swaplabel.c - ubase - suckless linux base utils | |
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swaplabel.c (1929B) | |
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1 /* See LICENSE file for copyright and license details. */ | |
2 #include <sys/types.h> | |
3 | |
4 #include <fcntl.h> | |
5 #include <stdio.h> | |
6 #include <stdlib.h> | |
7 #include <string.h> | |
8 #include <unistd.h> | |
9 | |
10 #include "util.h" | |
11 | |
12 #define SWAP_MAGIC1 "SWAPSPACE2" | |
13 #define SWAP_MAGIC2 "SWAP-SPACE" | |
14 #define SWAP_MAGIC_LENGTH (10) | |
15 #define SWAP_MAGIC_OFFSET (sysconf(_SC_PAGESIZE) - SWAP_MAGIC_LENGTH) | |
16 #define SWAP_LABEL_LENGTH (16) | |
17 #define SWAP_LABEL_OFFSET (1024 + 4 + 4 + 4 + 16) | |
18 | |
19 static void | |
20 usage(void) | |
21 { | |
22 eprintf("usage: %s [-L label] device\n", argv0); | |
23 } | |
24 | |
25 int | |
26 main(int argc, char *argv[]) | |
27 { | |
28 int setlabel = 0; | |
29 int fd; | |
30 char magic[SWAP_MAGIC_LENGTH]; | |
31 char *label; | |
32 char *device; | |
33 int i; | |
34 | |
35 ARGBEGIN { | |
36 case 'L': | |
37 setlabel = 1; | |
38 label = EARGF(usage()); | |
39 break; | |
40 default: | |
41 usage(); | |
42 } ARGEND; | |
43 | |
44 if (argc < 1) | |
45 usage(); | |
46 device = argv[0]; | |
47 | |
48 fd = open(device, O_RDWR); | |
49 if (fd < 0) | |
50 eprintf("open %s:", device); | |
51 | |
52 if (lseek(fd, SWAP_MAGIC_OFFSET, SEEK_SET) != SWAP_MAGIC_OFFSET) | |
53 eprintf("failed seeking to magic position:"); | |
54 if (read(fd, magic, SWAP_MAGIC_LENGTH) != SWAP_MAGIC_LENGTH) | |
55 eprintf("reading magic failed:"); | |
56 if (memcmp(magic, SWAP_MAGIC1, 10) && memcmp(magic, SWAP_MAGIC2,… | |
57 eprintf("%s: is not a swap partition\n", device); | |
58 if (lseek(fd, SWAP_LABEL_OFFSET, SEEK_SET) != SWAP_LABEL_OFFSET) | |
59 eprintf("failed seeking to label position:"); | |
60 | |
61 if (!setlabel) { | |
62 label = emalloc(SWAP_LABEL_LENGTH); | |
63 if (read(fd, label, SWAP_LABEL_LENGTH) != SWAP_LABEL_LEN… | |
64 eprintf("reading label failed:"); | |
65 for (i = 0; i < SWAP_LABEL_LENGTH && label[i] != '\0'; i… | |
66 if (i == (SWAP_LABEL_LENGTH - 1) && label[i] != … | |
67 eprintf("invalid label\n"); | |
68 printf("label: %s\n", label); | |
69 free(label); | |
70 } else { | |
71 if (strlen(label) + 1 > SWAP_LABEL_LENGTH) | |
72 eprintf("label too long\n"); | |
73 if (write(fd, label, strlen(label) + 1) != (ssize_t)strl… | |
74 eprintf("writing label failed:"); | |
75 } | |
76 | |
77 fsync(fd); | |
78 close(fd); | |
79 return 0; | |
80 } |