1 #include <stdio.h> 2 #include <unistd.h> 3 #include <asm/page.h> 4 #include <sys/swap.h> 5 #include <sys/types.h> 6 #include <sys/stat.h> 7 #include <fcntl.h> 8 9 /* XXX This needs to be obtained from kernel headers. See b/9336527 */ 10 struct linux_swap_header { 11 char bootbits[1024]; /* Space for disklabel etc. */ 12 uint32_t version; 13 uint32_t last_page; 14 uint32_t nr_badpages; 15 unsigned char sws_uuid[16]; 16 unsigned char sws_volume[16]; 17 uint32_t padding[117]; 18 uint32_t badpages[1]; 19 }; 20 21 #define MAGIC_SWAP_HEADER "SWAPSPACE2" 22 #define MAGIC_SWAP_HEADER_LEN 10 23 #define MIN_PAGES 10 24 25 int mkswap_main(int argc, char **argv) 26 { 27 int err = 0; 28 int fd; 29 ssize_t len; 30 off_t swap_size; 31 int pagesize; 32 struct linux_swap_header sw_hdr; 33 34 if (argc != 2) { 35 fprintf(stderr, "Usage: %s <filename>\n", argv[0]); 36 return -EINVAL; 37 } 38 39 fd = open(argv[1], O_WRONLY); 40 if (fd < 0) { 41 err = errno; 42 fprintf(stderr, "Cannot open %s\n", argv[1]); 43 return err; 44 } 45 46 pagesize = getpagesize(); 47 /* Determine the length of the swap file */ 48 swap_size = lseek(fd, 0, SEEK_END); 49 if (swap_size < MIN_PAGES * pagesize) { 50 fprintf(stderr, "Swap file needs to be at least %dkB\n", 51 (MIN_PAGES * pagesize) >> 10); 52 err = -ENOSPC; 53 goto err; 54 } 55 if (lseek(fd, 0, SEEK_SET)) { 56 err = errno; 57 fprintf(stderr, "Can't seek to the beginning of the file\n"); 58 goto err; 59 } 60 61 memset(&sw_hdr, 0, sizeof(sw_hdr)); 62 sw_hdr.version = 1; 63 sw_hdr.last_page = (swap_size / pagesize) - 1; 64 65 len = write(fd, &sw_hdr, sizeof(sw_hdr)); 66 if (len != sizeof(sw_hdr)) { 67 err = errno; 68 fprintf(stderr, "Failed to write swap header into %s\n", argv[1]); 69 goto err; 70 } 71 72 /* Write the magic header */ 73 if (lseek(fd, pagesize - MAGIC_SWAP_HEADER_LEN, SEEK_SET) < 0) { 74 err = errno; 75 fprintf(stderr, "Failed to seek into %s\n", argv[1]); 76 goto err; 77 } 78 79 len = write(fd, MAGIC_SWAP_HEADER, MAGIC_SWAP_HEADER_LEN); 80 if (len != MAGIC_SWAP_HEADER_LEN) { 81 err = errno; 82 fprintf(stderr, "Failed to write magic swap header into %s\n", argv[1]); 83 goto err; 84 } 85 86 if (fsync(fd) < 0) { 87 err = errno; 88 fprintf(stderr, "Failed to sync %s\n", argv[1]); 89 goto err; 90 } 91 err: 92 close(fd); 93 return err; 94 } 95
