1 files changed, 86 insertions, 0 deletions
diff --git a/lib/unistring/unistr/u8-check.c b/lib/unistring/unistr/u8-check.c
new file mode 100644
index 0000000..c1d69ee
--- /dev/null
+++ b/lib/unistring/unistr/u8-check.c
@@ -0,0 +1,86 @@
+/* Check UTF-8 string.
+   Copyright (C) 2002, 2006-2007, 2009-2021 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2002.
+
+   This program is free software: you can redistribute it and/or
+   modify it under the terms of either:
+
+     * 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.
+
+   or
+
+     * 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.
+
+   or both in parallel, as here.
+   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 <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include "unistr.h"
+
+const uint8_t *
+u8_check (const uint8_t *s, size_t n)
+{
+  const uint8_t *s_end = s + n;
+
+  while (s < s_end)
+    {
+      /* Keep in sync with unistr.h and u8-mbtouc-aux.c.  */
+      uint8_t c = *s;
+
+      if (c < 0x80)
+        {
+          s++;
+          continue;
+        }
+      if (c >= 0xc2)
+        {
+          if (c < 0xe0)
+            {
+              if (s + 2 <= s_end
+                  && (s[1] ^ 0x80) < 0x40)
+                {
+                  s += 2;
+                  continue;
+                }
+            }
+          else if (c < 0xf0)
+            {
+              if (s + 3 <= s_end
+                  && (s[1] ^ 0x80) < 0x40 && (s[2] ^ 0x80) < 0x40
+                  && (c >= 0xe1 || s[1] >= 0xa0)
+                  && (c != 0xed || s[1] < 0xa0))
+                {
+                  s += 3;
+                  continue;
+                }
+            }
+          else if (c < 0xf8)
+            {
+              if (s + 4 <= s_end
+                  && (s[1] ^ 0x80) < 0x40 && (s[2] ^ 0x80) < 0x40
+                  && (s[3] ^ 0x80) < 0x40
+                  && (c >= 0xf1 || s[1] >= 0x90)
+                  && (c < 0xf4 || (c == 0xf4 && s[1] < 0x90)))
+                {
+                  s += 4;
+                  continue;
+                }
+            }
+        }
+      /* invalid or incomplete multibyte character */
+      return s;
+    }
+  return NULL;
+}