* Better ungetc() implementation. Now we don't need to care about the

fuzzing method.

src/fd.c

@@ -256,6 +256,7 @@ void _zz_register(int fd)
 #if defined HAVE_FGETLN
     files[i].fuzz.tmp = NULL;
 #endif
+    files[i].fuzz.uflag = 0;
 
     if(autoinc)
         seed++;

src/fuzz.c

@@ -152,7 +152,7 @@ void _zz_fuzz(int fd, volatile uint8_t *buf, uint64_t len)
                 if(j >= r[0] && (r[0] == r[1] || j < r[1]))
                     goto range_ok;
 
-            continue; /* Not in a range */
+            continue; /* Not in one of the ranges, skip byte */
 
         range_ok:
             byte = aligned_buf[j];
@@ -168,6 +168,14 @@ void _zz_fuzz(int fd, volatile uint8_t *buf, uint64_t len)
             aligned_buf[j] = byte;
         }
     }
+
+    /* Handle ungetc() */
+    if(fuzz->uflag)
+    {
+        fuzz->uflag = 0;
+        if(fuzz->upos == pos)
+            buf[0] = fuzz->uchar;
+    }
 }
 
 static void readchars(int *table, char const *list)

src/lib-stream.c

@@ -378,7 +378,6 @@ char *NEW(fgets)(char *s, int size, FILE *stream)
 
 int NEW(ungetc)(int c, FILE *stream)
 {
-    unsigned char ch = c;
     int ret, fd;
 
     LOADSYM(ungetc);
@@ -386,22 +385,21 @@ int NEW(ungetc)(int c, FILE *stream)
     if(!_zz_ready || !_zz_iswatched(fd))
         return ORIG(ungetc)(c, stream);
 
-#if defined HAVE___SREFILL /* Don't fuzz or seek if we have __srefill() */
-#else
-    _zz_addpos(fd, -1);
-    _zz_fuzz(fd, &ch, 1);
-#endif
     _zz_lock(fd);
-    ret = ORIG(ungetc)((int)ch, stream);
+    ret = ORIG(ungetc)(c, stream);
     _zz_unlock(fd);
 
-    if(ret >= 0)
+    if(ret != EOF)
-        ret = c;
+    {
+        struct fuzz *fuzz = _zz_getfuzz(fd);
+        fuzz->uflag = 1;
+        fuzz->upos = _zz_getpos(fd) - 1;
+        fuzz->uchar = c;
 #if defined HAVE___SREFILL /* Don't fuzz or seek if we have __srefill() */
 #else
-    else
+        _zz_addpos(fd, -1);
-        _zz_addpos(fd, 1); /* revert what we did */
 #endif
+    }
 
     debug("%s(0x%02x, [%i]) = '%c'", __func__, c, fd, ret);
     return ret;

src/libzzuf.h

@@ -38,6 +38,7 @@ struct fuzz
 #ifdef HAVE_FGETLN
     char *tmp;
 #endif
+    int uflag; uint64_t upos; uint8_t uchar; /* ungetc stuff */
     uint8_t data[CHUNKBYTES];
 };