Simplify the FileTime implementation

The mode without the clock_gettime was added to support "older Unixes"
such as macOS < 10.12 (see aba193d23420777a309597fe64a9398076b6ff25).

Later, custom clock_gettime version was added for the
same reason (see 2aa3131bef6444a800f6e6259cecf44851eb0454).

MacOS < 10.12 is not supported anymore as probably all other Unixes
that do not support clock_gettime.
Another argument for that is that Qt 5.13 and above uses high-precision
time structs unconditionally - so, if Unix does not support such
structs, Qt won't compile as well.

Thus, copy the workaround for clock_gettime problem from Qt 5.13 and
remove the branch for low-precision file time at all.

Change-Id: I8aaa630f87d9a845578e7701c627ea190d4e17ac
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

3 files changed, 35 insertions, 73 deletions

diff --git a/src/lib/corelib/tools/fileinfo.cpp b/src/lib/corelib/tools/fileinfo.cpp
index 382843a33..afd125df5 100644
--- a/src/lib/corelib/tools/fileinfo.cpp
+++ b/src/lib/corelib/tools/fileinfo.cpp
@@ -354,10 +354,8 @@ FileTime FileInfo::lastModified() const
 {
 #if APPLE_STAT_TIMESPEC
     return m_stat.st_mtimespec;
-#elif HAS_CLOCK_GETTIME
-    return m_stat.st_mtim;
 #else
-    return m_stat.st_mtime;
+    return m_stat.st_mtim;
 #endif
 }
 
@@ -365,10 +363,8 @@ FileTime FileInfo::lastStatusChange() const
 {
 #if APPLE_STAT_TIMESPEC
     return m_stat.st_ctimespec;
-#elif HAS_CLOCK_GETTIME
-    return m_stat.st_ctim;
 #else
-    return m_stat.st_ctime;
+    return m_stat.st_ctim;
 #endif
 }
 
diff --git a/src/lib/corelib/tools/filetime.cpp b/src/lib/corelib/tools/filetime.cpp
index d115075a7..3f8ef1d69 100644
--- a/src/lib/corelib/tools/filetime.cpp
+++ b/src/lib/corelib/tools/filetime.cpp
@@ -50,23 +50,32 @@
 namespace qbs {
 namespace Internal {
 
-#ifdef APPLE_CUSTOM_CLOCK_GETTIME
-#include <sys/time.h>
+#if !defined(Q_OS_WIN)
 
-#ifndef CLOCK_REALTIME
-#define CLOCK_REALTIME 0
-#endif
-
-// clk_id isn't used, only the CLOCK_REALTIME case is implemented.
-int clock_gettime(int /*clk_id*/, struct timespec *t)
+// based on https://github.com/qt/qtbase/blob/5.13/src/corelib/kernel/qelapsedtimer_unix.cpp
+// for details why it is implemented this way, see Qt source code
+#  if !defined(CLOCK_REALTIME)
+#    define CLOCK_REALTIME 0
+static inline void qbs_clock_gettime(int, struct timespec *ts)
 {
+    // support clock_gettime with gettimeofday
     struct timeval tv;
-    // Resolution of gettimeofday is 1000nsecs = 1 microsecond.
-    int ret = gettimeofday(&tv, NULL);
-    t->tv_sec  = tv.tv_sec;
-    t->tv_nsec = tv.tv_usec * 1000;
-    return ret;
+    gettimeofday(&tv, 0);
+    ts->tv_sec = tv.tv_sec;
+    ts->tv_nsec = tv.tv_usec * 1000;
+}
+
+#    ifdef _POSIX_MONOTONIC_CLOCK
+#      undef _POSIX_MONOTONIC_CLOCK
+#      define _POSIX_MONOTONIC_CLOCK -1
+#    endif
+#  else
+static inline void qbs_clock_gettime(clockid_t clock, struct timespec *ts)
+{
+    clock_gettime(clock, ts);
 }
+#  endif
+
 #endif
 
 FileTime::FileTime()
@@ -75,16 +84,14 @@ FileTime::FileTime()
     static_assert(sizeof(FileTime::InternalType) == sizeof(FILETIME),
                   "FileTime::InternalType has wrong size.");
     m_fileTime = 0;
-#elif HAS_CLOCK_GETTIME
-    m_fileTime = {0, 0};
 #else
-    m_fileTime = 0;
+    m_fileTime = {0, 0};
 #endif
 }
 
 FileTime::FileTime(const FileTime::InternalType &ft) : m_fileTime(ft)
 {
-#if HAS_CLOCK_GETTIME
+#if !defined(Q_OS_WIN)
     if (m_fileTime.tv_sec == 0)
         m_fileTime.tv_nsec = 0; // stat() sets only the first member to 0 for non-existing files.
 #endif
@@ -96,7 +103,7 @@ int FileTime::compare(const FileTime &other) const
     auto const t1 = reinterpret_cast<const FILETIME *>(&m_fileTime);
     auto const t2 = reinterpret_cast<const FILETIME *>(&other.m_fileTime);
     return CompareFileTime(t1, t2);
-#elif HAS_CLOCK_GETTIME
+#else
     if (m_fileTime.tv_sec < other.m_fileTime.tv_sec)
         return -1;
     if (m_fileTime.tv_sec > other.m_fileTime.tv_sec)
@@ -106,18 +113,12 @@ int FileTime::compare(const FileTime &other) const
     if (m_fileTime.tv_nsec > other.m_fileTime.tv_nsec)
         return 1;
     return 0;
-#else
-    if (m_fileTime < other.m_fileTime)
-        return -1;
-    if (m_fileTime > other.m_fileTime)
-        return 1;
-    return 0;
 #endif
 }
 
