1 /* $OpenBSD: pwrite.c,v 1.3 2003/09/02 23:52:17 david Exp $ */ 2 /* 3 * Written by Artur Grabowski <art@openbsd.org> 2002 Public Domain. 4 */ 5 #include <stdio.h> 6 #include <stdlib.h> 7 #include <string.h> 8 #include <unistd.h> 9 #include <err.h> 10 #include <fcntl.h> 11 12 int 13 main(int argc, char *argv[]) 14 { 15 char temp[] = "/tmp/pwriteXXXXXXXXX"; 16 const char magic[10] = "0123456789"; 17 const char zeroes[10] = "0000000000"; 18 char buf[10]; 19 char c; 20 int fd; 21 22 if ((fd = mkstemp(temp)) < 0) 23 err(1, "mkstemp"); 24 remove(temp); 25 26 if (write(fd, zeroes, sizeof(zeroes)) != sizeof(zeroes)) 27 err(1, "write"); 28 29 if (lseek(fd, 5, SEEK_SET) != 5) 30 err(1, "lseek"); 31 32 if (pwrite(fd, &magic[1], 4, 4) != 4) 33 err(1, "pwrite"); 34 35 if (read(fd, &c, 1) != 1) 36 err(1, "read"); 37 38 if (c != '2') 39 errx(1, "read %c != %c", c, '2'); 40 41 c = '5'; 42 if (write(fd, &c, 1) != 1) 43 err(1, "write"); 44 45 if (pread(fd, buf, 10, 0) != 10) 46 err(1, "pread"); 47 48 if (memcmp(buf, "0000125400", 10) != 0) 49 errx(1, "data mismatch: %s != %s", buf, "0000125400"); 50 51 return 0; 52 } 53