New module 'strncat'.

ChangeLog

@@ -1,3 +1,20 @@
+2010-04-05  Bruno Haible  <bruno@clisp.org>
+
+	New module 'strncat'.
+	* lib/string.in.h (strncat): New declaration.
+	* lib/strncat.c: New file, based on lib/unistr/u-strncat.h.
+	* m4/strncat.m4: New file, based on m4/memchr.m4.
+	* modules/strncat: New file.
+	* m4/string_h.m4 (gl_HEADER_STRING_H_BODY): Also check whether strncat
+	is declared.
+	(gl_HEADER_STRING_H_DEFAULTS): Initialize GNULIB_STRNCAT,
+	REPLACE_STRNCAT.
+	* modules/string (Makefile.am): Substitute GNULIB_STRNCAT,
+	REPLACE_STRNCAT.
+	* doc/posix-functions/strncat.texi: Mention the Solaris bug and the new
+	module.
+	* tests/test-string-c++.cc: Check signature of strncat.
+
 2010-04-05  Jim Meyering  <meyering@redhat.com>
 
 	xstrtoumax-tests: convert to use init.sh

doc/posix-functions/strncat.texi

@@ -4,10 +4,13 @@
 
 POSIX specification: @url{http://www.opengroup.org/onlinepubs/9699919799/functions/strncat.html}
 
-Gnulib module: ---
+Gnulib module: strncat
 
 Portability problems fixed by Gnulib:
 @itemize
+@item
+This function dereferences too much memory on some platforms:
+Solaris 10 on SPARC.
 @end itemize
 
 Portability problems not fixed by Gnulib:

lib/string.in.h

@@ -320,6 +320,28 @@ _GL_WARN_ON_USE (strdup, "strdup is unportable - "
 # endif
 #endif
 
+/* Append no more than N characters from SRC onto DEST.  */
+#if @GNULIB_STRNCAT@
+# if @REPLACE_STRNCAT@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef strncat
+#   define strncat rpl_strncat
+#  endif
+_GL_FUNCDECL_RPL (strncat, char *, (char *dest, const char *src, size_t n)
+                                   _GL_ARG_NONNULL ((1, 2)));
+_GL_CXXALIAS_RPL (strncat, char *, (char *dest, const char *src, size_t n));
+# else
+_GL_CXXALIAS_SYS (strncat, char *, (char *dest, const char *src, size_t n));
+# endif
+_GL_CXXALIASWARN (strncat);
+#elif defined GNULIB_POSIXCHECK
+# undef strncat
+# if HAVE_RAW_DECL_STRNCAT
+_GL_WARN_ON_USE (strncat, "strncat is unportable - "
+                 "use gnulib module strncat for portability");
+# endif
+#endif
+
 /* Return a newly allocated copy of at most N bytes of STRING.  */
 #if @GNULIB_STRNDUP@
 # if @REPLACE_STRNDUP@

lib/strncat.c

@@ -0,0 +1,33 @@
+/* Concatenate strings.
+   Copyright (C) 1999, 2002, 2006, 2010 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 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 <string.h>
+
+char *
+strncat (char *dest, const char *src, size_t n)
+{
+  char *destptr = dest + strlen (dest);
+
+  for (; n > 0 && (*destptr = *src) != '\0'; src++, destptr++, n--)
+    ;
+  if (n == 0)
+    *destptr = '\0';
+  return dest;
+}

m4/string_h.m4

@@ -5,7 +5,7 @@
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
 
-# serial 15
+# serial 16
 
 # Written by Paul Eggert.
 
@@ -26,8 +26,10 @@ AC_DEFUN([gl_HEADER_STRING_H_BODY],
   dnl corresponding gnulib module is not in use, and which is not
   dnl guaranteed by C89.
   gl_WARN_ON_USE_PREPARE([[#include <string.h>
-    ]], [memmem mempcpy memrchr rawmemchr stpcpy stpncpy strchrnul strdup
+    ]],
-    strndup strnlen strpbrk strsep strcasestr strtok_r strsignal strverscmp])
+    [memmem mempcpy memrchr rawmemchr stpcpy stpncpy strchrnul strdup
+     strncat strndup strnlen strpbrk strsep strcasestr strtok_r strsignal
+     strverscmp])
 ])
 
