From aef44cbaa9aaa6fa40eb34c411cedd858e16101e Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Sun, 11 Oct 2020 16:38:46 +0000
Subject: [PATCH] Split out `commonChildInit`

---
 src/libstore/build.cc | 29 -----------------------------
 src/libutil/util.cc   | 29 +++++++++++++++++++++++++++++
 src/libutil/util.hh   |  2 ++
 3 files changed, 31 insertions(+), 29 deletions(-)

diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 05a9ef088eb..5757e5c3f76 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -456,35 +456,6 @@ void Goal::trace(const FormatOrString & fs)
 //////////////////////////////////////////////////////////////////////
 
 
-/* Common initialisation performed in child processes. */
-static void commonChildInit(Pipe & logPipe)
-{
-    restoreSignals();
-
-    /* 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 the write side of the logger pipe into stderr. */
-    if (dup2(logPipe.writeSide.get(), STDERR_FILENO) == -1)
-        throw SysError("cannot pipe standard error into log file");
-
-    /* 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);
-}
-
 void handleDiffHook(
     uid_t uid, uid_t gid,
     const Path & tryA, const Path & tryB,
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 9804e9a51fe..53342b5cb1e 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1660,4 +1660,33 @@ string showBytes(uint64_t bytes)
 }
 
 
+void commonChildInit(Pipe & logPipe)
+{
+    const static string pathNullDevice = "/dev/null";
+    restoreSignals();
+
+    /* 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 the write side of the logger pipe into stderr. */
+    if (dup2(logPipe.writeSide.get(), STDERR_FILENO) == -1)
+        throw SysError("cannot pipe standard error into log file");
+
+    /* 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);
+}
+
 }
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 129d59a9783..cafe93702b4 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -536,6 +536,8 @@ typedef std::function<bool(const Path & path)> PathFilter;
 
 extern PathFilter defaultPathFilter;
 
+/* Common initialisation performed in child processes. */
+void commonChildInit(Pipe & logPipe);
 
 /* Create a Unix domain socket in listen mode. */
 AutoCloseFD createUnixDomainSocket(const Path & path, mode_t mode);