intermittent segmentation fault after start on linux

[j5ndev]

I'm experiencing intermittent segmentation faults on Ubuntu after start up. It typically happens when resizing panes or switching between tabs. I'm unable to reproduce the issue consistently with the same actions.

$ github.com/ghostty-org/ghostty/zig-out/bin/ghostty 
info: ghostty version=1.0.2-main+5cb2fa6f
info: ghostty build optimize=ReleaseFast
info: runtime=apprt.Runtime.gtk
info: font_backend=font.main.Backend.fontconfig_freetype
info: dependency harfbuzz=8.4.0
info: dependency fontconfig=21402
info: renderer=renderer.OpenGL
info: libxev backend=main.Backend.io_uring
info(os): setlocale from env result=en_US.UTF-8
info(gtk): GTK version build=4.14.2 runtime=4.14.2
info: reading configuration file path=/home/mj/.config/ghostty/config
info(config): default shell source=env value=/usr/bin/zsh
warning(gtk): setting GDK_DEBUG=gl-disable-gles,gl-no-fractional,vulkan-disable
warning(gtk): setting GDK_DISABLE=
warning(gtk): setting GSK_RENDERER=opengl
info(gtk): libadwaita version build=1.5.0 runtime=1.5.0
info(grid): loaded OpenGL 4.6
info(io_exec): found Ghostty resources dir: /home/mj/projects/github.com/ghostty-org/ghostty/zig-out/share/ghostty
info(io_exec): shell integration automatically injected shell=termio.shell_integration.Shell.zsh
warning(gtk): unimplemented action=apprt.action.Action.Key.cell_size
info(io_exec): started subcommand path=/bin/sh pid=276400
info(io_exec): subcommand cgroup=-
info(grid): reallocating GPU buffer old=0 new=8
info(stream): OSC 1 (change icon) received and ignored icon=~/projects
warning(stream): unimplemented OSC command: change_window_icon
info(grid): reallocating GPU buffer old=8 new=38
info(grid): loaded OpenGL 4.6
info(io_exec): found Ghostty resources dir: /home/mj/projects/github.com/ghostty-org/ghostty/zig-out/share/ghostty
info(io_exec): shell integration automatically injected shell=termio.shell_integration.Shell.zsh
warning(gtk): unimplemented action=apprt.action.Action.Key.cell_size
warning(gtk): unimplemented action=apprt.action.Action.Key.cell_size
info(io_exec): started subcommand path=/bin/sh pid=276652
info(io_exec): subcommand cgroup=-
info(grid): reallocating GPU buffer old=0 new=38
info(grid): reallocating GPU buffer old=0 new=8
info(stream): OSC 1 (change icon) received and ignored icon=~/projects
warning(stream): unimplemented OSC command: change_window_icon
info(grid): reallocating GPU buffer old=8 new=38
info(grid): loaded OpenGL 4.6
info(io_exec): found Ghostty resources dir: /home/mj/projects/github.com/ghostty-org/ghostty/zig-out/share/ghostty
info(io_exec): shell integration automatically injected shell=termio.shell_integration.Shell.zsh
warning(gtk): unimplemented action=apprt.action.Action.Key.cell_size
warning(gtk): unimplemented action=apprt.action.Action.Key.cell_size
info(io_exec): started subcommand path=/bin/sh pid=276911
info(io_exec): subcommand cgroup=-
info(grid): reallocating GPU buffer old=0 new=38
info(grid): reallocating GPU buffer old=0 new=38
info(grid): reallocating GPU buffer old=0 new=8
info(stream): OSC 1 (change icon) received and ignored icon=~/projects
warning(stream): unimplemented OSC command: change_window_icon
info(grid): reallocating GPU buffer old=8 new=38
info(grid): loaded OpenGL 4.6
info(io_exec): found Ghostty resources dir: /home/mj/projects/github.com/ghostty-org/ghostty/zig-out/share/ghostty
info(io_exec): shell integration automatically injected shell=termio.shell_integration.Shell.zsh
warning(gtk): unimplemented action=apprt.action.Action.Key.cell_size
warning(gtk): unimplemented action=apprt.action.Action.Key.cell_size
info(io_exec): started subcommand path=/bin/sh pid=277172
info(io_exec): subcommand cgroup=-
info(grid): reallocating GPU buffer old=0 new=38
info(grid): reallocating GPU buffer old=0 new=38
info(grid): reallocating GPU buffer old=0 new=8
info(stream): OSC 1 (change icon) received and ignored icon=~/projects
warning(stream): unimplemented OSC command: change_window_icon
info(grid): reallocating GPU buffer old=8 new=38
info(grid): loaded OpenGL 4.6
info(io_exec): found Ghostty resources dir: /home/mj/projects/github.com/ghostty-org/ghostty/zig-out/share/ghostty
info(io_exec): shell integration automatically injected shell=termio.shell_integration.Shell.zsh
warning(gtk): unimplemented action=apprt.action.Action.Key.cell_size
warning(gtk): unimplemented action=apprt.action.Action.Key.cell_size
info(io_exec): started subcommand path=/bin/sh pid=277436
info(io_exec): subcommand cgroup=-
info(grid): reallocating GPU buffer old=0 new=38
info(grid): reallocating GPU buffer old=0 new=38
info(grid): reallocating GPU buffer old=0 new=8
info(stream): OSC 1 (change icon) received and ignored icon=~/projects
warning(stream): unimplemented OSC command: change_window_icon
info(grid): reallocating GPU buffer old=8 new=38
[1]    276374 segmentation fault (core dumped)  github.com/ghostty-org/ghostty/zig-out/bin/ghostty

