1 files changed, 97 insertions, 0 deletions
diff --git a/src/cow-dedupe-range.c b/src/cow-dedupe-range.c
new file mode 100644
index 0000000..7508f04
--- /dev/null
+++ b/src/cow-dedupe-range.c
@@ -0,0 +1,97 @@
+#define _GNU_SOURCE  /* for program_invocation_name */
+#include <assert.h>  /* for assert(3p) */
+#include <errno.h>   /* for errno, program_invocation_name */
+#include <error.h>   /* for error(3gnu) */
+#include <fcntl.h>   /* for O_RDONLY, O_RDWR */
+#include <getopt.h>  /* for getopt_long(3gnu), struct option, optind */
+#include <stdbool.h> /* for bool, true, false */
+#include <stdint.h>  /* for uint64_t */
+#include <stdio.h>   /* for printf(3gnu), fprintf(3p), stderr */
+#include <stdlib.h>  /* for strtoll(3p), calloc(3p), free(3p) */
+#include <string.h>  /* for strlen(3p) */
+#include <unistd.h>  /* for dup2(3p) */
+
+#include "dedupe-range.h" /* for dedupe_range, struct range */
+
+bool atou64(const char *str, uint64_t *ret) {
+	assert(sizeof(uint64_t) <= sizeof(unsigned long long int));
+	if (!('0' <= str[0] && str[0] <= '9'))
+		return false;
+	errno = 0;
+	char *end;
+	unsigned long long int n = strtoll(str, &end, 10);
+	if (end[0] != '\0' || errno != 0)
+		return false;
+	*ret = (uint64_t)n;
+	return true;
+}
+
+void usage() {
+	printf("Usage: %2$*1$s [OPTIONS] SRC_FILENAME SRC_OFFSET SRC_LENGTH \\\n"
+	       "       %3$*1$s           DST_FILENAME DST_OFFSET \\\n"
+	       "       %3$*1$s          [DST_FILENAME DST_OFFSET]...\n"
+	       "Submit a file deduplication request to the kernel.\n"
+	       "If the file ranges are not duplicates, the kernel will ignore this request.\n"
+	       "\n"
+	       "OPTIONS:\n"
+	       "   -r, --readonly  Open destination files read-only, rather than read/write.\n"
+	       "                   Generically, the destination must be open for writing.\n"
+	       "                   However, on Btrfs, this allows deduplication to be done\n"
+	       "                   on read-only subvolumes when invoked as root.\n"
+	       "   -h, --help      Display this help and exit.\n",
+	       (int)strlen(program_invocation_name), program_invocation_name, "");
+}
+
+int main(int argc, char *argv[]) {
+	int ro = 0;
+	struct option long_options[] = {
+		{"readonly", no_argument, &ro,  1},
+		{"help",     no_argument, NULL, 'h'},
+		{0}
+	};
+	int flag;
+	while ((flag = getopt_long(argc, argv, "rh", long_options, NULL)) >= 0) {
+		switch (flag) {
+		case 0:
+			break;
+		case 'r':
+			ro = 1;
+			break;
+		case 'h':
+			usage();
+			return 0;
+		case '?':
+			fprintf(stderr, "Try '%s --help' for more information.\n", program_invocation_name);
+			return 2;
+		default:
+			assert(false);
+		}
+	}
+
+	if (argc - optind < 5) {
+		error(0, 0, "too few arguments");
+		fprintf(stderr, "Try '%s --help' for more information.\n", program_invocation_name);
+		return 2;
+	}
+
+	struct range src;
+	src.filename = argv[optind];
+	src.flags = O_RDONLY;
+	if (!atou64(argv[optind+1], &src.offset))
+		error(2, errno, "invalid offset '%s'", argv[optind+1]);
+	if (!atou64(argv[optind+2], &src.length))
+		error(2, errno, "invalid length '%s'", argv[optind+2]);
+	
+	const size_t dst_count = (argc - optind - 3) / 2;
+	struct range *dsts = calloc(dst_count + 1, sizeof(struct range));
+	for (size_t i = 0; i < dst_count; i++) {
+		dsts[i].filename = argv[optind+3+(i*2)];
+		dsts[i].flags = ro ? O_RDONLY : O_RDWR;
+		if (!atou64(argv[optind+3+(i*2)+1], &dsts[i].offset))
+			error(2, errno, "invalid offset '%s'", argv[optind+3+(i*2)+1]);
+	}
+
+	dedupe_range(src, dsts);
+	free(dsts);
+	return 0;
+}