cdiGetFiletype: check whether file is empty or a directory.

src/cdi.h

@@ -36,11 +36,13 @@ extern "C" {
 #define  CDI_EEOF                  -1   // The end of file was encountered
 #define  CDI_ESYSTEM              -10   // Operating system error
 #define  CDI_EINVAL               -20   // Invalid argument
-#define  CDI_EUFTYPE              -21   // Unsupported file type
-#define  CDI_ELIBNAVAIL           -22   // xxx library not available
-#define  CDI_EUFSTRUCT            -23   // Unsupported file structure
-#define  CDI_EUNC4                -24   // Unsupported NetCDF4 structure
-#define  CDI_EDIMSIZE             -25   // Invalid dimension size
+#define  CDI_EISDIR               -21   // Is a directory
+#define  CDI_EISEMPTY             -22   // Is empty
+#define  CDI_EUFTYPE              -23   // Unsupported file type
+#define  CDI_ELIBNAVAIL           -24   // xxx library not available
+#define  CDI_EUFSTRUCT            -25   // Unsupported file structure
+#define  CDI_EUNC4                -26   // Unsupported NetCDF4 structure
+#define  CDI_EDIMSIZE             -27   // Invalid dimension size
 #define  CDI_ELIMIT               -99   // Internal limits exceeded
 
 /* File types */

src/cdi_error.c

 #if defined (HAVE_CONFIG_H)
-#  include "config.h"
+#include "config.h"
 #endif
 
 #include <stdio.h>
@@ -10,6 +10,8 @@
 const char *cdiStringError(int cdiErrno)
 {
   static const char UnknownError[] = "Unknown Error";
+  static const char _EISDIR[]      = "Is a directory";
+  static const char _EISEMPTY[]    = "File is empty";
   static const char _EUFTYPE[]     = "Unsupported file type";
   static const char _ELIBNAVAIL[]  = "Unsupported file type (library support not compiled in)";
   static const char _EUFSTRUCT[]   = "Unsupported file structure";
@@ -24,6 +26,8 @@ const char *cdiStringError(int cdiErrno)
       if ( cp == NULL ) break;
       return cp;
     }
+  case CDI_EISDIR:     return _EISDIR;
+  case CDI_EISEMPTY:   return _EISEMPTY;
   case CDI_EUFTYPE:    return _EUFTYPE;
   case CDI_ELIBNAVAIL: return _ELIBNAVAIL;
   case CDI_EUFSTRUCT:  return _EUFSTRUCT;

src/stream.c

@@ -6,6 +6,7 @@
 #define _XOPEN_SOURCE 600
 #endif
 
+#include <sys/stat.h> // struct stat
 #include <ctype.h>
 
 #include "binary.h"
@@ -78,7 +79,6 @@ int cdiGetFiletype(const char *filename, int *byteorder)
   int swap = 0;
   int version;
   long recpos;
-  char buffer[8];
 
   int fileID = fileOpen(filename, "r");
 
@@ -90,7 +90,18 @@ int cdiGetFiletype(const char *filename, int *byteorder)
 	return CDI_ESYSTEM;
     }
 
-  if ( fileRead(fileID, buffer, 8) != 8 ) return CDI_EUFTYPE;
+  char buffer[8];
+  if ( fileRead(fileID, buffer, 8) != 8 )
+    {
+      struct stat buf;
+      if ( stat(filename, &buf) == 0 )
+        {
+          if ( buf.st_size == 0 ) return CDI_EISEMPTY;
+          if ( buf.st_mode&S_IFDIR ) return CDI_EISDIR;
+        }
+
+      return CDI_EUFTYPE;
+    }
 
   fileRewind(fileID);