PR libstdc++/83626 handle ENOENT due to filesystem race

	PR libstdc++/83626
	* src/filesystem/ops.cc (remove(const path&, error_code&)): Do not
	report an error for ENOENT.
	(remove_all(const path&)): Fix type of result variable.
	(remove_all(const path&, error_code&)): Use non-throwing increment
	for directory iterator. Call POSIX remove directly to avoid redundant
	calls to symlink_status. Do not report errors for ENOENT.
	* src/filesystem/std-ops.cc: Likewise.
	* testsuite/27_io/filesystem/operations/remove_all.cc: Test throwing
	overload.
	* testsuite/experimental/filesystem/operations/remove_all.cc:
	Likewise.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@256283 138bc75d-0d04-0410-961f-82ee72b054a4

5 files changed, 111 insertions, 22 deletions

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 82de1ff85d0..fb2eb63a693 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,18 @@
+2018-01-05  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/83626
+	* src/filesystem/ops.cc (remove(const path&, error_code&)): Do not
+	report an error for ENOENT.
+	(remove_all(const path&)): Fix type of result variable.
+	(remove_all(const path&, error_code&)): Use non-throwing increment
+	for directory iterator. Call POSIX remove directly to avoid redundant
+	calls to symlink_status. Do not report errors for ENOENT.
+	* src/filesystem/std-ops.cc: Likewise.
+	* testsuite/27_io/filesystem/operations/remove_all.cc: Test throwing
+	overload.
+	* testsuite/experimental/filesystem/operations/remove_all.cc:
+	Likewise.
+
 2018-01-04  Jonathan Wakely  <jwakely@redhat.com>
 
 	PR libstdc++/83626
diff --git a/libstdc++-v3/src/filesystem/ops.cc b/libstdc++-v3/src/filesystem/ops.cc
index 5a7cb599bb6..3690fb94d63 100644
--- a/libstdc++-v3/src/filesystem/ops.cc
+++ b/libstdc++-v3/src/filesystem/ops.cc
@@ -1025,13 +1025,16 @@ fs::remove(const path& p, error_code& ec) noexcept
       ec.clear();
       return false; // Nothing to do, not an error.
     }
-  if (::remove(p.c_str()) != 0)
+  if (::remove(p.c_str()) == 0)
     {
-      ec.assign(errno, std::generic_category());
-      return false;
+      ec.clear();
+      return true;
     }
-  ec.clear();
-  return true;
+  else if (errno == ENOENT)
+    ec.clear();
+  else
+    ec.assign(errno, std::generic_category());
+  return false;
 }
 
 
@@ -1039,7 +1042,7 @@ std::uintmax_t
 fs::remove_all(const path& p)
 {
   error_code ec;
-  bool result = remove_all(p, ec);
+  const auto result = remove_all(p, ec);
   if (ec)
     _GLIBCXX_THROW_OR_ABORT(filesystem_error("cannot remove all", p, ec));
   return result;
@@ -1051,15 +1054,29 @@ fs::remove_all(const path& p, error_code& ec) noexcept
   const auto s = symlink_status(p, ec);
   if (!status_known(s))
     return -1;
+
   ec.clear();
+  if (s.type() == file_type::not_found)
+    return 0;
+
   uintmax_t count = 0;
   if (s.type() == file_type::directory)
-    for (directory_iterator d(p, ec), end; !ec && d != end; ++d)
-      count += fs::remove_all(d->path(), ec);
-  if (!ec && fs::remove(p, ec))
+    {
+      for (directory_iterator d(p, ec), end; !ec && d != end; d.increment(ec))
+	count += fs::remove_all(d->path(), ec);
+      if (ec.value() == ENOENT)
+	ec.clear();
+      else if (ec)
+	return -1;
+    }
+
+  if (::remove(p.c_str()) == 0)
     ++count;
-  if (ec)
-    return -1;
+  else if (errno != ENOENT)
+    {
+      ec.assign(errno, std::generic_category());
+      return -1;
+    }
   return count;
 }
 
diff --git a/libstdc++-v3/src/filesystem/std-ops.cc b/libstdc++-v3/src/filesystem/std-ops.cc
index 6ff280a9c76..2411bbb7977 100644
--- a/libstdc++-v3/src/filesystem/std-ops.cc
+++ b/libstdc++-v3/src/filesystem/std-ops.cc
@@ -1274,13 +1274,16 @@ fs::remove(const path& p, error_code& ec) noexcept
       ec.clear();
       return false; // Nothing to do, not an error.
     }
-  if (::remove(p.c_str()) != 0)
+  if (::remove(p.c_str()) == 0)
     {
-      ec.assign(errno, std::generic_category());
-      return false;
+      ec.clear();
+      return true;
     }
-  ec.clear();
-  return true;
+  else if (errno == ENOENT)
+    ec.clear();
+  else
+    ec.assign(errno, std::generic_category());
+  return false;
 }
 
