libstdc++: Add autoconf checks for mkdir, chmod, chdir, and getcwd

The filesystem code was using these functions without checking for their
existence, assuming that any UNIX-like libc with <unistd.h> would always
provide them. That's not true for some newlib targets like arm-eabi.

libstdc++-v3/ChangeLog:

	* acinclude.m4 (GLIBCXX_CHECK_FILESYSTEM_DEPS): Check for mkdir,
	chmod, chdir, and getcwd.
	* config.h.in: Regenerate.
	* configure: Regenerate.
	* src/c++17/fs_ops.cc (create_dir): Use USE_MKDIR macro.
	(fs::current_path): Use USE_GETCWD and USE_CHDIR macros.
	(fs::permissions): Use USE_CHMOD macro.
	* src/filesystem/ops-common.h [FILESYSTEM_IS_WINDOWS]
	(chmod, mkdir, getcwd, chdir): Define new macros.
	[FILESYSTEM_IS_WINDOWS] (chmod, mkdir, getcwd, chdir): Use
	new macros.
	* src/filesystem/ops.cc (create_dir): Use USE_MKDIR macro.
	(fs::current_path): Use USE_GETCWD and USE_CHDIR macros.
	(fs::permissions): Use USE_CHMOD macro.

6 files changed, 355 insertions, 9 deletions

diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index 15b3d74..13159d6 100644
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -4998,6 +4998,66 @@ dnl
     AC_DEFINE(HAVE_STRUCT_DIRENT_D_TYPE, 1, [Define to 1 if `d_type' is a member of `struct dirent'.])
   fi
 dnl
+  AC_CACHE_CHECK([for chmod], glibcxx_cv_chmod, [dnl
+    GCC_TRY_COMPILE_OR_LINK(
+      [
+       #include <sys/stat.h>
+      ],
+      [
+       int i = chmod("", S_IRUSR);
+      ],
+      [glibcxx_cv_chmod=yes],
+      [glibcxx_cv_chmod=no])
+  ])
+  if test $glibcxx_cv_chmod = yes; then
+    AC_DEFINE(_GLIBCXX_USE_CHMOD, 1, [Define if usable chmod is available in <sys/stat.h>.])
+  fi
+dnl
+  AC_CACHE_CHECK([for mkdir], glibcxx_cv_mkdir, [dnl
+    GCC_TRY_COMPILE_OR_LINK(
+      [
+       #include <sys/stat.h>
+      ],
+      [
+       int i = mkdir("", S_IRUSR);
+      ],
+      [glibcxx_cv_mkdir=yes],
+      [glibcxx_cv_mkdir=no])
+  ])
+  if test $glibcxx_cv_mkdir = yes; then
+    AC_DEFINE(_GLIBCXX_USE_MKDIR, 1, [Define if usable mkdir is available in <sys/stat.h>.])
+  fi
+dnl
+  AC_CACHE_CHECK([for chdir], glibcxx_cv_chdir, [dnl
+    GCC_TRY_COMPILE_OR_LINK(
+      [
+       #include <unistd.h>
+      ],
+      [
+       int i = chdir("");
+      ],
+      [glibcxx_cv_chdir=yes],
+      [glibcxx_cv_chdir=no])
+  ])
+  if test $glibcxx_cv_chdir = yes; then
+    AC_DEFINE(_GLIBCXX_USE_CHDIR, 1, [Define if usable chdir is available in <unistd.h>.])
+  fi
+dnl
+  AC_CACHE_CHECK([for getcwd], glibcxx_cv_getcwd, [dnl
+    GCC_TRY_COMPILE_OR_LINK(
+      [
+       #include <unistd.h>
+      ],
+      [
+       char* s = getcwd((char*)0, 1);
+      ],
+      [glibcxx_cv_getcwd=yes],
+      [glibcxx_cv_getcwd=no])
+  ])
+  if test $glibcxx_cv_getcwd = yes; then
+    AC_DEFINE(_GLIBCXX_USE_GETCWD, 1, [Define if usable getcwd is available in <unistd.h>.])
+  fi
+dnl
   AC_CACHE_CHECK([for realpath], glibcxx_cv_realpath, [dnl
     GCC_TRY_COMPILE_OR_LINK(
       [
diff --git a/libstdc++-v3/config.h.in b/libstdc++-v3/config.h.in
index 1c2224c..0abe62a 100644
--- a/libstdc++-v3/config.h.in
+++ b/libstdc++-v3/config.h.in
@@ -961,6 +961,12 @@
    namespace std::tr1. */
 #undef _GLIBCXX_USE_C99_STDINT_TR1
 
