X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=functions%2Fstdio%2Fungetc.c;h=56ba98b26c3b463ba08bd7f7bdd993a2fd93b6b9;hb=7a94eb4d268ab6780c774a50d59e8dd5e578ac7b;hp=fdafc9de1054f34ca1e5b09c42ea06507ecf59e2;hpb=e5112b619d1aae8ffc439389cfcbd3b2b4bd2454;p=pdclib

diff --git a/functions/stdio/ungetc.c b/functions/stdio/ungetc.c
index fdafc9d..56ba98b 100644
--- a/functions/stdio/ungetc.c
+++ b/functions/stdio/ungetc.c
@@ -1,5 +1,3 @@
-/* $Id$ */
-
 /* ungetc( int, FILE * )
 
    This file is part of the Public Domain C Library (PDCLib).
@@ -9,21 +7,60 @@
 #include <stdio.h>
 
 #ifndef REGTEST
+#include <_PDCLIB_io.h>
+
+int _PDCLIB_ungetc_unlocked( int c, FILE * stream )
+{
+    if ( c == EOF || stream->ungetidx == _PDCLIB_UNGETCBUFSIZE )
+    {
+        return -1;
+    }
+    return stream->ungetbuf[stream->ungetidx++] = (unsigned char) c;
+}
 
-int ungetc( int c, struct _PDCLIB_file_t * stream )
+int ungetc( int c, FILE * stream )
 {
-    /* TODO: Implement. */
-    return 0;
+    _PDCLIB_flockfile( stream );
+    int r = _PDCLIB_ungetc_unlocked( c, stream );
+    _PDCLIB_funlockfile( stream);
+    return r;
 }
 
 #endif
 
 #ifdef TEST
 #include <_PDCLIB_test.h>
+#include <stdlib.h>
+
+const char* hellostr = "Hello, world!";
 
 int main( void )
 {
-    TESTCASE( NO_TESTDRIVER );
+    // Also see ftell() for some testing
+
+    // PDCLIB-18: fread ignores ungetc
+    size_t bufsz = strlen( hellostr ) + 1;
+    char * buf = malloc( bufsz );
+    FILE * fh;
+
+    // Also fgets
+    TESTCASE( ( fh = tmpfile() ) != NULL );
+    TESTCASE( fputs(hellostr, fh) == 0 );
+    rewind(fh);
+    TESTCASE( fgetc( fh ) == 'H' );
+    TESTCASE( ungetc( 'H', fh ) == 'H' );
+    TESTCASE( fgets( buf, bufsz, fh ) != NULL );
+    TESTCASE( strcmp( buf, hellostr ) == 0 );
+
+    // fread
+    rewind(fh);
+    TESTCASE( fgetc( fh ) == 'H' );
+    TESTCASE( ungetc( 'H', fh ) == 'H' );
+    TESTCASE( fread( buf, bufsz - 1, 1, fh ) == 1 );
+    TESTCASE( strncmp( buf, hellostr, bufsz - 1 ) == 0 );
+
+
+
     return TEST_RESULTS;
 }