From 0669f71b0c78c0d3374571d266004d7503ca8b12 Mon Sep 17 00:00:00 2001
From: Thiago Macieira <thiago.macieira@intel.com>
Date: Tue, 6 Jun 2017 18:28:37 -0700
Subject: QRandomGenerator: don't internally rely on QT_HAS_INCLUDE

GCC didn't support it until version 5 or 6, so add configure tests for
both <random> and <sys/auxv.h>. Normally I'd say "upgrade", but this is
too low-level and important a feature.

There's a good chance that all our supported compilers have <random>
anyway. As for <sys/auxv.h>, it's present on Glibc, Bionic and MUSL, but
I don't see it in uClibc (AT_RANDOM is a Linux-specific feature).

Change-Id: Ia3e896da908f42939148fffd14c5b2af491f7a77
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
---
 src/corelib/configure.json                | 25 +++++++++++++++++++++++++
 src/corelib/global/qconfig-bootstrapped.h |  2 ++
 src/corelib/global/qrandom.cpp            |  6 +++---
 3 files changed, 30 insertions(+), 3 deletions(-)

(limited to 'src')

diff --git a/src/corelib/configure.json b/src/corelib/configure.json
index 7fca3137eb..0da3bff713 100644
--- a/src/corelib/configure.json
+++ b/src/corelib/configure.json
@@ -138,6 +138,11 @@
             "type": "compile",
             "test": "unix/cloexec"
         },
+        "cxx11_random": {
+            "label": "C++11 <random>",
+            "type": "compile",
+            "test": "unix/cxx11_random"
+        },
         "eventfd": {
             "label": "eventfd",
             "type": "compile",
@@ -208,6 +213,11 @@
             "type": "compile",
             "test": "unix/syslog"
         },
+        "sys_auxv": {
+            "label": "sys/auxv.h",
+            "type": "compile",
+            "test": "unix/sys_auxv"
+        },
         "xlocalescanprint": {
             "label": "xlocale.h (or equivalents)",
             "type": "compile",
@@ -242,6 +252,11 @@
             "condition": "features.doubleconversion && libs.doubleconversion",
             "output": [ "privateFeature" ]
         },
+        "cxx11_random": {
+            "label": "C++11 <random>",
+            "condition": "tests.cxx11_random",
+            "output": [ "privateFeature" ]
+        },
         "eventfd": {
             "label": "eventfd",
             "condition": "tests.eventfd",
@@ -394,6 +409,11 @@
             "condition": "tests.syslog",
             "output": [ "privateFeature" ]
         },
+        "sys_auxv": {
+            "label": "sys/auxv.h",
+            "condition": "config.linux && tests.sys_auxv",
+            "output": [ "privateFeature" ]
+        },
         "threadsafe-cloexec": {
             "label": "Threadsafe pipe creation",
             "condition": "tests.cloexec",
@@ -630,6 +650,11 @@ If your users intend to develop applications against this build,
 ensure that the IDEs they use either set QT_LOGGING_TO_CONSOLE to 1
 or are able to read the logged output from journald, syslog or slog2."
         },
+        {
+            "type": "warning",
+            "condition": "!config.win32 && !config.darwin && !config.bsd && !features.cxx11_random",
+            "message": "No high-quality PRNG available for QRandomGenerator fallback.\nIf the HW or OS RNG fails, Qt will abort execution."
+        },
         {
             "type": "error",
             "condition": "input.doubleconversion == 'no' && !tests.xlocalescanprint",
diff --git a/src/corelib/global/qconfig-bootstrapped.h b/src/corelib/global/qconfig-bootstrapped.h
index 374b53a9b5..a6a56b5d59 100644
--- a/src/corelib/global/qconfig-bootstrapped.h
+++ b/src/corelib/global/qconfig-bootstrapped.h
@@ -75,6 +75,7 @@
 #else
 # define QT_FEATURE_alloca_malloc_h -1
 #endif
+#define QT_FEATURE_cxx11_random (QT_HAS_INCLUDE(<random>) ? 1 : -1)
 #define QT_FEATURE_iconv -1
 #define QT_FEATURE_icu -1
 #define QT_FEATURE_journald -1
@@ -96,6 +97,7 @@
 #define QT_NO_GEOM_VARIANT
 #define QT_FEATURE_sharedmemory -1
 #define QT_FEATURE_systemsemaphore -1
+#define QT_FEATURE_sys_auxv (QT_HAS_INCLUDE(<sys/auxv.h>) ? 1 : -1)
 
 #ifdef QT_BUILD_QMAKE
 #define QT_FEATURE_commandlineparser -1
diff --git a/src/corelib/global/qrandom.cpp b/src/corelib/global/qrandom.cpp
index 83a309b143..6a92260c46 100644
--- a/src/corelib/global/qrandom.cpp
+++ b/src/corelib/global/qrandom.cpp
@@ -46,13 +46,13 @@
 #include <qthreadstorage.h>
 #include <private/qsimd_p.h>
 
-#if QT_HAS_INCLUDE(<random>)
+#if QT_CONFIG(cxx11_random)
 #  include <random>
 #  include "qdeadlinetimer.h"
 #  include "qhashfunctions.h"
 #endif
 
-#if QT_HAS_INCLUDE(<sys/auxv.h>)
+#if QT_CONFIG(sys_auxv)
 #  include <sys/auxv.h>
 #endif
 
@@ -213,7 +213,7 @@ static void fallback_fill(quint32 *ptr, qssize_t left) Q_DECL_NOTHROW
     // BSDs have arc4random(4) and these work even in chroot(2)
     arc4random_buf(ptr, left * sizeof(*ptr));
 }
-#elif QT_HAS_INCLUDE(<chrono>)
+#elif QT_CONFIG(cxx11_random)
 static QBasicAtomicInteger<unsigned> seed = Q_BASIC_ATOMIC_INITIALIZER(0U);
 static void fallback_update_seed(unsigned value)
 {
-- 
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