Refactoring time-related default port implementations (#4513)

In the non-Windows code paths:
- New approach to compute TZA without the need for GNU-specific
  `struct tm.tm_gmtoff`.
- Always using `usleep` to sleep. (No real need for `nanosleep` as
  port API has sleep granularity of milliseconds.)
- Not checking for "time.h" at build configuration time as that
  header is mandated by the C standard.
- Not checking for "unistd.h" at build configuration time as that
  header is mandated by the POSIX standard (the default port is
  targeting POSIX systems -- and Windows).
- Fixing some macro guards.

JerryScript-DCO-1.0-Signed-off-by: Akos Kiss akiss@inf.u-szeged.hu

3 files changed, 44 insertions, 66 deletions

diff --git a/jerry-port/default/CMakeLists.txt b/jerry-port/default/CMakeLists.txt
index 3560b072..f70ff24c 100644
--- a/jerry-port/default/CMakeLists.txt
+++ b/jerry-port/default/CMakeLists.txt
@@ -59,31 +59,6 @@ endif()
 # (should only be necessary if we used compiler default libc but not checking that)
 set(DEFINES_PORT_DEFAULT _BSD_SOURCE _DEFAULT_SOURCE)
 
-INCLUDE (CheckStructHasMember)
-# CHECK_STRUCT_HAS_MEMBER works by trying to compile some C code that accesses the
-# given field of the given struct. However, our default compiler options break this
-# C code, so turn a couple of them off for this.
-if(USING_GCC OR USING_CLANG)
-  set(CMAKE_REQUIRED_FLAGS "-Wno-error=strict-prototypes -Wno-error=old-style-definition -Wno-error=unused-value")
-endif()
-# tm.tm_gmtoff is non-standard, so glibc doesn't expose it in c99 mode
-# (our default). Define some macros to expose it anyway.
-set(CMAKE_REQUIRED_DEFINITIONS "-D_BSD_SOURCE -D_DEFAULT_SOURCE")
-CHECK_STRUCT_HAS_MEMBER ("struct tm" tm_gmtoff time.h HAVE_TM_GMTOFF)
-if(HAVE_TM_GMTOFF)
-  set(DEFINES_PORT_DEFAULT ${DEFINES_PORT_DEFAULT} HAVE_TM_GMTOFF)
-endif()
-
-# Sleep function availability check
-INCLUDE (CheckIncludeFiles)
-CHECK_INCLUDE_FILES (time.h HAVE_TIME_H)
-CHECK_INCLUDE_FILES (unistd.h HAVE_UNISTD_H)
-if(HAVE_TIME_H)
-  set(DEFINES_PORT_DEFAULT ${DEFINES_PORT_DEFAULT} HAVE_TIME_H)
-elseif(HAVE_UNISTD_H)
-  set(DEFINES_PORT_DEFAULT ${DEFINES_PORT_DEFAULT} HAVE_UNISTD_H)
-endif()
-
 # Default Jerry port implementation library
 add_library(${JERRY_PORT_DEFAULT_NAME} ${SOURCE_PORT_DEFAULT})
 target_include_directories(${JERRY_PORT_DEFAULT_NAME} PUBLIC ${INCLUDE_PORT_DEFAULT})
diff --git a/jerry-port/default/default-date.c b/jerry-port/default/default-date.c
index 240516b9..57ce6875 100644
--- a/jerry-port/default/default-date.c
+++ b/jerry-port/default/default-date.c
@@ -13,20 +13,17 @@
  * limitations under the License.
  */
 
-#ifdef HAVE_TM_GMTOFF
 #include <time.h>
-#endif /* HAVE_TM_GMTOFF */
 
 #ifdef _WIN32
 #include <windows.h>
 #include <winbase.h>
 #include <winnt.h>
-#include <time.h>
 #endif /* _WIN32 */
 
-#ifdef __GNUC__
+#if defined (__GNUC__) || defined (__clang__)
 #include <sys/time.h>
-#endif /* __GNUC__ */
+#endif /* __GNUC__ || __clang__ */
 
 #include "jerryscript-port.h"
 #include "jerryscript-port-default.h"
@@ -54,9 +51,7 @@ static double FileTimeToUnixTimeMs (FILETIME ft)
 #endif /* _WIN32 */
 
