[util] Add strndup and reentrant quicksort

Needed for portability.

include/compat.h

@@ -94,9 +94,26 @@ size_t strnlen (const char *str, size_t len);
 # define strnlen Q_strnlen
 # define need_qstring_h
 #endif
+#ifdef HAVE_STRNDUP
+# ifndef HAVE_STRNDUP_PROTO
+size_t strndup (const char *str, size_t len);
+# endif
+#else
+# define strndup Q_strndup
+# define need_qstring_h
+#endif
 
 #ifdef need_qstring_h
 # include "qstring.h"
 #endif
 
+#ifndef HAVE_QSORT_R
+# include "quicksort.h"
+# define qsort_r _quicksort
+#endif
+
+#ifndef HAVE_STRERROR_R
+#define strerror_r(err,buf,len) strerror_s (buf, len, err)
+#endif
+
 #endif // __compat_h

include/qstring.h

@@ -33,6 +33,7 @@
 
 const char * Q_strcasestr (const char *haystack, const char *needle) __attribute__((pure));
 size_t Q_strnlen (const char *s, size_t maxlen) __attribute__((pure));
+char *Q_strndup (const char *s, size_t maxlen);
 size_t Q_snprintfz (char *dest, size_t size, const char *fmt, ...) __attribute__((format(PRINTF,3,4)));
 size_t Q_vsnprintfz (char *dest, size_t size, const char *fmt, va_list argptr);
 

include/quicksort.h

@@ -0,0 +1,38 @@
+/*
+	quicksort.h
+
+	Reentrant qsort for systems that don't have it
+
+	Copyright (C) 2021 Bill Currie <bill@taniwha.org>
+
+	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 2
+	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, write to:
+
+		Free Software Foundation, Inc.
+		59 Temple Place - Suite 330
+		Boston, MA  02111-1307, USA
+
+*/
+
+#ifndef quicksort_h
+#define quicksort_h
+
+#include <sys/types.h>
+
+typedef int (*__compar_d_fn_t)(const void *, const void *, void *);
+
+void _quicksort(void *base, size_t nmemb, size_t size, __compar_d_fn_t cmp,
+				void *arg);
+
+#endif// quicksort_h

libs/util/Makemodule.am

@@ -68,6 +68,7 @@ libs_util_libQFutil_la_SOURCES= \
 	libs/util/plugin.c \
 	libs/util/qargs.c \
 	libs/util/qendian.c \
+	libs/util/qsort_r.c \
 	libs/util/quakefs.c \
 	libs/util/quakeio.c \
 	libs/util/riff.c \