$ github.com/ghostty-org/ghostty/zig-out/bin/ghostty +crash-report
No crash reports! 👻%

$ cat /etc/os-release                                             
PRETTY_NAME="Ubuntu 24.04.1 LTS"
NAME="Ubuntu"
VERSION_ID="24.04"
VERSION="24.04.1 LTS (Noble Numbat)"
VERSION_CODENAME=noble
ID=ubuntu
ID_LIKE=debian
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
UBUNTU_CODENAME=noble
LOGO=ubuntu-logo

Above I showed the logs after running the binary I compiled myself.

The latest snap is also crashing, but I wasn't able to track down the crash report:

$ which ghostty
/snap/bin/ghostty

$ ghostty version
info: ghostty version=1.0.2-add_snap_package+f1f6cf4b
info: ghostty build optimize=ReleaseFast
info: runtime=apprt.Runtime.gtk
info: font_backend=font.main.Backend.fontconfig_freetype
info: dependency harfbuzz=8.4.0
info: dependency fontconfig=21402
info: renderer=renderer.OpenGL
info: libxev backend=main.Backend.io_uring
info(os): setlocale from env result=C.UTF-8
info(gtk): GTK version build=4.14.2 runtime=4.14.2
info: reading configuration file path=/home/mj/.config/ghostty/config
info(config): default shell source=env value=/usr/bin/zsh
warning(gtk): configuration error: cli:1:version: invalid field
warning(gtk): CLI errors detected, exiting

$ snap info ghostty
name:      ghostty
summary:   A terminal emulator
publisher: Ken VanDine✪
store-url: https://snapcraft.io/ghostty
contact:   https://github.com/ghostty-org/ghostty/discussions
license:   MIT
description: |
  Ghostty is a fast, feature-rich, and cross-platform terminal emulator that
  uses platform-native UI and GPU acceleration.
commands:
  - ghostty
snap-id:      0Js0ucdWpbxjd5LqmGT5MVUywEWyNbvs
tracking:     latest/stable
refresh-date: 2 days ago, at 08:36 EST
channels:
  latest/stable:    1.0.2-tip-614-gce463482 2025-01-21 (10) 106MB classic
  latest/candidate: ↑                                             
  latest/beta:      ↑                                             
  latest/edge:      1.0.2-tip-614-gce463482 2025-01-21 (10) 106MB classic
installed:          1.0.2-tip-532-gf1f6cf4b             (9) 106MB classic

$ ghostty +crash-report
No crash reports! 👻%

[mitchellh]

Are you able to build a debug version to get a stack trace?

[j5ndev]

I was able to build a debug version.
I tried to trigger a segfault, but now it is behaving.
I'll continue to use the debug version and report back with a stack trace when it happens...

