Add an API to get the file extension for a compression type, and use it.

Add wtap_compressed_file_extension(), which returns NULL for
WTAP_UNCOMPRESSED and the appropriate file extension for other
compression types.

Add wtap_compression_type_supported(), which returns TRUE for
WTAP_UNCOMPRESSED and all supported compression types and FALSE
otherwise.  ("Supported" means "the code can decompmress files in that
compression format and can write files in that compression format", so
WTAP_GAIP_COMPRESSED is supported iff libwiretap is built with zlib.)

In MainWindow::fileAddExtension, instead of checking for
WTAP_GZIP_COMPRESSED and using ".gz" as the extension, use the extension
returned by wtap_compressed_file_extension() for the compression type.

Change-Id: I47cb0eca8c887ada3562df30b54e76509008180f
Reviewed-on: https://code.wireshark.org/review/30707
Reviewed-by: Guy Harris <guy@alum.mit.edu>

1 files changed, 40 insertions, 0 deletions

diff --git a/wiretap/wtap.c b/wiretap/wtap.c
index a9ee84c3eb..5d32180d56 100644
--- a/wiretap/wtap.c
+++ b/wiretap/wtap.c
@@ -86,6 +86,25 @@ wtap_get_compression_type(wtap *wth)
 	return is_compressed ? WTAP_GZIP_COMPRESSED : WTAP_UNCOMPRESSED;
 }
 
+/*
+ * Indicate whether a given compression type is supported.
+ */
+static const gboolean compression_type_supported[WTAP_NUM_COMPRESSION_TYPES] = {
+    TRUE,
+#ifdef HAVE_ZLIB
+    TRUE
+#else
+    FALSE
+#endif
+};
+
+gboolean
+wtap_compression_type_supported(wtap_compression_type compression_type)
+{
+	g_assert(compression_type >= 0 && compression_type < WTAP_NUM_COMPRESSION_TYPES);
+	return compression_type_supported[compression_type];
+}
+
 static const char *compression_type_descriptions[WTAP_NUM_COMPRESSION_TYPES] = {
 	NULL,	/* uncompressed */
 	"gzip compressed"
@@ -98,6 +117,27 @@ wtap_compression_type_description(wtap_compression_type compression_type)
 	return compression_type_descriptions[compression_type];
 }
 
+/*
+ * List of extensions for compressed files.
+ * If we add support for more compressed file types, this table
+ * might be expanded to include routines to handle the various
+ * compression types.
+ *
+ * The entry is NULL for WTAP_UNCOMPRESSED, as it's not a compression type,
+ * and thus has no suffix to indicate the compression type.
+ */
+static const char *compressed_file_extensions[WTAP_NUM_COMPRESSION_TYPES] = {
+    NULL,
+    "gz"
+};
+
+const char *
+wtap_compressed_file_extension(wtap_compression_type compression_type)
+{
+	g_assert(compression_type >= 0 && compression_type < WTAP_NUM_COMPRESSION_TYPES);
+	return compressed_file_extensions[compression_type];
+}
+
 guint
 wtap_snapshot_length(wtap *wth)
 {