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RIO package robust I/O function code_PHP tutorial
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- 2016-07-14 10:12:02922browse
[php]
The following is about
下面是关于[php]
#include
#include
#include
#include
#include
#include
#define MAXLINE 1024
/*unbuffer input/output function*/
ssize_t rio_readn(int fd,void *usrbuf,size_t n)
{
size_t nleft = n;
ssize_t nread;
char *bufp = usrbuf;
while(nleft > 0){
if((nread = read(fd,bufp,nleft)) < 0){
if(errno == EINTR){/*interrupted by sig handler return*/
nread = 0;
}else{
return -1;/*error*/
}
}else if(nread == 0){
break; /*EOF*/
}else{/*read content*/
nleft -= nread;
bufp += nread;
}
}
return (n - nleft);
}
ssize_t rio_writen(int fd,void *usrbuf,size_t n)
{
size_t nleft = n;
ssize_t nwritten;
char *bufp = usrbuf;
while(nwritten = write(fd,bufp,nleft) <= 0){
if(errno == EINTR){
nwritten = 0;
}else{
return -1;
}
nleft -= nwritten;
bufp += nwritten;
}
return n;
}
/******************************************************************************/
#define RIO_BUFSIZE 8192
typedef struct{
int rio_fd; /*To operate the file descriptor*/
int rio_cnt;/*unread bytes in internal buf*/
char *rio_bufptr;/*next unread byte int internal buf*/
char rio_buf[RIO_BUFSIZE];/*internal buf*/
}rio_t;
void rio_readinitb(rio_t *rp,int fd)
{
rp->rio_fd = fd;
rp->rio_cnt = 0;
rp->rio_bufptr = rp->rio_buf;
}
static ssize_t rio_read(rio_t *rp,char *usrbuf,size_t n)
{
int cnt;
while(rp->rio_cnt <= 0){/*Read the file content if buf is empty*/
rp->rio_cnt = read(rp->rio_fd, rp->rio_buf,sizeof(rp->rio_buf));
if(rp->rio_cnt < 0){
if(errno != EINTR){
return -1;
}
}else if(rp->rio_cnt == 0){/*EOF*/
return 0;
}else {/*reset buf ptr*/
rp->rio_bufptr = rp->rio_buf;
}
}
/*when n < rp->rio_cnt, need copy some times */
cnt = n;
if(rp->rio_cnt < n){/*one time copy end*/
cnt = rp->rio_cnt;
}
memcpy(usrbuf,rp->rio_bufptr,cnt);
rp->rio_bufptr += cnt;
rp->rio_cnt -= cnt;
return cnt;
}
ssize_t rio_readlineb(rio_t *rp, void *usrbuf,size_t maxlen)
{
int n,rc;
char c,*bufp = usrbuf;
for(n = 1; n < maxlen; n++){
if (( rc = rio_read(rp,&c,1)) == 1){
*bufp++ = c;
if(c == 'n'){
break;
}
}else if (rc == 0){
if(n == 1){/*EOF no data read*/
return 0;
}else{/*EOF some data read*/
break;
}
}else{/*ERROR*/
return -1;
}
}
*bufp = 0;/*string end sign :' '*/
return n;
}
ssize_t rio_readnb(rio_t *rp,void *usrbuf,size_t n)
{
size_t nleft = n;
ssize_t nread;
char *bufp = usrbuf;
while(nleft > 0){
if((nread = rio_read(rp,bufp, nleft)) < 0){
if(errno == EINTR){/*interrupted by sig handler return*/
nread =0;
}else{/*errno set by read() */
return -1;
}
}else if(nread == 0){/*EOF*/
break;
}
nleft -= nread;
bufp += nread;
}
return (n-nleft);/*return >=0*/
}
int main()
{
int n;
rio_t rio;
char buf[MAXLINE];
int fd = open("1.txt",O_RDONLY,755);
if(fd <=0){
printf("errorn");
}
rio_readinitb(&rio,fd);
while ((n = rio_readlineb(&rio,buf,MAXLINE)) != 0){
rio_writen(1,buf,n);
