mkswap: fix help text to not lie about supported options.

mkswap: use uint32, not int, to match kernel.
mkswap: optimization: use pre-zeroed buffer

2 files changed, 72 insertions, 34 deletions

diff --git a/include/usage.h b/include/usage.h
index 37cefeab1..df15dbb46 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -2335,14 +2335,17 @@ USE_FEATURE_BRCTL_FANCY("\n" \
        "$ mknod -m 644 /tmp/pipe p\n"
 
 #define mkswap_trivial_usage \
-       "[-c] [-v0|-v1] device [block-count]"
+       "DEVICE"
 #define mkswap_full_usage \
-       "Prepare a disk partition to be used as swap partition" \
-       "\n\nOptions:\n" \
-       "        -c              Check for read-ability\n" \
-       "        -v0             Make version 0 swap [max 128 Megs]\n" \
-       "        -v1             Make version 1 swap [big!] (default for kernels > 2.1.117)\n" \
-       "        block-count     Number of block to use (default is entire partition)"
+       "Prepare block device to be used as swap partition"
+#if 0
+       "[-c] [-v0|-v1] DEVICE [BLOCKS]"
+       "\n\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
 
 #define mktemp_trivial_usage \
        "[-dt] [-p DIR] TEMPLATE"
@@ -3312,34 +3315,36 @@ USE_FEATURE_RUN_PARTS_FANCY("\n	-l	Prints names of all matching files even when
 
 #define sort_trivial_usage \
        "[-nru" \
-        USE_FEATURE_SORT_BIG("gMcszbdfimSTokt] [-o outfile] [-k start[.offset][opts][,end[.offset][opts]] [-t char") \
+        USE_FEATURE_SORT_BIG("gMcszbdfimSTokt] [-o FILE] [-k start[.offset][opts][,end[.offset][opts]] [-t CHAR") \
        "] [FILE]..."
 #define sort_full_usage \
        "Sort lines of text in the specified files" \
-       "\n\nOptions:\n" \
-        USE_FEATURE_SORT_BIG( \
-       "        -b      Ignore leading blanks\n" \
-       "        -c      Check whether input is sorted\n" \
-       "        -d      Dictionary order (blank or alphanumeric only)\n" \
-       "        -f      Ignore case\n" \
-       "        -g      General numerical sort\n" \
-       "        -i      Ignore unprintable characters\n" \
-       "        -k      Sort key\n" \
-       "        -M      Sort month\n") \
-       "        -n      Sort numbers\n" \
+       "\n\nOptions:" \
         USE_FEATURE_SORT_BIG( \
-       "        -o      Output to file\n" \
-       "        -k      Sort by key\n" \
-       "        -t      Use key separator other than whitespace\n") \
-       "        -r      Reverse sort order\n" \
+     "\n        -b      Ignore leading blanks" \
+     "\n        -c      Check whether input is sorted" \
+     "\n        -d      Dictionary order (blank or alphanumeric only)" \
+     "\n        -f      Ignore case" \
+     "\n        -g      General numerical sort" \
+     "\n        -i      Ignore unprintable characters" \
+     "\n        -k      Sort key" \
+     "\n        -M      Sort month" \
+        ) \
+     "\n        -n      Sort numbers" \
         USE_FEATURE_SORT_BIG( \
-       "        -s      Stable (don't sort ties alphabetically)\n") \
-       "        -u      Suppress duplicate lines" \
+     "\n        -o      Output to file" \
+     "\n        -k      Sort by key" \
+     "\n        -t CHAR Key separator" \
+        ) \
+     "\n        -r      Reverse sort order" \
         USE_FEATURE_SORT_BIG( \
-       "\n      -z      Input terminated by nulls, not newlines\n") \
+     "\n        -s      Stable (don't sort ties alphabetically)" \
+        ) \
+     "\n        -u      Suppress duplicate lines" \
         USE_FEATURE_SORT_BIG( \
-       "        -mST    Ignored for GNU compatibility") \
-       ""
+     "\n        -z      Lines are terminated by NUL, not newline" \
+     "\n        -mST    Ignored for GNU compatibility") \
+
 #define sort_example_usage \
        "$ echo -e \"e\\nf\\nb\\nd\\nc\\na\" | sort\n" \
        "a\n" \
diff --git a/util-linux/mkswap.c b/util-linux/mkswap.c
index 31d577315..bf0d7b074 100644
--- a/util-linux/mkswap.c
+++ b/util-linux/mkswap.c
@@ -50,12 +50,47 @@ 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 */
+/*
+ * 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;
-        unsigned int hdr[129];
 
         // No options supported.
 
@@ -74,9 +109,7 @@ int mkswap_main(int argc, char **argv)
                         len - pagesize);
         mkswap_selinux_setcontext(fd, argv[1]);
 
-        // Make a header.
-
-        memset(hdr, 0, sizeof(hdr));
+        // Make a header. hdr is zero-filled so far...
         hdr[0] = 1;
         hdr[1] = (len / pagesize) - 1;
 
@@ -84,9 +117,9 @@ int mkswap_main(int argc, char **argv)
         // signature on disk (not in cache) during swapon.
 
         xlseek(fd, 1024, SEEK_SET);
-        xwrite(fd, hdr, sizeof(hdr));
+        xwrite(fd, hdr, NWORDS * 4);
         xlseek(fd, pagesize - 10, SEEK_SET);
-        xwrite(fd, "SWAPSPACE2", 10);
+        xwrite(fd, SWAPSPACE2, 10);
         fsync(fd);
 
         if (ENABLE_FEATURE_CLEAN_UP) close(fd);