On Thu, May 04, 2017 at 01:25:05PM -0500, Eric Sandeen wrote:
> 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...
>
> Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
> ---
>
> V2: don't allow interval of zero, or extra arguments
> other than the filename after the parsed options.
>
> V3: Ok, don't allow negative intervals or sizes, either.
>
>
>
> diff --git a/src/punch-alternating.c b/src/punch-alternating.c
> index 4148622..11aa65c 100644
> --- 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]);
Can size be 0? Seems not, otherwise we call fallocate with zero length.
I got this error if I use "-s 0"
$ ./src/punch-alternating -s 0 -i 8 testfile
-s: Invalid argument
And the "-s" part indicates that the perror call in 'err' label should
be updated too, i.e. argv[1] => argv[optind]
They're simple enough to be fixed at commit time, if you think they're
sane fixes :)
Thanks,
Eryu
> }
>
> - 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;
> }
>
>
> --
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