mkswap: add -L LABEL option. closes bug 689.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 50 insertions, 56 deletions

diff --git a/include/usage.h b/include/usage.h
index f703e3250..0d01577c7 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -2815,17 +2815,11 @@
        "$ mknod -m 644 /tmp/pipe p\n"
 
 #define mkswap_trivial_usage \
-       "DEVICE"
+       "[OPTIONS] BLOCKDEV" /* [SIZE_IN_KB] */
 #define mkswap_full_usage "\n\n" \
-       "Prepare block device to be used as swap partition"
-#if 0
-       "[-c] [-v0|-v1] DEVICE [BLOCKS]"
-     "\nOptions:"
-     "\n	-c	Check for readability"
-     "\n	-v0	Make swap version 0 (max 128M)"
-     "\n	-v1	Make swap version 1 (default for kernels > 2.1.117)"
-     "\n	BLOCKS	Number of blocks to use (default is entire partition)"
-#endif
+       "Prepare BLOCKDEV to be used as swap partition\n" \
+     "\nOptions:" \
+     "\n	-L LBL	Label" \
 
 #define mktemp_trivial_usage \
        "[-dt] [-p DIR] [TEMPLATE]"
diff --git a/util-linux/mkswap.c b/util-linux/mkswap.c
index 2f7827d6f..289692da3 100644
--- a/util-linux/mkswap.c
+++ b/util-linux/mkswap.c
@@ -50,72 +50,70 @@ static void mkswap_selinux_setcontext(int fd, const char *path)
 # define mkswap_selinux_setcontext(fd, path) ((void)0)
 #endif
 
-#if 0 /* from Linux 2.6.23 */
+/* 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...
+ * Magic header for a swap area. ... 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;
+struct swap_header_v1 {
+/*	char     bootbits[1024];    Space for disklabel etc. */
+	uint32_t version;        /* second kbyte, word 0 */
+	uint32_t last_page;      /* 1 */
+	uint32_t nr_badpages;    /* 2 */
+	char     sws_uuid[16];   /* 3,4,5,6 */
+	char     sws_volume[16]; /* 7,8,9,10 */
+	uint32_t padding[117];   /* 11..127 */
+	uint32_t badpages[1];    /* 128 */
+	/* total 129 32-bit words in 2nd kilobyte */
 };
-#endif
 
 #define NWORDS 129
-#define hdr ((uint32_t*)(&bb_common_bufsiz1))
+#define hdr ((struct swap_header_v1*)bb_common_bufsiz1)
 
-struct BUG_bufsiz1_is_too_small {
-	char BUG_bufsiz1_is_too_small[COMMON_BUFSIZE < (NWORDS * 4) ? -1 : 1];
+struct BUG_sizes {
+	char swap_header_v1_wrong[sizeof(*hdr)  != (NWORDS * 4) ? -1 : 1];
+	char 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 mkswap_main(int argc UNUSED_PARAM, char **argv)
 {
-	int fd, pagesize;
+	int fd;
+	unsigned pagesize;
 	off_t len;
+	const char *label = "";
 
-	// No options supported.
-
-	if (argc != 2) bb_show_usage();
+	opt_complementary = "=1";
+	/* TODO: -p PAGESZ, -U UUID,
+	 * optional SIZE_IN_KB 2nd param
+	 */
+	getopt32(argv, "L:", &label);
+	argv += optind;
 
-	// Figure out how big the device is and announce our intentions.
+	fd = xopen(argv[0], O_WRONLY);
 
-	fd = xopen(argv[1], O_RDWR);
+	/* Figure out how big the device is and announce our intentions */
 	/* fdlength was reported to be unreliable - use seek */
 	len = xlseek(fd, 0, SEEK_END);
-#if ENABLE_SELINUX
-	xlseek(fd, 0, SEEK_SET);
-#endif
+	if (ENABLE_SELINUX)
+		xlseek(fd, 0, SEEK_SET);
+
 	pagesize = getpagesize();
-	printf("Setting up swapspace version 1, size = %"OFF_FMT"u bytes\n",
-			len - pagesize);
-	mkswap_selinux_setcontext(fd, argv[1]);
+	len -= pagesize;
+	printf("Setting up swapspace version 1, size = %"OFF_FMT"u bytes\n", len);
+	mkswap_selinux_setcontext(fd, argv[0]);
+
+	/* Make a header. hdr is zero-filled so far... */
+	hdr->version = 1;
+	hdr->last_page = (uoff_t)len / pagesize;
 
-	// Make a header. hdr is zero-filled so far...
-	hdr[0] = 1;
-	hdr[1] = (len / pagesize) - 1;
 	if (ENABLE_FEATURE_MKSWAP_UUID) {
 		char uuid_string[32];
-		generate_uuid((void*) &hdr[3]);
-		bin2hex(uuid_string, (void*) &hdr[3], 16);
+		generate_uuid((void*)hdr->sws_uuid);
+		bin2hex(uuid_string, hdr->sws_uuid, 16);
 		/* f.e. UUID=dfd9c173-be52-4d27-99a5-c34c6c2ff55f */
 		printf("UUID=%.8s"  "-%.4s-%.4s-%.4s-%.12s\n",
 			uuid_string,
@@ -125,16 +123,18 @@ int mkswap_main(int argc, char **argv)
 			uuid_string+8+4+4+4
 		);
 	}
+	safe_strncpy(hdr->sws_volume, label, 16);
 
-	// Write the header.  Sync to disk because some kernel versions check
-	// signature on disk (not in cache) during swapon.
+	/* 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);
+	if (ENABLE_FEATURE_CLEAN_UP)
+		close(fd);
 
 	return 0;
 }