SIGABRT at startup on Ubuntu 26

[nosemeocurrenada]

When trying to view a pdf, the process gets killed with SIGABRT, and the Kitty terminal is left in an unusable state

Steps

1. Clone the v.0.4.1 tag

git clone --depth=1 --branch 'v0.4.1' https://github.com/freref/fancy-cat.git

2. Build

git submodule update --init --recursive && zig build

3. Got a small pdf

pdflatex <<EOF
\documentclass{article}
\begin{document}
\paragraph{Hello.}
  fancy-kitty
\end{document}
EOF

4. Ran fancy-cat with the pdf

fancy-cat/zig-out/bin/fancy-cat texput.pdf

After a while, it writes stuff on the terminal, aborts, and leaves the terminal unusable. See the screencast:
https://imgur.com/a/VZQMpRG

edit: after the process got killed I pressed the keys abcdshift-ctrl-altR

Versions

$ lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 26.04 LTS
Release:	26.04
Codename:	resolute
$ zig version
0.14.1
$ clang --version
Ubuntu clang version 21.1.8 (6ubuntu1)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/lib/llvm-21/bin

Additional context

The latest version of zig available on the Ubuntu repositories is 0.14.1 and snap provides the version 0.16.0, on master the minimum zig version is 0.15.2, the latest tag that supports 0.14 is v0.4.1

When installing with --release=small the behavior the same except that the signal is SIGILL

Dumps

fancy-cat

key_value: json.dynamic.Value{ .string = { 99, 111, 108, 111, 110 } }, key: colon, codepoint: 58
key_value: json.dynamic.Value{ .string = { 101, 115, 99, 97, 112, 101 } }, key: escape, codepoint: 27
key_value: json.dynamic.Value{ .string = { 101, 110, 116, 101, 114 } }, key: enter, codepoint: 13
info(vaxis): pixel mouse capability detected
info(vaxis): color_scheme_updates capability detected
info(vaxis): explicit width capability detected
info(vaxis): kitty keyboard capability detected
info(vaxis): kitty graphics capability detected
debug(vaxis): enabling mouse mode: pixel coordinates
debug(vaxis): resizing screen: width=144 height=39
debug(vaxis): resizing screen: width=144 height=39
Illegal instruction at address 0x17c39a5
/home/cristian/.cache/zig/p/fastb64z-1.0.0-AAAAAPufAAC1oOmqjUybDgnEHsOlgJKIjnUWwFy3i3TJ/src/shuffle.zig:13:5: 0x17c39a5 in encodeBytesVectorized (fancy-cat)
    return asm ("vpshufb %[mask], %[src], %[dst]"
    ^
/home/cristian/.cache/zig/p/fastb64z-1.0.0-AAAAAPufAAC1oOmqjUybDgnEHsOlgJKIjnUWwFy3i3TJ/src/fastb64.zig:112:47: 0x179cb67 in encode (fancy-cat)
                vector64.encodeBytesVectorized(source, dest, encoder.shift_lookup, idx, out_idx);
                                              ^
/home/cristian/Repos/fancy-cat/src/handlers/PdfHandler.zig:211:45: 0x179c25b in renderPage (fancy-cat)
        const encoded = base64Encoder.encode(b64_buf, samples[0..sample_count]);
                                            ^
/home/cristian/Repos/fancy-cat/src/handlers/DocumentHandler.zig:68:43: 0x179f0d9 in renderPage (fancy-cat)
    return try self.pdf_handler.renderPage(page_number, window_width, window_height);
                                          ^
/home/cristian/Repos/fancy-cat/src/Context.zig:227:67: 0x17a0315 in getPage (fancy-cat)
        const encoded_image = try self.document_handler.renderPage(
                                                                  ^
/home/cristian/Repos/fancy-cat/src/Context.zig:264:49: 0x17a1a95 in drawCurrentPage (fancy-cat)
            self.current_page = try self.getPage(
                                                ^
/home/cristian/Repos/fancy-cat/src/Context.zig:331:33: 0x17a569c in draw (fancy-cat)
        try self.drawCurrentPage(win);
                                ^
/home/cristian/Repos/fancy-cat/src/Context.zig:145:26: 0x17b308f in run (fancy-cat)
            try self.draw();
                         ^
/home/cristian/Repos/fancy-cat/src/main.zig:60:16: 0x17b413a in main (fancy-cat)
    try app.run();
               ^
/usr/lib/zig0.14/lib/std/start.zig:660:37: 0x17b4d07 in main (fancy-cat)
            const result = root.main() catch |err| {
                                    ^
../sysdeps/nptl/libc_start_call_main.h:59:16: 0x7cbfdb02a600 in __libc_start_call_main (../sysdeps/x86/libc-start.c)
../csu/libc-start.c:360:3: 0x7cbfdb02a717 in __libc_start_main_impl (../sysdeps/x86/libc-start.c)
???:?:?: 0x12fe564 in ??? (???)
???:?:?: 0x0 in ??? (???)