 AC_DEFUN([gl_STRING_MODULE_INDICATOR],
@@ -50,6 +52,7 @@ AC_DEFUN([gl_HEADER_STRING_H_DEFAULTS],
   GNULIB_STPNCPY=0;     AC_SUBST([GNULIB_STPNCPY])
   GNULIB_STRCHRNUL=0;   AC_SUBST([GNULIB_STRCHRNUL])
   GNULIB_STRDUP=0;      AC_SUBST([GNULIB_STRDUP])
+  GNULIB_STRNCAT=0;     AC_SUBST([GNULIB_STRNCAT])
   GNULIB_STRNDUP=0;     AC_SUBST([GNULIB_STRNDUP])
   GNULIB_STRNLEN=0;     AC_SUBST([GNULIB_STRNLEN])
   GNULIB_STRPBRK=0;     AC_SUBST([GNULIB_STRPBRK])
@@ -100,6 +103,7 @@ AC_DEFUN([gl_HEADER_STRING_H_DEFAULTS],
   REPLACE_STRSTR=0;             AC_SUBST([REPLACE_STRSTR])
   REPLACE_STRCASESTR=0;         AC_SUBST([REPLACE_STRCASESTR])
   REPLACE_STRERROR=0;           AC_SUBST([REPLACE_STRERROR])
+  REPLACE_STRNCAT=0;            AC_SUBST([REPLACE_STRNCAT])
   REPLACE_STRNDUP=0;            AC_SUBST([REPLACE_STRNDUP])
   REPLACE_STRSIGNAL=0;          AC_SUBST([REPLACE_STRSIGNAL])
   REPLACE_STRTOK_R=0;           AC_SUBST([REPLACE_STRTOK_R])

m4/strncat.m4

@@ -0,0 +1,106 @@
+# strncat.m4 serial 1
+dnl Copyright (C) 2002-2004, 2009-2010 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN_ONCE([gl_FUNC_STRNCAT],
+[
+  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+
+  dnl Check for prerequisites for memory fence checks.
+  gl_FUNC_MMAP_ANON
+  AC_CHECK_HEADERS_ONCE([sys/mman.h])
+  AC_CHECK_FUNCS_ONCE([mprotect])
+
+  dnl Detect bug in Solaris 8..10 on SPARC:
+  dnl strncat should not dereference more than n bytes, but always dereferences
+  dnl n+1 bytes if the first n bytes don't contain a NUL byte.
+  dnl Assume that strncat works on platforms that lack mprotect.
+  AC_CACHE_CHECK([whether strncat works], [gl_cv_func_strncat_works],
+    [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+#include <string.h>
+#if HAVE_SYS_MMAN_H
+# include <fcntl.h>
+# include <unistd.h>
+# include <sys/types.h>
+# include <sys/mman.h>
+# ifndef MAP_FILE
+#  define MAP_FILE 0
+# endif
+#endif
+]], [[
+  char *fence = NULL;
+#if HAVE_SYS_MMAN_H && HAVE_MPROTECT
+# if HAVE_MAP_ANONYMOUS
+  const int flags = MAP_ANONYMOUS | MAP_PRIVATE;
+  const int fd = -1;
+# else /* !HAVE_MAP_ANONYMOUS */
+  const int flags = MAP_FILE | MAP_PRIVATE;
+  int fd = open ("/dev/zero", O_RDONLY, 0666);
+  if (fd >= 0)
+# endif
+    {
+      int pagesize = getpagesize ();
+      char *two_pages =
+        (char *) mmap (NULL, 2 * pagesize, PROT_READ | PROT_WRITE,
+                       flags, fd, 0);
+      if (two_pages != (char *)(-1)
+          && mprotect (two_pages + pagesize, pagesize, PROT_NONE) == 0)
+        fence = two_pages + pagesize;
+    }
+#endif
+  if (fence)
+    {
+      char dest[8];
+
+      dest[0] = '*';
+      dest[1] = 'a';
+      dest[2] = '\0';
+      dest[3] = 'w';
+      dest[4] = 'x';
+      dest[5] = 'y';
+      dest[6] = 'z';
+
+      *(fence - 3) = '7';
+      *(fence - 2) = '2';
+      *(fence - 1) = '9';
+
+      if (strncat (dest + 1, fence - 3, 3) != dest + 1)
+        return 1;
+      if (dest[0] != '*')
+        return 2;
+      if (dest[1] != 'a'
+          || dest[2] != '7' || dest[3] != '2' || dest[4] != '9'
+          || dest[5] != '\0')
+        return 3;
+      if (dest[6] != 'z')
+        return 4;
+    }
+  return 0;
+]])], [gl_cv_func_strncat_works=yes], [gl_cv_func_strncat_works=no],
+       [
+        case "$host_os" in
+                    # Guess no on Solaris.
+          solaris*) gl_cv_func_strncat_works="guessing no";;
+                    # Guess yes otherwise.
+          *)        gl_cv_func_strncat_works="guessing yes";;
+        esac
+       ])
+    ])
+  case "$gl_cv_func_strncat_works" in
+    *yes) ;;
+    *)
+      REPLACE_STRNCAT=1
+      AC_LIBOBJ([strncat])
+      gl_PREREQ_STRNCAT
+      ;;
+  esac
+])
+
+# Prerequisites of lib/strncat.c.
+AC_DEFUN([gl_PREREQ_STRNCAT], [
+  :
+])

