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| author | Richard M. Stallman <rms@gnu.org> | 2004-05-10 16:55:38 +0000 |
|---|---|---|
| committer | Richard M. Stallman <rms@gnu.org> | 2004-05-10 16:55:38 +0000 |
| commit | c11326718786ba5aa701fd9ba97c57876deab90e (patch) | |
| tree | 39c5873c5097da0d2dc300a9f002e6dbf64abf6e /src/print.c | |
| parent | 6740652e6d63701107312f7dd1efcc623c4b38fc (diff) | |
| download | emacs-c11326718786ba5aa701fd9ba97c57876deab90e.tar.gz | |
(print_preprocess): Use being_printed, loop_count and
halftail to detect overdeep nesting and cyclic cdr chains.
Diffstat (limited to 'src/print.c')
| -rw-r--r-- | src/print.c | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/src/print.c b/src/print.c index e729b468fd1..27da81ae8eb 100644 --- a/src/print.c +++ b/src/print.c @@ -1280,6 +1280,26 @@ print_preprocess (obj) { int i; EMACS_INT size; + int loop_count = 0; + Lisp_Object halftail; + + /* Avoid infinite recursion for circular nested structure + in the case where Vprint_circle is nil. */ + if (NILP (Vprint_circle)) + { + for (i = 0; i < print_depth; i++) + if (EQ (obj, being_printed[i])) + return; + being_printed[print_depth] = obj; + } + + /* Give up if we go so deep that print_object will get an error. */ + /* See similar code in print_object. */ + if (print_depth >= PRINT_CIRCLE) + return; + + print_depth++; + halftail = obj; loop: if (STRINGP (obj) || CONSP (obj) || VECTORP (obj) @@ -1340,8 +1360,15 @@ print_preprocess (obj) break; case Lisp_Cons: + /* Use HALFTAIL and LOOP_COUNT to detect circular lists, + just as in print_object. */ + if (loop_count && EQ (obj, halftail)) + break; print_preprocess (XCAR (obj)); obj = XCDR (obj); + loop_count++; + if (!(loop_count & 1)) + halftail = XCDR (halftail); goto loop; case Lisp_Vectorlike: @@ -1356,6 +1383,7 @@ print_preprocess (obj) break; } } + print_depth--; } static void @@ -1426,6 +1454,7 @@ print_object (obj, printcharfun, escapeflag) print_depth++; + /* See similar code in print_preprocess. */ if (print_depth > PRINT_CIRCLE) error ("Apparently circular structure being printed"); #ifdef MAX_PRINT_CHARS |