 
@@ -1288,7 +1291,7 @@ std::uintmax_t
 fs::remove_all(const path& p)
 {
   error_code ec;
-  bool result = remove_all(p, ec);
+  const auto result = remove_all(p, ec);
   if (ec)
     _GLIBCXX_THROW_OR_ABORT(filesystem_error("cannot remove all", p, ec));
   return result;
@@ -1300,15 +1303,29 @@ fs::remove_all(const path& p, error_code& ec)
   const auto s = symlink_status(p, ec);
   if (!status_known(s))
     return -1;
+
   ec.clear();
+  if (s.type() == file_type::not_found)
+    return 0;
+
   uintmax_t count = 0;
   if (s.type() == file_type::directory)
-    for (directory_iterator d(p, ec), end; !ec && d != end; ++d)
-      count += fs::remove_all(d->path(), ec);
-  if (!ec && fs::remove(p, ec))
+    {
+      for (directory_iterator d(p, ec), end; !ec && d != end; d.increment(ec))
+	count += fs::remove_all(d->path(), ec);
+      if (ec.value() == ENOENT)
+	ec.clear();
+      else if (ec)
+	return -1;
+    }
+
+  if (::remove(p.c_str()) == 0)
     ++count;
-  if (ec)
-    return -1;
+  else if (errno != ENOENT)
+    {
+      ec.assign(errno, std::generic_category());
+      return -1;
+    }
   return count;
 }
 
diff --git a/libstdc++-v3/testsuite/27_io/filesystem/operations/remove_all.cc b/libstdc++-v3/testsuite/27_io/filesystem/operations/remove_all.cc
index 8ee5c4d39c1..633cde57243 100644
--- a/libstdc++-v3/testsuite/27_io/filesystem/operations/remove_all.cc
+++ b/libstdc++-v3/testsuite/27_io/filesystem/operations/remove_all.cc
@@ -85,8 +85,28 @@ test01()
   b2.path.clear();
 }
 
+void
+test02()
+{
+  const auto dir = __gnu_test::nonexistent_path();
+  create_directories(dir/"a/b/c");
+  std::uintmax_t n = remove_all(dir/"a");
+  VERIFY( n == 3 );
+  VERIFY( exists(dir) );
+  VERIFY( !exists(dir/"a") );
+
+  n = remove_all(dir/"a");
+  VERIFY( n == 0 );
+  VERIFY( exists(dir) );
+
+  n = remove_all(dir);
+  VERIFY( n == 1 );
+  VERIFY( !exists(dir) );
+}
+
 int
 main()
 {
   test01();
+  test02();
 }
diff --git a/libstdc++-v3/testsuite/experimental/filesystem/operations/remove_all.cc b/libstdc++-v3/testsuite/experimental/filesystem/operations/remove_all.cc
index fa146b4317c..67f6e989d27 100644
--- a/libstdc++-v3/testsuite/experimental/filesystem/operations/remove_all.cc
+++ b/libstdc++-v3/testsuite/experimental/filesystem/operations/remove_all.cc
@@ -85,8 +85,28 @@ test01()
   b2.path.clear();
 }
 
+void
+test02()
+{
+  const auto dir = __gnu_test::nonexistent_path();
+  create_directories(dir/"a/b/c");
+  std::uintmax_t n = remove_all(dir/"a");
+  VERIFY( n == 3 );
+  VERIFY( exists(dir) );
+  VERIFY( !exists(dir/"a") );
+
+  n = remove_all(dir/"a");
+  VERIFY( n == 0 );
+  VERIFY( exists(dir) );
+
+  n = remove_all(dir);
+  VERIFY( n == 1 );
+  VERIFY( !exists(dir) );
+}
+
 int
 main()
 {
   test01();
+  test02();
 }