[Gcl-devel] coerce_to_pathname

[Aurelien Chanudet]

Hi all,

I've just run across a problem in coerce_to_pathname when trying to 
build Maxima on Mac OS X using the local BFD tree.  My first thought 
was that the issue might originate  from a side-effet of a bug lurking 
somewhere in my BFD relocation code.  However, I fail to see the 
connection.  coerce_to_pathname is called from read_fasl_vector, which 
in turn is called from sfaslbfd.c.  As you know, Maxima is built by 
compiling lisp files into object files and subsequently loading them.  
The breakpoint I set in coerce_to_pathame (see below) was reached only 
once.  This breakpoint demonstrates that x->sm.sm_object1 was 
incorrectly set to null below.  This might be because, towards the 
beginning of fasload in sfaslbfd.c, we have a line saying :

    dum.sm.sm_object0=dum.sm.sm_object1=OBJNULL;

By contrast, towards the end of open_stream in file.d, we have a line 
saying :

        x->sm.sm_object1 = fn;

Any idea ?

Thanks,
Aurelien

---

-bash2.05b /src/src/gcl-2.7.0 $ gdb attach 3960
GNU gdb 5.3-20030128 (Apple version gdb-309) (Thu Dec  4 15:41:30 GMT 
2003)
Copyright 2003 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and 
you are
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conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for 
details.
This GDB was configured as "powerpc-apple-darwin".
attach: No such file or directory.
/src/src/gcl-2.7.0/3960: No such file or directory.
Attaching to process 3960.
Reading symbols for shared libraries . done
Reading symbols for shared libraries ....... done
0x0001b750 in insert_contblock (p=0x1ec6000 "", s=4096) at alloc.c:556
556         if ((*cbpp)->cb_size >= s) {
(gdb) list coerce_to_pathname
196     }
197
198     object
199     coerce_to_pathname(x)
200     object x;
201     {
202             object y;
203             int e;
204
205     L:
(gdb)
206             switch (type_of(x)) {
207             case t_symbol:
208             case t_string:
209                     /* !!!!! Bug Fix. NLG */
210                     y = parse_namestring(x, 0, x->st.st_fillp, &e);
211                     if (y == OBJNULL || e != x->st.st_fillp)
212                             goto CANNOT_COERCE;
213                     return(y);
214
215             case t_pathname:
(gdb)
216                     return(x);
217
218             case t_stream:
219                     switch (x->sm.sm_mode) {
220                     case smm_input:
221                     case smm_output:
222                     case smm_probe:
223                     case smm_io:
224                             x = x->sm.sm_object1;
225                             /*
(gdb)
226                                     The file was stored in 
sm.sm_object1.
227                                     See open.
228                             */
229                             goto L;
230
231                     case smm_synonym:
232                             x = symbol_value(x->sm.sm_object0);
233                             goto L;
234
235                     default:
(gdb) b 224
Breakpoint 3 at 0xa4040: file pathname.d, line 224.
(gdb) c
Continuing.

Breakpoint 3, coerce_to_pathname (x=0x4fa55c) at pathname.d:224
224                             x = x->sm.sm_object1;
(gdb) list
219                     switch (x->sm.sm_mode) {
220                     case smm_input:
221                     case smm_output:
222                     case smm_probe:
223                     case smm_io:
224                             x = x->sm.sm_object1;
225                             /*
226                                     The file was stored in 
sm.sm_object1.
227                                     See open.
228                             */
(gdb)
229                             goto L;
230
231                     case smm_synonym:
232                             x = symbol_value(x->sm.sm_object0);
233                             goto L;
234
235                     default:
236                             goto CANNOT_COERCE;
237                     }
238
(gdb) n
229                             goto L;
(gdb) p x
$2 = 0x0
(gdb) n
206             switch (type_of(x)) {
(gdb) p x
$3 = 0x0
(gdb) n

Program received signal EXC_BAD_ACCESS, Could not access memory.
0x000a3f5c in coerce_to_pathname (x=0x0) at pathname.d:206
206             switch (type_of(x)) {