splice

commit f48499265ba2c6f39a1c3f35955aaa3b72ecaaa8
Author: Louis Burda <quent.burda@gmail.com>
Date:   Fri, 29 Apr 2022 17:28:25 +0200

Simple binary patch

Diffstat:
A
.gitignore
 | 
1
+
A
Makefile
 | 
7
+++++++
A
fwpatch.c
 | 
60
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

3 files changed, 68 insertions(+), 0 deletions(-)
diff --git a/.gitignore b/.gitignore
@@ -0,0 +1 @@
+fwpatch
diff --git a/Makefile b/Makefile
@@ -0,0 +1,7 @@
+CFLAGS = -g
+
+.PHONY: all
+
+all: fwpatch
+
+fwpatch: fwpatch.c
diff --git a/fwpatch.c b/fwpatch.c
@@ -0,0 +1,60 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <stdint.h>
+
+const char usage[] = "USAGE: fwpatch TARGET OFFSET FILE";
+
+void
+die(const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+
+	exit(1);
+}
+
+int
+main(int argc, const char **argv)
+{
+	size_t addr, size;
+	FILE *file;
+	char *end, *data;
+
+	if (argc != 4)
+		die(usage);
+
+	addr = strtoull(argv[2], &end, 0);
+	if (*end) die("Invalid offset: %s", argv[2]);
+
+	file = fopen(argv[3], "rb");
+	if (!file) die("Failed to open: %s", argv[3]);
+
+	fseek(file, 0, SEEK_END);
+	size = ftell(file);
+
+	data = malloc(size);
+	if (!data) die("Out of memory\n");
+
+	fseek(file, 0, SEEK_SET);
+	if (fread(data, 1, size, file) != size)
+		die("Read failed\n");
+
+	fclose(file);
+
+	file = fopen(argv[1], "r+b");
+	if (!file) die("Failed to open: %s", argv[1]);
+
+	fseek(file, addr, SEEK_SET);
+	if (ftell(file) != addr) die("Invalid offset\n");
+
+	if (fwrite(data, 1, size, file) != size)
+		die("Write failed\n");
+
+	fclose(file);
+
+	free(data);
+}