1 /* $OpenBSD: pwrite.c,v 1.2 2003/07/31 21:48:09 deraadt Exp $ */ 2 /* 3 * Written by Artur Grabowski <art@openbsd.org> 2002 Public Domain. 4 */ 5 #include <stdio.h> 6 #include <stdlib.h> 7 #include <unistd.h> 8 #include <err.h> 9 #include <fcntl.h> 10 11 int 12 main(int argc, char *argv[]) 13 { 14 char temp[] = "/tmp/pwriteXXXXXXXXX"; 15 const char magic[10] = "0123456789"; 16 const char zeroes[10] = "0000000000"; 17 char buf[10]; 18 char c; 19 int fd; 20 21 if ((fd = mkstemp(temp)) < 0) 22 err(1, "mkstemp"); 23 remove(temp); 24 25 if (write(fd, zeroes, sizeof(zeroes)) != sizeof(zeroes)) 26 err(1, "write"); 27 28 if (lseek(fd, 5, SEEK_SET) != 5) 29 err(1, "lseek"); 30 31 if (pwrite(fd, &magic[1], 4, 4) != 4) 32 err(1, "pwrite"); 33 34 if (read(fd, &c, 1) != 1) 35 err(1, "read"); 36 37 if (c != '2') 38 errx(1, "read %c != %c", c, '2'); 39 40 c = '5'; 41 if (write(fd, &c, 1) != 1) 42 err(1, "write"); 43 44 if (pread(fd, buf, 10, 0) != 10) 45 err(1, "pread"); 46 47 if (memcmp(buf, "0000125400", 10) != 0) 48 errx(1, "data mismatch: %s != %s", buf, "0000125400"); 49 50 return 0; 51 } 52