portability macro flags updates, for Haiku

some non-trivial changes to platform.h and util.h,
initially related to compilation for Haiku,
but I used this opportunity to make them cleaner
and add some documentation.

Noticed several tests that could be improved
(too harsh conditions, useless exception, etc.)
but I did not dare modifying too many tests just before release.

programs/platform.h

@@ -65,39 +65,52 @@ extern "C" {
 
 /* ************************************************************
 *  Detect POSIX version
-*  PLATFORM_POSIX_VERSION = -1 for non-Unix e.g. Windows
+*  PLATFORM_POSIX_VERSION = 0 for non-Unix e.g. Windows
-*  PLATFORM_POSIX_VERSION = 0 for Unix-like non-POSIX
+*  PLATFORM_POSIX_VERSION = 1 for Unix-like but non-POSIX
-*  PLATFORM_POSIX_VERSION >= 1 is equal to found _POSIX_VERSION
+*  PLATFORM_POSIX_VERSION > 1 is equal to found _POSIX_VERSION
+*  Value of PLATFORM_POSIX_VERSION can be forced on command line
 ***************************************************************/
-#if !defined(_WIN32) && (defined(__unix__) || defined(__unix) || (defined(__APPLE__) && defined(__MACH__)) /* UNIX-like OS */ \
+#ifndef PLATFORM_POSIX_VERSION
-   || defined(__midipix__) || defined(__VMS) || defined(__HAIKU__))
+
 #  if (defined(__APPLE__) && defined(__MACH__)) || defined(__SVR4) || defined(_AIX) || defined(__hpux) /* POSIX.1-2001 (SUSv3) conformant */ \
-     || defined(__DragonFly__) || defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__)  /* BSD distros */ \
+     || defined(__DragonFly__) || defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__)  /* BSD distros */
-     || defined(__HAIKU__)
+     /* exception rule : force posix version to 200112L,
+      * note: it's better to use unistd.h's _POSIX_VERSION whenever possible */
 #    define PLATFORM_POSIX_VERSION 200112L
-#  else
+
+/* try to determine posix version through official unistd.h's _POSIX_VERSION (http://pubs.opengroup.org/onlinepubs/7908799/xsh/unistd.h.html).
+ * note : there is no simple way to know in advance if <unistd.h> is present or not on target system,
+ * Posix specification mandates its presence and its content, but target system must respect this spec.
+ * It's necessary to _not_ #include <unistd.h> whenever target OS is not unix-like
+ * otherwise it will block preprocessing stage.
+ * The following list of build macros tries to "guess" if target OS is likely unix-like, and therefore can #include <unistd.h>
+ */
+#  elif !defined(_WIN32) \
+     && (defined(__unix__) || defined(__unix) \
+     || defined(__midipix__) || defined(__VMS) || defined(__HAIKU__))
+
 #    if defined(__linux__) || defined(__linux)
 #      ifndef _POSIX_C_SOURCE
-#        define _POSIX_C_SOURCE 200112L  /* use feature test macro */
+#        define _POSIX_C_SOURCE 200112L  /* feature test macro : https://www.gnu.org/software/libc/manual/html_node/Feature-Test-Macros.html */
 #      endif
 #    endif
 #    include <unistd.h>  /* declares _POSIX_VERSION */
 #    if defined(_POSIX_VERSION)  /* POSIX compliant */
 #      define PLATFORM_POSIX_VERSION _POSIX_VERSION
 #    else
-#      define PLATFORM_POSIX_VERSION 0
+#      define PLATFORM_POSIX_VERSION 1
-#    endif
-#  endif
-#endif
-#if !defined(PLATFORM_POSIX_VERSION)
-#  define PLATFORM_POSIX_VERSION -1
 #    endif
 
+#  else  /* non-unix target platform (like Windows) */
+#    define PLATFORM_POSIX_VERSION 0
+#  endif
+
+#endif   /* PLATFORM_POSIX_VERSION */
 
 /*-*********************************************
 *  Detect if isatty() and fileno() are available
 ************************************************/
-#if (defined(__linux__) && (PLATFORM_POSIX_VERSION >= 1)) \
+#if (defined(__linux__) && (PLATFORM_POSIX_VERSION > 1)) \
  || (PLATFORM_POSIX_VERSION >= 200112L) \
  || defined(__DJGPP__) \
  || defined(__MSYS__)
@@ -160,6 +173,19 @@ static __inline int IS_CONSOLE(FILE* stdStream) {
 #endif
 
 
+#ifndef ZSTD_SETPRIORITY_SUPPORT
+   /* mandates presence of <sys/resource.h> and support for setpriority() : http://man7.org/linux/man-pages/man2/setpriority.2.html */
+#  define ZSTD_SETPRIORITY_SUPPORT (PLATFORM_POSIX_VERSION >= 200112L)
+#endif
+
+
+#ifndef ZSTD_NANOSLEEP_SUPPORT
+   /* mandates support of nanosleep() within <time.h> : http://man7.org/linux/man-pages/man2/nanosleep.2.html */
+#  define ZSTD_NANOSLEEP_SUPPORT (defined(__linux__) && (PLATFORM_POSIX_VERSION >= 199309L)) \
+                              || (PLATFORM_POSIX_VERSION >= 200112L)
+#endif
+
+
 #if defined (__cplusplus)
 }
 #endif

programs/util.h

@@ -26,7 +26,7 @@ extern "C" {
 #include <stdio.h>        /* fprintf */
 #include <string.h>       /* strncmp */
 #include <sys/types.h>    /* stat, utime */
-#include <sys/stat.h>     /* stat */
+#include <sys/stat.h>     /* stat, chmod */
 #if defined(_MSC_VER)
 #  include <sys/utime.h>  /* utime */
 #  include <io.h>         /* _chmod */
@@ -53,32 +53,34 @@ extern "C" {
 #endif
 
