sammccall updated this revision to Diff 149682.
sammccall added a comment.
clearerr() on (partial) successful read, and recover from EAGAIN during fread.
Repository:
rCTE Clang Tools Extra
https://reviews.llvm.org/D47643
Files:
clangd/ClangdLSPServer.cpp
clangd/ClangdLSPServer.h
clangd/JSONRPCDispatcher.cpp
clangd/JSONRPCDispatcher.h
clangd/tool/ClangdMain.cpp
test/clangd/too_large.test
Index: test/clangd/too_large.test
===================================================================
--- test/clangd/too_large.test
+++ test/clangd/too_large.test
@@ -4,4 +4,4 @@
#
Content-Length: 2147483648
-# STDERR: Skipped overly large message
+# STDERR: Refusing to read message
Index: clangd/tool/ClangdMain.cpp
===================================================================
--- clangd/tool/ClangdMain.cpp
+++ clangd/tool/ClangdMain.cpp
@@ -238,5 +238,5 @@
llvm::set_thread_name("clangd.main");
// Change stdin to binary to not lose \r\n on windows.
llvm::sys::ChangeStdinToBinary();
- return LSPServer.run(std::cin, InputStyle) ? 0 : NoShutdownRequestErrorCode;
+ return LSPServer.run(stdin, InputStyle) ? 0 : NoShutdownRequestErrorCode;
}
Index: clangd/JSONRPCDispatcher.h
===================================================================
--- clangd/JSONRPCDispatcher.h
+++ clangd/JSONRPCDispatcher.h
@@ -102,7 +102,9 @@
/// if it is.
/// Input stream(\p In) must be opened in binary mode to avoid preliminary
/// replacements of \r\n with \n.
-void runLanguageServerLoop(std::istream &In, JSONOutput &Out,
+/// We use C-style FILE* for reading as std::istream has unclear interaction
+/// with signals, which are sent by debuggers on some OSs.
+void runLanguageServerLoop(std::FILE *In, JSONOutput &Out,
JSONStreamStyle InputStyle,
JSONRPCDispatcher &Dispatcher, bool &IsDone);
Index: clangd/JSONRPCDispatcher.cpp
===================================================================
--- clangd/JSONRPCDispatcher.cpp
+++ clangd/JSONRPCDispatcher.cpp
@@ -14,6 +14,7 @@
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/Chrono.h"
+#include "llvm/Support/Errno.h"
#include "llvm/Support/SourceMgr.h"
#include <istream>
@@ -66,7 +67,7 @@
Outs << "Content-Length: " << S.size() << "\r\n\r\n" << S;
Outs.flush();
}
- log(llvm::Twine("--> ") + S);
+ log(llvm::Twine("--> ") + S + "\n");
}
void JSONOutput::log(const Twine &Message) {
@@ -180,47 +181,55 @@
return true;
}
-static llvm::Optional<std::string> readStandardMessage(std::istream &In,
+// Tries to read a line up to and including \n.
+// If failing, feof() or ferror() will be set.
+static bool readLine(std::FILE *In, std::string &Out) {
+ static constexpr int BufSize = 1024;
+ size_t Size = 0;
+ Out.clear();
+ for (;;) {
+ Out.resize(Size + BufSize);
+ // Handle EINTR which is sent when a debugger attaches on some platforms.
+ if (!llvm::sys::RetryAfterSignal(nullptr, ::fgets, &Out[Size], BufSize, In))
+ return false;
+ clearerr(In);
+ size_t Read = std::strlen(&Out[Size]);
+ if (Read < BufSize - 1) {
+ Out.resize(Size + Read);
+ return true;
+ }
+ Size += Read;
+ }
+}
+
+// Returns None when:
+// - ferror() or feof() are set.
