eldritch horrorsandjade
b0d7a81613
clangd broke because it can't look through symlinks. compile_commands manipulation does not fix it, clangd configuration does not fix it, a vfs overlay does not fix it, and while a combination of those can fix it with a bind mount in place that's just too cursed to even consider clangd bug: https://github.com/llvm/llvm-project/issues/116877 Change-Id: I8e3e8489548eb3a7aa65ac9d12a5ec8abf814aec
117 lines
3.7 KiB
C++
117 lines
3.7 KiB
C++
#include "lix/libutil/file-system.hh"
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#include "lix/libutil/processes.hh"
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#include "lix/libutil/unix-domain-socket.hh"
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#include "lix/libutil/strings.hh"
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#include <sys/socket.h>
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#include <sys/un.h>
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#include <unistd.h>
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namespace nix {
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AutoCloseFD createUnixDomainSocket()
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{
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AutoCloseFD fdSocket{socket(PF_UNIX, SOCK_STREAM
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#ifdef SOCK_CLOEXEC
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| SOCK_CLOEXEC
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#endif
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, 0)};
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if (!fdSocket)
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throw SysError("cannot create Unix domain socket");
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closeOnExec(fdSocket.get());
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return fdSocket;
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}
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AutoCloseFD createUnixDomainSocket(const Path & path, mode_t mode)
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{
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auto fdSocket = nix::createUnixDomainSocket();
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bind(fdSocket.get(), path);
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chmodPath(path.c_str(), mode);
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if (listen(fdSocket.get(), 100) == -1)
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throw SysError("cannot listen on socket '%1%'", path);
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return fdSocket;
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}
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/**
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* Workaround for the max length of Unix socket names being between 102
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* (darwin) and 108 (Linux), which is extremely short. This limitation is
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* caused by historical restrictions on sizeof(struct sockaddr):
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* https://unix.stackexchange.com/a/367012.
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*
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* Our solution here is to start a process inheriting the socket, chdir into
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* the directory of the socket, then connect with just the filename. This is
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* rather silly but it works around working directory being process-wide state,
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* and is as clearly sound as possible.
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*/
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static void bindConnectProcHelper(
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std::string_view operationName, auto && operation,
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int fd, const std::string & path)
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{
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struct sockaddr_un addr;
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addr.sun_family = AF_UNIX;
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// Casting between types like these legacy C library interfaces
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// require is forbidden in C++. To maintain backwards
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// compatibility, the implementation of the bind/connect functions
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// contains some hints to the compiler that allow for this
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// special case.
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auto * psaddr = reinterpret_cast<struct sockaddr *>(&addr);
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if (path.size() + 1 >= sizeof(addr.sun_path)) {
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Pipe pipe;
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pipe.create();
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Pid pid{startProcess([&] {
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try {
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pipe.readSide.close();
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Path dir = dirOf(path);
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if (chdir(dir.c_str()) == -1)
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throw SysError("chdir to '%s' failed", dir);
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std::string base(baseNameOf(path));
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if (base.size() + 1 >= sizeof(addr.sun_path))
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throw Error("socket path '%s' is too long", base);
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memcpy(addr.sun_path, base.c_str(), base.size() + 1);
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if (operation(fd, psaddr, sizeof(addr)) == -1)
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throw SysError("cannot %s to socket at '%s'", operationName, path);
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writeFull(pipe.writeSide.get(), "0\n");
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} catch (SysError & e) {
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writeFull(pipe.writeSide.get(), fmt("%d\n", e.errNo));
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} catch (...) {
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writeFull(pipe.writeSide.get(), "-1\n");
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}
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})};
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pipe.writeSide.close();
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auto errNo = string2Int<int>(chomp(drainFD(pipe.readSide.get())));
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if (!errNo || *errNo == -1)
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throw Error("cannot %s to socket at '%s'", operationName, path);
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else if (*errNo > 0) {
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errno = *errNo;
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throw SysError("cannot %s to socket at '%s'", operationName, path);
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}
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} else {
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memcpy(addr.sun_path, path.c_str(), path.size() + 1);
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if (operation(fd, psaddr, sizeof(addr)) == -1)
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throw SysError("cannot %s to socket at '%s'", operationName, path);
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}
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}
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void bind(int fd, const std::string & path)
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{
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unlink(path.c_str());
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bindConnectProcHelper("bind", ::bind, fd, path);
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}
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void connect(int fd, const std::string & path)
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{
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bindConnectProcHelper("connect", ::connect, fd, path);
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}
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}
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