 void FileTime::clear()
 {
-#if HAS_CLOCK_GETTIME
+#if !defined(Q_OS_WIN)
     m_fileTime = { 0, 0 };
 #else
     m_fileTime = 0;
@@ -138,19 +139,10 @@ FileTime FileTime::currentTime()
     auto const ft = reinterpret_cast<FILETIME *>(&result.m_fileTime);
     SystemTimeToFileTime(&st, ft);
     return result;
-#elif defined APPLE_CUSTOM_CLOCK_GETTIME
-    InternalType t;
-    // Explicitly use our custom version, so that we don't get an additional unresolved symbol on a
-    // system that actually provides one, but isn't used due to the minimium deployment target
-    // being lower.
-    qbs::Internal::clock_gettime(CLOCK_REALTIME, &t);
-    return t;
-#elif HAS_CLOCK_GETTIME
+#else
     InternalType t;
-    clock_gettime(CLOCK_REALTIME, &t);
+    qbs_clock_gettime(CLOCK_REALTIME, &t);
     return t;
-#else
-    return time(nullptr);
 #endif
 }
 
@@ -171,16 +163,14 @@ FileTime FileTime::oldestTime()
     auto const ft = reinterpret_cast<FILETIME *>(&result.m_fileTime);
     SystemTimeToFileTime(&st, ft);
     return result;
-#elif HAS_CLOCK_GETTIME
-    return FileTime({1, 0});
 #else
-    return 1;
+    return FileTime({1, 0});
 #endif
 }
 
 double FileTime::asDouble() const
 {
-#if HAS_CLOCK_GETTIME
+#if !defined(Q_OS_WIN)
     return static_cast<double>(m_fileTime.tv_sec);
 #else
     return static_cast<double>(m_fileTime);
@@ -200,11 +190,7 @@ QString FileTime::toString() const
     return result;
 #else
     QDateTime dt;
-#if HAS_CLOCK_GETTIME
-   dt.setMSecsSinceEpoch(m_fileTime.tv_sec * 1000 + m_fileTime.tv_nsec / 1000000);
-#else
-    dt.setTime_t(m_fileTime);
-#endif
+    dt.setMSecsSinceEpoch(m_fileTime.tv_sec * 1000 + m_fileTime.tv_nsec / 1000000);
     return dt.toString(Qt::ISODateWithMs);
 #endif
 }
diff --git a/src/lib/corelib/tools/filetime.h b/src/lib/corelib/tools/filetime.h
index 70f4f4461..c656608e0 100644
--- a/src/lib/corelib/tools/filetime.h
+++ b/src/lib/corelib/tools/filetime.h
@@ -45,28 +45,12 @@
 #include <QtCore/qdatastream.h>
 #include <QtCore/qdebug.h>
 
-#if defined(Q_OS_UNIX) && !defined(__APPLE__)
+#if defined(Q_OS_UNIX)
 #include <time.h>
-#  if defined(Q_OS_FREEBSD)
-// FreeBSD 9.0 and above supports m_tim
-#    define HAS_CLOCK_GETTIME (__FreeBSD_version >= 900000)
-#  else
-#    define HAS_CLOCK_GETTIME (_POSIX_C_SOURCE >= 199309L)
-#  endif
 #endif // Q_OS_UNIX
 
 #ifdef __APPLE__
 
-#if __MAC_OS_X_VERSION_MIN_REQUIRED >= 101200
-// macOS 10.12+ ships clock_gettime.
-#else
-// We implement our own clock_gettime.
-#define APPLE_CUSTOM_CLOCK_GETTIME 1
-#endif // __MAC_OS_X_VERSION_MIN_REQUIRED
-
-// Either way we have a clock_gettime in the end.
-#define HAS_CLOCK_GETTIME 1
-
 // Apple stat struct has slightly different names for time fields.
 #define APPLE_STAT_TIMESPEC 1
 
@@ -79,11 +63,7 @@ class QBS_AUTOTEST_EXPORT FileTime
 {
 public:
 #if defined(Q_OS_UNIX)
-#if HAS_CLOCK_GETTIME
     using InternalType = timespec;
-#else
-    using InternalType = time_t;
-#endif // HAS_CLOCK_GETTIME
 #elif defined(Q_OS_WIN)
     using InternalType = quint64;
 #else
@@ -112,7 +92,7 @@ public:
 
     template<PersistentPool::OpType opType> void completeSerializationOp(PersistentPool &pool)
     {
-#if HAS_CLOCK_GETTIME
+#if !defined(Q_OS_WIN)
         pool.serializationOp<opType>(m_fileTime.tv_sec, m_fileTime.tv_nsec);
 #else
         pool.serializationOp<opType>(m_fileTime);