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

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

1 files changed, 46 insertions, 46 deletions

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;
 }