Check that suffix of input file ends in '.deflate'

inflate.c

@@ -424,9 +424,24 @@ void read_block(char *buf, FILE *out) {
     } 
 }
 
-void inflate(FILE *fp) { 
+void truncate_suffix(char *fname) {
+    char *dot = strrchr(fname, '.'); 
+
+    char *suffix = ".deflate"; 
+    for (int i = 0; i < 8; i++) {
+        if (dot == NULL || *(dot + i) != suffix[i]) { 
+            fprintf(stderr, "error: must be a .deflate file"); 
+            exit(1);
+        }
+    }
+    *dot = '\0';
+}
+
+void inflate(FILE *fp, char *fname) { 
+    truncate_suffix(fname);
+
     /* Create output file */
-    FILE *out = fopen("test.txt", "wb+");
+    FILE *out = fopen(fname, "wb+");
     
     /* Read the file into a buffer */  
     fseek(fp, 0, SEEK_END);
@@ -441,7 +456,6 @@ void inflate(FILE *fp) {
 
     while (_CUR_BIT < 8 * size) {
         read_block(buf, out); 
-        break;
     } 
     
     fclose(out);
@@ -463,7 +477,7 @@ int main(int argc, char *argv[]) {
         return 1;
     }
     
-    inflate(fp);
+    inflate(fp, fname);
 
     fclose(fp);
     return 0;