[Bug-gnulib] sha.c merge from coreutils

[Paul Eggert]

I installed this:

2003-08-15  Jim Meyering  <address@hidden>

        * sha.c: Merge in some clean-up and optimization changes from glibc.
        * sha.c (sha_stream) [BLOCKSIZE]: Move definition to top of file.
        Ensure that it is a multiple of 64.
        Rearrange loop exit tests so as to avoid performing an
        additional fread after encountering an error or EOF.

Index: sha.c
===================================================================
RCS file: /cvsroot/gnulib/gnulib/lib/sha.c,v
retrieving revision 1.9
retrieving revision 1.10
diff -p -u -r1.9 -r1.10
--- sha.c       17 Nov 2001 13:29:42 -0000      1.9
+++ sha.c       16 Aug 2003 04:05:01 -0000      1.10
@@ -1,7 +1,7 @@
 /* sha.c - Functions to compute the SHA1 hash (message-digest) of files
    or blocks of memory.  Complies to the NIST specification FIPS-180-1.
 
-   Copyright (C) 2000, 2001 Scott G. Miller
+   Copyright (C) 2000, 2001, 2003 Scott G. Miller
 
    Credits:
       Robert Klep <address@hidden>  -- Expansion function fix
@@ -41,6 +41,13 @@
 # define SWAP(n) (n)
 #endif
 
+#define BLOCKSIZE 4096
+/* Ensure that BLOCKSIZE is a multiple of 64.  */
+#if BLOCKSIZE % 64 != 0
+/* FIXME-someday (soon?): use #error instead of this kludge.  */
+"invalid BLOCKSIZE"
+#endif
+
 /* This array contains the bytes used to pad the buffer to the next
    64-byte boundary.  (RFC 1321, 3.1: Step 1)  */
 static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ...  */ };
@@ -118,8 +125,6 @@ sha_finish_ctx (struct sha_ctx *ctx, voi
 int
 sha_stream (FILE *stream, void *resblock)
 {
-  /* Important: BLOCKSIZE must be a multiple of 64.  */
-#define BLOCKSIZE 4096
   struct sha_ctx ctx;
   char buffer[BLOCKSIZE + 72];
   size_t sum;
@@ -137,19 +142,31 @@ sha_stream (FILE *stream, void *resblock
       sum = 0;
 
       /* Read block.  Take care for partial reads.  */
-      do
+      while (1)
        {
          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))
+               return 1;
+             goto process_partial_block;
+           }
+
+         /* We've read at least one byte, so ignore errors.  But always
+            check for EOF, since feof may be true even though N > 0.
+            Otherwise, we could end up calling fread after EOF.  */
+         if (feof (stream))
+           goto process_partial_block;
        }
-      while (sum < BLOCKSIZE && n != 0);
-      if (n == 0 && ferror (stream))
-        return 1;
-
-      /* If end of file is reached, end the loop.  */
-      if (n == 0)
-       break;
 
       /* Process buffer with BLOCKSIZE bytes.  Note that
                        BLOCKSIZE % 64 == 0
@@ -157,7 +174,9 @@ sha_stream (FILE *stream, void *resblock
       sha_process_block (buffer, BLOCKSIZE, &ctx);
     }
 
-  /* Add the last bytes if necessary.  */
+ process_partial_block:;
+
+  /* Process any remaining bytes.  */
   if (sum > 0)
     sha_process_bytes (buffer, sum, &ctx);
 
@@ -198,13 +217,14 @@ sha_process_bytes (const void *buffer, s
       memcpy (&ctx->buffer[left_over], buffer, add);
       ctx->buflen += add;
 
-      if (left_over + add > 64)
+      if (ctx->buflen > 64)
        {
-         sha_process_block (ctx->buffer, (left_over + add) & ~63, ctx);
+         sha_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
+
+         ctx->buflen &= 63;
          /* The regions in the following copy operation cannot overlap.  */
          memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
-                 (left_over + add) & 63);
-         ctx->buflen = (left_over + add) & 63;
+                 ctx->buflen);
        }
 
       buffer = (const char *) buffer + add;
@@ -212,18 +232,46 @@ sha_process_bytes (const void *buffer, s
     }
 
   /* Process available complete blocks.  */
-  if (len > 64)
+  if (len >= 64)
     {
-      sha_process_block (buffer, len & ~63, ctx);
-      buffer = (const char *) buffer + (len & ~63);
-      len &= 63;
+#if !_STRING_ARCH_unaligned
+/* To check alignment gcc has an appropriate operator.  Other
+   compilers don't.  */
+# if __GNUC__ >= 2
+#  define UNALIGNED_P(p) (((md5_uintptr) p) % __alignof__ (md5_uint32) != 0)
+# else
+#  define UNALIGNED_P(p) (((md5_uintptr) p) % sizeof (md5_uint32) != 0)
+# endif
+      if (UNALIGNED_P (buffer))
+       while (len > 64)
+         {
+           sha_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
+           buffer = (const char *) buffer + 64;
+           len -= 64;
+         }
+      else
+#endif
+       {
+         sha_process_block (buffer, len & ~63, ctx);
+         buffer = (const char *) buffer + (len & ~63);
+         len &= 63;
+       }
     }
 
   /* Move remaining bytes in internal buffer.  */
   if (len > 0)
     {
-      memcpy (ctx->buffer, buffer, len);
-      ctx->buflen = len;
+      size_t left_over = ctx->buflen;
+
+      memcpy (&ctx->buffer[left_over], buffer, len);
+      left_over += len;
+      if (left_over >= 64)
+       {
+         sha_process_block (ctx->buffer, 64, ctx);
+         left_over -= 64;
+         memcpy (ctx->buffer, &ctx->buffer[64], left_over);
+       }
+      ctx->buflen = left_over;
     }
 }