libs/util/qsort_r.c

@@ -0,0 +1,250 @@
+/* Copyright (C) 1991-2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Written by Douglas C. Schmidt (schmidt@ics.uci.edu).
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* If you consider tuning this algorithm, you should consult first:
+   Engineering a sort function; Jon Bentley and M. Douglas McIlroy;
+   Software - Practice and Experience; Vol. 23 (11), 1249-1265, 1993.  */
+
+#include <limits.h>
+#include <string.h>
+
+#include "qfalloca.h"
+#include "quicksort.h"
+
+/* Byte-wise swap two items of size SIZE. */
+#define SWAP(a, b, size)						      \
+  do									      \
+    {									      \
+      size_t __size = (size);						      \
+      char *__a = (a), *__b = (b);					      \
+      do								      \
+	{								      \
+	  char __tmp = *__a;						      \
+	  *__a++ = *__b;						      \
+	  *__b++ = __tmp;						      \
+	} while (--__size > 0);						      \
+    } while (0)
+
+/* Discontinue quicksort algorithm when partition gets below this size.
+   This particular magic number was chosen to work best on a Sun 4/260. */
+#define MAX_THRESH 4
+
+/* Stack node declarations used to store unfulfilled partition obligations. */
+typedef struct
+  {
+    char *lo;
+    char *hi;
+  } stack_node;
+
+/* The next 4 #defines implement a very fast in-line stack abstraction. */
+/* The stack needs log (total_elements) entries (we could even subtract
+   log(MAX_THRESH)).  Since total_elements has type size_t, we get as
+   upper bound for log (total_elements):
+   bits per byte (CHAR_BIT) * sizeof(size_t).  */
+#define STACK_SIZE	(CHAR_BIT * sizeof(size_t))
+#define PUSH(low, high)	((void) ((top->lo = (low)), (top->hi = (high)), ++top))
+#define	POP(low, high)	((void) (--top, (low = top->lo), (high = top->hi)))
+#define	STACK_NOT_EMPTY	(stack < top)
+
+
+/* Order size using quicksort.  This implementation incorporates
+   four optimizations discussed in Sedgewick:
+
+   1. Non-recursive, using an explicit stack of pointer that store the
+      next array partition to sort.  To save time, this maximum amount
+      of space required to store an array of SIZE_MAX is allocated on the
+      stack.  Assuming a 32-bit (64 bit) integer for size_t, this needs
+      only 32 * sizeof(stack_node) == 256 bytes (for 64 bit: 1024 bytes).
+      Pretty cheap, actually.
+
+   2. Chose the pivot element using a median-of-three decision tree.
+      This reduces the probability of selecting a bad pivot value and
+      eliminates certain extraneous comparisons.
+
+   3. Only quicksorts TOTAL_ELEMS / MAX_THRESH partitions, leaving
+      insertion sort to order the MAX_THRESH items within each partition.
+      This is a big win, since insertion sort is faster for small, mostly
+      sorted array segments.
+
+   4. The larger of the two sub-partitions is always pushed onto the
+      stack first, with the algorithm then concentrating on the
+      smaller partition.  This *guarantees* no more than log (total_elems)
+      stack size is needed (actually O(1) in this case)!  */
+
+void
+_quicksort (void *const pbase, size_t total_elems, size_t size,
+	    __compar_d_fn_t cmp, void *arg)
+{
+  char *base_ptr = (char *) pbase;
+
+  const size_t max_thresh = MAX_THRESH * size;
+
+  if (total_elems == 0)
+    /* Avoid lossage with unsigned arithmetic below.  */
+    return;
+
+  if (total_elems > MAX_THRESH)
+    {
+      char *lo = base_ptr;
+      char *hi = &lo[size * (total_elems - 1)];
+      stack_node stack[STACK_SIZE];
+      stack_node *top = stack;
+
+      PUSH (NULL, NULL);
+
+      while (STACK_NOT_EMPTY)
+        {
+          char *left_ptr;
+          char *right_ptr;
+
+	  /* Select median value from among LO, MID, and HI. Rearrange
+	     LO and HI so the three values are sorted. This lowers the
+	     probability of picking a pathological pivot value and
+	     skips a comparison for both the LEFT_PTR and RIGHT_PTR in
+	     the while loops. */
+
+	  char *mid = lo + size * ((hi - lo) / size >> 1);
+
+	  if ((*cmp) ((void *) mid, (void *) lo, arg) < 0)
+	    SWAP (mid, lo, size);
+	  if ((*cmp) ((void *) hi, (void *) mid, arg) < 0)
+	    SWAP (mid, hi, size);
+	  else
+	    goto jump_over;
