81 lines
1.9 KiB
C
81 lines
1.9 KiB
C
/* See LICENSE file for copyright and license details. */
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#include <sys/types.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "util.h"
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#define SWAP_MAGIC1 "SWAPSPACE2"
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#define SWAP_MAGIC2 "SWAP-SPACE"
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#define SWAP_MAGIC_LENGTH (10)
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#define SWAP_MAGIC_OFFSET (sysconf(_SC_PAGESIZE) - SWAP_MAGIC_LENGTH)
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#define SWAP_LABEL_LENGTH (16)
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#define SWAP_LABEL_OFFSET (1024 + 4 + 4 + 4 + 16)
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static void
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usage(void)
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{
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eprintf("usage: %s [-L label] device\n", argv0);
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}
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int
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main(int argc, char *argv[])
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{
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int setlabel = 0;
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int fd;
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char magic[SWAP_MAGIC_LENGTH];
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char *label;
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char *device;
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int i;
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ARGBEGIN {
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case 'L':
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setlabel = 1;
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label = EARGF(usage());
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break;
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default:
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usage();
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} ARGEND;
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if (argc < 1)
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usage();
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device = argv[0];
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fd = open(device, O_RDWR);
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if (fd < 0)
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eprintf("open %s:", device);
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if (lseek(fd, SWAP_MAGIC_OFFSET, SEEK_SET) != SWAP_MAGIC_OFFSET)
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eprintf("failed seeking to magic position:");
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if (read(fd, magic, SWAP_MAGIC_LENGTH) != SWAP_MAGIC_LENGTH)
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eprintf("reading magic failed:");
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if (memcmp(magic, SWAP_MAGIC1, 10) && memcmp(magic, SWAP_MAGIC2, 10))
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eprintf("%s: is not a swap partition\n", device);
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if (lseek(fd, SWAP_LABEL_OFFSET, SEEK_SET) != SWAP_LABEL_OFFSET)
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eprintf("failed seeking to label position:");
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if (!setlabel) {
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label = emalloc(SWAP_LABEL_LENGTH);
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if (read(fd, label, SWAP_LABEL_LENGTH) != SWAP_LABEL_LENGTH)
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eprintf("reading label failed:");
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for (i = 0; i < SWAP_LABEL_LENGTH && label[i] != '\0'; i++)
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if (i == (SWAP_LABEL_LENGTH - 1) && label[i] != '\0')
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eprintf("invalid label\n");
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printf("label: %s\n", label);
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free(label);
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} else {
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if (strlen(label) + 1 > SWAP_LABEL_LENGTH)
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eprintf("label too long\n");
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if (write(fd, label, strlen(label) + 1) != (ssize_t)strlen(label) + 1)
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eprintf("writing label failed:");
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}
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fsync(fd);
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close(fd);
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return 0;
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}
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