dmg: Move libbz2 code to dmg-bz2.so

dmg.o was moved to block-obj-m in 5505e8b76 to become a separate module,
so that its reference to libbz2, since 6b383c08c, doesn't add an extra
library to the main executable.

Until recently, commit 06e60f70a (blockdev: Add dynamic module loading
for block drivers) moved it back to block-obj-y to simplify the design
of dynamic loading of block modules. But we don't want to lose the
feature of less library dependency on the main executable.

The solution here is to move only the bz2 related code to a separate
DSO file, and load it when dmg_open is called.

dmg_probe doesn't depend on bz2 support to work, and is the only code in
this file which can run before dmg_open.

While we are at it, fix the unhelpful cast of last argument passed to
dmg_uncompress_bz2.

Signed-off-by: Fam Zheng <famz@redhat.com>
Message-id: 1473043845-13197-4-git-send-email-famz@redhat.com
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

1 files changed, 61 insertions, 0 deletions

diff --git a/block/dmg-bz2.c b/block/dmg-bz2.c
new file mode 100644
index 0000000000..9059492a9f
--- /dev/null
+++ b/block/dmg-bz2.c
@@ -0,0 +1,61 @@
+/*
+ * DMG bzip2 uncompression
+ *
+ * Copyright (c) 2004 Johannes E. Schindelin
+ * Copyright (c) 2016 Red Hat, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#include "qemu/osdep.h"
+#include "qemu-common.h"
+#include "dmg.h"
+#include <bzlib.h>
+
+static int dmg_uncompress_bz2_do(char *next_in, unsigned int avail_in,
+                                 char *next_out, unsigned int avail_out)
+{
+    int ret;
+    uint64_t total_out;
+    bz_stream bzstream = {};
+
+    ret = BZ2_bzDecompressInit(&bzstream, 0, 0);
+    if (ret != BZ_OK) {
+        return -1;
+    }
+    bzstream.next_in = next_in;
+    bzstream.avail_in = avail_in;
+    bzstream.next_out = next_out;
+    bzstream.avail_out = avail_out;
+    ret = BZ2_bzDecompress(&bzstream);
+    total_out = ((uint64_t)bzstream.total_out_hi32 << 32) +
+                bzstream.total_out_lo32;
+    BZ2_bzDecompressEnd(&bzstream);
+    if (ret != BZ_STREAM_END ||
+        total_out != avail_out) {
+        return -1;
+    }
+    return 0;
+}
+
+__attribute__((constructor))
+static void dmg_bz2_init(void)
+{
+    assert(!dmg_uncompress_bz2);
+    dmg_uncompress_bz2 = dmg_uncompress_bz2_do;
+}