GDB backtrace

[New LWP 6472]
[New LWP 6475]
[New LWP 6473]

This GDB supports auto-downloading debuginfo from the following URLs:
  <https://debuginfod.ubuntu.com>
Enable debuginfod for this session? (y or [n]) [answered N; input not from terminal]
Debuginfod has been disabled.
To make this setting permanent, add 'set debuginfod enabled off' to .gdbinit.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `./fancy-cat /home/cristian/fancy-cat-test/texput.pdf'.
Program terminated with signal SIGABRT, Aborted.
#0  __pthread_kill_implementation (threadid=<optimized out>, signo=6, no_tid=0) at ./nptl/pthread_kill.c:44
[Current thread is 1 (Thread 0x7cbfdb239780 (LWP 6472))]
#0  __pthread_kill_implementation (threadid=<optimized out>, signo=6, no_tid=0) at ./nptl/pthread_kill.c:44
#1  __pthread_kill_internal (threadid=<optimized out>, signo=6) at ./nptl/pthread_kill.c:89
#2  __GI___pthread_kill (threadid=<optimized out>, signo=signo@entry=6) at ./nptl/pthread_kill.c:100
#3  0x00007cbfdb045b7e in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
#4  0x00007cbfdb0288ec in __GI_abort () at ./stdlib/abort.c:77
#5  0x00000000016e6c31 in posix.abort () at /usr/lib/zig0.14/lib/std/posix.zig:710
#6  0x00000000017c9adc in debug.handleSegfaultPosix (sig=4, info=0x7ffcfa112330, ctx_ptr=0x7ffcfa112200) at /usr/lib/zig0.14/lib/std/debug.zig:1456
#7  <signal handler called>
#8  shuffle.shuffle () at /home/cristian/.cache/zig/p/fastb64z-1.0.0-AAAAAPufAAC1oOmqjUybDgnEHsOlgJKIjnUWwFy3i3TJ/src/shuffle.zig:13
#9  shuffle.lookup_ByteVector () at /home/cristian/.cache/zig/p/fastb64z-1.0.0-AAAAAPufAAC1oOmqjUybDgnEHsOlgJKIjnUWwFy3i3TJ/src/shuffle.zig:31
#10 vector64.encodeBytesVectorized (src=..., dst=..., shift_lookup=..., sp=0, dp=0) at /home/cristian/.cache/zig/p/fastb64z-1.0.0-AAAAAPufAAC1oOmqjUybDgnEHsOlgJKIjnUWwFy3i3TJ/src/vector64.zig:97
#11 0x000000000179cb68 in fastb64.Base64Encoder.encode (encoder=0x1219cb0 <__anon_30033>, dest=..., source=...) at /home/cristian/.cache/zig/p/fastb64z-1.0.0-AAAAAPufAAC1oOmqjUybDgnEHsOlgJKIjnUWwFy3i3TJ/src/fastb64.zig:112
#12 0x000000000179c25c in handlers.PdfHandler.renderPage (self=0x7ffcfa11c228, page_number=0, window_width=1296, window_height=666) at /home/cristian/Repos/fancy-cat/src/handlers/PdfHandler.zig:211
#13 0x000000000179f0da in handlers.DocumentHandler.renderPage (self=0x7ffcfa11c228, page_number=0, window_width=1296, window_height=666) at /home/cristian/Repos/fancy-cat/src/handlers/DocumentHandler.zig:68
#14 0x00000000017a0316 in Context.Context.getPage (self=0x7ffcfa11c120, page_number=0, window_width=1296, window_height=666) at Context.zig:227
#15 0x00000000017a1a96 in Context.Context.drawCurrentPage (self=0x7ffcfa11c120, win=...) at Context.zig:264
#16 0x00000000017a569d in Context.Context.draw (self=0x7ffcfa11c120) at Context.zig:331
#17 0x00000000017b3090 in Context.Context.run (self=0x7ffcfa11c120) at Context.zig:145
#18 0x00000000017b413b in main.main () at main.zig:60
#19 0x00000000017b4d08 in start.callMain () at /usr/lib/zig0.14/lib/std/start.zig:660
#20 start.callMainWithArgs () at /usr/lib/zig0.14/lib/std/start.zig:620
#21 start.main (c_argc=2, c_argv=0x7ffcfa11caf8, c_envp=0x7ffcfa11cb10) at /usr/lib/zig0.14/lib/std/start.zig:635

