[PATCH v2 1/4] luks: extract block_crypto_calculate_payload_offset()

[Stefan Hajnoczi <stefanha@redhat.com>]

The qcow2 .bdrv_measure() code calculates the crypto payload offset.
This logic really belongs in block/crypto.c where it can be reused by
other image formats.

The "luks" block driver will need this same logic in order to implement
.bdrv_measure(), so extract the block_crypto_calculate_payload_offset()
function now.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/crypto.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++
 block/crypto.h |  5 ++++
 block/qcow2.c  | 59 ++++------------------------------------------
 3 files changed, 73 insertions(+), 55 deletions(-)

diff --git a/block/crypto.c b/block/crypto.c
index 24823835c1..ed32202fa2 100644
--- a/block/crypto.c
+++ b/block/crypto.c
@@ -185,6 +185,70 @@ block_crypto_create_opts_init(QDict *opts, Error **errp)
 }
 
 
+static ssize_t block_crypto_headerlen_hdr_init_func(QCryptoBlock *block,
+        size_t headerlen, void *opaque, Error **errp)
+{
+    size_t *headerlenp = opaque;
+
+    /* Stash away the payload size */
+    *headerlenp = headerlen;
+    return 0;
+}
+
+
+static ssize_t block_crypto_headerlen_hdr_write_func(QCryptoBlock *block,
+        size_t offset, const uint8_t *buf, size_t buflen,
+        void *opaque, Error **errp)
+{
+    /* Discard the bytes, we're not actually writing to an image */
+    return buflen;
+}
+
+
+/* Determine the number of bytes for the crypto header */
+bool block_crypto_calculate_payload_offset(QemuOpts *opts,
+                                           const char *optprefix,
+                                           size_t *len,
+                                           Error **errp)
+{
+    QDict *cryptoopts_qdict;
+    QCryptoBlockCreateOptions *cryptoopts;
+    QCryptoBlock *crypto;
+
+    /* Extract options into a qdict */
+    if (optprefix) {
+        QDict *opts_qdict = qemu_opts_to_qdict(opts, NULL);
+
+        qdict_extract_subqdict(opts_qdict, &cryptoopts_qdict, optprefix);
+        qobject_unref(opts_qdict);
+    } else {
+        cryptoopts_qdict = qemu_opts_to_qdict(opts, NULL);
+    }
+
+    /* Build QCryptoBlockCreateOptions object from qdict */
+    qdict_put_str(cryptoopts_qdict, "format", "luks");
+
+    cryptoopts = block_crypto_create_opts_init(cryptoopts_qdict, errp);
+    qobject_unref(cryptoopts_qdict);
+    if (!cryptoopts) {
+        return false;
+    }
+
+    /* Fake LUKS creation in order to determine the payload size */
+    crypto = qcrypto_block_create(cryptoopts, optprefix,
+                                  block_crypto_headerlen_hdr_init_func,
+                                  block_crypto_headerlen_hdr_write_func,
+                                  len, errp);
+    qapi_free_QCryptoBlockCreateOptions(cryptoopts);
+    if (!crypto) {
+        return false;
+    }
+
+    qcrypto_block_free(crypto);
+    return true;
+}
+
+
 static int block_crypto_open_generic(QCryptoBlockFormat format,
                                      QemuOptsList *opts_spec,
                                      BlockDriverState *bs,
diff --git a/block/crypto.h b/block/crypto.h
index b935695e79..5a39bee71b 100644
--- a/block/crypto.h
+++ b/block/crypto.h
@@ -94,4 +94,9 @@ block_crypto_create_opts_init(QDict *opts, Error **errp);
 QCryptoBlockOpenOptions *
 block_crypto_open_opts_init(QDict *opts, Error **errp);
 
+bool block_crypto_calculate_payload_offset(QemuOpts *opts,
+                                           const char *optprefix,
+                                           size_t *len,
+                                           Error **errp);
+
 #endif /* BLOCK_CRYPTO_H */
diff --git a/block/qcow2.c b/block/qcow2.c
index cef9d72b3a..3aaf79bbf6 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -4609,60 +4609,6 @@ static coroutine_fn int qcow2_co_flush_to_os(BlockDriverState *bs)
     return ret;
 }
 
-static ssize_t qcow2_measure_crypto_hdr_init_func(QCryptoBlock *block,
-        size_t headerlen, void *opaque, Error **errp)
-{
-    size_t *headerlenp = opaque;
-
-    /* Stash away the payload size */
-    *headerlenp = headerlen;
-    return 0;
-}
-
-static ssize_t qcow2_measure_crypto_hdr_write_func(QCryptoBlock *block,
-        size_t offset, const uint8_t *buf, size_t buflen,
-        void *opaque, Error **errp)
-{
-    /* Discard the bytes, we're not actually writing to an image */
-    return buflen;
-}
-
-/* Determine the number of bytes for the LUKS payload */
-static bool qcow2_measure_luks_headerlen(QemuOpts *opts, size_t *len,
-                                         Error **errp)
-{
-    QDict *opts_qdict;
-    QDict *cryptoopts_qdict;
-    QCryptoBlockCreateOptions *cryptoopts;
-    QCryptoBlock *crypto;
-
-    /* Extract "encrypt." options into a qdict */
-    opts_qdict = qemu_opts_to_qdict(opts, NULL);
-    qdict_extract_subqdict(opts_qdict, &cryptoopts_qdict, "encrypt.");
-    qobject_unref(opts_qdict);
-
-    /* Build QCryptoBlockCreateOptions object from qdict */
-    qdict_put_str(cryptoopts_qdict, "format", "luks");
-    cryptoopts = block_crypto_create_opts_init(cryptoopts_qdict, errp);
-    qobject_unref(cryptoopts_qdict);
-    if (!cryptoopts) {
-        return false;
-    }
-
-    /* Fake LUKS creation in order to determine the payload size */
-    crypto = qcrypto_block_create(cryptoopts, "encrypt.",
-                                  qcow2_measure_crypto_hdr_init_func,
-                                  qcow2_measure_crypto_hdr_write_func,
-                                  len, errp);
-    qapi_free_QCryptoBlockCreateOptions(cryptoopts);
-    if (!crypto) {
-        return false;
-    }
-
-    qcrypto_block_free(crypto);
-    return true;
-}
-
 static BlockMeasureInfo *qcow2_measure(QemuOpts *opts, BlockDriverState *in_bs,
                                        Error **errp)
 {
@@ -4715,7 +4661,10 @@ static BlockMeasureInfo *qcow2_measure(QemuOpts *opts, BlockDriverState *in_bs,
     if (has_luks) {
         size_t headerlen;
 
-        if (!qcow2_measure_luks_headerlen(opts, &headerlen, &local_err)) {
+        if (!block_crypto_calculate_payload_offset(opts,
+                                                   "encrypt.",
+                                                   &headerlen,
+                                                   &local_err)) {
             goto err;
         }
 
-- 
2.24.1