1 /* 2 * make-sparse.c --- make a sparse file from stdin 3 * 4 * Copyright 2004 by Theodore Ts'o. 5 * 6 * %Begin-Header% 7 * This file may be redistributed under the terms of the GNU Public 8 * License. 9 * %End-Header% 10 */ 11 12 #ifndef _LARGEFILE_SOURCE 13 #define _LARGEFILE_SOURCE 14 #endif 15 #ifndef _LARGEFILE64_SOURCE 16 #define _LARGEFILE64_SOURCE 17 #endif 18 19 #include <stdio.h> 20 #include <unistd.h> 21 #include <stdlib.h> 22 #include <sys/types.h> 23 #include <sys/stat.h> 24 #include <fcntl.h> 25 #include <errno.h> 26 27 int full_read(int fd, char *buf, size_t count) 28 { 29 int got, total = 0; 30 int pass = 0; 31 32 while (count > 0) { 33 got = read(fd, buf, count); 34 if (got == -1) { 35 if ((errno == EINTR) || (errno == EAGAIN)) 36 continue; 37 return total ? total : -1; 38 } 39 if (got == 0) { 40 if (pass++ >= 3) 41 return total; 42 continue; 43 } 44 pass = 0; 45 buf += got; 46 total += got; 47 count -= got; 48 } 49 return total; 50 } 51 52 int main(int argc, char **argv) 53 { 54 int fd, got, i; 55 int zflag = 0; 56 char buf[1024]; 57 58 if (argc != 2) { 59 fprintf(stderr, "Usage: make-sparse out-file\n"); 60 exit(1); 61 } 62 fd = open(argv[1], O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE, 0777); 63 if (fd < 0) { 64 perror(argv[1]); 65 exit(1); 66 } 67 while (1) { 68 got = full_read(0, buf, sizeof(buf)); 69 if (got == 0) 70 break; 71 if (got == sizeof(buf)) { 72 for (i=0; i < sizeof(buf); i++) 73 if (buf[i]) 74 break; 75 if (i == sizeof(buf)) { 76 lseek(fd, sizeof(buf), SEEK_CUR); 77 zflag = 1; 78 continue; 79 } 80 } 81 zflag = 0; 82 write(fd, buf, got); 83 } 84 if (zflag) { 85 lseek(fd, -1, SEEK_CUR); 86 buf[0] = 0; 87 write(fd, buf, 1); 88 } 89 return 0; 90 } 91 92
