Add the wcslcpy, wcslcat functions

These functions are about to be added to POSIX, under Austin Group
issue 986.

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

8 files changed, 335 insertions, 0 deletions

diff --git a/wcsmbs/Makefile b/wcsmbs/Makefile
index ea8ea7b3e6..d8512c8801 100644
--- a/wcsmbs/Makefile
+++ b/wcsmbs/Makefile
@@ -74,6 +74,8 @@ routines := \
   wcscpy \
   wcscspn \
   wcsdup \
+  wcslcat \
+  wcslcpy \
   wcslen \
   wcsmbsload \
   wcsncase \
@@ -155,6 +157,8 @@ tests := \
   tst-wchar-h \
   tst-wcpncpy \
   tst-wcrtomb \
+  tst-wcslcat \
+  tst-wcslcpy \
   tst-wcsnlen \
   tst-wcstod-nan-locale \
   tst-wcstod-nan-sign \
diff --git a/wcsmbs/Versions b/wcsmbs/Versions
index 2d9391348a..7bdfe43b4a 100644
--- a/wcsmbs/Versions
+++ b/wcsmbs/Versions
@@ -65,5 +65,7 @@ libc {
     __isoc23_vswscanf;
     __isoc23_vwscanf;
     __isoc23_wscanf;
+    wcslcat;
+    wcslcpy;
   }
 }
diff --git a/wcsmbs/bits/wchar2.h b/wcsmbs/bits/wchar2.h
index 8b41e6fbd6..9def8e9852 100644
--- a/wcsmbs/bits/wchar2.h
+++ b/wcsmbs/bits/wchar2.h
@@ -199,6 +199,45 @@ __NTH (wcsncat (wchar_t *__restrict __dest, const wchar_t *__restrict __src,
   return __wcsncat_alias (__dest, __src, __n);
 }
 
+#ifdef __USE_MISC
+extern size_t __wcslcpy_chk (wchar_t *__dest, const wchar_t *__src, size_t __n,
+			     size_t __destlen) __THROW;
+extern size_t __REDIRECT_NTH (__wcslcpy_alias,
+			      (wchar_t *__dest, const wchar_t *__src,
+			       size_t __n), wcslcpy);
+
+__fortify_function size_t
+__NTH (wcslcpy (wchar_t *__restrict __dest, const wchar_t *__restrict __src,
+		size_t __n))
+{
+  if (__glibc_objsize (__dest) != (size_t) -1
+      && (!__builtin_constant_p (__n
+				 > __glibc_objsize (__dest) / sizeof (wchar_t))
+	  || __n > __glibc_objsize (__dest) / sizeof (wchar_t)))
+    return __wcslcpy_chk (__dest, __src, __n,
+			  __glibc_objsize (__dest) / sizeof (wchar_t));
+  return __wcslcpy_alias (__dest, __src, __n);
+}
+
+extern size_t __wcslcat_chk (wchar_t *__dest, const wchar_t *__src, size_t __n,
+			     size_t __destlen) __THROW;
+extern size_t __REDIRECT_NTH (__wcslcat_alias,
+			      (wchar_t *__dest, const wchar_t *__src,
+			       size_t __n), wcslcat);
+
+__fortify_function size_t
+__NTH (wcslcat (wchar_t *__restrict __dest, const wchar_t *__restrict __src,
+		size_t __n))
+{
+  if (__glibc_objsize (__dest) != (size_t) -1
+      && (!__builtin_constant_p (__n > __glibc_objsize (__dest)
+				 / sizeof (wchar_t))
+	  || __n > __glibc_objsize (__dest) / sizeof (wchar_t)))
+    return __wcslcat_chk (__dest, __src, __n,
+			  __glibc_objsize (__dest) / sizeof (wchar_t));
+  return __wcslcat_alias (__dest, __src, __n);
+}
+#endif /* __USE_MISC */
 
