First cleanup pass over EVP_EncryptUpdate()

Use more sensible variable names in order to make the logic a bit easier
to follow. The variables may be renamed in a later pass. Unindent a block
that was squeezed too much to the right and make a few minor stylistic
tweaks.

ok jsing

diff --git a/lib/libcrypto/evp/evp_enc.c b/lib/libcrypto/evp/evp_enc.c
index edc15fd..47d062a 100644 (file)
--- a/lib/libcrypto/evp/evp_enc.c
+++ b/lib/libcrypto/evp/evp_enc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: evp_enc.c,v 1.61 2023/12/16 09:46:06 tb Exp $ */
+/* $OpenBSD: evp_enc.c,v 1.62 2023/12/16 15:22:40 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -296,7 +296,9 @@ int
 EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl,
     const unsigned char *in, int inl)
 {
-       int i, j, bl;
+       int block_size = ctx->cipher->block_size;
+       int block_mask = ctx->block_mask;
+       int buf_offset = ctx->buf_len;
        int len = 0, total_len = 0;
 
        *outl = 0;
@@ -310,49 +312,48 @@ EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl,
        if ((ctx->cipher->flags & EVP_CIPH_FLAG_CUSTOM_CIPHER) != 0)
                return evp_cipher(ctx, out, outl, in, inl);
 
-       if (ctx->buf_len == 0 && (inl & ctx->block_mask) == 0)
+       if (buf_offset == 0 && (inl & block_mask) == 0)
                return evp_cipher(ctx, out, outl, in, inl);
 
-       i = ctx->buf_len;
-       bl = ctx->cipher->block_size;
-       if ((size_t)bl > sizeof(ctx->buf)) {
+       /* XXX - check that block_size > buf_offset. */
+       if (block_size > sizeof(ctx->buf)) {
                EVPerror(EVP_R_BAD_BLOCK_LENGTH);
                return 0;
        }
-       if (i != 0) {
-               if (bl - i > inl) {
-                       memcpy(&(ctx->buf[i]), in, inl);
+
+       if (buf_offset != 0) {
+               int buf_avail;
+
+               if ((buf_avail = block_size - buf_offset) > inl) {
+                       memcpy(&ctx->buf[buf_offset], in, inl);
                        ctx->buf_len += inl;
                        return 1;
-               } else {
-                       j = bl - i;
+               }
 
-                       /*
-                        * Once we've processed the first j bytes from in, the
-                        * amount of data left that is a multiple of the block
-                        * length is (inl - j) & ~(bl - 1).  Ensure this plus
-                        * the block processed from ctx-buf doesn't overflow.
-                        */
-                       if (((inl - j) & ~(bl - 1)) > INT_MAX - bl) {
-                               EVPerror(EVP_R_TOO_LARGE);
-                               return 0;
-                       }
-                       memcpy(&(ctx->buf[i]), in, j);
+               /*
+                * Once the first buf_avail bytes from in are processed, the
+                * amount of data left that is a multiple of the block length is
+                * (inl - buf_avail) & ~block_mask.  Ensure that this plus the
+                * block processed from ctx->buf doesn't overflow.
+                */
+               if (((inl - buf_avail) & ~block_mask) > INT_MAX - block_size) {
+                       EVPerror(EVP_R_TOO_LARGE);
+                       return 0;
+               }
+               memcpy(&ctx->buf[buf_offset], in, buf_avail);
 
-                       len = 0;
-                       if (!evp_cipher(ctx, out, &len, ctx->buf, bl))
-                               return 0;
-                       total_len = len;
+               len = 0;
+               if (!evp_cipher(ctx, out, &len, ctx->buf, block_size))
+                       return 0;
+               total_len = len;
 
-                       inl -= j;
-                       in += j;
-                       out += len;
-               }
+               inl -= buf_avail;
+               in += buf_avail;
+               out += len;
        }
 
-       i = inl&(bl - 1);
-       inl -= i;
-       if (inl > 0) {
+       buf_offset = inl & block_mask;
+       if ((inl -= buf_offset) > 0) {
                if (INT_MAX - inl < total_len)
                        return 0;
                len = 0;
@@ -363,9 +364,9 @@ EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl,
                total_len += len;
        }
 
-       if (i != 0)
-               memcpy(ctx->buf, &(in[inl]), i);
-       ctx->buf_len = i;
+       if (buf_offset != 0)
+               memcpy(ctx->buf, &in[inl], buf_offset);
+       ctx->buf_len = buf_offset;
 
        *outl = total_len;