[PATCH] src/fssum: use newer EVP_* interface to replace deprecated MD5_* interace

[Qu Wenruo <wqu@xxxxxxxx>]

In OpenSSL 3.0, MD_Init/Update/Final() interfaces are marked deprecated,
and we have to go EVP_DigestInit/Update/Final() instead.

Personally I'm not a fan of this, especially the new EVP_MD_CTX
structure can no longer be stack allocated, thus we have to dynamically
allocate and free EVP_MD_CTX in sum_init() and sum_free().

Hopes this is proper way to go and would solve the problem until OpenSSL
chooses to change their interface again.

Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
---
 src/fssum.c | 23 +++++++++++++++++++++++
 src/md5.h   |  2 +-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/src/fssum.c b/src/fssum.c
index 3d97a70bf02f..390bfde02c7d 100644
--- a/src/fssum.c
+++ b/src/fssum.c
@@ -48,7 +48,11 @@ struct excludes {
 };
 
 typedef struct _sum {
+#ifdef HAVE_OPENSSL
+	EVP_MD_CTX	*ctx;
+#else
 	MD5_CTX 	md5;
+#endif
 	unsigned char	out[16];
 } sum_t;
 
@@ -175,19 +179,38 @@ alloc(size_t sz)
 void
 sum_init(sum_t *cs)
 {
+#ifdef HAVE_OPENSSL
+	cs->ctx = EVP_MD_CTX_new();
+	if (!cs->ctx) {
+		fprintf(stderr, "evp md ctx allocation failed\n");
+		exit(-1);
+	}
+	EVP_DigestInit(cs->ctx, EVP_md5());
+#else
 	MD5_Init(&cs->md5);
+#endif
 }
 
 void
 sum_fini(sum_t *cs)
 {
+#ifdef HAVE_OPENSSL
+	EVP_DigestFinal(cs->ctx, cs->out, NULL);
+	EVP_MD_CTX_free(cs->ctx);
+	cs->ctx = NULL;
+#else
 	MD5_Final(cs->out, &cs->md5);
+#endif
 }
 
 void
 sum_add(sum_t *cs, void *buf, int size)
 {
+#ifdef HAVE_OPENSSL
+	EVP_DigestUpdate(cs->ctx, buf, size);
+#else
 	MD5_Update(&cs->md5, buf, size);
+#endif
 }
 
 void
diff --git a/src/md5.h b/src/md5.h
index 2da44bf355a3..07c03ca304df 100644
--- a/src/md5.h
+++ b/src/md5.h
@@ -24,7 +24,7 @@
  */
 
 #ifdef HAVE_OPENSSL
-#include <openssl/md5.h>
+#include <openssl/evp.h>
 #elif !defined(_MD5_H)
 #define _MD5_H
 
-- 
2.35.0