Adding upstream version 8.32.upstream/8.32upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 385 insertions, 0 deletions

diff --git a/lib/mbsstr.c b/lib/mbsstr.c
new file mode 100644
index 0000000..d0b16e3
--- /dev/null
+++ b/lib/mbsstr.c
@@ -0,0 +1,385 @@
+/* Searching in a string.  -*- coding: utf-8 -*-
+   Copyright (C) 2005-2020 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2005.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <string.h>
+
+#include <stdbool.h>
+#include <stddef.h>  /* for NULL, in case a nonstandard string.h lacks it */
+#include <stdlib.h>
+
+#include "malloca.h"
+#include "mbuiter.h"
+
+/* Knuth-Morris-Pratt algorithm.  */
+#define UNIT unsigned char
+#define CANON_ELEMENT(c) c
+#include "str-kmp.h"
+
+/* Knuth-Morris-Pratt algorithm.
+   See https://en.wikipedia.org/wiki/Knuth-Morris-Pratt_algorithm
+   Return a boolean indicating success:
+   Return true and set *RESULTP if the search was completed.
+   Return false if it was aborted because not enough memory was available.  */
+static bool
+knuth_morris_pratt_multibyte (const char *haystack, const char *needle,
+                              const char **resultp)
+{
+  size_t m = mbslen (needle);
+  mbchar_t *needle_mbchars;
+  size_t *table;
+
+  /* Allocate room for needle_mbchars and the table.  */
+  void *memory = nmalloca (m, sizeof (mbchar_t) + sizeof (size_t));
+  void *table_memory;
+  if (memory == NULL)
+    return false;
+  needle_mbchars = memory;
+  table_memory = needle_mbchars + m;
+  table = table_memory;
+
+  /* Fill needle_mbchars.  */
+  {
+    mbui_iterator_t iter;
+    size_t j;
+
+    j = 0;
+    for (mbui_init (iter, needle); mbui_avail (iter); mbui_advance (iter), j++)
+      mb_copy (&needle_mbchars[j], &mbui_cur (iter));
+  }
+
+  /* Fill the table.
+     For 0 < i < m:
+       0 < table[i] <= i is defined such that
+       forall 0 < x < table[i]: needle[x..i-1] != needle[0..i-1-x],
+       and table[i] is as large as possible with this property.
+     This implies:
+     1) For 0 < i < m:
+          If table[i] < i,
+          needle[table[i]..i-1] = needle[0..i-1-table[i]].
+     2) For 0 < i < m:
+          rhaystack[0..i-1] == needle[0..i-1]
+          and exists h, i <= h < m: rhaystack[h] != needle[h]
+          implies
+          forall 0 <= x < table[i]: rhaystack[x..x+m-1] != needle[0..m-1].
+     table[0] remains uninitialized.  */
+  {
+    size_t i, j;
+
+    /* i = 1: Nothing to verify for x = 0.  */
+    table[1] = 1;
+    j = 0;
+
+    for (i = 2; i < m; i++)
+      {
+        /* Here: j = i-1 - table[i-1].
+           The inequality needle[x..i-1] != needle[0..i-1-x] is known to hold
+           for x < table[i-1], by induction.
+           Furthermore, if j>0: needle[i-1-j..i-2] = needle[0..j-1].  */
+        mbchar_t *b = &needle_mbchars[i - 1];
+
+        for (;;)
+          {
+            /* Invariants: The inequality needle[x..i-1] != needle[0..i-1-x]
+               is known to hold for x < i-1-j.
+               Furthermore, if j>0: needle[i-1-j..i-2] = needle[0..j-1].  */
+            if (mb_equal (*b, needle_mbchars[j]))
+              {
+                /* Set table[i] := i-1-j.  */
+                table[i] = i - ++j;
+                break;
+              }
+            /* The inequality needle[x..i-1] != needle[0..i-1-x] also holds
+               for x = i-1-j, because
+                 needle[i-1] != needle[j] = needle[i-1-x].  */
+            if (j == 0)
+              {
+                /* The inequality holds for all possible x.  */
+                table[i] = i;
+                break;
+              }
+            /* The inequality needle[x..i-1] != needle[0..i-1-x] also holds
+               for i-1-j < x < i-1-j+table[j], because for these x:
+                 needle[x..i-2]
+                 = needle[x-(i-1-j)..j-1]
+                 != needle[0..j-1-(x-(i-1-j))]  (by definition of table[j])
+                    = needle[0..i-2-x],
+               hence needle[x..i-1] != needle[0..i-1-x].
