#272 sox_formats_quit does not properly clean things up

[Stefano Guidoni]

The following simple program (attachment test.c) crashes when libsox is compiled dynamically ( i.e. --with_dyn_default ), e.g. in most Linux distros like Debian/Ubuntu or Fedora and derivatives.

The reason is that the end condition for the for cycle in "sox_find_format" ( from src/formats.c ) is "s_sox_format_fns[f].fn == NULL", a condition which does not occur if "s_sox_format_fns[f].fn" points to an in invalid address. Unfortunately, that's exactly what happens when libsox is compiled dynamically, the searched format is compiled in a plugin and the progam calls libsox more than once: the last ( f = NSTATIC_FORMATS ) "s_sox_format_fns[f].fn" is not NULL and points to the address of the first plugin function, when it was allocated the first time ( which of course is no more a valid address the second time it is allocated ).

A possible solution is in the attached patch: "sox_format_quit" ( from src/formats.c ) set "s_sox_format_fns[NSTATIC_FORMATS].fn" to NULL, so that the for cycle correctly ends if it doesn't find the format, that it was looking for, among those statically compiled. When libsox calls "sox_format_init" again, the addresses in "s_sox_format_fns[f].fn" are all valid again beyond NSTATIC_FORMATS and the function can work properly.

[Stefano Guidoni]

A working patch:

--- old/src/formats.c   2015-02-27 04:48:40.000000000 +0100
+++ new/src/formats.c   2016-01-10 22:14:58.203847117 +0100
@@ -1247,6 +1247,8 @@
     lsx_fail("lt_dlexit failed with %d error(s): %s", ret, lt_dlerror());
   plugins_initted = sox_false;
   nformats = NSTATIC_FORMATS;

+  s_sox_format_fns[NSTATIC_FORMATS].name = NULL;
+  s_sox_format_fns[NSTATIC_FORMATS].fn = NULL;
 #endif
 }

[Mans Rullgard]

Fixed.