#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>


int main(int argc, char** argv) 
{
	int fd = open("/tmp/fuck",O_RDONLY);
	if(fd < 0)
	{
		printf("[%d]%d %s\n",__LINE__,errno,strerror(errno));
		return -1;
	}

	struct stat sb;
	if (fstat(fd, &sb) == -1)
	{
		printf("[%d]%d %s\n",__LINE__,errno,strerror(errno));
		return -1;
	}
	const char* buf = (const char*)mmap(0, sb.st_size, PROT_READ, MAP_SHARED, fd, 0);
	if (buf == MAP_FAILED)
	{
		printf("[%d]%d %s\n",__LINE__,errno,strerror(errno));
		return -1;
	}
	printf("%s\n",buf);
	close(fd);
	return 0;
}

#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/sendfile.h>


int main(int argc, char** argv) 
{
	int fd = open("/tmp/fuck",O_RDONLY | O_RDONLY);
	if(fd < 0)
	{
		printf("[%d]%d %s\n",__LINE__,errno,strerror(errno));
		return -1;
	}
	int fd2 = open("/tmp/fuck1",O_CREAT | O_TRUNC | O_WRONLY);
	if(fd2 < 0)
	{
		printf("[%d]%d %s\n",__LINE__,errno,strerror(errno));
		return -1;
	}

	struct stat sb;
	if (fstat(fd, &sb) == -1)
	{
		printf("[%d]%d %s\n",__LINE__,errno,strerror(errno));
		return -1;
	}
	if(sendfile(fd2,fd,NULL,sb.st_size) < 0)
	{
		printf("[%d]%d %s\n",__LINE__,errno,strerror(errno));
		return -1;
	}
	close(fd);
	close(fd2);
	return 0;
}

#define _GNU_SOURCE
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/sendfile.h>


int main(int argc, char** argv) 
{
	int fd = open("/tmp/fuck",O_RDONLY | O_RDONLY);
	if(fd < 0)
	{
		printf("[%d]%d %s\n",__LINE__,errno,strerror(errno));
		return -1;
	}
	int fd2 = open("/tmp/fuck1",O_CREAT | O_TRUNC | O_WRONLY);
	if(fd2 < 0)
	{
		printf("[%d]%d %s\n",__LINE__,errno,strerror(errno));
		return -1;
	}

	struct stat sb;
	if (fstat(fd, &sb) == -1)
	{
		printf("[%d]%d %s\n",__LINE__,errno,strerror(errno));
		return -1;
	}
	int pipefd[2];
	if(pipe( pipefd ) < 0)
	{
		printf("[%d]%d %s\n",__LINE__,errno,strerror(errno));
		return -1;
	}

	loff_t off_out=0;
	loff_t off_in=0;
	int max_read = 4096;
	while(sb.st_size > off_in)
	{
		int toread = (sb.st_size - off_in > max_read)?max_read:sb.st_size - off_in ;
		int readlen = splice(fd, &off_in, pipefd[1], NULL, toread, SPLICE_F_MORE |SPLICE_F_MOVE);
		splice(pipefd[0], NULL, fd2, &off_out, readlen, SPLICE_F_MORE |SPLICE_F_MOVE);
	}
	close(fd);
	close(fd2);
	return 0;
}