libstdc++: Fix error handling in filesystem::remove_all (PR93201)

When recursing into a directory, any errors that occur while removing a
directory entry are ignored, because the subsequent increment of the
directory iterator clears the error_code object.

This fixes that bug by checking the result of each recursive operation
before incrementing. This is a change in observable behaviour, because
previously other directory entries would still be removed even if one
(or more) couldn't be removed due to errors. Now the operation stops on
the first error, which is what the code intended to do all along. The
standard doesn't specify what happens in this case (because the order
that the entries are processed is unspecified anyway).

	PR libstdc++/93201
	* src/c++17/fs_ops.cc (remove_all(const path&, error_code&)): Check
	result of recursive call before incrementing iterator.
	* src/filesystem/ops.cc (remove_all(const path&, error_code&)):
	Likewise.
	* testsuite/27_io/filesystem/operations/remove_all.cc: Check errors
	are reported correctly.
	* testsuite/experimental/filesystem/operations/remove_all.cc: Likewise.

From-SVN: r280021

5 files changed, 99 insertions, 12 deletions

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 16f3f10..cba45e0 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,14 @@
+2020-01-08  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/93201
+	* src/c++17/fs_ops.cc (remove_all(const path&, error_code&)): Check
+	result of recursive call before incrementing iterator.
+	* src/filesystem/ops.cc (remove_all(const path&, error_code&)):
+	Likewise.
+	* testsuite/27_io/filesystem/operations/remove_all.cc: Check errors
+	are reported correctly.
+	* testsuite/experimental/filesystem/operations/remove_all.cc: Likewise.
+
 2019-10-24  Jonathan Wakely  <jwakely@redhat.com>
 
 	Backport from mainline
diff --git a/libstdc++-v3/src/filesystem/ops.cc b/libstdc++-v3/src/filesystem/ops.cc
index de29062..4b0a4ff 100644
--- a/libstdc++-v3/src/filesystem/ops.cc
+++ b/libstdc++-v3/src/filesystem/ops.cc
@@ -1070,12 +1070,17 @@ fs::remove_all(const path& p, error_code& ec) noexcept
   uintmax_t count = 0;
   if (s.type() == file_type::directory)
     {
-      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;
+      directory_iterator d(p, ec), end;
+      while (!ec && d != end)
+	{
+	  const auto removed = fs::remove_all(d->path(), ec);
+	  if (removed == numeric_limits<uintmax_t>::max())
+	    return -1;
+	  count += removed;
+	  d.increment(ec);
+	  if (ec)
+	    return -1;
+	}
     }
 
   if (fs::remove(p, ec))
diff --git a/libstdc++-v3/src/filesystem/std-ops.cc b/libstdc++-v3/src/filesystem/std-ops.cc
index 40de0de..97fcfa1 100644
--- a/libstdc++-v3/src/filesystem/std-ops.cc
+++ b/libstdc++-v3/src/filesystem/std-ops.cc
@@ -1350,12 +1350,17 @@ fs::remove_all(const path& p, error_code& ec)
   uintmax_t count = 0;
   if (s.type() == file_type::directory)
     {
-      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;
+      directory_iterator d(p, ec), end;
+      while (!ec && d != end)
+	{
+	  const auto removed = fs::remove_all(d->path(), ec);
+	  if (removed == numeric_limits<uintmax_t>::max())
+	    return -1;
+	  count += removed;
+	  d.increment(ec);
+	  if (ec)
+	    return -1;
+	}
     }
 
   if (fs::remove(p, ec))
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 633cde5..a3904ea 100644
--- a/libstdc++-v3/testsuite/27_io/filesystem/operations/remove_all.cc
+++ b/libstdc++-v3/testsuite/27_io/filesystem/operations/remove_all.cc
@@ -104,9 +104,42 @@ test02()
   VERIFY( !exists(dir) );
 }
 
+void
+test04()
+{
+#if defined(__MINGW32__) || defined(__MINGW64__)
+  // no permissions
+#else
+  // PR libstdc++/93201
+  std::error_code ec;
+  std::uintmax_t n;
+
+  auto dir = __gnu_test::nonexistent_path();
+  fs::create_directory(dir);
+  __gnu_test::scoped_file f(dir/"file");
+  // remove write permission on the directory:
+  fs::permissions(dir, fs::perms::owner_read|fs::perms::owner_exec);
+  n = fs::remove_all(dir, ec);
+  VERIFY( n == -1 );
+  VERIFY( ec == std::errc::permission_denied ); // not ENOTEMPTY
+
+  try {
+    fs::remove_all(dir);
+    VERIFY( false );
+  } catch (const fs::filesystem_error& e) {
+    VERIFY( e.code() == std::errc::permission_denied );
+    // First path is the argument to remove_all
+    VERIFY( e.path1() == dir );
+  }
+
+  fs::permissions(dir, fs::perms::owner_write, fs::perm_options::add);
+#endif
+}
+
 int
 main()
 {
   test01();
   test02();
+  test04();
 }
diff --git a/libstdc++-v3/testsuite/experimental/filesystem/operations/remove_all.cc b/libstdc++-v3/testsuite/experimental/filesystem/operations/remove_all.cc
index ddf150b..af78b9e 100644
--- a/libstdc++-v3/testsuite/experimental/filesystem/operations/remove_all.cc
+++ b/libstdc++-v3/testsuite/experimental/filesystem/operations/remove_all.cc
@@ -104,9 +104,42 @@ test02()
   VERIFY( !exists(dir) );
 }
 
+void
+test04()
+{
+#if defined(__MINGW32__) || defined(__MINGW64__)
+  // no permissions
+#else
+  // PR libstdc++/93201
+  std::error_code ec;
+  std::uintmax_t n;
+
+  auto dir = __gnu_test::nonexistent_path();
+  fs::create_directory(dir);
+  __gnu_test::scoped_file f(dir/"file");
+  // remove write permission on the directory:
+  fs::permissions(dir, fs::perms::owner_read|fs::perms::owner_exec);
+  n = fs::remove_all(dir, ec);
+  VERIFY( n == -1 );
+  VERIFY( ec == std::errc::permission_denied ); // not ENOTEMPTY
+
+  try {
+    fs::remove_all(dir);
+    VERIFY( false );
+  } catch (const fs::filesystem_error& e) {
+    VERIFY( e.code() == std::errc::permission_denied );
+    // First path is the argument to remove_all
+    VERIFY( e.path1() == dir );
+  }
+
+  fs::permissions(dir, fs::perms::owner_write|fs::perms::add_perms);
+#endif
+}
+
 int
 main()
 {
   test01();
   test02();
+  test04();
 }