+/* Define if usable chdir is available in <unistd.h>. */
+#undef _GLIBCXX_USE_CHDIR
+
+/* Define if usable chmod is available in <sys/stat.h>. */
+#undef _GLIBCXX_USE_CHMOD
+
 /* Defined if clock_gettime syscall has monotonic and realtime clock support.
    */
 #undef _GLIBCXX_USE_CLOCK_GETTIME_SYSCALL
@@ -991,6 +997,9 @@
 /* Define if fseeko and ftello are available. */
 #undef _GLIBCXX_USE_FSEEKO_FTELLO
 
+/* Define if usable getcwd is available in <unistd.h>. */
+#undef _GLIBCXX_USE_GETCWD
+
 /* Defined if gettimeofday is available. */
 #undef _GLIBCXX_USE_GETTIMEOFDAY
 
@@ -1009,6 +1018,9 @@
 /* Define if lstat is available in <sys/stat.h>. */
 #undef _GLIBCXX_USE_LSTAT
 
+/* Define if usable mkdir is available in <sys/stat.h>. */
+#undef _GLIBCXX_USE_MKDIR
+
 /* Defined if nanosleep is available. */
 #undef _GLIBCXX_USE_NANOSLEEP
 
diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure
index 22cb5b0..51c1d49 100755
--- a/libstdc++-v3/configure
+++ b/libstdc++-v3/configure
@@ -71839,6 +71839,258 @@ $as_echo "$glibcxx_cv_dirent_d_type" >&6; }
 $as_echo "#define HAVE_STRUCT_DIRENT_D_TYPE 1" >>confdefs.h
 
