Correct mishandling of invalid characters in printf() format specs.

diff --git a/winsup/mingw/ChangeLog b/winsup/mingw/ChangeLog
index da6a589..58fc95a 100644 (file)
--- a/winsup/mingw/ChangeLog
+++ b/winsup/mingw/ChangeLog
@@ -1,3 +1,13 @@
+2008-12-31  Keith Marshall  <keithmarshall@users.sourceforge.net>
+
+       Partial fix for MinGW-Bug [2457778]: (Reported by Sisyphus).
+       Correct mishandling of invalid characters in printf() format specs.
+
+       * mingwex/stdio/pformat.c (__pformat): Save `fmt' scan position in...
+       (backtrack): ...this new automatic variable, at start of each format
+       conversion specification substring; use it to backtrack, and print the
+       substring literally, if any invalid character is encountered.
+
 2008-12-16 Danny Smith <dannysmith@users.sourceforge.net>
 
        * msvcrt.def.in (___lc_codepage_func, ___lc_collate_cp_func,

diff --git a/winsup/mingw/mingwex/stdio/pformat.c b/winsup/mingw/mingwex/stdio/pformat.c
index 8b3e93e..2151a09 100644 (file)
--- a/winsup/mingw/mingwex/stdio/pformat.c
+++ b/winsup/mingw/mingwex/stdio/pformat.c
@@ -1813,6 +1813,11 @@ int __pformat( int flags, void *dest, int max, const char *fmt, va_list argv )
       __pformat_state_t  state = PFORMAT_INIT;
       __pformat_length_t length = PFORMAT_LENGTH_INT;
 
+      /* Save the current format scan position, so that we can backtrack
+       * in the event of encountering an invalid format specification...
+       */
+      char *backtrack = fmt;
+
       /* Restart capture for dynamic field width and precision specs...
        */
       int *width_spec = &stream.width;
@@ -2490,12 +2495,15 @@ int __pformat( int flags, void *dest, int max, const char *fmt, va_list argv )
            }
 
            else
+           {
              /* We found a digit out of context, or some other character
-              * with no designated meaning; silently reject it, and any
-              * further characters other than argument length modifiers,
-              * until this format specification is completely resolved.
+              * with no designated meaning; reject this format specification,
+              * backtrack, and emit it as literal text...
               */
-             state = PFORMAT_END;
+             fmt = backtrack;
+             __pformat_putc( '%', &stream );
+             goto format_scan;
+           }
        }
       }
     }