+// - Content-Length is missing or empty (protocol error)
+static llvm::Optional<std::string> readStandardMessage(std::FILE *In,
JSONOutput &Out) {
// A Language Server Protocol message starts with a set of HTTP headers,
// delimited by \r\n, and terminated by an empty line (\r\n).
unsigned long long ContentLength = 0;
- while (In.good()) {
- std::string Line;
- std::getline(In, Line);
- if (!In.good() && errno == EINTR) {
- In.clear();
- continue;
- }
+ std::string Line;
+ while (true) {
+ if (feof(In) || ferror(In) || !readLine(In, Line))
+ return llvm::None;
Out.mirrorInput(Line);
- // Mirror '\n' that gets consumed by std::getline, but is not included in
- // the resulting Line.
- // Note that '\r' is part of Line, so we don't need to mirror it
- // separately.
- if (!In.eof())
- Out.mirrorInput("\n");
-
llvm::StringRef LineRef(Line);
// We allow comments in headers. Technically this isn't part
// of the LSP specification, but makes writing tests easier.
if (LineRef.startswith("#"))
continue;
- // Content-Type is a specified header, but does nothing.
- // Content-Length is a mandatory header. It specifies the length of the
- // following JSON.
- // It is unspecified what sequence headers must be supplied in, so we
- // allow any sequence.
- // The end of headers is signified by an empty line.
+ // Content-Length is a mandatory header, and the only one we handle.
if (LineRef.consume_front("Content-Length: ")) {
if (ContentLength != 0) {
log("Warning: Duplicate Content-Length header received. "
"The previous value for this message (" +
- llvm::Twine(ContentLength) + ") was ignored.\n");
+ llvm::Twine(ContentLength) + ") was ignored.");
}
-
llvm::getAsUnsignedInteger(LineRef.trim(), 0, ContentLength);
continue;
} else if (!LineRef.trim().empty()) {
@@ -233,46 +242,45 @@
}
}
- // Guard against large messages. This is usually a bug in the client code
- // and we don't want to crash downstream because of it.
+ // The fuzzer likes crashing us by sending "Content-Length: 9999999999999999"
if (ContentLength > 1 << 30) { // 1024M
- In.ignore(ContentLength);
- log("Skipped overly large message of " + Twine(ContentLength) +
- " bytes.\n");
+ log("Refusing to read message with long Content-Length: " +
+ Twine(ContentLength) + ". Expect protocol errors.");
+ return llvm::None;
+ }
+ if (ContentLength == 0) {
+ log("Warning: Missing Content-Length header, or zero-length message.");
return llvm::None;
}
- if (ContentLength > 0) {
- std::string JSON(ContentLength, '\0');
- In.read(&JSON[0], ContentLength);
- Out.mirrorInput(StringRef(JSON.data(), In.gcount()));
-
- // If the stream is aborted before we read ContentLength bytes, In
- // will have eofbit and failbit set.
- if (!In) {
- log("Input was aborted. Read only " + llvm::Twine(In.gcount()) +
- " bytes of expected " + llvm::Twine(ContentLength) + ".\n");
+ std::string JSON(ContentLength, '\0');
+ for (size_t Pos = 0, Read; Pos < ContentLength; Pos += Read) {
+ // Handle EINTR which is sent when a debugger attaches on some platforms.
+ Read = llvm::sys::RetryAfterSignal(0u, ::fread, &JSON[Pos], 1,
+ ContentLength - Pos, In);
+ Out.mirrorInput(StringRef(&JSON[Pos], Read));
+ if (Read == 0) {
+ log("Input was aborted. Read only " + llvm::Twine(Pos) +
+ " bytes of expected " + llvm::Twine(ContentLength) + ".");
return llvm::None;
}
- return std::move(JSON);
- } else {
- log("Warning: Missing Content-Length header, or message has zero "
- "length.\n");
- return llvm::None;
+ clearerr(In); // If we're done, the error was transient. If we're not done,
+ // either it was transient or we'll see it again on retry.
+ Pos += Read;
}
+ return std::move(JSON);
}
// For lit tests we support a simplified syntax:
// - messages are delimited by '---' on a line by itself
// - lines starting with # are ignored.
// This is a testing path, so favor simplicity over performance here.
