X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=functions%2Fstdio%2Fftell.c;h=ba79db3b8218268efaf100027dfbedbd6759b8bc;hb=b5b6c4a890795ea76f9b92b817b0a83c6bb4862c;hp=63c7f75e1d5de1ebf786a1d9e38e1c9b592a1492;hpb=d6cfb7e99a6b183b62b606947673cdca47c2fb91;p=pdclib.old

diff --git a/functions/stdio/ftell.c b/functions/stdio/ftell.c
index 63c7f75..ba79db3 100644
--- a/functions/stdio/ftell.c
+++ b/functions/stdio/ftell.c
@@ -7,47 +7,42 @@
 */
 
 #include <stdio.h>
+#include <stdint.h>
 #include <limits.h>
+#include <errno.h>
 
 #ifndef REGTEST
+#include <_PDCLIB_io.h>
 
-long int ftell( struct _PDCLIB_file_t * stream )
+long int _PDCLIB_ftell_unlocked( FILE * stream )
 {
-    /* If offset is too large for return type, report error instead of wrong
-       offset value.
-       FIXME: A bit too fuzzy in the head right now; stream->ungetidx should be
-       in here somewhere.
-    */
-    if ( stream->pos.offset > ( LONG_MAX - stream->bufidx ) )
+    uint_fast64_t off64 = _PDCLIB_ftell64_unlocked( stream );
+
+    if ( off64 > LONG_MAX )
     {
         /* integer overflow */
-        _PDCLIB_errno = _PDCLIB_EINVAL;
+        errno = ERANGE;
         return -1;
     }
-    /* ftell() must take into account:
-       - the actual *physical* offset of the file, i.e. the offset as recognized
-         by the operating system (and stored in stream->pos.offset); and
-       - any buffers held by PDCLib, which
-         - in case of unwritten buffers, count in *addition* to the offset; or
-         - in case of unprocessed pre-read buffers, count in *substraction* to
-           the offset. (Remember to count ungetidx into this number.)
-       Conveniently, the calculation ( ( bufend - bufidx ) + ungetidx ) results
-       in just the right number in both cases:
-         - in case of unwritten buffers, ( ( 0 - unwritten ) + 0 )
-           i.e. unwritten bytes as negative number
-         - in case of unprocessed pre-read, ( ( preread - processed ) + unget )
-           i.e. unprocessed bytes as positive number.
-       That is how the somewhat obscure return-value calculation works.
-    */
-    return (long int)( stream->pos.offset - ( ( stream->bufend - stream->bufidx ) + stream->ungetidx ) );
+    return off64;
+}
+
+long int ftell( FILE * stream )
+{
+    _PDCLIB_flockfile( stream );
+    long int off = _PDCLIB_ftell_unlocked( stream );
+    _PDCLIB_funlockfile( stream );
+    return off;
 }
 
 #endif
 
 #ifdef TEST
 #include <_PDCLIB_test.h>
-
 #include <stdlib.h>
+#ifndef REGTEST
+#include <_PDCLIB_io.h>
+#endif
 
 int main( void )
 {
@@ -63,6 +58,13 @@ int main( void )
     FILE * fh;
     TESTCASE( ( fh = tmpfile() ) != NULL );
     TESTCASE( setvbuf( fh, buffer, _IOLBF, 4 ) == 0 );
+    /* Testing ungetc() at offset 0 */
+    rewind( fh );
+    TESTCASE( ungetc( 'x', fh ) == 'x' );
+    TESTCASE( ftell( fh ) == -1l );
+    rewind( fh );
+    TESTCASE( ftell( fh ) == 0l );
+    /* Commence "normal" tests */
     TESTCASE( fputc( '1', fh ) == '1' );
     TESTCASE( fputc( '2', fh ) == '2' );
     TESTCASE( fputc( '3', fh ) == '3' );