Merge branch 'jk/no-looking-at-dotgit-outside-repo'

A small code cleanup.

* jk/no-looking-at-dotgit-outside-repo:
sha1_name: make wraparound of the index into ring-buffer explicit

diff --combined sha1_name.c
index 06409a38451971121e6cf6abd4a8af5bffd231c1,45aa26b3227b235fb918df93ae1da0d9accbdca2..73a915ff1b3278f08ef4f327a55fe61d238f720a
--- 1/sha1_name.c
--- 2/sha1_name.c
+++ b/sha1_name.c
@@@ -448,46 -448,10 +448,46 @@@ int for_each_abbrev(const char *prefix
        return ret;
  }
  
 +/*
 + * Return the slot of the most-significant bit set in "val". There are various
 + * ways to do this quickly with fls() or __builtin_clzl(), but speed is
 + * probably not a big deal here.
 + */
 +static unsigned msb(unsigned long val)
 +{
 +      unsigned r = 0;
 +      while (val >>= 1)
 +              r++;
 +      return r;
 +}
 +
  int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
  {
        int status, exists;
  
 +      if (len < 0) {
 +              unsigned long count = approximate_object_count();
 +              /*
 +               * Add one because the MSB only tells us the highest bit set,
 +               * not including the value of all the _other_ bits (so "15"
 +               * is only one off of 2^4, but the MSB is the 3rd bit.
 +               */
 +              len = msb(count) + 1;
 +              /*
 +               * We now know we have on the order of 2^len objects, which
 +               * expects a collision at 2^(len/2). But we also care about hex
 +               * chars, not bits, and there are 4 bits per hex. So all
 +               * together we need to divide by 2; but we also want to round
 +               * odd numbers up, hence adding one before dividing.
 +               */
 +              len = (len + 1) / 2;
 +              /*
 +               * For very small repos, we stick with our regular fallback.
 +               */
 +              if (len < FALLBACK_DEFAULT_ABBREV)
 +                      len = FALLBACK_DEFAULT_ABBREV;
 +      }
 +
        sha1_to_hex_r(hex, sha1);
        if (len == 40 || !len)
                return 40;
@@@ -510,7 -474,8 +510,8 @@@ const char *find_unique_abbrev(const un
  {
        static int bufno;
        static char hexbuffer[4][GIT_SHA1_HEXSZ + 1];
-       char *hex = hexbuffer[3 & ++bufno];
+       char *hex = hexbuffer[bufno];
+       bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
        find_unique_abbrev_r(hex, sha1, len);
        return hex;
  }