From 50dc1f5b71f7e0e4ba628904b9a47d9f9d875b3e Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Thu, 31 Jul 2014 10:31:17 +0200
Subject: [PATCH] =?UTF-8?q?Restore=20default=20SIGPIPE=20handler=20before?=
 =?UTF-8?q?=20invoking=20=E2=80=98man=E2=80=99?=
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Fixes NixOS/nixpkgs#3410.
---
 src/libmain/shared.cc |  6 +++---
 src/libstore/build.cc | 12 ------------
 src/libutil/util.cc   | 10 ++++++++++
 src/libutil/util.hh   |  4 ++++
 4 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc
index 14263446f..47c38e33e 100644
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@@ -244,9 +244,9 @@ static void initAndRun(int argc, char * * argv)
 
 void showManPage(const string & name)
 {
-    string cmd = "man " + name;
-    if (system(cmd.c_str()) != 0)
-        throw Error(format("command `%1%' failed") % cmd);
+    restoreSIGPIPE();
+    execlp("man", "man", name.c_str(), NULL);
+    throw SysError(format("command `man %1%' failed") % name.c_str());
 }
 
 
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 4376a8322..479bc4a24 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -413,18 +413,6 @@ const char * * strings2CharPtrs(const Strings & ss)
 }
 
 
-/* Restore default handling of SIGPIPE, otherwise some programs will
-   randomly say "Broken pipe". */
-static void restoreSIGPIPE()
-{
-    struct sigaction act, oact;
-    act.sa_handler = SIG_DFL;
-    act.sa_flags = 0;
-    sigemptyset(&act.sa_mask);
-    if (sigaction(SIGPIPE, &act, &oact)) throw SysError("resetting SIGPIPE");
-}
-
-
 //////////////////////////////////////////////////////////////////////
 
 
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index aa9d99ec3..f762b79c2 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -927,6 +927,16 @@ void closeOnExec(int fd)
 }
 
 
+void restoreSIGPIPE()
+{
+    struct sigaction act, oact;
+    act.sa_handler = SIG_DFL;
+    act.sa_flags = 0;
+    sigemptyset(&act.sa_mask);
+    if (sigaction(SIGPIPE, &act, &oact)) throw SysError("resetting SIGPIPE");
+}
+
+
 //////////////////////////////////////////////////////////////////////
 
 
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index ad0d377a4..64250c522 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -273,6 +273,10 @@ void closeMostFDs(const set<int> & exceptions);
 /* Set the close-on-exec flag for the given file descriptor. */
 void closeOnExec(int fd);
 
+/* Restore default handling of SIGPIPE, otherwise some programs will
+   randomly say "Broken pipe". */
+void restoreSIGPIPE();
+
 
 /* User interruption. */