   fi
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for chmod" >&5
+$as_echo_n "checking for chmod... " >&6; }
+if ${glibcxx_cv_chmod+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+      if test x$gcc_no_link = xyes; then
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+       #include <sys/stat.h>
+
+int
+main ()
+{
+
+       int i = chmod("", S_IRUSR);
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  glibcxx_cv_chmod=yes
+else
+  glibcxx_cv_chmod=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+else
+  if test x$gcc_no_link = xyes; then
+  as_fn_error $? "Link tests are not allowed after GCC_NO_EXECUTABLES." "$LINENO" 5
+fi
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+       #include <sys/stat.h>
+
+int
+main ()
+{
+
+       int i = chmod("", S_IRUSR);
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_link "$LINENO"; then :
+  glibcxx_cv_chmod=yes
+else
+  glibcxx_cv_chmod=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $glibcxx_cv_chmod" >&5
+$as_echo "$glibcxx_cv_chmod" >&6; }
+  if test $glibcxx_cv_chmod = yes; then
+
+$as_echo "#define _GLIBCXX_USE_CHMOD 1" >>confdefs.h
+
+  fi
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for mkdir" >&5
+$as_echo_n "checking for mkdir... " >&6; }
+if ${glibcxx_cv_mkdir+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+      if test x$gcc_no_link = xyes; then
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+       #include <sys/stat.h>
+
+int
+main ()
+{
+
+       int i = mkdir("", S_IRUSR);
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  glibcxx_cv_mkdir=yes
+else
+  glibcxx_cv_mkdir=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+else
+  if test x$gcc_no_link = xyes; then
+  as_fn_error $? "Link tests are not allowed after GCC_NO_EXECUTABLES." "$LINENO" 5
+fi
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+       #include <sys/stat.h>
+
+int
+main ()
+{
+
+       int i = mkdir("", S_IRUSR);
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_link "$LINENO"; then :
+  glibcxx_cv_mkdir=yes
+else
+  glibcxx_cv_mkdir=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $glibcxx_cv_mkdir" >&5
+$as_echo "$glibcxx_cv_mkdir" >&6; }
+  if test $glibcxx_cv_mkdir = yes; then
+
+$as_echo "#define _GLIBCXX_USE_MKDIR 1" >>confdefs.h
+
+  fi
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for chdir" >&5
+$as_echo_n "checking for chdir... " >&6; }
+if ${glibcxx_cv_chdir+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+      if test x$gcc_no_link = xyes; then
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+       #include <unistd.h>
+
+int
+main ()
+{
+
+       int i = chdir("");
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  glibcxx_cv_chdir=yes
+else
+  glibcxx_cv_chdir=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+else
+  if test x$gcc_no_link = xyes; then
+  as_fn_error $? "Link tests are not allowed after GCC_NO_EXECUTABLES." "$LINENO" 5
+fi
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+       #include <unistd.h>
+
+int
+main ()
+{
+
+       int i = chdir("");
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_link "$LINENO"; then :
+  glibcxx_cv_chdir=yes
+else
+  glibcxx_cv_chdir=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $glibcxx_cv_chdir" >&5
+$as_echo "$glibcxx_cv_chdir" >&6; }
+  if test $glibcxx_cv_chdir = yes; then
+
+$as_echo "#define _GLIBCXX_USE_CHDIR 1" >>confdefs.h
+
+  fi
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for getcwd" >&5
+$as_echo_n "checking for getcwd... " >&6; }
+if ${glibcxx_cv_getcwd+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+      if test x$gcc_no_link = xyes; then
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+       #include <unistd.h>
+
+int
+main ()
+{
+
+       char* s = getcwd((char*)0, 1);
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  glibcxx_cv_getcwd=yes
+else
+  glibcxx_cv_getcwd=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+else
+  if test x$gcc_no_link = xyes; then
+  as_fn_error $? "Link tests are not allowed after GCC_NO_EXECUTABLES." "$LINENO" 5
+fi
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+       #include <unistd.h>
+
+int
+main ()
+{
+
+       char* s = getcwd((char*)0, 1);
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_link "$LINENO"; then :
+  glibcxx_cv_getcwd=yes
+else
+  glibcxx_cv_getcwd=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $glibcxx_cv_getcwd" >&5
+$as_echo "$glibcxx_cv_getcwd" >&6; }
+  if test $glibcxx_cv_getcwd = yes; then
+
+$as_echo "#define _GLIBCXX_USE_GETCWD 1" >>confdefs.h
+
+  fi
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking for realpath" >&5
 $as_echo_n "checking for realpath... " >&6; }
 if ${glibcxx_cv_realpath+:} false; then :
diff --git a/libstdc++-v3/src/c++17/fs_ops.cc b/libstdc++-v3/src/c++17/fs_ops.cc
index 6cdeac1..241db68 100644
--- a/libstdc++-v3/src/c++17/fs_ops.cc
+++ b/libstdc++-v3/src/c++17/fs_ops.cc
@@ -577,7 +577,7 @@ namespace
   create_dir(const fs::path& p, fs::perms perm, std::error_code& ec)
   {
     bool created = false;
-#ifdef _GLIBCXX_HAVE_SYS_STAT_H
+#if _GLIBCXX_USE_MKDIR
     posix::mode_t mode = static_cast<std::underlying_type_t<fs::perms>>(perm);
     if (posix::mkdir(p.c_str(), mode))
       {
@@ -735,7 +735,7 @@ fs::path
 fs::current_path(error_code& ec)
 {
   path p;
-#if defined _GLIBCXX_HAVE_UNISTD_H && ! defined __AVR__
+#if _GLIBCXX_USE_GETCWD
 #if defined __GLIBC__ || defined _GLIBCXX_FILESYSTEM_IS_WINDOWS
   if (char_ptr cwd = char_ptr{posix::getcwd(nullptr, 0)})
     {
@@ -783,7 +783,7 @@ fs::current_path(error_code& ec)
 	}
     }
 #endif  // __GLIBC__
-#else   // _GLIBCXX_HAVE_UNISTD_H
+#else   // _GLIBCXX_USE_GETCWD
   ec = std::make_error_code(std::errc::function_not_supported);
 #endif
   return p;
@@ -801,7 +801,7 @@ fs::current_path(const path& p)
 void
 fs::current_path(const path& p, error_code& ec) noexcept
 {
-#ifdef _GLIBCXX_HAVE_UNISTD_H
+#if _GLIBCXX_USE_CHDIR
   if (posix::chdir(p.c_str()))
     ec.assign(errno, std::generic_category());
   else
@@ -1097,6 +1097,7 @@ void
 fs::permissions(const path& p, perms prms, perm_options opts,
 		error_code& ec) noexcept
 {
+#if _GLIBCXX_USE_FCHMODAT || _GLIBCXX_USE_CHMOD
   const bool replace = is_set(opts, perm_options::replace);
   const bool add = is_set(opts, perm_options::add);
   const bool remove = is_set(opts, perm_options::remove);
@@ -1138,6 +1139,9 @@ fs::permissions(const path& p, perms prms, perm_options opts,
     ec.assign(err, std::generic_category());
   else
     ec.clear();
+#else
+  ec = std::make_error_code(std::errc::function_not_supported);
+#endif
 }
 
 fs::path
diff --git a/libstdc++-v3/src/filesystem/ops-common.h b/libstdc++-v3/src/filesystem/ops-common.h
index 79dcb75..1f4060c 100644
--- a/libstdc++-v3/src/filesystem/ops-common.h
+++ b/libstdc++-v3/src/filesystem/ops-common.h
@@ -35,7 +35,7 @@
 # endif
 # if defined(_GLIBCXX_HAVE_SYS_STAT_H) && defined(_GLIBCXX_HAVE_SYS_TYPES_H)
 #  include <sys/types.h>
-#  include <sys/stat.h>
+#  include <sys/stat.h>  // mkdir, chmod
 # endif
 #endif
 #if !_GLIBCXX_USE_UTIMENSAT && _GLIBCXX_HAVE_UTIME_H
@@ -133,15 +133,19 @@ namespace __gnu_posix
 
