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-rw-r--r--lib/sha256-stream.c145
1 files changed, 145 insertions, 0 deletions
diff --git a/lib/sha256-stream.c b/lib/sha256-stream.c
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+/* 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:
+ */