+               Furthermore
+                 needle[i-1-j+table[j]..i-2]
+                 = needle[table[j]..j-1]
+                 = needle[0..j-1-table[j]]  (by definition of table[j]).  */
+            j = j - table[j];
+          }
+        /* Here: j = i - table[i].  */
+      }
+  }
+
+  /* Search, using the table to accelerate the processing.  */
+  {
+    size_t j;
+    mbui_iterator_t rhaystack;
+    mbui_iterator_t phaystack;
+
+    *resultp = NULL;
+    j = 0;
+    mbui_init (rhaystack, haystack);
+    mbui_init (phaystack, haystack);
+    /* Invariant: phaystack = rhaystack + j.  */
+    while (mbui_avail (phaystack))
+      if (mb_equal (needle_mbchars[j], mbui_cur (phaystack)))
+        {
+          j++;
+          mbui_advance (phaystack);
+          if (j == m)
+            {
+              /* The entire needle has been found.  */
+              *resultp = mbui_cur_ptr (rhaystack);
+              break;
+            }
+        }
+      else if (j > 0)
+        {
+          /* Found a match of needle[0..j-1], mismatch at needle[j].  */
+          size_t count = table[j];
+          j -= count;
+          for (; count > 0; count--)
+            {
+              if (!mbui_avail (rhaystack))
+                abort ();
+              mbui_advance (rhaystack);
+            }
+        }
+      else
+        {
+          /* Found a mismatch at needle[0] already.  */
+          if (!mbui_avail (rhaystack))
+            abort ();
+          mbui_advance (rhaystack);
+          mbui_advance (phaystack);
+        }
+  }
+
+  freea (memory);
+  return true;
+}
+
+/* Find the first occurrence of the character string NEEDLE in the character
+   string HAYSTACK.  Return NULL if NEEDLE is not found in HAYSTACK.  */
+char *
+mbsstr (const char *haystack, const char *needle)
+{
+  /* Be careful not to look at the entire extent of haystack or needle
+     until needed.  This is useful because of these two cases:
+       - haystack may be very long, and a match of needle found early,
+       - needle may be very long, and not even a short initial segment of
+         needle may be found in haystack.  */
+  if (MB_CUR_MAX > 1)
+    {
+      mbui_iterator_t iter_needle;
+
+      mbui_init (iter_needle, needle);
+      if (mbui_avail (iter_needle))
+        {
+          /* Minimizing the worst-case complexity:
+             Let n = mbslen(haystack), m = mbslen(needle).
+             The naïve algorithm is O(n*m) worst-case.
+             The Knuth-Morris-Pratt algorithm is O(n) worst-case but it needs a
+             memory allocation.
+             To achieve linear complexity and yet amortize the cost of the
+             memory allocation, we activate the Knuth-Morris-Pratt algorithm
+             only once the naïve algorithm has already run for some time; more
+             precisely, when
+               - the outer loop count is >= 10,
+               - the average number of comparisons per outer loop is >= 5,
+               - the total number of comparisons is >= m.
+             But we try it only once.  If the memory allocation attempt failed,
+             we don't retry it.  */
+          bool try_kmp = true;
+          size_t outer_loop_count = 0;
+          size_t comparison_count = 0;
+          size_t last_ccount = 0;                  /* last comparison count */
+          mbui_iterator_t iter_needle_last_ccount; /* = needle + last_ccount */
+
+          mbui_iterator_t iter_haystack;
+
+          mbui_init (iter_needle_last_ccount, needle);
+          mbui_init (iter_haystack, haystack);
+          for (;; mbui_advance (iter_haystack))
+            {
+              if (!mbui_avail (iter_haystack))
+                /* No match.  */
+                return NULL;
+
+              /* See whether it's advisable to use an asymptotically faster
+                 algorithm.  */
+              if (try_kmp
+                  && outer_loop_count >= 10
+                  && comparison_count >= 5 * outer_loop_count)
+                {
+                  /* See if needle + comparison_count now reaches the end of
+                     needle.  */
+                  size_t count = comparison_count - last_ccount;
+                  for (;
+                       count > 0 && mbui_avail (iter_needle_last_ccount);
+                       count--)
+                    mbui_advance (iter_needle_last_ccount);
+                  last_ccount = comparison_count;
+                  if (!mbui_avail (iter_needle_last_ccount))
+                    {
+                      /* Try the Knuth-Morris-Pratt algorithm.  */
+                      const char *result;
+                      bool success =
+                        knuth_morris_pratt_multibyte (haystack, needle,
+                                                      &result);
+                      if (success)
+                        return (char *) result;
+                      try_kmp = false;
+                    }
+                }
+
+              outer_loop_count++;
+              comparison_count++;
+              if (mb_equal (mbui_cur (iter_haystack), mbui_cur (iter_needle)))
