1 #include <stdio.h> 2 #include <unistd.h> 3 #include <sys/swap.h> 4 #include <sys/types.h> 5 #include <sys/stat.h> 6 #include <fcntl.h> 7 8 /* XXX This needs to be obtained from kernel headers. See b/9336527 */ 9 struct linux_swap_header { 10 char bootbits[1024]; /* Space for disklabel etc. */ 11 uint32_t version; 12 uint32_t last_page; 13 uint32_t nr_badpages; 14 unsigned char sws_uuid[16]; 15 unsigned char sws_volume[16]; 16 uint32_t padding[117]; 17 uint32_t badpages[1]; 18 }; 19 20 #define MAGIC_SWAP_HEADER "SWAPSPACE2" 21 #define MAGIC_SWAP_HEADER_LEN 10 22 #define MIN_PAGES 10 23 24 int mkswap_main(int argc, char **argv) 25 { 26 int err = 0; 27 int fd; 28 ssize_t len; 29 off_t swap_size; 30 int pagesize; 31 struct linux_swap_header sw_hdr; 32 33 if (argc != 2) { 34 fprintf(stderr, "Usage: %s <filename>\n", argv[0]); 35 return -EINVAL; 36 } 37 38 fd = open(argv[1], O_WRONLY); 39 if (fd < 0) { 40 err = errno; 41 fprintf(stderr, "Cannot open %s\n", argv[1]); 42 return err; 43 } 44 45 pagesize = getpagesize(); 46 /* Determine the length of the swap file */ 47 swap_size = lseek(fd, 0, SEEK_END); 48 if (swap_size < MIN_PAGES * pagesize) { 49 fprintf(stderr, "Swap file needs to be at least %dkB\n", 50 (MIN_PAGES * pagesize) >> 10); 51 err = -ENOSPC; 52 goto err; 53 } 54 if (lseek(fd, 0, SEEK_SET)) { 55 err = errno; 56 fprintf(stderr, "Can't seek to the beginning of the file\n"); 57 goto err; 58 } 59 60 memset(&sw_hdr, 0, sizeof(sw_hdr)); 61 sw_hdr.version = 1; 62 sw_hdr.last_page = (swap_size / pagesize) - 1; 63 64 len = write(fd, &sw_hdr, sizeof(sw_hdr)); 65 if (len != sizeof(sw_hdr)) { 66 err = errno; 67 fprintf(stderr, "Failed to write swap header into %s\n", argv[1]); 68 goto err; 69 } 70 71 /* Write the magic header */ 72 if (lseek(fd, pagesize - MAGIC_SWAP_HEADER_LEN, SEEK_SET) < 0) { 73 err = errno; 74 fprintf(stderr, "Failed to seek into %s\n", argv[1]); 75 goto err; 76 } 77 78 len = write(fd, MAGIC_SWAP_HEADER, MAGIC_SWAP_HEADER_LEN); 79 if (len != MAGIC_SWAP_HEADER_LEN) { 80 err = errno; 81 fprintf(stderr, "Failed to write magic swap header into %s\n", argv[1]); 82 goto err; 83 } 84 85 if (fsync(fd) < 0) { 86 err = errno; 87 fprintf(stderr, "Failed to sync %s\n", argv[1]); 88 goto err; 89 } 90 err: 91 close(fd); 92 return err; 93 } 94
