Sync our copy of the timezone library with IANA release tzcode2016h.

This absorbs a fix for a symlink-manipulation bug in zic that was
introduced in 2016g.  It probably isn't interesting for our use-case,
but I'm not quite sure, so let's update while we're at it.

diff --git a/src/timezone/zic.c b/src/timezone/zic.c
index 3f714ef46cb980a300493ccc1ce3fd0364d0b8ae..d624b23a8eb84976edc3c200c1ea1dc2f30d1faa 100644 (file)
--- a/src/timezone/zic.c
+++ b/src/timezone/zic.c
@@ -789,6 +789,56 @@ namecheck(const char *name)
    return componentcheck(name, component, cp);
 }
 
+/*
+ * Create symlink contents suitable for symlinking FROM to TO, as a
+ * freshly allocated string.  FROM should be a relative file name, and
+ * is relative to the global variable DIRECTORY.  TO can be either
+ * relative or absolute.
+ */
+#ifdef HAVE_SYMLINK
+static char *
+relname(char const * from, char const * to)
+{
+   size_t      i,
+               taillen,
+               dotdotetcsize;
+   size_t      dir_len = 0,
+               dotdots = 0,
+               linksize = SIZE_MAX;
+   char const *f = from;
+   char       *result = NULL;
+
+   if (*to == '/')
+   {
+       /* Make F absolute too.  */
+       size_t      len = strlen(directory);
+       bool        needslash = len && directory[len - 1] != '/';
+
+       linksize = len + needslash + strlen(from) + 1;
+       f = result = emalloc(linksize);
+       strcpy(result, directory);
+       result[len] = '/';
+       strcpy(result + len + needslash, from);
+   }
+   for (i = 0; f[i] && f[i] == to[i]; i++)
+       if (f[i] == '/')
+           dir_len = i + 1;
+   for (; f[i]; i++)
+       dotdots += f[i] == '/' && f[i - 1] != '/';
+   taillen = i - dir_len;
+   dotdotetcsize = 3 * dotdots + taillen + 1;
+   if (dotdotetcsize <= linksize)
+   {
+       if (!result)
+           result = emalloc(dotdotetcsize);
+       for (i = 0; i < dotdots; i++)
+           memcpy(result + 3 * i, "../", 3);
+       memmove(result + 3 * dotdots, f + dir_len, taillen + 1);
+   }
+   return result;
+}
+#endif   /* HAVE_SYMLINK */
+
 static void
 dolink(char const * fromfield, char const * tofield, bool staysymlink)
 {
@@ -832,31 +882,17 @@ dolink(char const * fromfield, char const * tofield, bool staysymlink)
    if (link_errno != 0)
    {
 #ifdef HAVE_SYMLINK
-       const char *s = fromfield;
-       const char *t;
-       char       *p;
-       size_t      dotdots = 0;
-       char       *symlinkcontents;
-       int         symlink_errno;
+       bool        absolute = *fromfield == '/';
+       char       *linkalloc = absolute ? NULL : relname(fromfield, tofield);
+       char const *contents = absolute ? fromfield : linkalloc;
+       int         symlink_errno = symlink(contents, tofield) == 0 ? 0 : errno;
 
-       do
-           t = s;
-       while ((s = strchr(s, '/'))
-              && strncmp(fromfield, tofield, ++s - fromfield) == 0);
-
-       for (s = tofield + (t - fromfield); *s; s++)
-           dotdots += *s == '/';
-       symlinkcontents = emalloc(3 * dotdots + strlen(t) + 1);
-       for (p = symlinkcontents; dotdots-- != 0; p += 3)
-           memcpy(p, "../", 3);
-       strcpy(p, t);
-       symlink_errno = symlink(symlinkcontents, tofield) == 0 ? 0 : errno;
        if (symlink_errno == ENOENT && !todirs_made)
        {
            mkdirs(tofield, true);
-           symlink_errno = symlink(symlinkcontents, tofield) == 0 ? 0 : errno;
+           symlink_errno = symlink(contents, tofield) == 0 ? 0 : errno;
        }
-       free(symlinkcontents);
+       free(linkalloc);
        if (symlink_errno == 0)
        {
            if (link_errno != ENOTSUP)