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130 lines
3.4 KiB
C
130 lines
3.4 KiB
C
/* vi: set sw=4 ts=4: */
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/* mkswap.c - format swap device (Linux v1 only)
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*
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* Copyright 2006 Rob Landley <rob@landley.net>
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*
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* Licensed under GPL version 2, see file LICENSE in this tarball for details.
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*/
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#include "libbb.h"
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#if ENABLE_SELINUX
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static void mkswap_selinux_setcontext(int fd, const char *path)
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{
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struct stat stbuf;
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if (!is_selinux_enabled())
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return;
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if (fstat(fd, &stbuf) < 0)
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bb_perror_msg_and_die("fstat failed");
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if (S_ISREG(stbuf.st_mode)) {
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security_context_t newcon;
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security_context_t oldcon = NULL;
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context_t context;
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if (fgetfilecon(fd, &oldcon) < 0) {
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if (errno != ENODATA)
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goto error;
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if (matchpathcon(path, stbuf.st_mode, &oldcon) < 0)
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goto error;
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}
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context = context_new(oldcon);
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if (!context || context_type_set(context, "swapfile_t"))
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goto error;
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newcon = context_str(context);
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if (!newcon)
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goto error;
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/* fsetfilecon_raw is hidden */
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if (strcmp(oldcon, newcon) != 0 && fsetfilecon(fd, newcon) < 0)
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goto error;
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if (ENABLE_FEATURE_CLEAN_UP) {
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context_free(context);
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freecon(oldcon);
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}
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}
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return;
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error:
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bb_perror_msg_and_die("SELinux relabeling failed");
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}
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#else
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#define mkswap_selinux_setcontext(fd, path) ((void)0)
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#endif
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#if 0 /* from Linux 2.6.23 */
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/*
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* Magic header for a swap area. The first part of the union is
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* what the swap magic looks like for the old (limited to 128MB)
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* swap area format, the second part of the union adds - in the
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* old reserved area - some extra information. Note that the first
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* kilobyte is reserved for boot loader or disk label stuff...
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*/
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union swap_header {
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struct {
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char reserved[PAGE_SIZE - 10];
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char magic[10]; /* SWAP-SPACE or SWAPSPACE2 */
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} magic;
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struct {
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char bootbits[1024]; /* Space for disklabel etc. */
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__u32 version; /* second kbyte, word 0 */
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__u32 last_page; /* 1 */
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__u32 nr_badpages; /* 2 */
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unsigned char sws_uuid[16]; /* 3,4,5,6 */
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unsigned char sws_volume[16]; /* 7,8,9,10 */
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__u32 padding[117]; /* 11..127 */
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__u32 badpages[1]; /* 128, total 129 32-bit words */
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} info;
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};
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#endif
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#define NWORDS 129
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#define hdr ((uint32_t*)(&bb_common_bufsiz1))
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struct BUG_bufsiz1_is_too_small {
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char BUG_bufsiz1_is_too_small[COMMON_BUFSIZE < (NWORDS * 4) ? -1 : 1];
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};
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/* Stored without terminating NUL */
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static const char SWAPSPACE2[sizeof("SWAPSPACE2")-1] ALIGN1 = "SWAPSPACE2";
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int mkswap_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int mkswap_main(int argc, char **argv)
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{
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int fd, pagesize;
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off_t len;
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// No options supported.
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if (argc != 2) bb_show_usage();
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// Figure out how big the device is and announce our intentions.
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fd = xopen(argv[1], O_RDWR);
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/* fdlength was reported to be unreliable - use seek */
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len = xlseek(fd, 0, SEEK_END);
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#if ENABLE_SELINUX
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xlseek(fd, 0, SEEK_SET);
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#endif
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pagesize = getpagesize();
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printf("Setting up swapspace version 1, size = %"OFF_FMT"u bytes\n",
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len - pagesize);
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mkswap_selinux_setcontext(fd, argv[1]);
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// Make a header. hdr is zero-filled so far...
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hdr[0] = 1;
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hdr[1] = (len / pagesize) - 1;
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// Write the header. Sync to disk because some kernel versions check
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// signature on disk (not in cache) during swapon.
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xlseek(fd, 1024, SEEK_SET);
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xwrite(fd, hdr, NWORDS * 4);
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xlseek(fd, pagesize - 10, SEEK_SET);
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xwrite(fd, SWAPSPACE2, 10);
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fsync(fd);
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if (ENABLE_FEATURE_CLEAN_UP) close(fd);
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return 0;
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}
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