findhex

commit 8fde78de2cf95793fe4aed00b899aca2695164b6
Author: Louis Burda <quent.burda@gmail.com>
Date:   Wed, 21 Sep 2022 00:51:10 +0200

Initial version

Diffstat:
A
.gitignore
 | 
1
+
A
Makefile
 | 
9
+++++++++
A
findhex.c
 | 
92
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

3 files changed, 102 insertions(+), 0 deletions(-)
diff --git a/.gitignore b/.gitignore
@@ -0,0 +1 @@
+findhex
diff --git a/Makefile b/Makefile
@@ -0,0 +1,9 @@
+
+all: findhex
+
+clean:
+	rm -f findhex
+
+findhex: findhex.c
+
+.PHONY: all clean
diff --git a/findhex.c b/findhex.c
@@ -0,0 +1,92 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdint.h>
+#include <stdarg.h>
+
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+
+void
+die(const char *msg, ...)
+{
+	va_list ap;
+
+	va_start(ap, msg);
+	vfprintf(stderr, "%s\n", ap);
+	va_end(ap);
+
+	exit(1);
+}
+
+int
+main(int argc, const char **argv)
+{
+	uint8_t *pattern, *pattern_mask;
+	size_t patlen;
+	uint8_t *buf;
+	size_t buflen;
+	ssize_t nread;
+	size_t i, k;
+	size_t pos, off;
+	size_t arglen;
+	FILE *file;
+
+	setvbuf(stdout, NULL, _IONBF, 0);
+
+	if (argc < 2 || argc > 3) die("Usage: findhex PATTERN [FILE]");
+
+	arglen = strlen(argv[1]);
+	if (!arglen || arglen % 2 != 0)
+		die("Pattern length invalid");
+	patlen = arglen / 2;
+
+	pattern = calloc(patlen, 1);
+	pattern_mask = calloc(patlen, 1);
+	if (!pattern || !pattern_mask) die("Out of Memory");
+
+	buflen = MAX(patlen * 2, 16 * 1024);
+	buf = malloc(buflen);
+	if (!buf) die("Out of Memory");
+
+	for (i = 0; i < arglen; i += 2) {
+		if (!strncmp(argv[1] + i, "__", 2))
+			continue;
+		if (!sscanf(argv[1] + i, "%02hX", &pattern[i / 2]))
+			die("Invalid hex in pattern");
+		pattern_mask[i / 2] = 0xff;
+	}
+
+	if (argc == 3) {
+		file = fopen(argv[1], "r");
+		if (!file) die("Failed to open file");
+	} else {
+		file = stdin;
+	}
+
+	off = patlen > 0 ? patlen - 1 : 0;
+	if (fread(buf, 1, off, file) != off)
+		exit(0);
+
+	pos = 0;
+	while (1) {
+		nread = fread(buf + off, 1, buflen - off, file);
+		if (nread == 0) break;
+		if (nread < 0) die("%016llX: Read failed", pos);
+
+		for (i = 0; i <= nread + off - patlen; i++) {
+			for (k = 0; k < patlen; k++) {
+				if (!pattern_mask[k])
+					continue;
+				if (buf[i+k] != pattern[k])
+					break;
+			}
+			if (k == patlen)
+				printf("%016llX\n", pos + i);
+		}
+
+		pos += nread;
+		memcpy(buf, buf + buflen - off, off);
+	}
+
+	fclose(file);
+}