sparc: refactor piggy_32.c

Refactoring to increase readability (a little).
- sort includes
- spaces around operators
- small helpers introduced
- added a few comments

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/arch/sparc/boot/piggyback_32.c b/arch/sparc/boot/piggyback_32.c
index ac944ae..cfd95ec 100644 (file)
--- a/arch/sparc/boot/piggyback_32.c
+++ b/arch/sparc/boot/piggyback_32.c
@@ -9,7 +9,7 @@
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.
-   
+
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
@@ -18,15 +18,16 @@
    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
-   
-#include <stdio.h>
+
+#include <dirent.h>
+#include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
 #include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
-#include <dirent.h>
-#include <unistd.h>
-#include <stdlib.h>
+#include <stdio.h>
+
 #include <sys/types.h>
 #include <sys/stat.h>
 
@@ -35,16 +36,19 @@
  * as PROM looks for a.out image only.
  */
 
+/* read two bytes as big endian */
 static unsigned short ld2(char *p)
 {
        return (p[0] << 8) | p[1];
 }
 
+/* read 4 bytes as big endian */
 static unsigned int ld4(char *p)
 {
        return (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
 }
 
+/* save 4 bytes as big endian */
 static void st4(char *p, unsigned int x)
 {
        p[0] = x >> 24;
@@ -53,6 +57,12 @@ static void st4(char *p, unsigned int x)
        p[3] = x;
 }
 
+static void die(const char *str)
+{
+       perror(str);
+       exit(1);
+}
+
 static void usage(void)
 {
        /* fs_img.gz is an image of initial ramdisk. */
@@ -61,10 +71,57 @@ static void usage(void)
        exit(1);
 }
 
-static void die(char *str)
+static int start_line(const char *line)
 {
-       perror (str);
-       exit(1);
+       if (strcmp(line + 8, " T start\n") == 0)
+               return 1;
+       else if (strcmp(line + 16, " T start\n") == 0)
+               return 1;
+       return 0;
+}
+
+static int end_line(const char *line)
+{
+       if (strcmp(line + 8, " A _end\n") == 0)
+               return 1;
+       else if (strcmp (line + 16, " A _end\n") == 0)
+               return 1;
+       return 0;
+}
+
+/*
+ * Find address for start and end in System.map.
+ * The file looks like this:
+ * f0004000 T start
+ * f0379f79 A _end
+ * 1234567890123456
+ * ^coloumn 1
+ * There is support for 64 bit addresses too.
+ *
+ * Return 0 if either start or end is not found
+ */
+static int get_start_end(const char *filename, unsigned int *start, unsigned int *end)
+{
+       FILE *map;
+       char buffer[1024];
+
+       *start = 0;
+       *end = 0;
+       map = fopen(filename, "r");
+       if (!map)
+               die(filename);
+       while (fgets(buffer, 1024, map)) {
+               if (start_line(buffer))
+                       *start = strtoul(buffer, NULL, 16);
+               else if (end_line(buffer))
+                       *end = strtoul(buffer, NULL, 16);
+       }
+       fclose (map);
+
+       if (*start == 0 || *end == 0)
+               return 0;
+
+       return 1;
 }
 
 int main(int argc,char **argv)
@@ -72,33 +129,29 @@ int main(int argc,char **argv)
        static char aout_magic[] = { 0x01, 0x03, 0x01, 0x07 };
        char buffer[1024], *q, *r;
        unsigned int i, j, k, start, end, offset;
-       FILE *map;
        struct stat s;
        int image, tail;
 
