101/118: On Linux, disable address space randomization

[Ludovic Courtès]

civodul pushed a commit to branch nix
in repository guix.

commit e63c8aaa0511d1d0a5487c45dec9f8cbd66b4cc6
Author: Eelco Dolstra <address@hidden>
Date:   Wed Sep 17 17:21:13 2014 +0200

    On Linux, disable address space randomization
---
 nix/libstore/build.cc |   14 +++++++++-----
 1 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/nix/libstore/build.cc b/nix/libstore/build.cc
index 36c6ea8..19d22ac 100644
--- a/nix/libstore/build.cc
+++ b/nix/libstore/build.cc
@@ -57,9 +57,8 @@
 #include <netinet/ip.h>
 #endif
 
-#if HAVE_SYS_PERSONALITY_H
+#if __linux__
 #include <sys/personality.h>
-#define CAN_DO_LINUX32_BUILDS
 #endif
 
 #if HAVE_STATVFS
@@ -1194,7 +1193,7 @@ static string get(const StringPairs & map, const string & 
key)
 static bool canBuildLocally(const string & platform)
 {
     return platform == settings.thisSystem
-#ifdef CAN_DO_LINUX32_BUILDS
+#if __linux__
         || (platform == "i686-linux" && settings.thisSystem == "x86_64-linux")
 #endif
         ;
@@ -2107,7 +2106,7 @@ void DerivationGoal::initChild()
         /* Close all other file descriptors. */
         closeMostFDs(set<int>());
 
-#ifdef CAN_DO_LINUX32_BUILDS
+#if __linux__
         /* Change the personality to 32-bit if we're doing an
            i686-linux build on an x86_64-linux machine. */
         struct utsname utsbuf;
@@ -2115,7 +2114,7 @@ void DerivationGoal::initChild()
         if (drv.platform == "i686-linux" &&
             (settings.thisSystem == "x86_64-linux" ||
              (!strcmp(utsbuf.sysname, "Linux") && !strcmp(utsbuf.machine, 
"x86_64")))) {
-            if (personality(0x0008 | 0x8000000 /* == PER_LINUX32_3GB */) == -1)
+            if (personality(PER_LINUX32_3GB) == -1)
                 throw SysError("cannot set i686-linux personality");
         }
 
@@ -2125,6 +2124,11 @@ void DerivationGoal::initChild()
             int cur = personality(0xffffffff);
             if (cur != -1) personality(cur | 0x0020000 /* == UNAME26 */);
         }
+
+        /* Disable address space randomization for improved
+           determinism. */
+        int cur = personality(0xffffffff);
+        if (cur != -1) personality(cur | ADDR_NO_RANDOMIZE);
 #endif
 
         /* Fill in the environment. */