 
 extern int __REDIRECT_NTH_LDBL (__swprintf_alias,
diff --git a/wcsmbs/tst-wcslcat.c b/wcsmbs/tst-wcslcat.c
new file mode 100644
index 0000000000..63c3a164b5
--- /dev/null
+++ b/wcsmbs/tst-wcslcat.c
@@ -0,0 +1,93 @@
+/* Test the wcslcat function.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <array_length.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+#include <wchar.h>
+
+static int
+do_test (void)
+{
+  struct {
+    wchar_t buf1[16];
+    wchar_t buf2[16];
+  } s;
+
+  /* Nothing is written to the destination if its size is 0.  */
+  wmemset (s.buf1, '@', array_length (s.buf1));
+  wmemset (s.buf2, '@', array_length (s.buf2));
+  TEST_COMPARE (wcslcat (s.buf1, L"", 0), 0);
+  TEST_COMPARE_BLOB (&s, sizeof (s), L"@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@", 128);
+  TEST_COMPARE (wcslcat (s.buf1, L"Hello!", 0), 6);
+  TEST_COMPARE_BLOB (&s, sizeof (s), L"@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@", 128);
+
+  /* No bytes are are modified in the target buffer if the source
+     string is short enough.  */
+  wmemset (s.buf1, '@', array_length (s.buf1));
+  wmemset (s.buf2, '@', array_length (s.buf2));
+  wcscpy (s.buf1, L"He");
+  TEST_COMPARE (wcslcat (s.buf1, L"llo!", array_length (s.buf1)), 6);
+  TEST_COMPARE_BLOB (&s, sizeof (s), L"Hello!\0@@@@@@@@@@@@@@@@@@@@@@@@@", 128);
+
+  /* A source string which fits exactly into the destination buffer is
+     not truncated.  */
+  wmemset (s.buf1, '@', array_length (s.buf1));
+  wmemset (s.buf2, '@', array_length (s.buf2));
+  wcscpy (s.buf1, L"H");
+  TEST_COMPARE (wcslcat (s.buf1, L"ello, world!!!", array_length (s.buf1)),
+                15);
+  TEST_COMPARE_BLOB (&s, sizeof (s),
+		     L"Hello, world!!!\0@@@@@@@@@@@@@@@@@@@@@@@@@", 128);
+
+  /* A source string one character longer than the destination buffer
+     is truncated by one character.  The total length is returned.  */
+  wmemset (s.buf1, '@', array_length (s.buf1));
+  wmemset (s.buf2, '@', array_length (s.buf2));
+  wcscpy (s.buf1, L"Hello");
+  TEST_COMPARE (wcslcat (s.buf1, L", world!!!!", array_length (s.buf1)), 16);
+  TEST_COMPARE_BLOB (&s, sizeof (s),
+		     L"Hello, world!!!\0@@@@@@@@@@@@@@@@@@@@@@@@@", 128);
+
+  /* An even longer source string is truncated as well, and the total
+     length is returned.  */
+  wmemset (s.buf1, '@', array_length (s.buf1));
+  wmemset (s.buf2, '@', array_length (s.buf2));
+  wcscpy (s.buf1, L"Hello,");
+  TEST_COMPARE (wcslcat (s.buf1, L" world!!!!!!!!", array_length (s.buf1)),
+                20);
+  TEST_COMPARE_BLOB (&s, sizeof (s),
+		     L"Hello, world!!!\0@@@@@@@@@@@@@@@@@@@@@@@@@", 128);
+
+  /* A destination string which is not NUL-terminated does not result
+     in any changes to the buffer.  */
+  wmemset (s.buf1, '$', array_length (s.buf1));
+  wmemset (s.buf2, '@', array_length (s.buf2));
+  TEST_COMPARE (wcslcat (s.buf1, L"", array_length (s.buf1)), 16);
+  TEST_COMPARE_BLOB (&s, sizeof (s), L"$$$$$$$$$$$$$$$$@@@@@@@@@@@@@@@@", 128);
+  TEST_COMPARE (wcslcat (s.buf1, L"Hello!", array_length (s.buf1)), 22);
