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+
+/***************************************************************************
+ * charpool.cc -- Handles Nmap's "character pool" memory allocation        *
+ * system.                                                                 *
+ *                                                                         *
+ ***********************IMPORTANT NMAP LICENSE TERMS************************
+ *
+ * The Nmap Security Scanner is (C) 1996-2023 Nmap Software LLC ("The Nmap
+ * Project"). Nmap is also a registered trademark of the Nmap Project.
+ *
+ * This program is distributed under the terms of the Nmap Public Source
+ * License (NPSL). The exact license text applying to a particular Nmap
+ * release or source code control revision is contained in the LICENSE
+ * file distributed with that version of Nmap or source code control
+ * revision. More Nmap copyright/legal information is available from
+ * https://nmap.org/book/man-legal.html, and further information on the
+ * NPSL license itself can be found at https://nmap.org/npsl/ . This
+ * header summarizes some key points from the Nmap license, but is no
+ * substitute for the actual license text.
+ *
+ * Nmap is generally free for end users to download and use themselves,
+ * including commercial use. It is available from https://nmap.org.
+ *
+ * The Nmap license generally prohibits companies from using and
+ * redistributing Nmap in commercial products, but we sell a special Nmap
+ * OEM Edition with a more permissive license and special features for
+ * this purpose. See https://nmap.org/oem/
+ *
+ * If you have received a written Nmap license agreement or contract
+ * stating terms other than these (such as an Nmap OEM license), you may
+ * choose to use and redistribute Nmap under those terms instead.
+ *
+ * The official Nmap Windows builds include the Npcap software
+ * (https://npcap.com) for packet capture and transmission. It is under
+ * separate license terms which forbid redistribution without special
+ * permission. So the official Nmap Windows builds may not be redistributed
+ * without special permission (such as an Nmap OEM license).
+ *
+ * Source is provided to this software because we believe users have a
+ * right to know exactly what a program is going to do before they run it.
+ * This also allows you to audit the software for security holes.
+ *
+ * Source code also allows you to port Nmap to new platforms, fix bugs, and add
+ * new features. You are highly encouraged to submit your changes as a Github PR
+ * or by email to the dev@nmap.org mailing list for possible incorporation into
+ * the main distribution. Unless you specify otherwise, it is understood that
+ * you are offering us very broad rights to use your submissions as described in
+ * the Nmap Public Source License Contributor Agreement. This is important
+ * because we fund the project by selling licenses with various terms, and also
+ * because the inability to relicense code has caused devastating problems for
+ * other Free Software projects (such as KDE and NASM).
+ *
+ * The free version of Nmap 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. Warranties,
+ * indemnification and commercial support are all available through the
+ * Npcap OEM program--see https://nmap.org/oem/
+ *
+ ***************************************************************************/
+
+/* $Id$ */
+
+#include <stddef.h>
+#undef NDEBUG
+#include <assert.h>
+
+#include "nbase.h"
+
+/* Character pool memory allocation */
+#include "charpool.h"
+#include "nmap_error.h"
+
+static CharPool g_charpool (16384);
+
+const char *cp_strndup(const char *src, int len) {
+  return g_charpool.dup(src, len);
+}
+const char *cp_strdup(const char *src) {
+  return g_charpool.dup(src);
+}
+void cp_free(void) {
+  return g_charpool.clear();
+}
+
+class StrTable {
+  public:
+  StrTable() {
+    memset(table, 0, sizeof(table));
+    for (int i = 1; i <= CHAR_MAX; i++) {
+      table[i*2] = static_cast<char>(i);
+    }
+  }
+  const char *get(char c) { assert(c >= 0); return &table[c*2]; }
+  private:
+  char table[2*(CHAR_MAX + 1)];
+};
+static StrTable g_table;
+
+const char *cp_char2str(char c) {
+  return g_table.get(c);
+}
+
+CharPool::CharPool(size_t init_sz) {
+  assert(init_sz >= 256);
+  /* Create our char pool */
+  currentbucketsz = init_sz;
+  nexti = 0;
+  char *b = (char *) safe_malloc(currentbucketsz);
+  buckets.push_back(b);
+}
+
+void CharPool::clear(void) {
+  for (BucketList::iterator it=buckets.begin(); it != buckets.end(); it++) {
+    free(*it);
+  }
+  buckets.clear();
+}
+
+const char *CharPool::dup(const char *src, int len) {
+  if (len < 0)
+    len = strlen(src);
+  if (len == 0)
+    return g_table.get('\0');
+  else if (len == 1)
+    return g_table.get(*src);
+
+  int sz = len + 1;
+  char *p = buckets.back() + nexti;
+
+  while (nexti + sz > currentbucketsz) {
+    /* Doh!  We've got to make room */
+    currentbucketsz <<= 1;
+    nexti = 0;
+    p = (char *) safe_malloc(currentbucketsz);
+    buckets.push_back(p);
+  }
+
+  nexti += sz;
+  p[len] = '\0';
+  return (const char *) memcpy(p, src, len);
+}