUFFER_SIZE];
	ssize_t	n;

	if( argc < 2 )
	{
		fprintf( stdout, "Usage:%s <filename>\n",argv[0] );
		exit(1);
	}

	/* open FIFO */
	if( (fd = open(argv[1], O_RDONLY)) < 0 )
	{
		fprintf( stderr, "open FIFO %s for reading failed:%s\n", argv[1], strerror(errno) );
		exit(1);
	}

	fprintf( stdout, "open FIFO %s for reading successed.\n", argv[1] );
	
	while( 1 )
	{
		again:
			if( (n = read( fd, buffer, BUFFER_SIZE )) < 0 )
			{
				printf( "waiting..." );
				if( errno == EINTR )
				{
					printf( "waiting..." );
					goto	again;
				}
				else
				{
					fprintf( stderr, "read failed on %s:%s\n", argv[1], strerror(errno) );
					exit(1);
				}
			}
			else if( n == 0 )
			{
				fprintf( stderr, "peer closed fifo.\n" );
				break;
			}
			else
			{
				buffer[n-1] = '\0';
				fprintf( stdout, "read %d bytes from FIFO:%s\n", n, buffer );
			}
	}
	return 0;
}