Use magic number to identify index

common.c

@@ -74,7 +74,7 @@ void free_file_index(void) {
     gFileIndex = gLastFile = NULL;
 }
 
-void read_file_index(void) {    
+bool read_file_index(void) {    
     // find the last block
     lzma_index_iter iter;
 	lzma_index_iter_init(&iter, gIndex);
@@ -86,6 +86,14 @@ void read_file_index(void) {
     gFileIndexBuf = malloc(gFIBSize);
     gStream.avail_out = gFIBSize;
     gStream.avail_in = 0;
+    
+    // Check if this is really an index
+    read_file_index_data();
+    if (xle64dec(gFileIndexBuf + gFIBPos) != PIXZ_INDEX_MAGIC) {
+        gLastFile = gFileIndex = NULL;
+        return false;
+    }
+    
     while (true) {
         char *name = read_file_index_name();
         if (!name)
@@ -106,6 +114,8 @@ void read_file_index(void) {
     free(gFileIndexBuf);
     lzma_end(&gStream);
     free(bdata);
+    
+    return true;
 }
 
 static char *read_file_index_name(void) {

list.c

@@ -7,19 +7,6 @@
 
 int main(int argc, char **argv) {
     char *progname = argv[0];
-    int ch;
-    bool tar = false;
-    while ((ch = getopt(argc, argv, "t")) != -1) {
-        switch (ch) {
-            case 't':
-                tar = true;
-                break;
-            default:
-                die("Unknown option");
-        }
-    }
-    argc -= optind - 1;
-    argv += optind - 1;
     
     if (argc != 2)
         die("Usage: %s [-t] file", progname);
@@ -35,9 +22,8 @@ int main(int argc, char **argv) {
             (uintmax_t)iter.block.uncompressed_size);
     }
     
-    if (tar) {
+    if (read_file_index()) {
         fprintf(stderr, "\n");
-        read_file_index();
         dump_file_index();
         free_file_index();
     }

pixz.h

@@ -13,6 +13,8 @@
 
 #pragma mark DEFINES
 
+#define PIXZ_INDEX_MAGIC 0xDBAE14D62E324CA6LL
+
 #define CHECK LZMA_CHECK_CRC32
 #define MEMLIMIT (64L * 1024 * 1024 * 1024) // crazy high
 
@@ -70,7 +72,7 @@ size_t num_threads(void);
 void decode_index(void);
 void *decode_block_start(off_t block_seek);
 
-void read_file_index(void);
+bool read_file_index(void);
 void dump_file_index(void);
 void free_file_index(void);
 

read.c

@@ -17,7 +17,8 @@ int main(int argc, char **argv) {
     char *target = argv[2];
     
     decode_index();
-    read_file_index();
+    if (!read_file_index())
+        die("File has no index");
     
     extract_file(target);
     

write.c

@@ -435,7 +435,9 @@ static void write_file_index(void) {
     if (lzma_block_encoder(&gStream, &block) != LZMA_OK)
         die("Error creating file index encoder");
     
-    uint8_t offbuf[sizeof(uint64_t)]; 
+    uint8_t offbuf[sizeof(uint64_t)];
+    xle64enc(offbuf, PIXZ_INDEX_MAGIC);
+    write_file_index_bytes(sizeof(offbuf), offbuf);
     for (file_index_t *f = gFileIndex; f != NULL; f = f->next) {
         char *name = f->name ? f->name : "";
         size_t len = strlen(name);