Split up util.{hh,cc}

All OS and IO operations should be moved out, leaving only some misc
portable pure functions.

This is useful to avoid copious CPP when doing things like Windows and
Emscripten ports.

Newly exposed functions to break cycles:

 - `restoreSignals`
 - `updateWindowSize`

src/libcmd/editor-for.cc

@@ -1,5 +1,5 @@
-#include "util.hh"
 #include "editor-for.hh"
+#include "environment-variables.hh"
 
 namespace nix {
 

src/libcmd/installable-attr-path.hh

@@ -4,7 +4,6 @@
 #include "globals.hh"
 #include "installable-value.hh"
 #include "outputs-spec.hh"
-#include "util.hh"
 #include "command.hh"
 #include "attr-path.hh"
 #include "common-eval-args.hh"

src/libcmd/installables.cc

@@ -4,6 +4,7 @@
 #include "installable-attr-path.hh"
 #include "installable-flake.hh"
 #include "outputs-spec.hh"
+#include "users.hh"
 #include "util.hh"
 #include "command.hh"
 #include "attr-path.hh"

src/libcmd/installables.hh

@@ -1,7 +1,6 @@
 #pragma once
 ///@file
 
-#include "util.hh"
 #include "path.hh"
 #include "outputs-spec.hh"
 #include "derived-path.hh"

src/libcmd/markdown.cc

@@ -1,6 +1,7 @@
 #include "markdown.hh"
 #include "util.hh"
 #include "finally.hh"
+#include "terminal.hh"
 
 #include <sys/queue.h>
 #include <lowdown.h>

src/libcmd/repl.cc

@@ -22,6 +22,7 @@ extern "C" {
 #include "repl.hh"
 
 #include "ansicolor.hh"
+#include "signals.hh"
 #include "shared.hh"
 #include "eval.hh"
 #include "eval-cache.hh"
@@ -36,6 +37,8 @@ extern "C" {
 #include "globals.hh"
 #include "flake/flake.hh"
 #include "flake/lockfile.hh"
+#include "users.hh"
+#include "terminal.hh"
 #include "editor-for.hh"
 #include "finally.hh"
 #include "markdown.hh"

src/libexpr/eval-cache.cc

@@ -1,3 +1,4 @@
+#include "users.hh"
 #include "eval-cache.hh"
 #include "sqlite.hh"
 #include "eval.hh"

src/libexpr/eval-settings.cc

@@ -1,3 +1,4 @@
+#include "users.hh"
 #include "globals.hh"
 #include "profiles.hh"
 #include "eval.hh"

src/libexpr/eval.cc

@@ -12,6 +12,7 @@
 #include "function-trace.hh"
 #include "profiles.hh"
 #include "print.hh"
+#include "signals.hh"
 
 #include <algorithm>
 #include <chrono>

src/libexpr/flake/config.cc

@@ -1,6 +1,7 @@
-#include "flake.hh"
+#include "users.hh"
 #include "globals.hh"
 #include "fetch-settings.hh"
+#include "flake.hh"
 
 #include <nlohmann/json.hpp>
 

src/libexpr/flake/flake.cc

@@ -1,3 +1,4 @@
+#include "terminal.hh"
 #include "flake.hh"
 #include "eval.hh"
 #include "eval-settings.hh"

src/libexpr/parser.y

@@ -19,6 +19,7 @@
 #include <variant>
 
 #include "util.hh"
+#include "users.hh"
 
 #include "nixexpr.hh"
 #include "eval.hh"

src/libexpr/primops.cc

@@ -10,6 +10,7 @@
 #include "path-references.hh"
 #include "store-api.hh"
 #include "util.hh"
+#include "processes.hh"
 #include "value-to-json.hh"
 #include "value-to-xml.hh"
 #include "primops.hh"

src/libexpr/value-to-json.cc

@@ -2,6 +2,7 @@
 #include "eval-inline.hh"
 #include "util.hh"
 #include "store-api.hh"
+#include "signals.hh"
 
