Created
January 16, 2011 03:00
-
-
Save thinkhy/781509 to your computer and use it in GitHub Desktop.
APUE: readn and writen
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
#include "apue.h" | |
ssize_t /* Read "n" bytes from a descriptor */ | |
readn(int fd, void *ptr, size_t n) | |
{ | |
size_t nleft; | |
ssize_t nread; | |
nleft = n; | |
while (nleft > 0) { | |
if ((nread = read(fd, ptr, nleft)) < 0) { | |
if (nleft == n) | |
return(-1); /* error, return -1 */ | |
else | |
break; /* error, return amount read so far */ | |
} else if (nread == 0) { | |
break; /* EOF */ | |
} | |
nleft -= nread; | |
ptr += nread; | |
} | |
return(n - nleft); /* return >= 0 */ | |
} | |
ssize_t /* Write "n" bytes to a descriptor */ | |
writen(int fd, const void *ptr, size_t n) | |
{ | |
size_t nleft; | |
ssize_t nwritten; | |
nleft = n; | |
while (nleft > 0) { | |
if ((nwritten = write(fd, ptr, nleft)) < 0) { | |
if (nleft == n) | |
return(-1); /* error, return -1 */ | |
else | |
break; /* error, return amount written so far */ | |
} else if (nwritten == 0) { | |
break; | |
} | |
nleft -= nwritten; | |
ptr += nwritten; | |
} | |
return(n - nleft); /* return >= 0 */ | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment