1 files changed, 145 insertions, 0 deletions
diff --git a/lib/sha256-stream.c b/lib/sha256-stream.c
new file mode 100644
index 0000000..c2e6398
--- /dev/null
+++ b/lib/sha256-stream.c
@@ -0,0 +1,145 @@
+/* sha256.c - Functions to compute SHA256 and SHA224 message digest of files or
+   memory blocks according to the NIST specification FIPS-180-2.
+
+   Copyright (C) 2005-2006, 2008-2022 Free Software Foundation, Inc.
+
+   This file is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Lesser General Public License as
+   published by the Free Software Foundation; either version 2.1 of the
+   License, or (at your option) any later version.
+
+   This file is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* Written by David Madore, considerably copypasting from
+   Scott G. Miller's sha1.c
+*/
+
+#include <config.h>
+
+/* Specification.  */
+#if HAVE_OPENSSL_SHA256
+# define GL_OPENSSL_INLINE _GL_EXTERN_INLINE
+#endif
+#include "sha256.h"
+
+#include <stdlib.h>
+
+#if USE_UNLOCKED_IO
+# include "unlocked-io.h"
+#endif
+
+#include "af_alg.h"
+
+#define BLOCKSIZE 32768
+#if BLOCKSIZE % 64 != 0
+# error "invalid BLOCKSIZE"
+#endif
+
+/* Compute message digest for bytes read from STREAM using algorithm ALG.
+   Write the message digest into RESBLOCK, which contains HASHLEN bytes.
+   The initial and finishing operations are INIT_CTX and FINISH_CTX.
+   Return zero if and only if successful.  */
+static int
+shaxxx_stream (FILE *stream, char const *alg, void *resblock,
+               ssize_t hashlen, void (*init_ctx) (struct sha256_ctx *),
+               void *(*finish_ctx) (struct sha256_ctx *, void *))
+{
+  switch (afalg_stream (stream, alg, resblock, hashlen))
+    {
+    case 0: return 0;
+    case -EIO: return 1;
+    }
+
+  char *buffer = malloc (BLOCKSIZE + 72);
+  if (!buffer)
+    return 1;
+
+  struct sha256_ctx ctx;
+  init_ctx (&ctx);
+  size_t sum;
+
+  /* Iterate over full file contents.  */
+  while (1)
+    {
+      /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
+         computation function processes the whole buffer so that with the
+         next round of the loop another block can be read.  */
+      size_t n;
+      sum = 0;
+
+      /* Read block.  Take care for partial reads.  */
+      while (1)
+        {
+          /* Either process a partial fread() from this loop,
+             or the fread() in afalg_stream may have gotten EOF.
+             We need to avoid a subsequent fread() as EOF may
+             not be sticky.  For details of such systems, see:
+             https://sourceware.org/bugzilla/show_bug.cgi?id=1190  */
+          if (feof (stream))
+            goto process_partial_block;
+
+          n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
+
+          sum += n;
+
+          if (sum == BLOCKSIZE)
+            break;
+
+          if (n == 0)
+            {
+              /* Check for the error flag IFF N == 0, so that we don't
+                 exit the loop after a partial read due to e.g., EAGAIN
+                 or EWOULDBLOCK.  */
+              if (ferror (stream))
+                {
+                  free (buffer);
+                  return 1;
+                }
+              goto process_partial_block;
+            }
+        }
+
+      /* Process buffer with BLOCKSIZE bytes.  Note that
+                        BLOCKSIZE % 64 == 0
+       */
+      sha256_process_block (buffer, BLOCKSIZE, &ctx);
+    }
+
+ process_partial_block:;
+
+  /* Process any remaining bytes.  */
+  if (sum > 0)
+    sha256_process_bytes (buffer, sum, &ctx);
+
+  /* Construct result in desired memory.  */
+  finish_ctx (&ctx, resblock);
+  free (buffer);
+  return 0;
+}
+
+int
+sha256_stream (FILE *stream, void *resblock)
+{
+  return shaxxx_stream (stream, "sha256", resblock, SHA256_DIGEST_SIZE,
+                        sha256_init_ctx, sha256_finish_ctx);
+}
+
+int
+sha224_stream (FILE *stream, void *resblock)
+{
+  return shaxxx_stream (stream, "sha224", resblock, SHA224_DIGEST_SIZE,
+                        sha224_init_ctx, sha224_finish_ctx);
+}
+
+/*
+ * Hey Emacs!
+ * Local Variables:
+ * coding: utf-8
+ * End:
+ */