modules/string

@@ -50,6 +50,7 @@ string.h: string.in.h $(CXXDEFS_H) $(ARG_NONNULL_H) $(WARN_ON_USE_H)
 	      -e 's|@''GNULIB_STPNCPY''@|$(GNULIB_STPNCPY)|g' \
 	      -e 's|@''GNULIB_STRCHRNUL''@|$(GNULIB_STRCHRNUL)|g' \
 	      -e 's|@''GNULIB_STRDUP''@|$(GNULIB_STRDUP)|g' \
+	      -e 's|@''GNULIB_STRNCAT''@|$(GNULIB_STRNCAT)|g' \
 	      -e 's|@''GNULIB_STRNDUP''@|$(GNULIB_STRNDUP)|g' \
 	      -e 's|@''GNULIB_STRNLEN''@|$(GNULIB_STRNLEN)|g' \
 	      -e 's|@''GNULIB_STRPBRK''@|$(GNULIB_STRPBRK)|g' \
@@ -86,6 +87,7 @@ string.h: string.in.h $(CXXDEFS_H) $(ARG_NONNULL_H) $(WARN_ON_USE_H)
 	      -e 's|@''REPLACE_STRDUP''@|$(REPLACE_STRDUP)|g' \
 	      -e 's|@''REPLACE_STRSTR''@|$(REPLACE_STRSTR)|g' \
 	      -e 's|@''REPLACE_STRERROR''@|$(REPLACE_STRERROR)|g' \
+	      -e 's|@''REPLACE_STRNCAT''@|$(REPLACE_STRNCAT)|g' \
 	      -e 's|@''REPLACE_STRNDUP''@|$(REPLACE_STRNDUP)|g' \
 	      -e 's|@''REPLACE_STRSIGNAL''@|$(REPLACE_STRSIGNAL)|g' \
 	      -e 's|@''REPLACE_STRTOK_R''@|$(REPLACE_STRTOK_R)|g' \

modules/strncat

@@ -0,0 +1,25 @@
+Description:
+strncat() function: append part of a string to a string.
+
+Files:
+lib/strncat.c
+m4/strncat.m4
+m4/mmap-anon.m4
+
+Depends-on:
+string
+
+configure.ac:
+gl_FUNC_STRNCAT
+gl_STRING_MODULE_INDICATOR([strncat])
+
+Makefile.am:
+
+Include:
+<string.h>
+
+License:
+LGPLv2+
+
+Maintainer:
+Bruno Haible

tests/test-string-c++.cc

@@ -68,6 +68,11 @@ SIGNATURE_CHECK (GNULIB_NAMESPACE::strchrnul, char *, (char const *, int));
 SIGNATURE_CHECK (GNULIB_NAMESPACE::strdup, char *, (char const *));
 #endif
 
+#if GNULIB_TEST_STRNCAT
+SIGNATURE_CHECK (GNULIB_NAMESPACE::strncat, char *,
+                 (char *, const char *, size_t));
+#endif
+
 #if GNULIB_TEST_STRNDUP
 SIGNATURE_CHECK (GNULIB_NAMESPACE::strndup, char *, (char const *, size_t));
 #endif