[llvm] 75cbf6d - Re-land "Optimize path::remove_dots"
Reid Kleckner via llvm-commits
llvm-commits at lists.llvm.org
Mon May 4 16:45:06 PDT 2020
Author: Reid Kleckner
Date: 2020-05-04T16:40:39-07:00
New Revision: 75cbf6dc5cdb844ba4dd4631a984412e06c5387c
URL: https://github.com/llvm/llvm-project/commit/75cbf6dc5cdb844ba4dd4631a984412e06c5387c
DIFF: https://github.com/llvm/llvm-project/commit/75cbf6dc5cdb844ba4dd4631a984412e06c5387c.diff
LOG: Re-land "Optimize path::remove_dots"
This reverts commit fb5fd74685e728b1d5e68d33e9842bcd734b98e6.
Re-instates commit 53913a65b408ade2956061b4c0aaed6bba907403
The fix is to trim off trailing separators, as in `/foo/bar/` and
produce `/foo/bar`. VFS tests rely on this. I added unit tests for
remove_dots.
Added:
Modified:
llvm/lib/Support/Path.cpp
llvm/lib/Support/Windows/Path.inc
llvm/unittests/Support/Path.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Support/Path.cpp b/llvm/lib/Support/Path.cpp
index 6f065b9c5a3c..0a4d5818703b 100644
--- a/llvm/lib/Support/Path.cpp
+++ b/llvm/lib/Support/Path.cpp
@@ -684,43 +684,69 @@ StringRef remove_leading_dotslash(StringRef Path, Style style) {
return Path;
}
-static SmallString<256> remove_dots(StringRef path, bool remove_dot_dot,
- Style style) {
+// Remove path traversal components ("." and "..") when possible, and
+// canonicalize slashes.
+bool remove_dots(SmallVectorImpl<char> &the_path, bool remove_dot_dot,
+ Style style) {
+ style = real_style(style);
+ StringRef remaining(the_path.data(), the_path.size());
+ bool needs_change = false;
SmallVector<StringRef, 16> components;
- // Skip the root path, then look for traversal in the components.
- StringRef rel = path::relative_path(path, style);
- for (StringRef C :
- llvm::make_range(path::begin(rel, style), path::end(rel))) {
- if (C == ".")
- continue;
- // Leading ".." will remain in the path unless it's at the root.
- if (remove_dot_dot && C == "..") {
+ // Consume the root path, if present.
+ StringRef root = path::root_path(remaining, style);
+ bool absolute = !root.empty();
+ if (absolute)
+ remaining = remaining.drop_front(root.size());
+
+ // Loop over path components manually. This makes it easier to detect
+ // non-preferred slashes and double separators that must be canonicalized.
+ while (!remaining.empty()) {
+ size_t next_slash = remaining.find_first_of(separators(style));
+ if (next_slash == StringRef::npos)
+ next_slash = remaining.size();
+ StringRef component = remaining.take_front(next_slash);
+ remaining = remaining.drop_front(next_slash);
+
+ // Eat the slash, and check if it is the preferred separator.
+ if (!remaining.empty()) {
+ needs_change |= remaining.front() != preferred_separator(style);
+ remaining = remaining.drop_front();
+ // The path needs to be rewritten if it has a trailing slash.
+ // FIXME: This is emergent behavior that could be removed.
+ needs_change |= remaining.empty();
+ }
+
+ // Check for path traversal components or double separators.
+ if (component.empty() || component == ".") {
+ needs_change = true;
+ } else if (remove_dot_dot && component == "..") {
+ needs_change = true;
+ // Do not allow ".." to remove the root component. If this is the
+ // beginning of a relative path, keep the ".." component.
if (!components.empty() && components.back() != "..") {
components.pop_back();
- continue;
+ } else if (!absolute) {
+ components.push_back(component);
}
- if (path::is_absolute(path, style))
- continue;
+ } else {
+ components.push_back(component);
}
- components.push_back(C);
}
- SmallString<256> buffer = path::root_path(path, style);
- for (StringRef C : components)
- path::append(buffer, style, C);
- return buffer;
-}
-
-bool remove_dots(SmallVectorImpl<char> &path, bool remove_dot_dot,
- Style style) {
- StringRef p(path.data(), path.size());
-
- SmallString<256> result = remove_dots(p, remove_dot_dot, style);
- if (result == path)
+ // Avoid rewriting the path unless we have to.
