Hi Christian,
On Tue, 23 Aug 2011, Christian Brunner wrote:
> We needed to get an md5 checksum of an rbd image. Since librbd is using a
> lot of sparse operations, this was not possible without writing an image
> to a local disk.
>
> With this patch exporting the image is no longer needed. You can do
> "rbd md5 image" and you will get the same output as you would call "md5sum".
>
> Thanks,
> Christian
> ---
> src/rbd.cc | 83 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 files changed, 82 insertions(+), 1 deletions(-)
>
> diff --git a/src/rbd.cc b/src/rbd.cc
> index a18c029..a9c33ad 100644
> --- a/src/rbd.cc
> +++ b/src/rbd.cc
> @@ -38,6 +38,11 @@
> #include <time.h>
> #include <sys/ioctl.h>
>
> +#define CRYPTOPP_ENABLE_NAMESPACE_WEAK 1
> +#include <cryptopp/cryptlib.h>
> +#include <cryptopp/md5.h>
> +#include <cryptopp/hex.h>
> +
We need to build with both cryptopp and libnss. See common/ceph_crypto.h,
which defines the SHA1 HMAC. Adding MD5 should be pretty straightforward.
We may as well support both, though?
> #include "include/rbd_types.h"
>
> #include <linux/fs.h>
> @@ -49,6 +54,7 @@
>
> static string dir_oid = RBD_DIRECTORY;
> static string dir_info_oid = RBD_INFO;
> +static size_t lastofs;
>
> void usage()
> {
> @@ -65,6 +71,7 @@ void usage()
> << " export [image-name] [dest-path] export image to file\n"
> << " import [path] [dst-image] import image from file (dest defaults\n"
> << " as the filename part of file)\n"
> + << " md5 [image-name] print md5 checksum for image\n"
> << " <cp | copy> [src-image] [dest-image] copy image to dest\n"
> << " <mv | rename> [src-image] [dest-image] copy image to dest\n"
> << " snap ls [image-name] dump list of image snapshots\n"
> @@ -262,6 +269,66 @@ static int do_export(librbd::Image& image, const char *path)
> return 0;
> }
>
> +static int md5_read_cb(uint64_t ofs, size_t len, const char *buf, void *arg)
> +{
> + ssize_t dif;
> + CryptoPP::HashTransformation *Hash = (CryptoPP::HashTransformation *)arg;
> +
> + dif = ofs-lastofs;
> + if (dif > 0) {
> + byte *tempbuf = (byte *) malloc(dif);
> + memset(tempbuf, 0, dif);
> + Hash->Update((const byte *) tempbuf, dif);
> + free(tempbuf);
> + }
> +
> + if (buf) {
> + Hash->Update((const byte *) buf, len);
> + }
If buf == NULL we are processing a hole. The zeroes should probably be
fed to the hash too?
sage
> +
> + lastofs = ofs + len;
> +
> + return 0;
> +}
> +
> +static int do_md5(librbd::Image& image, const char *imgname)
> +{
> + int64_t r;
> + librbd::image_info_t info;
> +
> + lastofs = 0;
> +
> + CryptoPP::HashTransformation *Hash =
> + (CryptoPP::HashTransformation *) new CryptoPP::Weak1::MD5;
> +
> + r = image.stat(info, sizeof(info));
> + if (r < 0)
> + return r;
> +
> + r = image.read_iterate(0, info.size, md5_read_cb, (void *)Hash);
> + if (r < 0)
> + return r;
> +
> + if (lastofs < info.size) {
> + md5_read_cb(info.size, 0, NULL, (void *)Hash);
> + }
> +
> + byte digest[CryptoPP::Weak1::MD5::DIGESTSIZE];
> + Hash->Final(digest);
> +
> + std::string output;
> + CryptoPP::StringSource(digest, sizeof(digest), true,
> + new CryptoPP::HexEncoder(
> + new CryptoPP::StringSink(output),
> + false
> + )
> + );
> +
> + cout << output << " " << imgname << std::endl;
> +
> + return 0;
> +}
> +
> static const char *imgname_from_path(const char *path)
> {
> const char *imgname;
> @@ -739,6 +806,7 @@ enum {
> OPT_MAP,
> OPT_UNMAP,
> OPT_SHOWMAPPED,
> + OPT_MD5,
> };
>
> static int get_cmd(const char *cmd, bool *snapcmd)
> @@ -766,6 +834,8 @@ static int get_cmd(const char *cmd, bool *snapcmd)
> return OPT_EXPORT;
> if (strcmp(cmd, "import") == 0)
> return OPT_IMPORT;
> + if (strcmp(cmd, "md5") == 0)
> + return OPT_MD5;
> if (strcmp(cmd, "copy") == 0 ||
> strcmp(cmd, "cp") == 0)
> return OPT_COPY;
> @@ -888,6 +958,9 @@ int main(int argc, const char **argv)
> case OPT_IMPORT:
> set_conf_param(CEPH_ARGPARSE_VAL, &path, &destname);
> break;
> + case OPT_MD5:
> + set_conf_param(CEPH_ARGPARSE_VAL, &imgname, NULL);
> + break;
> case OPT_COPY:
> case OPT_RENAME:
> set_conf_param(CEPH_ARGPARSE_VAL, &imgname, &destname);
> @@ -966,7 +1039,7 @@ int main(int argc, const char **argv)
> (opt_cmd == OPT_RESIZE || opt_cmd == OPT_INFO || opt_cmd == OPT_SNAP_LIST ||
> opt_cmd == OPT_SNAP_CREATE || opt_cmd == OPT_SNAP_ROLLBACK ||
> opt_cmd == OPT_SNAP_REMOVE || opt_cmd == OPT_EXPORT || opt_cmd == OPT_WATCH ||
> - opt_cmd == OPT_COPY)) {
> + opt_cmd == OPT_COPY || opt_cmd == OPT_MD5)) {
> r = rbd.open(io_ctx, image, imgname);
> if (r < 0) {
> cerr << "error opening image " << imgname << ": " << strerror(r) << std::endl;
> @@ -1127,6 +1200,14 @@ int main(int argc, const char **argv)
> }
> break;
>
> + case OPT_MD5:
> + r = do_md5(image, imgname);
> + if (r < 0) {
> + cerr << "md5 hashing failed: " << strerror(-r) << std::endl;
> + exit(1);
> + }
> + break;
> +
> case OPT_COPY:
> r = do_copy(image, dest_io_ctx, destname);
> if (r < 0) {
> --
> 1.7.1
>
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