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	swaplabel.c - ubase - suckless linux base utils
	git clone git://git.suckless.org/ubase
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	---
	swaplabel.c (1929B)
	---
	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 }