UNIX环境下的高级IO技术.rar_非阻塞

#include <sys/types.h> #include <sys/stat.h> #include <sys/mman.h> /* mmap() */ #include <fcntl.h> #include "ourhdr.h" #ifndef MAP_FILE /* 44BSD defines this & requires it to mmap files */ #define MAP_FILE 0 /* to compile under systems other than 44BSD */ #endif int main(int argc, char *argv[]) { int fdin, fdout; char *src, *dst; struct stat statbuf; if (argc != 3) err_quit("usage: a.out <fromfile> <tofile>"); if ( (fdin = open(argv[1], O_RDONLY)) < 0) err_sys("can't open %s for reading", argv[1]); if ( (fdout = open(argv[2], O_RDWR | O_CREAT | O_TRUNC, FILE_MODE)) < 0) err_sys("can't creat %s for writing", argv[1]); if (fstat(fdin, &statbuf) < 0) /* need size of input file */ err_sys("fstat error"); /* set size of output file */ if (lseek(fdout, statbuf.st_size - 1, SEEK_SET) == -1) err_sys("lseek error"); if (write(fdout, "", 1) != 1) err_sys("write error"); if ( (src = mmap(0, statbuf.st_size, PROT_READ, MAP_FILE | MAP_SHARED, fdin, 0)) == (caddr_t) -1) err_sys("mmap error for input"); if ( (dst = mmap(0, statbuf.st_size, PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, fdout, 0)) == (caddr_t) -1) err_sys("mmap error for output"); memcpy(dst, src, statbuf.st_size); /* does the file copy */ exit(0); }