initial commit of holes

1 files changed, 89 insertions, 0 deletions

diff --git a/holes.c b/holes.c
new file mode 100644
index 0000000..865ea50
--- /dev/null
+++ b/holes.c
@@ -0,0 +1,89 @@
+/* holes - find holes (= runs of zero bytes) in input files */
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+ssize_t minlen = 64;
+int ret;
+char *argv0;
+
+void
+holes(FILE *input, char *filename)
+{
+	off_t offset = 0;
+	off_t run = 0;	
+	int ch;
+
+	while ((ch = getc_unlocked(input)) != EOF) {
+		if (ch == 0) {
+			run++;
+		} else {
+			if (run >= minlen) {
+				if (filename)
+					printf("%s: ", filename);
+				printf("%08lx %ld\n", offset - run, run);
+			}
+			run = 0;
+		}
+		offset++;
+	}
+	if (ferror(input)) {
+		fprintf(stderr, "%s: can't read '%s': %s\n",
+		    argv0, filename ? filename : "-", strerror(errno));
+		ret = 1;
+		return;
+	}
+
+	if (offset == 0 ||	// empty file
+	    run >= minlen) {
+		if (filename)
+			printf("%s: ", filename);
+		printf("%08lx %ld\n", offset - run, run);
+	}
+}
+
+int
+main(int argc, char *argv[])
+{
+	int c, i;
+
+	argv0 = argv[0];
+
+	while ((c = getopt(argc, argv, "n:")) != -1)
+		switch(c) {
+                case 'n':
+			minlen = atoll(optarg);
+			break;
+                default:
+                        fprintf(stderr,
+			    "Usage: %s [-n MINLEN] [FILES...]\n", argv0);
+			exit(2);
+		}
+
+	if (minlen < 1) {
+		fprintf(stderr, "%s: MINLEN must not be smaller than 1.\n",
+		    argv0);
+		exit(2);
+	}
+
+	if (optind == argc)
+		holes(stdin, 0);
+	else
+		for (i = optind; i < argc; i++) {
+			FILE *input = (strcmp(argv[i], "-") == 0) ?
+			    stdin : fopen(argv[i], "rb");
+			
+			if (!input) {
+				fprintf(stderr, "%s: can't open file '%s': %s\n",
+				    argv0, argv[i], strerror(errno));
+				ret = 1;
+			} else {
+				holes(input, argc - optind > 1 ? argv[i] : 0);
+			}
+		}
+
+	return ret;
+}