[nosemeocurrenada]

Update: I've installed zig 0.15.2 from https://ziglang.org/download/index.json
and now I'm using the master branch
the behavior was the same.

Part of the issue seems to be that fastb64z uses the instruction vpshufb that my processor doesn't have.
I've applied the following patch to remove the dependency

diff --git a/src/handlers/PdfHandler.zig b/src/handlers/PdfHandler.zig
index 70d5bac..770b736 100644
--- a/src/handlers/PdfHandler.zig
+++ b/src/handlers/PdfHandler.zig
@@ -206,7 +206,7 @@ pub fn renderPage(
         const height = @as(usize, @intCast(@abs(bbox.y1)));
         const samples = c.fz_pixmap_samples(self.ctx, pix);
 
-        const base64Encoder = fastb64z.standard.Encoder;
+        const base64Encoder = std.base64.standard.Encoder;
         const sample_count = width * height * 3;
 
         const b64_buf = try self.allocator.alloc(u8, base64Encoder.calcSize(sample_count));

now the exception is raised inside vaxis, see the dump below.

info(vaxis): pixel mouse capability detected
info(vaxis): color_scheme_updates capability detected
info(vaxis): explicit width capability detected
info(vaxis): multi cursor capability detected
info(vaxis): scaled text capability detected
info(vaxis): kitty keyboard capability detected
info(vaxis): kitty graphics capability detected
debug(vaxis): enabling mouse mode: pixel coordinates
debug(vaxis): resizing screen: width=144 height=38
debug(vaxis): resizing screen: width=144 height=38
Segmentation fault at address 0x7043cc66026a
/home/cristian/Repos/zig/zig-x86_64-linux-0.15.2/lib/std/mem.zig:737:32: 0x132177a in eqlBytes (std.zig)
            const x = (a[0] ^ b[0]) | (a[a.len - 1] ^ b[a.len - 1]) | (a[a.len / 2] ^ b[a.len / 2]);
                               ^
/home/cristian/Repos/zig/zig-x86_64-linux-0.15.2/lib/std/mem.zig:697:24: 0x12e7653 in eql__anon_4614 (std.zig)
        return eqlBytes(sliceAsBytes(a), sliceAsBytes(b));
                       ^
/home/cristian/.cache/zig/p/vaxis-0.5.1-BWNV_LosCQAGmCCNOLljCIw6j6-yt53tji6n6rwJ2BhS/src/InternalScreen.zig:32:27: 0x1437713 in eql (main.zig)
        return std.mem.eql(u8, self.char.items, cell.char.grapheme) and
                          ^
/home/cristian/.cache/zig/p/vaxis-0.5.1-BWNV_LosCQAGmCCNOLljCIw6j6-yt53tji6n6rwJ2BhS/src/Vaxis.zig:437:21: 0x13ef5cb in render (main.zig)
            last.eql(cell) and
                    ^
/home/cristian/Repos/fancy-cat/src/Context.zig:183:31: 0x14100b7 in run (main.zig)
            try self.vx.render(buffered);
                              ^
/home/cristian/Repos/fancy-cat/src/main.zig:68:16: 0x14111ed in main (main.zig)
    try app.run();
               ^
/home/cristian/Repos/zig/zig-x86_64-linux-0.15.2/lib/std/start.zig:627:37: 0x1411b7d in main (std.zig)
            const result = root.main() catch |err| {
                                    ^
../sysdeps/nptl/libc_start_call_main.h:59:16: 0x7043cfa2a600 in __libc_start_call_main (../sysdeps/x86/libc-start.c)
../csu/libc-start.c:360:3: 0x7043cfa2a717 in __libc_start_main_impl (../sysdeps/x86/libc-start.c)
???:?:?: 0x155ffa4 in ??? (???)
???:?:?: 0x0 in ??? (???)

