1 files changed, 23 insertions, 41 deletions

diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 539d0b21b278..08f44b392b00 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -415,18 +415,6 @@ static void commonChildInit(Pipe & logPipe)
 }
 
 
-/* Convert a string list to an array of char pointers.  Careful: the
-   string list should outlive the array. */
-const char * * strings2CharPtrs(const Strings & ss)
-{
-    const char * * arr = new const char * [ss.size() + 1];
-    const char * * p = arr;
-    foreach (Strings::const_iterator, i, ss) *p++ = i->c_str();
-    *p = 0;
-    return arr;
-}
-
-
 //////////////////////////////////////////////////////////////////////
 
 
@@ -816,8 +804,8 @@ private:
     /* Start building a derivation. */
     void startBuilder();
 
-    /* Initialise the builder's process. */
-    void initChild();
+    /* Run the builder's process. */
+    void runChild();
 
     friend int childEntry(void *);
 
@@ -1914,9 +1902,11 @@ void DerivationGoal::startBuilder()
     builderOut.create();
 
     /* Fork a child to build the package. */
+    ProcessOptions options;
+    options.allowVfork = !buildUser.enabled();
     pid = startProcess([&]() {
-        initChild();
-    });
+        runChild();
+    }, options);
 
     /* parent */
     pid.setSeparatePG(true);
@@ -1936,7 +1926,7 @@ void DerivationGoal::startBuilder()
 }
 
 
-void DerivationGoal::initChild()
+void DerivationGoal::runChild()
 {
     /* Warning: in the child we should absolutely not make any SQLite
        calls! */
@@ -1986,9 +1976,11 @@ void DerivationGoal::initChild()
 
             /* 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"
@@ -2122,11 +2114,7 @@ void DerivationGoal::initChild()
         Strings envStrs;
         foreach (Environment::const_iterator, i, env)
             envStrs.push_back(rewriteHashes(i->first + "=" + i->second, rewritesToTmp));
-        const char * * envArr = strings2CharPtrs(envStrs);
-
-        Path program = drv.builder.c_str();
-        std::vector<const char *> args; /* careful with c_str()! */
-        string user; /* must be here for its c_str()! */
+        auto envArr = stringsToCharPtrs(envStrs);
 
         /* If we are running in `build-users' mode, then switch to the
            user we allocated above.  Make sure that we drop all root
@@ -2135,8 +2123,6 @@ void DerivationGoal::initChild()
            setuid() when run as root sets the real, effective and
            saved UIDs. */
         if (buildUser.enabled()) {
-            printMsg(lvlChatty, format("switching to user ‘%1%’") % buildUser.getUser());
-
             if (setgroups(0, 0) == -1)
                 throw SysError("cannot clear the set of supplementary groups");
 
@@ -2152,29 +2138,25 @@ void DerivationGoal::initChild()
         }
 
         /* Fill in the arguments. */
+        Strings args;
         string builderBasename = baseNameOf(drv.builder);
-        args.push_back(builderBasename.c_str());
-        foreach (Strings::iterator, i, drv.args) {
-            auto re = rewriteHashes(*i, rewritesToTmp);
-            auto cstr = new char[re.length()+1];
-            std::strcpy(cstr, re.c_str());
-
-            args.push_back(cstr);
-        }
-        args.push_back(0);
+        args.push_back(builderBasename);
+        foreach (Strings::iterator, i, drv.args)
+            args.push_back(rewriteHashes(*i, rewritesToTmp));
+        auto argArr = stringsToCharPtrs(args);
 
         restoreSIGPIPE();
 
         /* Indicate that we managed to set up the build environment. */
-        writeToStderr("\n");
+        writeFull(STDERR_FILENO, "\n");
 
         /* Execute the program.  This should not return. */
-        execve(program.c_str(), (char * *) &args[0], (char * *) envArr);
+        execve(drv.builder.c_str(), (char * *) &argArr[0], (char * *) &envArr[0]);
 
         throw SysError(format("executing ‘%1%’") % drv.builder);
 
     } catch (std::exception & e) {
-        writeToStderr("while setting up the build environment: " + string(e.what()) + "\n");
+        writeFull(STDERR_FILENO, "while setting up the build environment: " + string(e.what()) + "\n");
         _exit(1);
     }
 }
@@ -2487,7 +2469,7 @@ void DerivationGoal::handleChildOutput(int fd, const string & data)
             BZ2_bzWrite(&err, bzLogFile, (unsigned char *) data.data(), data.size());
             if (err != BZ_OK) throw Error(format("cannot write to compressed log file (BZip2 error = %1%)") % err);
         } else if (fdLogFile != -1)
-            writeFull(fdLogFile, (unsigned char *) data.data(), data.size());
+            writeFull(fdLogFile, data);
     }
 
     if (hook && fd == hook->fromHook.readSide)
@@ -2797,7 +2779,7 @@ void SubstitutionGoal::tryToRun()
     args.push_back("--substitute");
     args.push_back(storePath);
     args.push_back(destPath);
-    const char * * argArr = strings2CharPtrs(args);
+    auto argArr = stringsToCharPtrs(args);
 
     /* Fork the substitute program. */
     pid = startProcess([&]() {
@@ -2807,7 +2789,7 @@ void SubstitutionGoal::tryToRun()
         if (dup2(outPipe.writeSide, STDOUT_FILENO) == -1)
             throw SysError("cannot dup output pipe into stdout");
 
-        execv(sub.c_str(), (char * *) argArr);
+        execv(sub.c_str(), (char * *) &argArr[0]);
 
         throw SysError(format("executing ‘%1%’") % sub);
     });