grep branch, master, updated. v3.7-5-g0687c51

[Paul Eggert]

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http://git.savannah.gnu.org/cgit/grep.git/commit/?id=0687c51c4792b997988c03a34a8b57717d9961cc


commit 0687c51c4792b997988c03a34a8b57717d9961cc
Author: Paul Eggert <eggert@cs.ucla.edu>
Date:   Tue Aug 17 13:58:13 2021 -0700

    grep: djb2 correction
    
    Problem reported by Alex Murray (bug#50093).
    * src/grep.c (hash_pattern): Use a nonzero initial value.

diff --git a/src/grep.c b/src/grep.c
index 271b6b9..7a33686 100644
--- a/src/grep.c
+++ b/src/grep.c
@@ -126,7 +126,15 @@ static Hash_table *pattern_table;
 static size_t _GL_ATTRIBUTE_PURE
 hash_pattern (void const *pat, size_t n_buckets)
 {
-  size_t h = 0;
+  /* This uses the djb2 algorithm, except starting with a larger prime
+     in place of djb2's 5381, if size_t is wide enough.  The primes
+     are taken from the primeth recurrence sequence
+     <https://oeis.org/A007097>.  h15, h32 and h64 are the largest
+     sequence members that fit into 15, 32 and 64 bits, respectively.
+     Since any H will do, hashing works correctly on oddball machines
+     where size_t has some other width.  */
+  uint_fast64_t h15 = 5381, h32 = 3657500101, h64 = 4123221751654370051;
+  size_t h = h64 <= SIZE_MAX ? h64 : h32 <= SIZE_MAX ? h32 : h15;
   intptr_t pat_offset = (intptr_t) pat - 1;
   unsigned char const *s = (unsigned char const *) pattern_array + pat_offset;
   for ( ; *s != '\n'; s++)

-----------------------------------------------------------------------

Summary of changes:
 src/grep.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)


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