Patches from Norman Vine <nhv@cape.com> to catch and properly report "errno"

conditions.

simgear/misc/fgstream.cxx

@@ -23,6 +23,12 @@
 
 #include <ctype.h> // isspace()
 
+#ifdef FG_HAVE_STD_INCLUDES
+# include <cerrno>
+#else
+# include <errno.h>
+#endif
+
 #include "fgstream.hxx"
 
 fg_gzifstream::fg_gzifstream()

simgear/misc/zfstream.cxx

@@ -22,7 +22,16 @@
 //
 // $Id$
 
+#include <simgear/compiler.h>
+
+#ifdef FG_HAVE_STD_INCLUDES
+# include <cerrno>
+#else
+# include <errno.h>
+#endif
 #include <memory.h>
+#include <stdio.h>
+
 #include "zfstream.hxx"
 
 //
@@ -106,8 +115,11 @@ gzfilebuf::open( const char *name, ios_openmode io_mode )
 
     char char_mode[10];
     cvt_iomode( char_mode, io_mode );
-    if ( (file = gzopen(name, char_mode)) == NULL )
+    if ( (file = gzopen(name, char_mode)) == NULL ) {
+	perror( "gzfilebuf::open(): " );
+	errno = 0;
 	return NULL;
+    }
 
     own_file_descriptor = true;
 
@@ -122,8 +134,11 @@ gzfilebuf::attach( int file_descriptor, ios_openmode io_mode )
 
     char char_mode[10];
     cvt_iomode( char_mode, io_mode );
-    if ( (file = gzdopen(file_descriptor, char_mode)) == NULL )
+    if ( (file = gzdopen(file_descriptor, char_mode)) == NULL ) {
+	perror( "gzfilebuf::attach(): " );
+	errno = 0;
 	return NULL;
+    }
 
     own_file_descriptor = false;
 

simgear/timing/lowleveltime.cxx

@@ -862,8 +862,12 @@ void fgtzfile_read (const char *file)
 //     }
 
   f = fopen (file, "rb");
-  if (f == NULL)
+
-    return;
+  if (f == NULL) {
+      perror( "fgtzfile_read(): " );
+      errno = 0;
+      return;
+  }
 
   if (fread ((void *) &tzhead, sizeof (tzhead), 1, f) != 1)
     goto lose;

simgear/timing/sg_time.cxx

@@ -410,7 +410,16 @@ time_t sgTimeGetGMT(int year, int month, int day, int hour, int min, int sec)
 #if defined( HAVE_TIMEGM )
     return ( timegm(&mt) );
 #elif defined( MK_TIME_IS_GMT )
-    return ( mktime(&mt) );
+    time_t ret = mktime(&mt);
+    // This is necessary as some mktime() calls may
+    // try to access the system timezone files
+    // if this open fails errno is set to 2
+    // CYGWIN for one does this
+    if ( errno ) {
+	perror( "sgTimeGetGMT(): " );
+	errno = 0;
+    }
+    return ret;
 #else // ! defined ( MK_TIME_IS_GMT )
 
     // timezone seems to work as a proper offset for Linux & Solaris