 #include <cstdlib>
 #include <iomanip>

src/libexpr/value-to-xml.cc

@@ -2,6 +2,7 @@
 #include "xml-writer.hh"
 #include "eval-inline.hh"
 #include "util.hh"
+#include "signals.hh"
 
 #include <cstdlib>
 

src/libexpr/value/context.cc

@@ -1,3 +1,4 @@
+#include "util.hh"
 #include "value/context.hh"
 
 #include <optional>

src/libexpr/value/context.hh

@@ -1,7 +1,6 @@
 #pragma once
 ///@file
 
-#include "util.hh"
 #include "comparator.hh"
 #include "derived-path.hh"
 #include "variant-wrapper.hh"

src/libfetchers/cache.cc

@@ -1,4 +1,5 @@
 #include "cache.hh"
+#include "users.hh"
 #include "sqlite.hh"
 #include "sync.hh"
 #include "store-api.hh"

src/libfetchers/fetch-settings.hh

@@ -3,7 +3,6 @@
 
 #include "types.hh"
 #include "config.hh"
-#include "util.hh"
 
 #include <map>
 #include <limits>

src/libfetchers/git.cc

@@ -1,10 +1,12 @@
 #include "fetchers.hh"
+#include "users.hh"
 #include "cache.hh"
 #include "globals.hh"
 #include "tarfile.hh"
 #include "store-api.hh"
 #include "url-parts.hh"
 #include "pathlocks.hh"
+#include "processes.hh"
 #include "util.hh"
 #include "git.hh"
 

src/libfetchers/input-accessor.hh

@@ -4,6 +4,7 @@
 #include "types.hh"
 #include "archive.hh"
 #include "canon-path.hh"
+#include "file-system.hh"
 #include "repair-flag.hh"
 
 namespace nix {

src/libfetchers/mercurial.cc

@@ -1,4 +1,6 @@
 #include "fetchers.hh"
+#include "processes.hh"
+#include "users.hh"
 #include "cache.hh"
 #include "globals.hh"
 #include "tarfile.hh"

src/libfetchers/registry.cc

@@ -1,5 +1,6 @@
 #include "registry.hh"
 #include "fetchers.hh"
+#include "users.hh"
 #include "util.hh"
 #include "globals.hh"
 #include "store-api.hh"

src/libmain/common-args.cc

@@ -1,6 +1,8 @@
 #include "common-args.hh"
 #include "globals.hh"
+#include "logging.hh"
 #include "loggers.hh"
+#include "util.hh"
 
 namespace nix {
 

src/libmain/loggers.cc

@@ -1,6 +1,8 @@
 #include "loggers.hh"
+#include "environment-variables.hh"
 #include "progress-bar.hh"
 #include "util.hh"
+#include "util.hh"
 
 namespace nix {
 

src/libmain/progress-bar.cc

@@ -1,4 +1,5 @@
 #include "progress-bar.hh"
+#include "terminal.hh"
 #include "util.hh"
 #include "sync.hh"
 #include "store-api.hh"

src/libmain/shared.cc

@@ -1,10 +1,12 @@
 #include "globals.hh"
+#include "ambient-authority.hh"
 #include "shared.hh"
 #include "store-api.hh"
 #include "gc-store.hh"
 #include "util.hh"
 #include "loggers.hh"
 #include "progress-bar.hh"
+#include "signals.hh"
 
 #include <algorithm>
 #include <cctype>

src/libmain/shared.hh

@@ -1,7 +1,7 @@
 #pragma once
 ///@file
 
-#include "util.hh"
+#include "processes.hh"
 #include "args.hh"
 #include "common-args.hh"
 #include "path.hh"

src/libstore/binary-cache-store.cc

@@ -11,6 +11,7 @@
 #include "nar-accessor.hh"
 #include "thread-pool.hh"
 #include "callback.hh"
+#include "signals.hh"
 
