WIP

Co-Authored-By volth <volth@volth.com>

src/libutil/unix/util-unix.hh

@@ -0,0 +1,73 @@
+#pragma once
+///@file
+
+#include "util.hh"
+
+namespace nix {
+
+/**
+ * @return the given user's home directory from /etc/passwd.
+ */
+Path getHomeOf(uid_t userId);
+
+/**
+ * Kill all processes running under the specified uid by sending them
+ * a SIGKILL.
+ */
+void killUser(uid_t uid);
+
+
+/**
+ * Start a thread that handles various signals. Also block those signals
+ * on the current thread (and thus any threads created by it).
+ * Saves the signal mask before changing the mask to block those signals.
+ * See saveSignalMask().
+ */
+void startSignalHandlerThread();
+
+/**
+ * Saves the signal mask, which is the signal mask that nix will restore
+ * before creating child processes.
+ * See setChildSignalMask() to set an arbitrary signal mask instead of the
+ * current mask.
+ */
+void saveSignalMask();
+
+/**
+ * Sets the signal mask. Like saveSignalMask() but for a signal set that doesn't
+ * necessarily match the current thread's mask.
+ * See saveSignalMask() to set the saved mask to the current mask.
+ */
+void setChildSignalMask(sigset_t *sigs);
+
+struct InterruptCallback
+{
+    virtual ~InterruptCallback() { };
+};
+
+/**
+ * Register a function that gets called on SIGINT (in a non-signal
+ * context).
+ */
+std::unique_ptr<InterruptCallback> createInterruptCallback(
+    std::function<void()> callback);
+
+void triggerInterrupt();
+
+/**
+ * A RAII class that causes the current thread to receive SIGUSR1 when
+ * the signal handler thread receives SIGINT. That is, this allows
+ * SIGINT to be multiplexed to multiple threads.
+ */
+struct ReceiveInterrupts
+{
+    pthread_t target;
+    std::unique_ptr<InterruptCallback> callback;
+
+    ReceiveInterrupts()
+        : target(pthread_self())
+        , callback(createInterruptCallback([&]() { pthread_kill(target, SIGUSR1); }))
+    { }
+};
+
+}

src/libutil/unix/util.cc

@@ -0,0 +1,63 @@
+#include "util.hh"
+#include "sync.hh"
+#include "finally.hh"
+#include "serialise.hh"
+#include "cgroup.hh"
+
+#include <array>
+#include <cctype>
+#include <cerrno>
+#include <climits>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <future>
+#include <iostream>
+#include <mutex>
+#include <sstream>
+#include <thread>
+
+#include <fcntl.h>
+#include <grp.h>
+#include <pwd.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/wait.h>
+#include <sys/time.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+#ifdef __APPLE__
+#include <sys/syscall.h>
+#include <mach-o/dyld.h>
+#endif
+
+#ifdef __linux__
+#include <sys/prctl.h>
+#include <sys/resource.h>
+#include <sys/mman.h>
+
+#include <cmath>
+#endif
+
+
+extern char * * environ __attribute__((weak));
+
+
+namespace nix {
+
+void clearEnv()
+{
+    for (auto & name : getEnv())
+        unsetenv(name.first.c_str());
+}
+
+void replaceEnv(const std::map<std::string, std::string> & newEnv)
+{
+    clearEnv();
+    for (auto & newEnvVar : newEnv)
+        setenv(newEnvVar.first.c_str(), newEnvVar.second.c_str(), 1);
+}
+
+}