+	  if ((*cmp) ((void *) mid, (void *) lo, arg) < 0)
+	    SWAP (mid, lo, size);
+	jump_over:;
+
+	  left_ptr  = lo + size;
+	  right_ptr = hi - size;
+
+	  /* Here's the famous ``collapse the walls'' section of quicksort.
+	     Gotta like those tight inner loops!  They are the main reason
+	     that this algorithm runs much faster than others. */
+	  do
+	    {
+	      while ((*cmp) ((void *) left_ptr, (void *) mid, arg) < 0)
+		left_ptr += size;
+
+	      while ((*cmp) ((void *) mid, (void *) right_ptr, arg) < 0)
+		right_ptr -= size;
+
+	      if (left_ptr < right_ptr)
+		{
+		  SWAP (left_ptr, right_ptr, size);
+		  if (mid == left_ptr)
+		    mid = right_ptr;
+		  else if (mid == right_ptr)
+		    mid = left_ptr;
+		  left_ptr += size;
+		  right_ptr -= size;
+		}
+	      else if (left_ptr == right_ptr)
+		{
+		  left_ptr += size;
+		  right_ptr -= size;
+		  break;
+		}
+	    }
+	  while (left_ptr <= right_ptr);
+
+          /* Set up pointers for next iteration.  First determine whether
+             left and right partitions are below the threshold size.  If so,
+             ignore one or both.  Otherwise, push the larger partition's
+             bounds on the stack and continue sorting the smaller one. */
+
+          if ((size_t) (right_ptr - lo) <= max_thresh)
+            {
+              if ((size_t) (hi - left_ptr) <= max_thresh)
+		/* Ignore both small partitions. */
+                POP (lo, hi);
+              else
+		/* Ignore small left partition. */
+                lo = left_ptr;
+            }
+          else if ((size_t) (hi - left_ptr) <= max_thresh)
+	    /* Ignore small right partition. */
+            hi = right_ptr;
+          else if ((right_ptr - lo) > (hi - left_ptr))
+            {
+	      /* Push larger left partition indices. */
+              PUSH (lo, right_ptr);
+              lo = left_ptr;
+            }
+          else
+            {
+	      /* Push larger right partition indices. */
+              PUSH (left_ptr, hi);
+              hi = right_ptr;
+            }
+        }
+    }
+
+  /* Once the BASE_PTR array is partially sorted by quicksort the rest
+     is completely sorted using insertion sort, since this is efficient
+     for partitions below MAX_THRESH size. BASE_PTR points to the beginning
+     of the array to sort, and END_PTR points at the very last element in
+     the array (*not* one beyond it!). */
+
+#define min(x, y) ((x) < (y) ? (x) : (y))
+
+  {
+    char *const end_ptr = &base_ptr[size * (total_elems - 1)];
+    char *tmp_ptr = base_ptr;
+    char *thresh = min(end_ptr, base_ptr + max_thresh);
+    char *run_ptr;
+
+    /* Find smallest element in first threshold and place it at the
+       array's beginning.  This is the smallest array element,
+       and the operation speeds up insertion sort's inner loop. */
+
+    for (run_ptr = tmp_ptr + size; run_ptr <= thresh; run_ptr += size)
+      if ((*cmp) ((void *) run_ptr, (void *) tmp_ptr, arg) < 0)
+        tmp_ptr = run_ptr;
+
+    if (tmp_ptr != base_ptr)
+      SWAP (tmp_ptr, base_ptr, size);
+
+    /* Insertion sort, running from left-hand-side up to right-hand-side.  */
+
+    run_ptr = base_ptr + size;
+    while ((run_ptr += size) <= end_ptr)
+      {
+	tmp_ptr = run_ptr - size;
+	while ((*cmp) ((void *) run_ptr, (void *) tmp_ptr, arg) < 0)
+	  tmp_ptr -= size;
+
+	tmp_ptr += size;
+        if (tmp_ptr != run_ptr)
+          {
+            char *trav;
+
+	    trav = run_ptr + size;
+	    while (--trav >= run_ptr)
+              {
+                char c = *trav;
+                char *hi, *lo;
+
+                for (hi = lo = trav; (lo -= size) >= tmp_ptr; hi = lo)
+                  *hi = *lo;
+                *hi = c;
+              }
+          }
+      }
+  }
+}

libs/util/string.c

@@ -35,6 +35,7 @@
 # include <strings.h>
 #endif
 #include <stdio.h>
+#include <stdlib.h>
 
 #include "qstring.h"
 
@@ -72,6 +73,16 @@ Q_strnlen (const char *s, size_t maxlen)
 	return i;
 }
 
+char *
+Q_strndup (const char *s, size_t n)
+{
+	size_t l = strnlen (s, n);
+	char *str = malloc (l + 1);
+	strncpy (str, s, l);
+	str[l] = 0;
+	return str;
+}
+
 #if defined(HAVE__VSNPRINTF) && !defined(HAVE_VSNPRINTF)
 size_t
 Q_snprintfz (char *dest, size_t size, const char *fmt, ...)