punch-alternating: add some options

I didn't end up using this, but somebody else might find
it useful, so sending it.

This change lets us specify punch patterns other than
literally every other block.

i.e. punch-alternating with no options will do:

...HDHDHDHDHDHD...

-i 4 -s 2 will do:

...DDHHDDHHDDHH...

or -i 3 -s 1 will do:

...DDHDDHDDHDDH...

[eguan: don't allow 0 size and fixed perror string]

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>

diff --git a/src/punch-alternating.c b/src/punch-alternating.c
index 4148622f8a96c9b448d80f2cac3c31aaa6f7afed..25228cd5cbed3a75860153543425ca79ba05f446 100644 (file)
--- a/src/punch-alternating.c
+++ b/src/punch-alternating.c
@@ -11,6 +11,14 @@
 #include <string.h>
 #include "global.h"
 
+void usage(char *cmd)
+{
+       printf("Usage: %s [-i interval] [-s size] file\n", cmd);
+       printf("Punches every other block in the file by default,\n");
+       printf("or 'size' blocks every 'interval' blocks with options.\n");
+       exit(1);
+}
+
 int main(int argc, char *argv[])
 {
        struct stat     s;
@@ -21,14 +29,37 @@ int main(int argc, char *argv[])
        off_t           sz;
        int             mode;
        int             error;
+       int             c;
+       int             size = 1;       /* punch $SIZE blocks ... */
+       int             interval = 2;   /* every $INTERVAL blocks */
+
+       while ((c = getopt(argc, argv, "i:s:")) != EOF) {
+               switch (c) {
+               case 'i':
+                       interval = atoi(optarg);
+                       break;
+               case 's':
+                       size = atoi(optarg);
+                       break;
+               default:
+                       usage(argv[0]);
+               }
+       }
+
+       if (interval <= 0) {
+               printf("interval must be > 0\n");
+               usage(argv[0]);
+       }
 
-       if (argc != 2) {
-               printf("Usage: %s file\n", argv[0]);
-               printf("Punches every other block in the file.\n");
-               return 1;
+       if (size <= 0) {
+               printf("size must be > 0\n");
+               usage(argv[0]);
        }
 
-       fd = open(argv[1], O_WRONLY);
+       if (optind != argc - 1)
+               usage(argv[0]);
+
+       fd = open(argv[optind], O_WRONLY);
        if (fd < 0)
                goto err;
 
@@ -44,8 +75,8 @@ int main(int argc, char *argv[])
        blksz = sf.f_bsize;
 
        mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
-       for (offset = 0; offset < sz; offset += blksz * 2) {
-               error = fallocate(fd, mode, offset, blksz);
+       for (offset = 0; offset < sz; offset += blksz * interval) {
+               error = fallocate(fd, mode, offset, blksz * size);
                if (error)
                        goto err;
        }
@@ -59,6 +90,6 @@ int main(int argc, char *argv[])
                goto err;
        return 0;
 err:
-       perror(argv[1]);
+       perror(argv[optind]);
        return 2;
 }