Fix -Wcast-align compilation warnings on arm

Apparently, gcc is also not smart enough to infer the alignment
of structure fields, for details see
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89133

Use unions to avoid these casts altogether, this fixes compilation
warnings reported by gcc on arm, e.g.:

md5.c: In function 'MD5Update':
md5.c:92:35: error: cast increases required alignment of target type [-Werror=cast-align]
   92 |   MD5Name(MD5Transform)(ctx->buf, (uint32 *) ctx->in);
      |                                   ^
md5.c:101:35: error: cast increases required alignment of target type [-Werror=cast-align]
  101 |   MD5Name(MD5Transform)(ctx->buf, (uint32 *) ctx->in);
      |                                   ^
md5.c: In function 'MD5Final':
md5.c:136:35: error: cast increases required alignment of target type [-Werror=cast-align]
  136 |   MD5Name(MD5Transform)(ctx->buf, (uint32 *) ctx->in);
      |                                   ^
md5.c:147:9: error: cast increases required alignment of target type [-Werror=cast-align]
  147 |  memcpy((uint32 *)ctx->in + 14, ctx->bits, 2*sizeof(uint32));
      |         ^
md5.c:149:34: error: cast increases required alignment of target type [-Werror=cast-align]
  149 |  MD5Name(MD5Transform)(ctx->buf, (uint32 *) ctx->in);
      |                                  ^

* modules/pam_namespace/md5.h (struct MD5Context): Replace "buf" and
"in" fields with unions.  All users updated.
* modules/pam_unix/md5.h (struct MD5Context): Likewise.
* modules/pam_timestamp/sha1.h (struct sha1_context.pending): Replace
with a union.  All users updated.

Complements: v1.4.0~195 ("Fix most of clang -Wcast-align compilation warnings")

2 files changed, 14 insertions, 12 deletions

diff --git a/modules/pam_timestamp/sha1.c b/modules/pam_timestamp/sha1.c
index af3ccb97..d713aed1 100644
--- a/modules/pam_timestamp/sha1.c
+++ b/modules/pam_timestamp/sha1.c
@@ -156,8 +156,8 @@ sha1_update(struct sha1_context *ctx, const unsigned char *data, size_t length)
 	while (l + ctx->pending_count >= SHA1_BLOCK_SIZE) {
 		c = ctx->pending_count;
 		t = SHA1_BLOCK_SIZE - c;
-		memcpy(ctx->pending + c, &data[i], t);
-		sha1_process(ctx, (uint32_t*) ctx->pending);
+		memcpy(ctx->pending.c + c, &data[i], t);
+		sha1_process(ctx, ctx->pending.i);
 		i += t;
 		l -= t;
 		ctx->pending_count = 0;
@@ -165,7 +165,7 @@ sha1_update(struct sha1_context *ctx, const unsigned char *data, size_t length)
 
 	/* Save what's left of the data block as a pending data block. */
 	c = ctx->pending_count;
-	memcpy(ctx->pending + c, &data[i], l);
+	memcpy(ctx->pending.c + c, &data[i], l);
 	ctx->pending_count += l;
 
 	/* Update the message length. */
@@ -193,18 +193,17 @@ sha1_output(struct sha1_context *ctx, unsigned char *out)
 
 		/* Pad this block. */
 		c = ctx2.pending_count;
-		memcpy(ctx2.pending + c,
+		memcpy(ctx2.pending.c + c,
 		       padding, SHA1_BLOCK_SIZE - c);
 
 		/* Do we need to process two blocks now? */
 		if (c >= (SHA1_BLOCK_SIZE - (sizeof(uint32_t) * 2))) {
 			/* Process this block. */
-			sha1_process(&ctx2,
-				    (uint32_t*) ctx2.pending);
+			sha1_process(&ctx2, ctx2.pending.i);
 			/* Set up another block. */
 			ctx2.pending_count = 0;
-			memset(ctx2.pending, 0, SHA1_BLOCK_SIZE);
-                        ctx2.pending[0] =
+			memset(ctx2.pending.c, 0, SHA1_BLOCK_SIZE);
+                        ctx2.pending.c[0] =
 				(c == SHA1_BLOCK_SIZE) ? 0x80 : 0;
 		}
 
@@ -217,11 +216,11 @@ sha1_output(struct sha1_context *ctx, unsigned char *out)
 		ctx2.counts[0] <<= 3;
 		ctx2.counts[0] = htonl(ctx2.counts[0]);
 		ctx2.counts[1] = htonl(ctx2.counts[1]);
-		memcpy(ctx2.pending + 56,
+		memcpy(ctx2.pending.c + 56,
 		       &ctx2.counts[1], sizeof(uint32_t));
-		memcpy(ctx2.pending + 60,
+		memcpy(ctx2.pending.c + 60,
 		       &ctx2.counts[0], sizeof(uint32_t));
-		sha1_process(&ctx2, (uint32_t*) ctx2.pending);
+		sha1_process(&ctx2, ctx2.pending.i);
 
 		/* Output the data. */
 		out[ 3] = (ctx2.a >>  0) & 0xff;
diff --git a/modules/pam_timestamp/sha1.h b/modules/pam_timestamp/sha1.h
index a1c38917..69f432e6 100644
--- a/modules/pam_timestamp/sha1.h
+++ b/modules/pam_timestamp/sha1.h
@@ -46,7 +46,10 @@
 
 struct sha1_context {
 	size_t count;
-	unsigned char pending[SHA1_BLOCK_SIZE] PAM_ATTRIBUTE_ALIGNED(4);
+	union {
+		unsigned char c[SHA1_BLOCK_SIZE];
+		uint32_t i[SHA1_BLOCK_SIZE / sizeof(uint32_t)];
+	} pending;
 	uint32_t counts[2];
 	size_t pending_count;
 	uint32_t a, b, c, d, e;