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-rw-r--r--lib/fstream/compress/gzip.c81
1 files changed, 81 insertions, 0 deletions
diff --git a/lib/fstream/compress/gzip.c b/lib/fstream/compress/gzip.c
new file mode 100644
index 0000000..f604b71
--- /dev/null
+++ b/lib/fstream/compress/gzip.c
@@ -0,0 +1,81 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * gzip.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "../internal.h"
+
+#include <zlib.h>
+
+typedef struct {
+ ostream_comp_t base;
+
+ z_stream strm;
+} ostream_gzip_t;
+
+static int flush_inbuf(ostream_comp_t *base, bool finish)
+{
+ ostream_gzip_t *gzip = (ostream_gzip_t *)base;
+ size_t have;
+ int ret;
+
+ gzip->strm.avail_in = base->inbuf_used;
+ gzip->strm.next_in = base->inbuf;
+
+ do {
+ gzip->strm.avail_out = BUFSZ;
+ gzip->strm.next_out = base->outbuf;
+
+ ret = deflate(&gzip->strm, finish ? Z_FINISH : Z_NO_FLUSH);
+
+ if (ret == Z_STREAM_ERROR) {
+ fprintf(stderr,
+ "%s: internal error in gzip compressor.\n",
+ base->wrapped->get_filename(base->wrapped));
+ return -1;
+ }
+
+ have = BUFSZ - gzip->strm.avail_out;
+
+ if (base->wrapped->append(base->wrapped, base->outbuf, have))
+ return -1;
+ } while (gzip->strm.avail_out == 0);
+
+ base->inbuf_used = 0;
+ return 0;
+}
+
+static void cleanup(ostream_comp_t *base)
+{
+ ostream_gzip_t *gzip = (ostream_gzip_t *)base;
+
+ deflateEnd(&gzip->strm);
+}
+
+ostream_comp_t *ostream_gzip_create(const char *filename)
+{
+ ostream_gzip_t *gzip = calloc(1, sizeof(*gzip));
+ ostream_comp_t *base = (ostream_comp_t *)gzip;
+ int ret;
+
+ if (gzip == NULL) {
+ fprintf(stderr, "%s: creating gzip wrapper: %s.\n",
+ filename, strerror(errno));
+ return NULL;
+ }
+
+ ret = deflateInit2(&gzip->strm, 9, Z_DEFLATED, 16 + 15, 8,
+ Z_DEFAULT_STRATEGY);
+ if (ret != Z_OK) {
+ fprintf(stderr,
+ "%s: internal error creating gzip compressor.\n",
+ filename);
+ free(gzip);
+ return NULL;
+ }
+
+ base->flush_inbuf = flush_inbuf;
+ base->cleanup = cleanup;
+ return base;
+}