-       if (argc != 4) usage();
-       start = end = 0;
-       if (stat (argv[3], &s) < 0) die (argv[3]);
-       map = fopen (argv[2], "r");
-       if (!map) die(argv[2]);
-       while (fgets (buffer, 1024, map)) {
-               if (!strcmp (buffer + 8, " T start\n") || !strcmp (buffer + 16, " T start\n"))
-                       start = strtoul (buffer, NULL, 16);
-               else if (!strcmp (buffer + 8, " A _end\n") || !strcmp (buffer + 16, " A _end\n"))
-                       end = strtoul (buffer, NULL, 16);
-       }
-       fclose (map);
-       if (!start || !end) {
-               fprintf (stderr, "Could not determine start and end from System.map\n");
+       if (argc != 4)
+               usage();
+       if (stat (argv[3], &s) < 0)
+               die(argv[3]);
+
+       if (!get_start_end(argv[2], &start, &end)) {
+               fprintf (stderr, "Could not determine start and end from %s\n", argv[2]);
                exit(1);
        }
-       if ((image = open(argv[1],O_RDWR)) < 0) die(argv[1]);
-       if (read(image,buffer,512) != 512) die(argv[1]);
+       if ((image = open(argv[1], O_RDWR)) < 0)
+               die(argv[1]);
+       if (read(image, buffer, 512) != 512)
+               die(argv[1]);
        if (memcmp (buffer, "\177ELF", 4) == 0) {
                q = buffer + ld4(buffer + 28);
                i = ld4(q + 4) + ld4(buffer + 24) - ld4(q + 8);
-               if (lseek(image,i,0) < 0) die("lseek");
-               if (read(image,buffer,512) != 512) die(argv[1]);
+               if (lseek(image, i, 0) < 0)
+                       die("lseek");
+               if (read(image, buffer, 512) != 512)
+                       die(argv[1]);
                j = 0;
        } else if (memcmp(buffer, aout_magic, 4) == 0) {
                i = j = 32;
@@ -107,9 +160,11 @@ int main(int argc,char **argv)
                exit(1);
        }
        k = i;
-       i += (ld2(buffer + j + 2)<<2) - 512;
-       if (lseek(image,i,0) < 0) die("lseek");
-       if (read(image,buffer,1024) != 1024) die(argv[1]);
+       i += (ld2(buffer + j + 2) << 2) - 512;
+       if (lseek(image, i, 0) < 0)
+               die("lseek");
+       if (read(image, buffer, 1024) != 1024)
+               die(argv[1]);
        for (q = buffer, r = q + 512; q < r; q += 4) {
                if (*q == 'H' && q[1] == 'd' && q[2] == 'r' && q[3] == 'S')
                        break;
@@ -119,19 +174,26 @@ int main(int argc,char **argv)
                exit(1);
        }
        offset = i + (q - buffer) + 10;
-       if (lseek(image, offset, 0) < 0) die ("lseek");
+       if (lseek(image, offset, 0) < 0)
+               die("lseek");
 
        st4(buffer, 0);
        st4(buffer + 4, 0x01000000);
        st4(buffer + 8, (end + 32 + 4095) & ~4095);
        st4(buffer + 12, s.st_size);
 
-       if (write(image,buffer+2,14) != 14) die (argv[1]);
-       if (lseek(image, k - start + ((end + 32 + 4095) & ~4095), 0) < 0) die ("lseek");
-       if ((tail = open(argv[3],O_RDONLY)) < 0) die(argv[3]);
-       while ((i = read (tail,buffer,1024)) > 0)
-               if (write(image,buffer,i) != i) die (argv[1]);
-       if (close(image) < 0) die("close");
-       if (close(tail) < 0) die("close");
-       return 0;
+       if (write(image, buffer + 2, 14) != 14)
+               die(argv[1]);
+       if (lseek(image, k - start + ((end + 32 + 4095) & ~4095), 0) < 0)
+               die("lseek");
+       if ((tail = open(argv[3],O_RDONLY)) < 0)
+               die(argv[3]);
+       while ((i = read (tail, buffer, 1024)) > 0)
+               if (write(image, buffer, i) != i)
+                       die(argv[1]);
+       if (close(image) < 0)
+               die("close");
+       if (close(tail) < 0)
+               die("close");
+       return 0;
 }