08/27: Silence some warnings on GCC 4.9

[Ludovic Courtès]

civodul pushed a commit to branch nix
in repository guix.

commit b499d2efbfbe83c4683e2c778494541937c816f3
Author: Eelco Dolstra <address@hidden>
Date:   Fri Dec 12 17:14:28 2014 +0100

    Silence some warnings on GCC 4.9
---
 nix/libstore/build.cc        |    6 ++++--
 nix/libstore/remote-store.cc |    2 +-
 nix/nix-daemon/nix-daemon.cc |   10 +++++++---
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/nix/libstore/build.cc b/nix/libstore/build.cc
index 7e61f96..c99bbed 100644
--- a/nix/libstore/build.cc
+++ b/nix/libstore/build.cc
@@ -2009,9 +2009,11 @@ void DerivationGoal::runChild()
 
             /* Set the hostname etc. to fixed values. */
             char hostname[] = "localhost";
-            sethostname(hostname, sizeof(hostname));
+            if (sethostname(hostname, sizeof(hostname)) == -1)
+                throw SysError("cannot set host name");
             char domainname[] = "(none)"; // kernel default
-            setdomainname(domainname, sizeof(domainname));
+            if (setdomainname(domainname, sizeof(domainname)) == -1)
+                throw SysError("cannot set domain name");
 
             /* Make all filesystems private.  This is necessary
                because subtrees may have been mounted as "shared"
diff --git a/nix/libstore/remote-store.cc b/nix/libstore/remote-store.cc
index 448d9b6..9d75282 100644
--- a/nix/libstore/remote-store.cc
+++ b/nix/libstore/remote-store.cc
@@ -109,7 +109,7 @@ void RemoteStore::connectToDaemon()
        applications... */
     AutoCloseFD fdPrevDir = open(".", O_RDONLY);
     if (fdPrevDir == -1) throw SysError("couldn't open current directory");
-    chdir(dirOf(socketPath).c_str());
+    if (chdir(dirOf(socketPath).c_str()) == -1) throw SysError("couldn't 
change current directory");
     Path socketPathRel = "./" + baseNameOf(socketPath);
 
     struct sockaddr_un addr;
diff --git a/nix/nix-daemon/nix-daemon.cc b/nix/nix-daemon/nix-daemon.cc
index ecff25d..5801989 100644
--- a/nix/nix-daemon/nix-daemon.cc
+++ b/nix/nix-daemon/nix-daemon.cc
@@ -793,6 +793,9 @@ bool matchUser(const string & user, const string & group, 
const Strings & users)
 
 static void daemonLoop()
 {
+    if (chdir("/") == -1)
+        throw SysError("cannot change current directory");
+
     /* Get rid of children automatically; don't let them become
        zombies. */
     setSigChldAction(true);
@@ -821,7 +824,8 @@ static void daemonLoop()
         /* Urgh, sockaddr_un allows path names of only 108 characters.
            So chdir to the socket directory so that we can pass a
            relative path name. */
-        chdir(dirOf(socketPath).c_str());
+        if (chdir(dirOf(socketPath).c_str()) == -1)
+            throw SysError("cannot change current directory");
         Path socketPathRel = "./" + baseNameOf(socketPath);
 
         struct sockaddr_un addr;
@@ -841,7 +845,8 @@ static void daemonLoop()
         if (res == -1)
             throw SysError(format("cannot bind to socket `%1%'") % socketPath);
 
-        chdir("/"); /* back to the root */
+        if (chdir("/") == -1) /* back to the root */
+            throw SysError("cannot change current directory");
 
         if (listen(fdSocket, 5) == -1)
             throw SysError(format("cannot listen on socket `%1%'") % 
socketPath);
@@ -945,7 +950,6 @@ void run(Strings args)
         if (arg == "--daemon") /* ignored for backwards compatibility */;
     }
 
-    chdir("/");
     daemonLoop();
 }