}
close(fd);
return 0;
}
#include
#include
#include
#include
#include
#include
#define MAXLINE 1024
/*unbuffer input/output function*/
ssize_t rio_readn(int fd,void *usrbuf,size_t n)
{
size_t nleft = n;
ssize_t nread;
char *bufp = usrbuf;
while(nleft > 0){
if((nread = read(fd,bufp,nleft)) < 0){
if(errno == EINTR){/*interrupted by sig handler return*/
nread = 0;
}else{
return -1;/*error*/
}
}else if(nread == 0){
break; /*EOF*/
}else{/*read content*/
nleft -= nread;
bufp += nread;
}
}
return (n - nleft);
}
ssize_t rio_writen(int fd,void *usrbuf,size_t n)
{
size_t nleft = n;
ssize_t nwritten;
char *bufp = usrbuf;
while(nwritten = write(fd,bufp,nleft) <= 0){
if(errno == EINTR){
nwritten = 0;
}else{
return -1;
}
nleft -= nwritten;
bufp += nwritten;
}
return n;
}
/******************************************************************************/
#define RIO_BUFSIZE 8192
typedef struct{
int rio_fd; /*To operate the file descriptor*/
int rio_cnt;/*unread bytes in internal buf*/
char *rio_bufptr;/*next unread byte int internal buf*/
char rio_buf[RIO_BUFSIZE];/*internal buf*/
}rio_t;
void rio_readinitb(rio_t *rp,int fd)
{
rp->rio_fd = fd;
rp->rio_cnt = 0;
rp->rio_bufptr = rp->rio_buf;
}
static ssize_t rio_read(rio_t *rp,char *usrbuf,size_t n)
{
int cnt;
while(rp->rio_cnt <= 0){/*Read the file content if buf is empty*/
rp->rio_cnt = read(rp->rio_fd, rp->rio_buf,sizeof(rp->rio_buf));
if(rp->rio_cnt < 0){
if(errno != EINTR){
return -1;
}
}else if(rp->rio_cnt == 0){/*EOF*/
return 0;
}else {/*reset buf ptr*/
rp->rio_bufptr = rp->rio_buf;
}
}
/*when n < rp->rio_cnt, need copy some times */
cnt = n;
if(rp->rio_cnt < n){/*one time copy end*/
cnt = rp->rio_cnt;
}
memcpy(usrbuf,rp->rio_bufptr,cnt);
rp->rio_bufptr += cnt;
rp->rio_cnt -= cnt;
return cnt;
}
ssize_t rio_readlineb(rio_t *rp, void *usrbuf,size_t maxlen)
{
int n,rc;
char c,*bufp = usrbuf;
for(n = 1; n < maxlen; n++){
if (( rc = rio_read(rp,&c,1)) == 1){
*bufp++ = c;
if(c == 'n'){
break;
}
}else if (rc == 0){
if(n == 1){/*EOF no data read*/
return 0;
}else{/*EOF some data read*/
break;
}
}else{/*ERROR*/
return -1;
}
}
*bufp = 0;/*string end sign :' '*/
return n;
}
ssize_t rio_readnb(rio_t *rp,void *usrbuf,size_t n)
{
size_t nleft = n;
ssize_t nread;
char *bufp = usrbuf;
while(nleft > 0){
if((nread = rio_read(rp,bufp, nleft)) < 0){
if(errno == EINTR){/*interrupted by sig handler return*/
nread =0;
}else{/*errno set by read() */
return -1;
}
}else if(nread == 0){/*EOF*/
break;
}
nleft -= nread;
bufp += nread;
}
return (n-nleft);/*return >=0*/
}
int main()
{
int n;
rio_t rio;
char buf[MAXLINE];
int fd = open("1.txt",O_RDONLY,755);
if(fd <=0){
printf("errorn");
}
rio_readinitb(&rio,fd);
while ((n = rio_readlineb(&rio,buf,MAXLINE)) != 0){
rio_writen(1,buf,n);
}
close(fd);
return 0;
}
上面的函数式ＲＩＯ包提供的两类不同的函数：
１、不带缓冲的输入输出函数
2、带缓冲的输入函数
这里主要针对文件Io，因为标准Io本身就是带缓冲的，我们在对文件进行读写操作时，一般会优先使用标准的Io函数，但是在网络编程中，只能使用文件Io的函数，这里可能就用到我们上面的函数编写，有兴趣的可以多了解下上面的机制。在网络通信中，这种机制方法运用还是比较多的！