[PATCH 1/3] util/gmime-extra: add g_mime_stream_gzfile_{new, open}

[David Bremner]

These are usable as standard GMime streams, and transparently
decompress gzipped files.
---
 util/gmime-extra.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++
 util/gmime-extra.h |  8 +++++++
 2 files changed, 64 insertions(+)

diff --git a/util/gmime-extra.c b/util/gmime-extra.c
index bc1e3c4d..b3f91c55 100644
--- a/util/gmime-extra.c
+++ b/util/gmime-extra.c
@@ -1,6 +1,62 @@
 #include "gmime-extra.h"
 #include <string.h>
 
+static
+GMimeStream *
+_gzfile_maybe_filter (GMimeStream *file_stream) {
+    char buf[4];
+    int bytes_read;
+
+    if ((bytes_read = g_mime_stream_read (file_stream, buf, sizeof (buf))) < 0)
+	return NULL;
+
+    if (g_mime_stream_reset (file_stream))
+	return NULL;
+
+    /* check for gzipped input */
+    if (bytes_read >= 2 && buf[0] == 0x1f && (unsigned char)buf[1] == 0x8b) {
+	GMimeStream *gzstream;
+	GMimeFilter *gzfilter;
+
+	gzfilter = g_mime_filter_gzip_new (GMIME_FILTER_GZIP_MODE_UNZIP, 0);
+	if (! gzfilter)
+	    return NULL;
+
+	gzstream = g_mime_stream_filter_new (file_stream);
+	if (! gzstream)
+	    return NULL;
+
+	g_mime_stream_filter_add ((GMimeStreamFilter *)gzstream, gzfilter);
+	return gzstream;
+    } else {
+	return file_stream;
+    }
+}
+
+GMimeStream *
+g_mime_stream_gzfile_new (int fd)
+{
+    GMimeStream *file_stream;
+
+    file_stream = g_mime_stream_fs_new (fd);
+    if (! file_stream)
+	return NULL;
+
+    return _gzfile_maybe_filter (file_stream);
+}
+
+GMimeStream *
+g_mime_stream_gzfile_open (const char *filename)
+{
+    GMimeStream *file_stream;
+
+    file_stream = g_mime_stream_fs_open (filename, 0, 0, NULL);
+    if (! file_stream)
+	return NULL;
+
+    return _gzfile_maybe_filter (file_stream);
+}
+
 GMimeStream *
 g_mime_stream_stdout_new()
 {
diff --git a/util/gmime-extra.h b/util/gmime-extra.h
index 5d8c52f7..cb8f5e33 100644
--- a/util/gmime-extra.h
+++ b/util/gmime-extra.h
@@ -9,6 +9,14 @@ extern "C" {
 
 GMimeStream *g_mime_stream_stdout_new(void);
 
+/* Return a GMime stream for this open file descriptor, un-gzipping if
+ * necessary */
+GMimeStream *g_mime_stream_gzfile_new (int fd);
+
+/* Return a GMime stream for this path, un-gzipping if
+ * necessary */
+GMimeStream *g_mime_stream_gzfile_open (const char *filename);
+
 #if (GMIME_MAJOR_VERSION < 3)
 
 #define GMIME_ADDRESS_TYPE_TO GMIME_RECIPIENT_TYPE_TO
-- 
2.20.1