Crash without any fonts

[jbeich]

Trying to run in a clean jail crashes Watershot instead of showing the following error: https://github.com/Kirottu/watershot/blob/2d0c6522e1ad434624a59ef443b4e1e5a9c9cfea/src/runtime_data.rs#L83 Note,font_family: "nonexistent" in ~/.config/watershot.ron still doesn't trigger the error.

$ fc-list
$ watershot
Segmentation fault

* thread #1, name = 'watershot', stop reason = signal SIGSEGV: invalid address (fault address: 0x10)
    frame #0: 0x00000aa93c70fecc libfontconfig.so.1`FcRefIsConst(r=0x0000000000000010) at fcatomic.h:169:71
   166  static inline int    FcRefDec      (FcRef *r) { return fc_atomic_int_add (r->count, -1); }
   167  static inline int    FcRefAdd      (FcRef *r, int v) { return fc_atomic_int_add (r->count, v); }
   168  static inline void   FcRefSetConst (FcRef *r) { r->count = FC_REF_CONSTANT_VALUE; }
-> 169  static inline FcBool FcRefIsConst  (const FcRef *r) { return r->count == FC_REF_CONSTANT_VALUE; }
   170
   171  #endif /* _FCATOMIC_H_ */
(lldb) bt
* thread #1, name = 'watershot', stop reason = signal SIGSEGV: invalid address (fault address: 0x10)
  * frame #0: 0x00000aa93c70fecc libfontconfig.so.1`FcRefIsConst(r=0x0000000000000010) at fcatomic.h:169:71
    frame #1: 0x00000aa93c712349 libfontconfig.so.1`IA__FcPatternReference(p=0x0000000000000000) at fcpat.c:1218:10
    frame #2: 0x00000aa119b8976e watershot`fontconfig::Pattern::from_pattern::h27d2b79756aa8a86(fc=0x00000aa93aa40308, pat=0x0000000000000000) at lib.rs:197:9
    frame #3: 0x00000aa119b89aa1 watershot`fontconfig::Pattern::font_match::h5514b8e8980d9251(self=0x00000aa93aa3fdf8) at lib.rs:292:13
    frame #4: 0x00000aa119b892a5 watershot`fontconfig::Font::find::h49d5c33175243cca(fc=0x00000aa93aa40308, family=(data_ptr = "monospaceoⶢ\U0000000e", length = 9), style=Option<&str> @ 0x00000aa93aa3fde8) at lib.rs:152:26
    frame #5: 0x00000aa119b88fca watershot`fontconfig::Fontconfig::find::hfd07258ab079598d(self=0x00000aa93aa40308, family=(data_ptr = "monospaceoⶢ\U0000000e", length = 9), style=Option<&str> @ 0x00000aa93aa3ff28) at lib.rs:118:9
    frame #6: 0x00000aa11917e16d watershot`watershot::runtime_data::RuntimeData::new::hce5681281c457f20(qh=0x00000aa93aa412b0, globals=0x00000aa93aa411c0, args=(copy = false, stdout = false, grim = core::option::Option<alloc::string::String> @ 0x00000aa93aa418d8, save = core::option::Option<watershot::types::SaveLocation> @ 0x00000aa93aa418b8)) at runtime_data.rs:81:23
    frame #7: 0x00000aa1191ce163 watershot`watershot::gui::h945d8e0e356f1264(args=0x00000aa93aa434c0) at main.rs:102:28
    frame #8: 0x00000aa1191ccc89 watershot`watershot::main::hea9f55f4eb1c4f64 at main.rs:33:26
    frame #9: 0x00000aa1191ee49b watershot`core::ops::function::FnOnce::call_once::h6a4c4bb0bfd20375((null)=(watershot`watershot::main::hea9f55f4eb1c4f64 at main.rs:29), (null)=<unavailable>) at function.rs:250:5
    frame #10: 0x00000aa11923e86e watershot`std::sys_common::backtrace::__rust_begin_short_backtrace::h4f6dbe38327542d6(f=(watershot`watershot::main::hea9f55f4eb1c4f64 at main.rs:29)) at backtrace.rs:135:18
    frame #11: 0x00000aa1191cfcc1 watershot`std::rt::lang_start::_$u7b$$u7b$closure$u7d$$u7d$::h9903a531f48c65c6 at rt.rs:166:18
    frame #12: 0x00000aa11a07f877 watershot`std::panicking::try::h09ab0ca6a50f9591 + 23
    frame #13: 0x00000aa11a09badb watershot`std::rt::lang_start_internal::h3e0793a574932966 + 43
    frame #14: 0x00000aa1191cfc9a watershot`std::rt::lang_start::h5e046485b1630588(main=(watershot`watershot::main::hea9f55f4eb1c4f64 at main.rs:29), argc=1, argv=0x00000aa93aa43da8, sigpipe='\0') at rt.rs:165:17
    frame #15: 0x00000aa1191cee3e watershot`main + 30
    frame #16: 0x00000aa11916f48d watershot`_start(ap=<unavailable>, cleanup=<unavailable>) at crt1_c.c:75:7

[Kirottu]

That's very weird, if I point it to a nonexistent font it just loads the default. But you do most certainly need fonts to run Watershot and it seems like that segfault originates from the fontconfig lib that I use anyway.