From 81a1093d3e69b4996e56bc291759f1c17dbc2344 Mon Sep 17 00:00:00 2001
From: Michael Gernoth <michael@gernoth.net>
Date: Sun, 1 Feb 2009 13:16:04 +0100
Subject: [PATCH] add functions to reliably read files in the filesystem, to be
 used by the property functions.

---
 extract.c | 88 ++++++++++++++++++++++++++++++++-----------------------
 extract.h |  8 +++++
 2 files changed, 60 insertions(+), 36 deletions(-)

diff --git a/extract.c b/extract.c
index 5d2a6fc..86491d1 100644
--- a/extract.c
+++ b/extract.c
@@ -12,43 +12,61 @@
 #include "rsb-lz.h"
 #include "extract.h"
 
+struct file_entry* get_next_file(unsigned char *fw, int len)
+{
+	static unsigned char *pos;
+	static unsigned char *end;
+	static struct file_entry fent;
+	int name_length;
+
+	if (fw != NULL && len != 0) {
+		pos = fw + 0x28;
+
+		printf("Start of filesystem: 0x%08x\n", *((unsigned int*)pos));
+		pos = fw + *((unsigned int*)pos);
+		end = fw + len;
+	}
+
+	fent.unknown = *pos;
+	pos++;
+
+	name_length = *((unsigned int*)pos);
+	pos += 4;
+
+	fent.length = *((unsigned int*)pos);
+	pos += 4;
+
+	if ((fent.length > (end - pos)) ||
+	    (name_length > (end - pos))) {
+		printf("EOF reached\n");
+		return NULL;
+	}
+
+	fent.name = (char*)pos;
+	pos += name_length;
+
+	fent.start = pos;
+	pos += fent.length;
+
+	return &fent;
+}
+
 void extract_files(unsigned char *fw, int len)
 {
-	unsigned char *pos;
-	unsigned int content_length;
-	unsigned int name_length;
-	unsigned char unknown;
-	char *name;
-
-	pos = fw + 0x28;
-	printf("Start of filesystem: 0x%08x\n", *((unsigned int*)pos));
-
-	pos = fw + *((unsigned int*)pos);
-
-	while (pos < (fw + len)) {
-		unknown = *pos; pos++;
-		name_length = *((unsigned int*)pos);
-		pos += 4;
-		content_length = *((unsigned int*)pos);
-		pos += 4;
-		name = (char*)pos;
-
-		if (((pos + content_length) > (fw + len)) ||
-		    ((pos + name_length) > (fw + len))) {
-			printf("EOF reached\n");
-			break;
-		}
-		pos += name_length;
+	struct file_entry *fent;
 
+	fent = get_next_file(fw, len);
+	
+	while (fent) {
 		printf("%s: unknown: 0x%02x, length: %d",
-			name, unknown, content_length);
+			fent->name, fent->unknown, fent->length);
 
-		if (content_length > 0) {
-			write_file(name, pos, content_length);
-			if (*((unsigned int*)pos) == LZ_MAGIC) {
+		if (fent->length > 0) {
+			write_file(fent->name, fent->start, fent->length);
+			if (*((unsigned int*)fent->start) == LZ_MAGIC) {
 				char *lzname;
 
-				if ((lzname = strdup(name)) == NULL) {
+				if ((lzname = strdup(fent->name)) == NULL) {
 					perror("strdup");
 					exit(1);
 				}
@@ -61,16 +79,16 @@ void extract_files(unsigned char *fw, int len)
 
 				printf("%s: packed file found", lzname);
 
-				extract_lz_file(pos, (unsigned char*)lzname);
+				extract_lz_file(fent->start, (unsigned char*)lzname);
 				free(lzname);
-			} else if (!strcmp(name, "firmware")) {
+			} else if (!strcmp(fent->name, "firmware")) {
 				unsigned char *lzpos;
 				char lzname[128];
 
 				bzero(lzname, sizeof(lzname));
 				strcpy(lzname, "firmware.");
 
-				lzpos = pos + *((unsigned int*)(pos + 0x20));
+				lzpos = fent->start + *((unsigned int*)(fent->start + 0x20));
 				memcpy(lzname + strlen(lzname), lzpos - 4, 4);
 				lzpos += 4;
 				if (*((unsigned int*)(lzpos)) == LZ_MAGIC) {
@@ -79,9 +97,7 @@ void extract_files(unsigned char *fw, int len)
 				}
 			}
 		}
-
-		pos += content_length;
-
+		fent = get_next_file(NULL, 0);
 	}
 }
 
diff --git a/extract.h b/extract.h
index d8b8d32..ee35618 100644
--- a/extract.h
+++ b/extract.h
@@ -1,2 +1,10 @@
+struct file_entry {
+	char *name;
+	unsigned char *start;
+	int length;
+	unsigned char unknown;
+};
+
+struct file_entry* get_next_file(unsigned char *fw, int len);
 void extract_files(unsigned char *fw, int len);
 void write_file(char *fname, unsigned char *buf, int len);
-- 
2.39.2