Rename module 'memxfrm' to 'amemxfrm'.

[gnulib.git] / lib / amemxfrm.c

diff --git a/lib/amemxfrm.c b/lib/amemxfrm.c
new file mode 100644 (file)
index 0000000..3823ce4
--- /dev/null
+++ b/lib/amemxfrm.c
@@ -0,0 +1,180 @@
+/* Locale dependent memory area transformation for comparison.
+   Copyright (C) 2009, 2010 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2009.
+
+   This program 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 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include "amemxfrm.h"
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+
+char *
+amemxfrm (char *s, size_t n, char *resultbuf, size_t *lengthp)
+{
+  /* Result accumulator.  */
+  char *result;
+  size_t length;
+  size_t allocated;
+
+  char orig_sentinel;
+
+  /* Initial memory allocation.  */
+  if (resultbuf != NULL && *lengthp > 0)
+    {
+      result = resultbuf;
+      allocated = *lengthp;
+    }
+  else
+    {
+      allocated = (n > 0 ? n : 1);
+      result = (char *) malloc (allocated);
+      if (result == NULL)
+        goto out_of_memory_2;
+    }
+  length = 0;
+
+  /* Add sentinel.byte.  */
+  orig_sentinel = s[n];
+  s[n] = '\0';
+
+  /* Iterate through S, transforming each NUL terminated segment.
+     Accumulate the resulting transformed segments in result, separated by
+     NULs.  */
+  {
+    const char *p_end = s + n + 1;
+    const char *p;
+
+    p = s;
+    for (;;)
+      {
+        /* Search next NUL byte.  */
+        size_t l = strlen (p);
+
+        for (;;)
+          {
+            size_t k;
+
+            /* A call to strxfrm costs about 20 times more than a call to
+               strdup of the result.  Therefore it is worth to try to avoid
+               calling strxfrm more than once on a given string, by making
+               enough room before calling strxfrm.
+               The size of the strxfrm result, k, is likely to be between
+               l and 3 * l.  */
+            if (3 * l >= allocated - length)
+              {
+                /* Grow the result buffer.  */
+                size_t new_allocated;
+                char *new_result;
+
+                new_allocated = length + 3 * l + 1;
+                if (new_allocated < 2 * allocated)
+                  new_allocated = 2 * allocated;
+                if (new_allocated < 64)
+                  new_allocated = 64;
+                if (result == resultbuf)
+                  new_result = (char *) malloc (new_allocated);
+                else
+                  new_result = (char *) realloc (result, new_allocated);
+                if (new_result != NULL)
+                  {
+                    allocated = new_allocated;
+                    result = new_result;
+                  }
+              }
+
+            errno = 0;
+            k = strxfrm (result + length, p, allocated - length);
+            if (errno != 0)
+              goto fail;
+            if (k >= allocated - length)
+              {
+                /* Grow the result buffer.  */
+                size_t new_allocated;
+                char *new_result;
+
+                new_allocated = length + k + 1;
+                if (new_allocated < 2 * allocated)
+                  new_allocated = 2 * allocated;
+                if (new_allocated < 64)
+                  new_allocated = 64;
+                if (result == resultbuf)
+                  new_result = (char *) malloc (new_allocated);
+                else
+                  new_result = (char *) realloc (result, new_allocated);
+                if (new_result == NULL)
+                  goto out_of_memory_1;
+                allocated = new_allocated;
+                result = new_result;
+              }
+            else
+              {
+                length += k;
+                break;
+              }
+          }
+
+        p = p + l + 1;
+        if (p == p_end)
+          break;
+        result[length] = '\0';
+        length++;
+      }
+  }
+
+  /* Shrink the allocated memory if possible.
+     It is not worth calling realloc when length + 1 == allocated; it would
+     save just one byte.  */
+  if (result != resultbuf && length + 1 < allocated)
+    {
+      if ((length > 0 ? length : 1) <= *lengthp)
+        {
+          memcpy (resultbuf, result, length);
+          free (result);
+          result = resultbuf;
+        }
+      else
+        {
+          char *memory = (char *) realloc (result, length > 0 ? length : 1);
+          if (memory != NULL)
+            result = memory;
+        }
+    }
+
+  s[n] = orig_sentinel;
+  *lengthp = length;
+  return result;
+
+ fail:
+  {
+    int saved_errno = errno;
+    if (result != resultbuf)
+      free (result);
+    s[n] = orig_sentinel;
+    errno = saved_errno;
+    return NULL;
+  }
+
+ out_of_memory_1:
+  if (result != resultbuf)
+    free (result);
+  s[n] = orig_sentinel;
+ out_of_memory_2:
+  errno = ENOMEM;
+  return NULL;
+}