[PATCH 6/9] crypto, zstd: Implement zbufsize()

Kees Cook
2018-08-02T21:51:35Z

This implements the worst-case compression size querying interface for
zstd, based on the logic originally used by pstore.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
crypto/zstd.c | 22 +++++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/crypto/zstd.c b/crypto/zstd.c
index 9a76b3ed8b8b..ce8efd40f27f 100644
--- a/crypto/zstd.c
+++ b/crypto/zstd.c
@@ -212,6 +212,24 @@ static int zstd_sdecompress(struct crypto_scomp *tfm, const u8 *src,
return __zstd_decompress(src, slen, dst, dlen, ctx);
}

+static int __zstd_zbufsize(unsigned int slen, unsigned int *dlen)
+{
+ *dlen = ZSTD_compressBound(slen);
+ return 0;
+}
+
+static int zstd_zbufsize(struct crypto_tfm *tfm, unsigned int slen,
+ unsigned int *dlen)
+{
+ return __zstd_zbufsize(slen, dlen);
+}
+
+static int zstd_szbufsize(struct crypto_scomp *tfm, unsigned int slen,
+ unsigned int *dlen, void *ctx)
+{
+ return __zstd_zbufsize(slen, dlen);
+}
+
static struct crypto_alg alg = {
.cra_name = "zstd",
.cra_flags = CRYPTO_ALG_TYPE_COMPRESS,
@@ -221,7 +239,8 @@ static struct crypto_alg alg = {
.cra_exit = zstd_exit,
.cra_u = { .compress = {
.coa_compress = zstd_compress,
- .coa_decompress = zstd_decompress } }
+ .coa_decompress = zstd_decompress,
+ .coa_zbufsize = zstd_zbufsize } }
};

static struct scomp_alg scomp = {
@@ -229,6 +248,7 @@ static struct scomp_alg scomp = {
.free_ctx = zstd_free_ctx,
.compress = zstd_scompress,
.decompress = zstd_sdecompress,
+ .zbufsize = zstd_szbufsize,
.base = {
.cra_name = "zstd",
.cra_driver_name = "zstd-scomp",
--
2.17.1