 #include <chrono>
 #include <future>

src/libstore/build/child.cc

@@ -0,0 +1,81 @@
+#include "util.hh"
+#include "users.hh"
+#include "ambient-authority.hh"
+#include "environment-variables.hh"
+#include "file-system.hh"
+#include "signals.hh"
+#include "processes.hh"
+#include "unix-domain-socket.hh"
+#include "sync.hh"
+#include "finally.hh"
+#include "serialise.hh"
+#include "cgroup.hh"
+#include "child.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
+
+namespace nix {
+
+void commonChildInit()
+{
+    logger = makeSimpleLogger();
+
+    const static std::string pathNullDevice = "/dev/null";
+    restoreProcessContext(false);
+
+    /* Put the child in a separate session (and thus a separate
+       process group) so that it has no controlling terminal (meaning
+       that e.g. ssh cannot open /dev/tty) and it doesn't receive
+       terminal signals. */
+    if (setsid() == -1)
+        throw SysError("creating a new session");
+
+    /* Dup stderr to stdout. */
+    if (dup2(STDERR_FILENO, STDOUT_FILENO) == -1)
+        throw SysError("cannot dup stderr into stdout");
+
+    /* Reroute stdin to /dev/null. */
+    int fdDevNull = open(pathNullDevice.c_str(), O_RDWR);
+    if (fdDevNull == -1)
+        throw SysError("cannot open '%1%'", pathNullDevice);
+    if (dup2(fdDevNull, STDIN_FILENO) == -1)
+        throw SysError("cannot dup null device into stdin");
+    close(fdDevNull);
+}
+
+}

src/libstore/build/child.hh

@@ -0,0 +1,11 @@
+#pragma once
+///@file
+
+namespace nix {
+
+/**
+ * Common initialisation performed in child processes.
+ */
+void commonChildInit();
+
+}

src/libstore/build/hook-instance.cc

@@ -1,5 +1,7 @@
 #include "globals.hh"
 #include "hook-instance.hh"
+#include "file-system.hh"
+#include "child.hh"
 
 namespace nix {
 

src/libstore/build/hook-instance.hh

@@ -3,6 +3,7 @@
 
 #include "logging.hh"
 #include "serialise.hh"
+#include "processes.hh"
 
 namespace nix {
 

src/libstore/build/local-derivation-goal.cc

@@ -15,7 +15,10 @@
 #include "json-utils.hh"
 #include "cgroup.hh"
 #include "personality.hh"
-#include "namespaces.hh"
+#include "ambient-authority.hh"
+#include "linux-namespace.hh"
+#include "child.hh"
+#include "unix-domain-socket.hh"
 
 #include <regex>
 #include <queue>

src/libstore/build/local-derivation-goal.hh

@@ -3,6 +3,7 @@
 
 #include "derivation-goal.hh"
 #include "local-store.hh"
+#include "processes.hh"
 
 namespace nix {
 

src/libstore/build/worker.cc

@@ -4,6 +4,7 @@
 #include "drv-output-substitution-goal.hh"
 #include "local-derivation-goal.hh"
 #include "hook-instance.hh"
+#include "signals.hh"
 
 #include <poll.h>
 

src/libstore/crypto.cc

@@ -1,4 +1,5 @@
 #include "crypto.hh"
+#include "file-system.hh"
 #include "util.hh"
 #include "globals.hh"
 

src/libstore/derived-path-map.cc

@@ -1,4 +1,5 @@
 #include "derived-path-map.hh"
+#include "util.hh"
 
 namespace nix {
 

src/libstore/derived-path.hh

@@ -1,10 +1,10 @@
 #pragma once
 ///@file
 
-#include "util.hh"
 #include "path.hh"
 #include "outputs-spec.hh"
 #include "comparator.hh"
+#include "config.hh"
 
 #include <variant>