+                /* The first character matches.  */
+                {
+                  mbui_iterator_t rhaystack;
+                  mbui_iterator_t rneedle;
+
+                  memcpy (&rhaystack, &iter_haystack, sizeof (mbui_iterator_t));
+                  mbui_advance (rhaystack);
+
+                  mbui_init (rneedle, needle);
+                  if (!mbui_avail (rneedle))
+                    abort ();
+                  mbui_advance (rneedle);
+
+                  for (;; mbui_advance (rhaystack), mbui_advance (rneedle))
+                    {
+                      if (!mbui_avail (rneedle))
+                        /* Found a match.  */
+                        return (char *) mbui_cur_ptr (iter_haystack);
+                      if (!mbui_avail (rhaystack))
+                        /* No match.  */
+                        return NULL;
+                      comparison_count++;
+                      if (!mb_equal (mbui_cur (rhaystack), mbui_cur (rneedle)))
+                        /* Nothing in this round.  */
+                        break;
+                    }
+                }
+            }
+        }
+      else
+        return (char *) haystack;
+    }
+  else
+    {
+      if (*needle != '\0')
+        {
+          /* Minimizing the worst-case complexity:
+             Let n = strlen(haystack), m = strlen(needle).
+             The naïve algorithm is O(n*m) worst-case.
+             The Knuth-Morris-Pratt algorithm is O(n) worst-case but it needs a
+             memory allocation.
+             To achieve linear complexity and yet amortize the cost of the
+             memory allocation, we activate the Knuth-Morris-Pratt algorithm
+             only once the naïve algorithm has already run for some time; more
+             precisely, when
+               - the outer loop count is >= 10,
+               - the average number of comparisons per outer loop is >= 5,
+               - the total number of comparisons is >= m.
+             But we try it only once.  If the memory allocation attempt failed,
+             we don't retry it.  */
+          bool try_kmp = true;
+          size_t outer_loop_count = 0;
+          size_t comparison_count = 0;
+          size_t last_ccount = 0;                  /* last comparison count */
+          const char *needle_last_ccount = needle; /* = needle + last_ccount */
+
+          /* Speed up the following searches of needle by caching its first
+             character.  */
+          char b = *needle++;
+
+          for (;; haystack++)
+            {
+              if (*haystack == '\0')
+                /* No match.  */
+                return NULL;
+
+              /* See whether it's advisable to use an asymptotically faster
+                 algorithm.  */
+              if (try_kmp
+                  && outer_loop_count >= 10
+                  && comparison_count >= 5 * outer_loop_count)
+                {
+                  /* See if needle + comparison_count now reaches the end of
+                     needle.  */
+                  if (needle_last_ccount != NULL)
+                    {
+                      needle_last_ccount +=
+                        strnlen (needle_last_ccount,
+                                 comparison_count - last_ccount);
+                      if (*needle_last_ccount == '\0')
+                        needle_last_ccount = NULL;
+                      last_ccount = comparison_count;
+                    }
+                  if (needle_last_ccount == NULL)
+                    {
+                      /* Try the Knuth-Morris-Pratt algorithm.  */
+                      const unsigned char *result;
+                      bool success =
+                        knuth_morris_pratt ((const unsigned char *) haystack,
+                                            (const unsigned char *) (needle - 1),
+                                            strlen (needle - 1),
+                                            &result);
+                      if (success)
+                        return (char *) result;
+                      try_kmp = false;
+                    }
+                }
+
+              outer_loop_count++;
+              comparison_count++;
+              if (*haystack == b)
+                /* The first character matches.  */
+                {
+                  const char *rhaystack = haystack + 1;
+                  const char *rneedle = needle;
+
+                  for (;; rhaystack++, rneedle++)
+                    {
+                      if (*rneedle == '\0')
+                        /* Found a match.  */
+                        return (char *) haystack;
+                      if (*rhaystack == '\0')
+                        /* No match.  */
+                        return NULL;
+                      comparison_count++;
+                      if (*rhaystack != *rneedle)
+                        /* Nothing in this round.  */
+                        break;
+                    }
+                }
+            }
+        }
+      else
+        return (char *) haystack;
+    }
+}