[clang-tools-extra] r333993 - [clangd] Rewrite JSON dispatcher loop using C IO (FILE*) instead of std::istream.
Sam McCall via cfe-commits
cfe-commits at lists.llvm.org
Fri Jun 8 13:31:45 PDT 2018
Oops, thank you!
r334315 should fix this.
On Fri, Jun 8, 2018 at 9:45 PM Kostya Serebryany <kcc at google.com> wrote:
> Looks like this broke the clang-fuzzer:
> https://oss-fuzz-build-logs.storage.googleapis.com/index.html
>
> Step #4: /src/llvm/tools/clang/tools/extra/clangd/fuzzer/ClangdFuzzer.cpp:31:17: error: no viable conversion from 'std::istringstream' (aka 'basic_istringstream<char>') to 'std::FILE *' (aka '_IO_FILE *')
> Step #4: LSPServer.run(In);
> Step #4: ^~
> Step #4: /src/llvm/tools/clang/tools/extra/clangd/fuzzer/../ClangdLSPServer.h:46:23: note: passing argument to parameter 'In' here
> Step #4: bool run(std::FILE *In,
> Step #4: ^
> Step #4: 1 error generated.
> Step #4: ninja: build stopped: subcommand failed.
>
>
>
> On Tue, Jun 5, 2018 at 2:38 AM Sam McCall via cfe-commits <
> cfe-commits at lists.llvm.org> wrote:
>
>> Author: sammccall
>> Date: Tue Jun 5 02:34:46 2018
>> New Revision: 333993
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=333993&view=rev
>> Log:
>> [clangd] Rewrite JSON dispatcher loop using C IO (FILE*) instead of
>> std::istream.
>>
>> Summary:
>> The EINTR loop around getline was added to fix an issue with mac gdb, but
>> seems
>> to loop infinitely in rare cases on linux where the parent editor exits
>> (most
>> reports with VSCode).
>> I can't work out how to fix this in a portable way with std::istream, but
>> the
>> C APIs have clearer contracts and LLVM has a RetryAfterSignal function
>> for use
>> with them which seems battle-tested.
>>
>> While here, clean up some inconsistency around \n in log messages (now
>> add it only after JSON payloads), and reduce the scope of the
>> long-message handling which was only really added to fight fuzzers.
>>
>> Reviewers: malaperle, ilya-biryukov
>>
>> Subscribers: klimek, ioeric, jkorous, cfe-commits
>>
>> Differential Revision: https://reviews.llvm.org/D47643
>>
>> Modified:
>> clang-tools-extra/trunk/clangd/ClangdLSPServer.cpp
>> clang-tools-extra/trunk/clangd/ClangdLSPServer.h
>> clang-tools-extra/trunk/clangd/JSONRPCDispatcher.cpp
>> clang-tools-extra/trunk/clangd/JSONRPCDispatcher.h
>> clang-tools-extra/trunk/clangd/tool/ClangdMain.cpp
>> clang-tools-extra/trunk/test/clangd/too_large.test
>>
>> Modified: clang-tools-extra/trunk/clangd/ClangdLSPServer.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clangd/ClangdLSPServer.cpp?rev=333993&r1=333992&r2=333993&view=diff
>>
>> ==============================================================================
>> --- clang-tools-extra/trunk/clangd/ClangdLSPServer.cpp (original)
>> +++ clang-tools-extra/trunk/clangd/ClangdLSPServer.cpp Tue Jun 5
>> 02:34:46 2018
>> @@ -396,7 +396,7 @@ ClangdLSPServer::ClangdLSPServer(JSONOut
>> 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.
>>
>> Modified: clang-tools-extra/trunk/clangd/ClangdLSPServer.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clangd/ClangdLSPServer.h?rev=333993&r1=333992&r2=333993&view=diff
>>
>> ==============================================================================
>> --- clang-tools-extra/trunk/clangd/ClangdLSPServer.h (original)
>> +++ clang-tools-extra/trunk/clangd/ClangdLSPServer.h Tue Jun 5 02:34:46
>> 2018
>> @@ -42,8 +42,8 @@ public:
>> /// 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:
>>
>> Modified: clang-tools-extra/trunk/clangd/JSONRPCDispatcher.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clangd/JSONRPCDispatcher.cpp?rev=333993&r1=333992&r2=333993&view=diff
>>
>> ==============================================================================
>> --- clang-tools-extra/trunk/clangd/JSONRPCDispatcher.cpp (original)
>> +++ clang-tools-extra/trunk/clangd/JSONRPCDispatcher.cpp Tue Jun 5
>> 02:34:46 2018
>> @@ -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 @@ void JSONOutput::writeMessage(const json
>> 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) {
>> @@ -180,27 +181,43 @@ bool JSONRPCDispatcher::call(const json:
>> 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);
>> + // If the line contained null bytes, anything after it (including
>> \n) will
>> + // be ignored. Fortunately this is not a legal header or JSON.
>> + size_t Read = std::strlen(&Out[Size]);
>> + if (Read > 0 && Out[Size + Read - 1] == '\n') {
>> + 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
>> @@ -208,19 +225,13 @@ static llvm::Optional<std::string> readS
>> 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 +244,45 @@ static llvm::Optional<std::string> readS
>> }
>> }
>>
>> - // 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 +294,47 @@ static llvm::Optional<std::string> readD
>> 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;
>> }
>> }
>>
>> Modified: clang-tools-extra/trunk/clangd/JSONRPCDispatcher.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clangd/JSONRPCDispatcher.h?rev=333993&r1=333992&r2=333993&view=diff
>>
>> ==============================================================================
>> --- clang-tools-extra/trunk/clangd/JSONRPCDispatcher.h (original)
>> +++ clang-tools-extra/trunk/clangd/JSONRPCDispatcher.h Tue Jun 5
>> 02:34:46 2018
>> @@ -102,7 +102,9 @@ enum JSONStreamStyle {
>> /// 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);
>>
>>
>> Modified: clang-tools-extra/trunk/clangd/tool/ClangdMain.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clangd/tool/ClangdMain.cpp?rev=333993&r1=333992&r2=333993&view=diff
>>
>> ==============================================================================
>> --- clang-tools-extra/trunk/clangd/tool/ClangdMain.cpp (original)
>> +++ clang-tools-extra/trunk/clangd/tool/ClangdMain.cpp Tue Jun 5
>> 02:34:46 2018
>> @@ -238,5 +238,5 @@ int main(int argc, char *argv[]) {
>> 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;
>> }
>>
>> Modified: clang-tools-extra/trunk/test/clangd/too_large.test
>> URL:
>> http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/test/clangd/too_large.test?rev=333993&r1=333992&r2=333993&view=diff
>>
>> ==============================================================================
>> --- clang-tools-extra/trunk/test/clangd/too_large.test (original)
>> +++ clang-tools-extra/trunk/test/clangd/too_large.test Tue Jun 5
>> 02:34:46 2018
>> @@ -4,4 +4,4 @@
>> #
>> Content-Length: 2147483648
>>
>> -# STDERR: Skipped overly large message
>> +# STDERR: Refusing to read message
>>
>>
>> _______________________________________________
>> cfe-commits mailing list
>> cfe-commits at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20180608/e3fead84/attachment-0001.html>
More information about the cfe-commits
mailing list