Add ENCHIVE_FILE_EXTENSION compile-time option (#9)

README.md

@@ -266,6 +266,11 @@ The default program to use for `pinentry`.
 
 Whether or not to use `pinentry` by default when reading passphrases.
 
+#### `ENCHIVE_FILE_EXTENSION`
+
+The file extension to add when archiving and remove when extracting. The
+default is `.enchive`, as it appears in the examples.
+
 #### `ENCHIVE_KEY_DERIVE_ITERATIONS`
 
 Power-of-two exponent for protection key derivation. Can be configured

config.h

@@ -11,6 +11,10 @@
 #  define ENCHIVE_FORMAT_VERSION 3
 #endif
 
+#ifndef ENCHIVE_FILE_EXTENSION
+#  define ENCHIVE_FILE_EXTENSION .enchive
+#endif
+
 #ifndef ENCHIVE_KEY_DERIVE_ITERATIONS
 #  define ENCHIVE_KEY_DERIVE_ITERATIONS 25  /* 32MB */
 #endif

src/enchive.c

@@ -28,7 +28,7 @@ static char *pinentry_path = STR(ENCHIVE_PINENTRY_DEFAULT);
 static char *pinentry_path = 0;
 #endif
 
-static const char enchive_suffix[] = ".enchive";
+static const char enchive_suffix[] = STR(ENCHIVE_FILE_EXTENSION);
 
 static struct {
     char *name;