gbfile: Check return codes within 'gbftell' and 'gbfseek'.

diff --git a/gbfile.c b/gbfile.c
index a9e9c499e64acf83d369b6fc541c6ec34a8b7fec..0d3d1c6f46a9a6b5271eea302feb6c4163051c85 100644 (file)
--- a/gbfile.c
+++ b/gbfile.c
@@ -471,7 +471,7 @@ gbferror(gbfile *file)
 void
 gbfrewind(gbfile *file)
 {
-       (void)gbfseek(file, 0, SEEK_SET);
+       (void) gbfseek(file, 0, SEEK_SET);
        gbfclearerr(file);
 }
 
@@ -482,9 +482,9 @@ gbfrewind(gbfile *file)
 int
 gbfseek(gbfile *file, gbint32 offset, int whence)
 {
+       int result;
 
        if (file->gzapi) {
-               int result;
                
                assert(whence != SEEK_END);
 
@@ -501,10 +501,26 @@ gbfseek(gbfile *file, gbint32 offset, int whence)
                        fatal("%s: online compression not yet supported for this format!", file->module);
                }
                return 0;
-               
        }
        else {
-               return fseek(file->handle.std, offset, whence);
+               gbsize_t pos = 0;
+               
+               if (whence != SEEK_SET) pos = ftell(file->handle.std);
+
+               result = fseek(file->handle.std, offset, whence);
+               if (result != 0) {
+                       switch (whence) {
+                       case SEEK_CUR:
+                       case SEEK_END: pos = pos + offset; break;
+                       case SEEK_SET: pos = offset; break;
+                       default:
+                               fatal("%s: Unknown seek operation (%d) for file %s!\n",
+                                       file->module, whence, file->name);
+                       }
+                       fatal("%s: Unable to set file (%s) to position (%d)!\n",
+                               file->module, file->name, pos);
+               }
+               return 0;
        }
 }
 
@@ -515,22 +531,27 @@ gbfseek(gbfile *file, gbint32 offset, int whence)
 gbsize_t 
 gbftell(gbfile *file)
 {
+       gbsize_t result;
+       
        if (file->gzapi) {
 #if !ZLIB_INHIBITED
-               gbsize_t result = gztell(file->handle.gz);
+               result = gztell(file->handle.gz);
                if (file->back != -1) {
 //                     file->back = -1;
                        result--;
                }
-               return result;
 #else
                fatal(NO_ZLIB);
-               return -1;
+               result = -1;
 #endif
        }
        else {
-               return ftell(file->handle.std);
+               result = ftell(file->handle.std);
        }
+       if ((signed) result == -1)
+               fatal("%s: Could not determine position of file '%s'!\n",
+                       file->module, file->name);
+       return result;
 }
 
 /*