lscpu

Architecture:                            x86_64
CPU op-mode(s):                          32-bit, 64-bit
Address sizes:                           39 bits physical, 48 bits virtual
Byte Order:                              Little Endian
CPU(s):                                  4
On-line CPU(s) list:                     0-3
Vendor ID:                               GenuineIntel
Model name:                              Intel(R) Pentium(R) CPU 4417U @ 2.30GHz
CPU family:                              6
Model:                                   142
Thread(s) per core:                      2
Core(s) per socket:                      2
Socket(s):                               1
Stepping:                                10
CPU(s) scaling MHz:                      35%
CPU max MHz:                             2300.0000
CPU min MHz:                             400.0000
BogoMIPS:                                4599.93
Flags:                                   fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 sdbg cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb pti ssbd ibrs ibpb stibp tpr_shadow flexpriority ept vpid ept_ad fsgsbase tsc_adjust smep erms invpcid mpx rdseed smap clflushopt intel_pt xsaveopt xsavec xgetbv1 xsaves dtherm arat pln pts hwp hwp_notify hwp_act_window hwp_epp vnmi md_clear flush_l1d arch_capabilities
Virtualization:                          VT-x
L1d cache:                               64 KiB (2 instances)
L1i cache:                               64 KiB (2 instances)
L2 cache:                                512 KiB (2 instances)
L3 cache:                                2 MiB (1 instance)
NUMA node(s):                            1
NUMA node0 CPU(s):                       0-3
Vulnerability Gather data sampling:      Not affected
Vulnerability Ghostwrite:                Not affected
Vulnerability Indirect target selection: Not affected
Vulnerability Itlb multihit:             KVM: Mitigation: Split huge pages
Vulnerability L1tf:                      Mitigation; PTE Inversion; VMX conditional cache flushes, SMT vulnerable
Vulnerability Mds:                       Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Meltdown:                  Mitigation; PTI
Vulnerability Mmio stale data:           Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Old microcode:             Not affected
Vulnerability Reg file data sampling:    Not affected
Vulnerability Retbleed:                  Mitigation; IBRS
Vulnerability Spec rstack overflow:      Not affected
Vulnerability Spec store bypass:         Mitigation; Speculative Store Bypass disabled via prctl
Vulnerability Spectre v1:                Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2:                Mitigation; IBRS; IBPB conditional; STIBP conditional; RSB filling; PBRSB-eIBRS Not affected; BHI Not affected
Vulnerability Srbds:                     Mitigation; Microcode
Vulnerability Tsa:                       Not affected
Vulnerability Tsx async abort:           Not affected
Vulnerability Vmscape:                   Mitigation; IBPB before exit to userspace

[freref]

Thank you for trying to debug this issue, I will take a look at it. On what machine are you running this?

[nosemeocurrenada]

On what machine are you running this?

It's an Acer Aspire A315-53
a laptop with a Pentium 4417U