 
-/*-****************************************
+/*-*************************************************
-*  Sleep functions: Windows - Posix - others
+*  Sleep & priority functions: Windows - Posix - others
-******************************************/
+***************************************************/
 #if defined(_WIN32)
 #  include <windows.h>
 #  define SET_REALTIME_PRIORITY SetPriorityClass(GetCurrentProcess(), REALTIME_PRIORITY_CLASS)
 #  define UTIL_sleep(s) Sleep(1000*s)
 #  define UTIL_sleepMilli(milli) Sleep(milli)
-#elif PLATFORM_POSIX_VERSION >= 0 /* Unix-like operating system */
+
-#  include <unistd.h>
+#elif PLATFORM_POSIX_VERSION > 0 /* Unix-like operating system */
-#  include <sys/resource.h> /* setpriority */
+#  include <unistd.h>   /* sleep */
-#  if defined(PRIO_PROCESS)
-#    define SET_REALTIME_PRIORITY setpriority(PRIO_PROCESS, 0, -20)
-#  else
-#    define SET_REALTIME_PRIORITY /* disabled */
-#  endif
 #  define UTIL_sleep(s) sleep(s)
-#  if (defined(__linux__) && (PLATFORM_POSIX_VERSION >= 199309L)) || (PLATFORM_POSIX_VERSION >= 200112L)  /* nanosleep requires POSIX.1-2001 */
+#  if ZSTD_NANOSLEEP_SUPPORT
 #      define UTIL_sleepMilli(milli) { struct timespec t; t.tv_sec=0; t.tv_nsec=milli*1000000ULL; nanosleep(&t, NULL); }
 #  else
 #      define UTIL_sleepMilli(milli) /* disabled */
 #  endif
+#  if ZSTD_SETPRIORITY_SUPPORT
+#    include <sys/resource.h> /* setpriority */
+#    define SET_REALTIME_PRIORITY setpriority(PRIO_PROCESS, 0, -20)
 #  else
 #    define SET_REALTIME_PRIORITY /* disabled */
+#  endif
+
+#else  /* unknown non-unix operating systen */
 #  define UTIL_sleep(s)          /* disabled */
 #  define UTIL_sleepMilli(milli) /* disabled */
+#  define SET_REALTIME_PRIORITY  /* disabled */
 #endif
 
 
@@ -119,6 +121,7 @@ static int g_utilDisplayLevel;
 #if defined(_WIN32)   /* Windows */
     #define UTIL_TIME_INITIALIZER { { 0, 0 } }
     typedef LARGE_INTEGER UTIL_time_t;
+
     UTIL_STATIC UTIL_time_t UTIL_getTime(void) { UTIL_time_t x; QueryPerformanceCounter(&x); return x; }
     UTIL_STATIC U64 UTIL_getSpanTimeMicro(UTIL_time_t clockStart, UTIL_time_t clockEnd)
     {
@@ -148,6 +151,7 @@ static int g_utilDisplayLevel;
     #include <mach/mach_time.h>
     #define UTIL_TIME_INITIALIZER 0
     typedef U64 UTIL_time_t;
+
     UTIL_STATIC UTIL_time_t UTIL_getTime(void) { return mach_absolute_time(); }
     UTIL_STATIC U64 UTIL_getSpanTimeMicro(UTIL_time_t clockStart, UTIL_time_t clockEnd)
     {
@@ -179,6 +183,7 @@ static int g_utilDisplayLevel;
     #define UTIL_TIME_INITIALIZER { 0, 0 }
     typedef struct timespec UTIL_freq_t;
     typedef struct timespec UTIL_time_t;
+
     UTIL_STATIC UTIL_time_t UTIL_getTime(void)
     {
         UTIL_time_t time;
@@ -186,6 +191,7 @@ static int g_utilDisplayLevel;
             UTIL_DISPLAYLEVEL(1, "ERROR: Failed to get time\n");   /* we could also exit() */
         return time;
     }
+
     UTIL_STATIC UTIL_time_t UTIL_getSpanTime(UTIL_time_t begin, UTIL_time_t end)
     {
         UTIL_time_t diff;
@@ -198,6 +204,7 @@ static int g_utilDisplayLevel;
         }
         return diff;
     }
+
     UTIL_STATIC U64 UTIL_getSpanTimeMicro(UTIL_time_t begin, UTIL_time_t end)
     {
         UTIL_time_t const diff = UTIL_getSpanTime(begin, end);
@@ -206,6 +213,7 @@ static int g_utilDisplayLevel;
         micro += diff.tv_nsec / 1000ULL;
         return micro;
     }
+
     UTIL_STATIC U64 UTIL_getSpanTimeNano(UTIL_time_t begin, UTIL_time_t end)
     {
         UTIL_time_t const diff = UTIL_getSpanTime(begin, end);
@@ -214,6 +222,7 @@ static int g_utilDisplayLevel;
         nano += diff.tv_nsec;
         return nano;
     }
+
 #else   /* relies on standard C (note : clock_t measurements can be wrong when using multi-threading) */
     typedef clock_t UTIL_time_t;
     #define UTIL_TIME_INITIALIZER 0