+  TEST_COMPARE_BLOB (&s, sizeof (s), L"$$$$$$$$$$$$$$$$@@@@@@@@@@@@@@@@", 128);
+  TEST_COMPARE (wcslcat (s.buf1, L"Hello, world!!!!!!!!",
+                         array_length (s.buf1)), 36);
+  TEST_COMPARE_BLOB (&s, sizeof (s), L"$$$$$$$$$$$$$$$$@@@@@@@@@@@@@@@@", 128);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/wcsmbs/tst-wcslcpy.c b/wcsmbs/tst-wcslcpy.c
new file mode 100644
index 0000000000..8eaffbf0c4
--- /dev/null
+++ b/wcsmbs/tst-wcslcpy.c
@@ -0,0 +1,78 @@
+/* Test the wcslcpy function.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <array_length.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+#include <wchar.h>
+
+static int
+do_test (void)
+{
+  struct {
+    wchar_t buf1[16];
+    wchar_t buf2[16];
+  } s;
+
+  /* Nothing is written to the destination if its size is 0.  */
+  wmemset (s.buf1, '@', array_length (s.buf1));
+  wmemset (s.buf2, '@', array_length (s.buf2));
+  TEST_COMPARE (wcslcpy (s.buf1, L"Hello!", 0), 6);
+  TEST_COMPARE_BLOB (&s, sizeof (s), L"@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@", 128);
+
+  /* No bytes are are modified in the target buffer if the source
+     string is short enough.  */
+  wmemset (s.buf1, '@', array_length (s.buf1));
+  wmemset (s.buf2, '@', array_length (s.buf2));
+  TEST_COMPARE (wcslcpy (s.buf1, L"Hello!", array_length (s.buf1)), 6);
+  TEST_COMPARE_BLOB (&s, sizeof (s),
+                     L"Hello!\0@@@@@@@@@@@@@@@@@@@@@@@@@", 128);
+
+  /* A source string which fits exactly into the destination buffer is
+     not truncated.  */
+  wmemset (s.buf1, '@', array_length (s.buf1));
+  wmemset (s.buf2, '@', array_length (s.buf2));
+  TEST_COMPARE (wcslcpy (s.buf1, L"Hello, world!!!", array_length (s.buf1)),
+                15);
+  TEST_COMPARE_BLOB (&s, sizeof (s),
+                     L"Hello, world!!!\0@@@@@@@@@@@@@@@@@@@@@@@@@", 128);
+
+  /* A source string one character longer than the destination buffer
+     is truncated by one character.  The untruncated source length is
+     returned.  */
+  wmemset (s.buf1, '@', array_length (s.buf1));
+  wmemset (s.buf2, '@', array_length (s.buf2));
+  TEST_COMPARE (wcslcpy (s.buf1, L"Hello, world!!!!", array_length (s.buf1)),
+                16);
+  TEST_COMPARE_BLOB (&s, sizeof (s),
+                     L"Hello, world!!!\0@@@@@@@@@@@@@@@@@@@@@@@@@", 128);
+
+  /* An even longer source string is truncated as well, and the
+     original length is returned.  */
+  wmemset (s.buf1, '@', array_length (s.buf1));
+  wmemset (s.buf2, '@', array_length (s.buf2));
+  TEST_COMPARE (wcslcpy (s.buf1, L"Hello, world!!!!!!!!",
+                         array_length (s.buf1)), 20);
+  TEST_COMPARE_BLOB (&s, sizeof (s),
+                     L"Hello, world!!!\0@@@@@@@@@@@@@@@@@@@@@@@@@", 128);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/wcsmbs/wchar.h b/wcsmbs/wchar.h
index d16f2e6951..531b3c83c6 100644
--- a/wcsmbs/wchar.h
+++ b/wcsmbs/wchar.h
@@ -104,6 +104,19 @@ extern wchar_t *wcsncpy (wchar_t *__restrict __dest,
 			 const wchar_t *__restrict __src, size_t __n)
      __THROW __nonnull ((1, 2));
 