-static llvm::Optional<std::string> readDelimitedMessage(std::istream &In,
+// When returning None, feof() or ferror() will be set.
+static llvm::Optional<std::string> readDelimitedMessage(std::FILE *In,
JSONOutput &Out) {
std::string JSON;
std::string Line;
- while (std::getline(In, Line)) {
- Line.push_back('\n'); // getline() consumed the newline.
-
+ while (readLine(In, Line)) {
auto LineRef = llvm::StringRef(Line).trim();
if (LineRef.startswith("#")) // comment
continue;
@@ -284,39 +292,47 @@
JSON += Line;
}
- if (In.bad()) {
+ if (ferror(In)) {
log("Input error while reading message!");
return llvm::None;
- } else {
+ } else { // Including EOF
Out.mirrorInput(
llvm::formatv("Content-Length: {0}\r\n\r\n{1}", JSON.size(), JSON));
return std::move(JSON);
}
}
-void clangd::runLanguageServerLoop(std::istream &In, JSONOutput &Out,
+// The use of C-style std::FILE* IO deserves some explanation.
+// Previously, std::istream was used. When a debugger attached on MacOS, the
+// process received EINTR, the stream went bad, and clangd exited.
+// A retry-on-EINTR loop around reads solved this problem, but caused clangd to
+// sometimes hang rather than exit on other OSes. The interaction between
+// istreams and signals isn't well-specified, so it's hard to get this right.
+// The C APIs seem to be clearer in this respect.
+void clangd::runLanguageServerLoop(std::FILE *In, JSONOutput &Out,
JSONStreamStyle InputStyle,
JSONRPCDispatcher &Dispatcher,
bool &IsDone) {
auto &ReadMessage =
(InputStyle == Delimited) ? readDelimitedMessage : readStandardMessage;
- while (In.good()) {
+ while (!IsDone && !feof(In)) {
+ if (ferror(In)) {
+ log("IO error: " + llvm::sys::StrError());
+ return;
+ }
if (auto JSON = ReadMessage(In, Out)) {
if (auto Doc = json::parse(*JSON)) {
// Log the formatted message.
log(llvm::formatv(Out.Pretty ? "<-- {0:2}\n" : "<-- {0}\n", *Doc));
// Finally, execute the action for this JSON message.
if (!Dispatcher.call(*Doc, Out))
- log("JSON dispatch failed!\n");
+ log("JSON dispatch failed!");
} else {
// Parse error. Log the raw message.
log(llvm::formatv("<-- {0}\n" , *JSON));
log(llvm::Twine("JSON parse error: ") +
- llvm::toString(Doc.takeError()) + "\n");
+ llvm::toString(Doc.takeError()));
}
}
- // If we're done, exit the loop.
- if (IsDone)
- break;
}
}
Index: clangd/ClangdLSPServer.h
===================================================================
--- clangd/ClangdLSPServer.h
+++ clangd/ClangdLSPServer.h
@@ -42,8 +42,8 @@
/// class constructor. This method must not be executed more than once for
/// each instance of ClangdLSPServer.
///
- /// \return Wether we received a 'shutdown' request before an 'exit' request
- bool run(std::istream &In,
+ /// \return Whether we received a 'shutdown' request before an 'exit' request.
+ bool run(std::FILE *In,
JSONStreamStyle InputStyle = JSONStreamStyle::Standard);
private:
Index: clangd/ClangdLSPServer.cpp
===================================================================
--- clangd/ClangdLSPServer.cpp
+++ clangd/ClangdLSPServer.cpp
@@ -396,7 +396,7 @@
SupportedSymbolKinds(defaultSymbolKinds()),
Server(CDB, FSProvider, /*DiagConsumer=*/*this, Opts) {}
-bool ClangdLSPServer::run(std::istream &In, JSONStreamStyle InputStyle) {
+bool ClangdLSPServer::run(std::FILE *In, JSONStreamStyle InputStyle) {
assert(!IsDone && "Run was called before");
// Set up JSONRPCDispatcher.
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