+ if (!needs_change)
return false;
- path.swap(result);
+ SmallString<256> buffer = root;
+ if (!components.empty()) {
+ buffer += components[0];
+ for (StringRef C : makeArrayRef(components).drop_front()) {
+ buffer += preferred_separator(style);
+ buffer += C;
+ }
+ }
+ the_path.swap(buffer);
return true;
}
diff --git a/llvm/lib/Support/Windows/Path.inc b/llvm/lib/Support/Windows/Path.inc
index 2e1488479095..ec62e656ddf0 100644
--- a/llvm/lib/Support/Windows/Path.inc
+++ b/llvm/lib/Support/Windows/Path.inc
@@ -101,18 +101,13 @@ std::error_code widenPath(const Twine &Path8, SmallVectorImpl<wchar_t> &Path16,
}
// Remove '.' and '..' because long paths treat these as real path components.
+ llvm::sys::path::native(Path8Str, path::Style::windows);
llvm::sys::path::remove_dots(Path8Str, true);
const StringRef RootName = llvm::sys::path::root_name(Path8Str);
assert(!RootName.empty() &&
"Root name cannot be empty for an absolute path!");
- // llvm::sys::path::remove_dots, used above, can leave a '/' after the root
- // name and long paths must use '\' as the separator.
- const size_t RootNameSize = RootName.size();
- if (RootNameSize < Path8Str.size() && Path8Str[RootNameSize] == '/')
- Path8Str[RootNameSize] = '\\';
-
SmallString<2 * MAX_PATH> FullPath(LongPathPrefix);
if (RootName[1] != ':') { // Check if UNC.
FullPath.append("UNC\\");
diff --git a/llvm/unittests/Support/Path.cpp b/llvm/unittests/Support/Path.cpp
index 3030fb2ebb2e..b2eddd52e68a 100644
--- a/llvm/unittests/Support/Path.cpp
+++ b/llvm/unittests/Support/Path.cpp
@@ -1253,6 +1253,30 @@ TEST(Support, RemoveDots) {
remove_dots("..\\a\\b\\..\\c", true, path::Style::windows));
EXPECT_EQ("..\\..\\a\\c",
remove_dots("..\\..\\a\\b\\..\\c", true, path::Style::windows));
+ EXPECT_EQ("C:\\a\\c", remove_dots("C:\\foo\\bar//..\\..\\a\\c", true,
+ path::Style::windows));
+
+ // FIXME: These leading forward slashes are emergent behavior. VFS depends on
+ // this behavior now.
+ EXPECT_EQ("C:/bar",
+ remove_dots("C:/foo/../bar", true, path::Style::windows));
+ EXPECT_EQ("C:/foo\\bar",
+ remove_dots("C:/foo/bar", true, path::Style::windows));
+ EXPECT_EQ("C:/foo\\bar",
+ remove_dots("C:/foo\\bar", true, path::Style::windows));
+ EXPECT_EQ("/", remove_dots("/", true, path::Style::windows));
+ EXPECT_EQ("C:/", remove_dots("C:/", true, path::Style::windows));
+
+ // Some clients of remove_dots expect it to remove trailing slashes. Again,
+ // this is emergent behavior that VFS relies on, and not inherently part of
+ // the specification.
+ EXPECT_EQ("C:\\foo\\bar",
+ remove_dots("C:\\foo\\bar\\", true, path::Style::windows));
+ EXPECT_EQ("/foo/bar",
+ remove_dots("/foo/bar/", true, path::Style::posix));
+
+ // A double separator is rewritten.
+ EXPECT_EQ("C:/foo\\bar", remove_dots("C:/foo//bar", true, path::Style::windows));
SmallString<64> Path1(".\\.\\c");
EXPECT_TRUE(path::remove_dots(Path1, true, path::Style::windows));
@@ -1271,6 +1295,11 @@ TEST(Support, RemoveDots) {
EXPECT_EQ("/a/c", remove_dots("/../../a/c", true, path::Style::posix));
EXPECT_EQ("/a/c",
remove_dots("/../a/b//../././/c", true, path::Style::posix));
+ EXPECT_EQ("/", remove_dots("/", true, path::Style::posix));
+
+ // FIXME: Leaving behind this double leading slash seems like a bug.
+ EXPECT_EQ("//foo/bar",
+ remove_dots("//foo/bar/", true, path::Style::posix));
SmallString<64> Path2("././c");
EXPECT_TRUE(path::remove_dots(Path2, true, path::Style::posix));
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