+#ifdef __USE_MISC
+/* Copy at most N - 1 characters from SRC to DEST.  */
+extern size_t wcslcpy (wchar_t *__restrict __dest,
+		       const wchar_t *__restrict __src, size_t __n)
+  __THROW __nonnull ((1, 2)) __attr_access ((__write_only__, 1, 3));
+
+/* Append SRC to DEST, possibly with truncation to keep the total size
+   below N.  */
+extern size_t wcslcat (wchar_t *__restrict __dest,
+		       const wchar_t *__restrict __src, size_t __n)
+  __THROW __nonnull ((1, 2))  __attr_access ((__read_write__, 1, 3));
+#endif
+
 /* Append SRC onto DEST.  */
 extern wchar_t *wcscat (wchar_t *__restrict __dest,
 			const wchar_t *__restrict __src)
diff --git a/wcsmbs/wcslcat.c b/wcsmbs/wcslcat.c
new file mode 100644
index 0000000000..3bac6a2aa0
--- /dev/null
+++ b/wcsmbs/wcslcat.c
@@ -0,0 +1,60 @@
+/* Append a null-terminated wide string to another, with length checking.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <stdint.h>
+#include <wchar.h>
+
+size_t
+__wcslcat (wchar_t *__restrict dest, const wchar_t *__restrict src,
+           size_t size)
+{
+  size_t src_length = __wcslen (src);
+
+  /* Our implementation strlcat supports dest == NULL if size == 0
+     (for consistency with snprintf and strlcpy), but wcsnlen does
+     not, so we have to cover this case explicitly.  */
+  if (size == 0)
+    return src_length;
+
+  size_t dest_length = __wcsnlen (dest, size);
+  if (dest_length != size)
+    {
+      /* Copy at most the remaining number of characters in the
+	 destination buffer.  Leave for the null terminator.  */
+      size_t to_copy = size - dest_length - 1;
+      /* But not more than what is available in the source string.  */
+      if (to_copy > src_length)
+	to_copy = src_length;
+
+      wchar_t *target = dest + dest_length;
+      __wmemcpy (target, src, to_copy);
+      target[to_copy] = '\0';
+    }
+
+  /* If the sum wraps around, we have more than SIZE_MAX + 2 bytes in
+     the two input strings (including both null terminators).  If each
+     byte in the address space can be assigned a unique size_t value
+     (which the static_assert checks), then by the pigeonhole
+     principle, the two input strings must overlap, which is
+     undefined.  */
+  _Static_assert (sizeof (uintptr_t) == sizeof (size_t),
+		  "theoretical maximum object size covers address space");
+  return dest_length + src_length;
+}
+libc_hidden_def (__wcslcat)
+weak_alias (__wcslcat, wcslcat)
diff --git a/wcsmbs/wcslcpy.c b/wcsmbs/wcslcpy.c
new file mode 100644
index 0000000000..a1b1f1b43f
--- /dev/null
+++ b/wcsmbs/wcslcpy.c
@@ -0,0 +1,46 @@
+/* Copy a null-terminated wide string to a fixed-size buffer.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   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/>.  */
+
+#include <wchar.h>
+
+size_t
+__wcslcpy (wchar_t *__restrict dest, const wchar_t *__restrict src, size_t size)
+{
+  size_t src_length = __wcslen (src);
+
+  if (__glibc_unlikely (src_length >= size))
+    {
+      if (size > 0)
+	{
+	  /* Copy the leading portion of the string.  The last
+	     character is subsequently overwritten with the null
+	     terminator, but the destination size is usually a
+	     multiple of a small power of two, so writing it twice
+	     should be more efficient than copying an odd number of
+	     character.  */
+	  __wmemcpy (dest, src, size);
+	  dest[size - 1] = '\0';
+	}
+    }
+  else
+    /* Copy the string and its terminating null character.  */
+    __wmemcpy (dest, src, src_length + 1);
+  return src_length;
+}
+libc_hidden_def (__wcslcpy)
+weak_alias (__wcslcpy, wcslcpy)