 /**
- * Default implementation of jerry_port_get_local_time_zone_adjustment. Uses the 'tm_gmtoff' field
- * of 'struct tm' (a GNU extension) filled by 'localtime_r' if available on the
- * system, does nothing otherwise.
+ * Default implementation of jerry_port_get_local_time_zone_adjustment.
  *
  * @return offset between UTC and local time at the given unix timestamp, if
  *         available. Otherwise, returns 0, assuming UTC time.
@@ -64,19 +59,6 @@ static double FileTimeToUnixTimeMs (FILETIME ft)
 double jerry_port_get_local_time_zone_adjustment (double unix_ms,  /**< ms since unix epoch */
                                                   bool is_utc)  /**< is the time above in UTC? */
 {
-#ifdef HAVE_TM_GMTOFF
-  struct tm tm;
-  time_t now = (time_t) (unix_ms / 1000);
-  localtime_r (&now, &tm);
-  if (!is_utc)
-  {
-    now -= tm.tm_gmtoff;
-    localtime_r (&now, &tm);
-  }
-  return ((double) tm.tm_gmtoff) * 1000;
-#else /* !HAVE_TM_GMTOFF */
-  (void) unix_ms;
-  (void) is_utc;
 #ifdef _WIN32
   FILETIME fileTime, localFileTime;
   SYSTEMTIME systemTime, localSystemTime;
@@ -94,9 +76,39 @@ double jerry_port_get_local_time_zone_adjustment (double unix_ms,  /**< ms since
     localTime.HighPart = localFileTime.dwHighDateTime;
     return (double) (((LONGLONG) localTime.QuadPart - (LONGLONG) time.QuadPart) / TicksPerMs);
   }
-#endif /* _WIN32 */
+#elif defined (__GNUC__) || defined (__clang__)
+  time_t now_time = (time_t) (unix_ms / 1000);
+  double tza_s = 0.0;
+
+  while (true)
+  {
+    struct tm now_tm;
+    if (!gmtime_r (&now_time, &now_tm))
+    {
+      break;
+    }
+    now_tm.tm_isdst = -1; /* if not overridden, DST will not be taken into account */
+    time_t local_time = mktime (&now_tm);
+    if (local_time == (time_t) -1)
+    {
+      break;
+    }
+    tza_s = difftime (now_time, local_time);
+
+    if (is_utc)
+    {
+      break;
+    }
+    now_time -= (time_t) tza_s;
+    is_utc = true;
+  }
+
+  return tza_s * 1000;
+#else /* !_WIN32 && !__GNUC__ && !__clang__ */
+  (void) unix_ms; /* unused */
+  (void) is_utc; /* unused */
   return 0.0;
-#endif /* HAVE_TM_GMTOFF */
+#endif /* _WIN32 */
 } /* jerry_port_get_local_time_zone_adjustment */
 
 /**
@@ -113,14 +125,15 @@ double jerry_port_get_current_time (void)
   FILETIME ft;
   GetSystemTimeAsFileTime (&ft);
   return FileTimeToUnixTimeMs (ft);
-#elif __GNUC__
+#elif defined (__GNUC__) || defined (__clang__)
   struct timeval tv;
 
   if (gettimeofday (&tv, NULL) == 0)
   {
     return ((double) tv.tv_sec) * 1000.0 + ((double) tv.tv_usec) / 1000.0;
   }
-#endif /* _WIN32 */
-
   return 0.0;
+#else /* !_WIN32 && !__GNUC__ && !__clang__ */
+  return 0.0;
+#endif /* _WIN32 */
 } /* jerry_port_get_current_time */
diff --git a/jerry-port/default/default-debugger.c b/jerry-port/default/default-debugger.c
index b5f55c69..7131e426 100644
--- a/jerry-port/default/default-debugger.c
+++ b/jerry-port/default/default-debugger.c
@@ -21,9 +21,7 @@
 
 #ifdef _WIN32
 #include <windows.h>
-#elif defined (HAVE_TIME_H)
-#include <time.h>
-#elif defined (HAVE_UNISTD_H)
+#else /* !_WIN32 */
 #include <unistd.h>
 #endif /* _WIN32 */
 
@@ -31,22 +29,14 @@
 #include "jerryscript-port-default.h"
 
 /**
- * Default implementation of jerry_port_sleep. Uses 'nanosleep' or 'usleep' if
- * available on the system, does nothing otherwise.
+ * Default implementation of jerry_port_sleep. Uses 'usleep' if available on the
+ * system, does nothing otherwise.
  */
 void jerry_port_sleep (uint32_t sleep_time) /**< milliseconds to sleep */
 {
 #ifdef _WIN32
   Sleep (sleep_time);
-#elif defined (HAVE_TIME_H)
-  struct timespec sleep_timespec;
-  sleep_timespec.tv_sec = (time_t) sleep_time / 1000;
-  sleep_timespec.tv_nsec = ((long int) sleep_time % 1000) * 1000000L;
-
-  nanosleep (&sleep_timespec, NULL);
-#elif defined (HAVE_UNISTD_H)
+#else /* !_WIN32 */
   usleep ((useconds_t) sleep_time * 1000);
-#else
-  (void) sleep_time;
-#endif /* HAVE_TIME_H */
+#endif /* _WIN32 */
 } /* jerry_port_sleep */