diff options
Diffstat (limited to 'util-linux/mkswap.c')
| -rw-r--r-- | util-linux/mkswap.c | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/util-linux/mkswap.c b/util-linux/mkswap.c new file mode 100644 index 0000000..11c411b --- /dev/null +++ b/util-linux/mkswap.c @@ -0,0 +1,129 @@ +/* vi: set sw=4 ts=4: */ +/* mkswap.c - format swap device (Linux v1 only) + * + * Copyright 2006 Rob Landley <rob@landley.net> + * + * Licensed under GPL version 2, see file LICENSE in this tarball for details. + */ + +#include "libbb.h" + +#if ENABLE_SELINUX +static void mkswap_selinux_setcontext(int fd, const char *path) +{ + struct stat stbuf; + + if (!is_selinux_enabled()) + return; + + if (fstat(fd, &stbuf) < 0) + bb_perror_msg_and_die("fstat failed"); + if (S_ISREG(stbuf.st_mode)) { + security_context_t newcon; + security_context_t oldcon = NULL; + context_t context; + + if (fgetfilecon(fd, &oldcon) < 0) { + if (errno != ENODATA) + goto error; + if (matchpathcon(path, stbuf.st_mode, &oldcon) < 0) + goto error; + } + context = context_new(oldcon); + if (!context || context_type_set(context, "swapfile_t")) + goto error; + newcon = context_str(context); + if (!newcon) + goto error; + /* fsetfilecon_raw is hidden */ + if (strcmp(oldcon, newcon) != 0 && fsetfilecon(fd, newcon) < 0) + goto error; + if (ENABLE_FEATURE_CLEAN_UP) { + context_free(context); + freecon(oldcon); + } + } + return; + error: + bb_perror_msg_and_die("SELinux relabeling failed"); +} +#else +#define mkswap_selinux_setcontext(fd, path) ((void)0) +#endif + +#if 0 /* from Linux 2.6.23 */ +/* + * Magic header for a swap area. The first part of the union is + * what the swap magic looks like for the old (limited to 128MB) + * swap area format, the second part of the union adds - in the + * old reserved area - some extra information. Note that the first + * kilobyte is reserved for boot loader or disk label stuff... + */ +union swap_header { + struct { + char reserved[PAGE_SIZE - 10]; + char magic[10]; /* SWAP-SPACE or SWAPSPACE2 */ + } magic; + struct { + char bootbits[1024]; /* Space for disklabel etc. */ + __u32 version; /* second kbyte, word 0 */ + __u32 last_page; /* 1 */ + __u32 nr_badpages; /* 2 */ + unsigned char sws_uuid[16]; /* 3,4,5,6 */ + unsigned char sws_volume[16]; /* 7,8,9,10 */ + __u32 padding[117]; /* 11..127 */ + __u32 badpages[1]; /* 128, total 129 32-bit words */ + } info; +}; +#endif + +#define NWORDS 129 +#define hdr ((uint32_t*)(&bb_common_bufsiz1)) + +struct BUG_bufsiz1_is_too_small { + char BUG_bufsiz1_is_too_small[COMMON_BUFSIZE < (NWORDS * 4) ? -1 : 1]; +}; + +/* Stored without terminating NUL */ +static const char SWAPSPACE2[sizeof("SWAPSPACE2")-1] ALIGN1 = "SWAPSPACE2"; + +int mkswap_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; +int mkswap_main(int argc, char **argv) +{ + int fd, pagesize; + off_t len; + + // No options supported. + + if (argc != 2) bb_show_usage(); + + // Figure out how big the device is and announce our intentions. + + fd = xopen(argv[1], O_RDWR); + /* fdlength was reported to be unreliable - use seek */ + len = xlseek(fd, 0, SEEK_END); +#if ENABLE_SELINUX + xlseek(fd, 0, SEEK_SET); +#endif + pagesize = getpagesize(); + printf("Setting up swapspace version 1, size = %"OFF_FMT"u bytes\n", + len - pagesize); + mkswap_selinux_setcontext(fd, argv[1]); + + // Make a header. hdr is zero-filled so far... + hdr[0] = 1; + hdr[1] = (len / pagesize) - 1; + + // Write the header. Sync to disk because some kernel versions check + // signature on disk (not in cache) during swapon. + + xlseek(fd, 1024, SEEK_SET); + xwrite(fd, hdr, NWORDS * 4); + xlseek(fd, pagesize - 10, SEEK_SET); + xwrite(fd, SWAPSPACE2, 10); + fsync(fd); + + if (ENABLE_FEATURE_CLEAN_UP) close(fd); + + return 0; +} |