List can be a filter too; update usage

Makefile

@@ -32,6 +32,9 @@ write: write.o common.o endian.o cpu.o
 read: read.o common.o endian.o
 	$(LD) $@ $^ -llzma
 
+pread: pread.o common.o endian.o
+	$(LD) $@ $^ -llzma
+
 clean:
 	rm -f *.o $(PROGS)
 

list.c

@@ -8,10 +8,14 @@
 int main(int argc, char **argv) {
     char *progname = argv[0];
     
-    if (argc != 2)
-        die("Usage: %s [-t] file", progname);
-    if (!(gInFile = fopen(argv[1], "r")))
-        die("Can't open input file");
+    if (argc == 1) {
+        gInFile = stdin;
+    } else if (argc == 2) {
+        if (!(gInFile = fopen(argv[1], "r")))
+            die("Can't open input file");
+    } else {
+        die("Usage: %s [FILE]", progname);
+    }
     
     decode_index();
     lzma_index_iter iter;

write.c

@@ -82,6 +82,7 @@ static void write_file_index_buf(lzma_action action);
 #pragma mark FUNCTION DEFINITIONS
 
 int main(int argc, char **argv) {
+    char *progname = argv[0];
     debug("launch");
     
     int ch;
@@ -111,7 +112,7 @@ int main(int argc, char **argv) {
         if (!(gOutFile = fopen(argv[2], "w")))
             die("Can't open output file");
     } else {
-        die("Need two arguments");
+        die("Usage: %s [-t] [INPUT OUTPUT]", progname);
     }
     
     // xz options