   inline int chmod(const wchar_t* path, mode_t mode)
   { return ::_wchmod(path, mode); }
+#define _GLIBCXX_USE_CHMOD 1
 
   inline int mkdir(const wchar_t* path, mode_t)
   { return ::_wmkdir(path); }
+#define _GLIBCXX_USE_MKDIR 1
 
   inline wchar_t* getcwd(wchar_t* buf, size_t size)
   { return ::_wgetcwd(buf, size > (size_t)INT_MAX ? INT_MAX : (int)size); }
+#define _GLIBCXX_USE_GETCWD 1
 
   inline int chdir(const wchar_t* path)
   { return ::_wchdir(path); }
+#define _GLIBCXX_USE_CHDIR 1
 
 #if !_GLIBCXX_USE_UTIMENSAT && _GLIBCXX_HAVE_UTIME_H
   using utimbuf = _utimbuf;
@@ -190,10 +194,18 @@ namespace __gnu_posix
 #  endif
 # endif
   using ::mode_t;
+# if _GLIBCXX_USE_CHMOD
   using ::chmod;
+# endif
+# if _GLIBCXX_USE_MKDIR
   using ::mkdir;
+# endif
+# if _GLIBCXX_USE_GETCWD
   using ::getcwd;
+# endif
+# if _GLIBCXX_USE_CHDIR
   using ::chdir;
+# endif
 # if !_GLIBCXX_USE_UTIMENSAT && _GLIBCXX_USE_UTIME
   using ::utimbuf;
   using ::utime;
@@ -549,8 +561,10 @@ _GLIBCXX_BEGIN_NAMESPACE_FILESYSTEM
     if (::fchmod(out.fd, from_st->st_mode))
 #elif defined _GLIBCXX_USE_FCHMODAT && ! defined _GLIBCXX_FILESYSTEM_IS_WINDOWS
     if (::fchmodat(AT_FDCWD, to, from_st->st_mode, 0))
-#else
+#elif defined _GLIBCXX_USE_CHMOD
     if (posix::chmod(to, from_st->st_mode))
+#else
+    if (false)
 #endif
       {
 	ec.assign(errno, std::generic_category());
diff --git a/libstdc++-v3/src/filesystem/ops.cc b/libstdc++-v3/src/filesystem/ops.cc
index d33c13d..0102c67 100644
--- a/libstdc++-v3/src/filesystem/ops.cc
+++ b/libstdc++-v3/src/filesystem/ops.cc
@@ -488,7 +488,7 @@ namespace
   create_dir(const fs::path& p, fs::perms perm, std::error_code& ec)
   {
     bool created = false;
-#ifdef _GLIBCXX_HAVE_SYS_STAT_H
+#if _GLIBCXX_USE_MKDIR
     posix::mode_t mode = static_cast<std::underlying_type_t<fs::perms>>(perm);
     if (posix::mkdir(p.c_str(), mode))
       {
@@ -645,7 +645,7 @@ fs::path
 fs::current_path(error_code& ec)
 {
   path p;
-#ifdef _GLIBCXX_HAVE_UNISTD_H
+#if _GLIBCXX_USE_GETCWD
 #if defined __GLIBC__ || defined _GLIBCXX_FILESYSTEM_IS_WINDOWS
   if (char_ptr cwd = char_ptr{posix::getcwd(nullptr, 0)})
     {
@@ -711,7 +711,7 @@ fs::current_path(const path& p)
 void
 fs::current_path(const path& p, error_code& ec) noexcept
 {
-#ifdef _GLIBCXX_HAVE_UNISTD_H
+#if _GLIBCXX_USE_CHDIR
   if (posix::chdir(p.c_str()))
     ec.assign(errno, std::generic_category());
   else
@@ -947,6 +947,7 @@ fs::permissions(const path& p, perms prms)
 void
 fs::permissions(const path& p, perms prms, error_code& ec) noexcept
 {
+#if _GLIBCXX_USE_FCHMODAT || _GLIBCXX_USE_CHMOD
   const bool add = is_set(prms, perms::add_perms);
   const bool remove = is_set(prms, perms::remove_perms);
   const bool nofollow = is_set(prms, perms::symlink_nofollow);
@@ -987,6 +988,9 @@ fs::permissions(const path& p, perms prms, error_code& ec) noexcept
     ec.assign(err, std::generic_category());
   else
     ec.clear();
+#else
+  ec = std::make_error_code(std::errc::function_not_supported);
+#endif
 }
 
 fs::path