[j5ndev]

I found that the issue was dependent on where I called the executable from.
Calling it from the repository directory $ zig-out/bin/ghostty did not eventually result in a segfault.
Calling it from my home directory $ projects/github.com/ghostty-org/ghostty/zig-out/bin/ghostty did eventually result in a segfault. Steps to reproduce in this second case:

1. right click ghostty
2. select Split Right from the context menu
3. click and hold center line between panes to resize
4. shake it like a Polaroid picture (continue holding and shaking center line to resize without letting go; eventually it segfaults)

debug(terminal): c=FE0E grapheme attach to left=1 primary_cp=2716
debug(terminal): c=FE0E grapheme attach to left=1 primary_cp=2716
debug(renderer_thread): mailbox message=renderer.message.Message{ .resize = renderer.size.Size{ .screen = renderer.size.ScreenSize{ .width = 538, .height = 1080 }, .cell = renderer.size.CellSize{ .width = 10, .height = 22 }, .padding = renderer.size.Padding{ .top = 2, .bottom = 2, .right = 2, .left = 2 } } }
debug(grid): screen size size=renderer.size.Size{ .screen = renderer.size.ScreenSize{ .width = 538, .height = 1080 }, .cell = renderer.size.CellSize{ .width = 10, .height = 22 }, .padding = renderer.size.Padding{ .top = 2, .bottom = 2, .right = 2, .left = 2 } }
/home/mj/.cache/zig/p/1220b81f6ecfb3fd222f76cf9106fecfa6554ab07ec7fdc4124b9bb063ae2adf969d/builds/unix/ftsystem.c:113:12: 0x40ca130 in ft_alloc (/home/mj/.cache/zig/p/1220b81f6ecfb3fd222f76cf9106fecfa6554ab07ec7fdc4124b9bb063ae2adf969d/builds/unix/ftsystem.c)
    return malloc( size );
           ^
/home/mj/.cache/zig/p/1220b81f6ecfb3fd222f76cf9106fecfa6554ab07ec7fdc4124b9bb063ae2adf969d/src/base/ftutil.c:145:15: 0x40bec1e in ft_mem_qrealloc (/home/mj/.cache/zig/p/1220b81f6ecfb3fd222f76cf9106fecfa6554ab07ec7fdc4124b9bb063ae2adf969d/src/base/ftbase.c)
      block = memory->alloc( memory, new_count * item_size );
              ^
/home/mj/.cache/zig/p/1220b81f6ecfb3fd222f76cf9106fecfa6554ab07ec7fdc4124b9bb063ae2adf969d/src/base/ftutil.c:101:13: 0x40b8c40 in ft_mem_realloc (/home/mj/.cache/zig/p/1220b81f6ecfb3fd222f76cf9106fecfa6554ab07ec7fdc4124b9bb063ae2adf969d/src/base/ftbase.c)
    block = ft_mem_qrealloc( memory, item_size,
            ^
/home/mj/.cache/zig/p/1220b81f6ecfb3fd222f76cf9106fecfa6554ab07ec7fdc4124b9bb063ae2adf969d/src/smooth/ftsmooth.c:485:10: 0x42ab974 in ft_smooth_render (/home/mj/.cache/zig/p/1220b81f6ecfb3fd222f76cf9106fecfa6554ab07ec7fdc4124b9bb063ae2adf969d/src/smooth/smooth.c)
    if ( FT_ALLOC_MULT( bitmap->buffer, bitmap->rows, bitmap->pitch ) )
         ^
/home/mj/.cache/zig/p/1220b81f6ecfb3fd222f76cf9106fecfa6554ab07ec7fdc4124b9bb063ae2adf969d/src/base/ftobjs.c:4848:19: 0x40c04f3 in FT_Render_Glyph_Internal (/home/mj/.cache/zig/p/1220b81f6ecfb3fd222f76cf9106fecfa6554ab07ec7fdc4124b9bb063ae2adf969d/src/base/ftbase.c)
          error = renderer->render( renderer, slot, render_mode, NULL );
                  ^
/home/mj/.cache/zig/p/1220b81f6ecfb3fd222f76cf9106fecfa6554ab07ec7fdc4124b9bb063ae2adf969d/src/base/ftobjs.c:5008:12: 0x40bbc5b in FT_Render_Glyph (/home/mj/.cache/zig/p/1220b81f6ecfb3fd222f76cf9106fecfa6554ab07ec7fdc4124b9bb063ae2adf969d/src/base/ftbase.c)
    return FT_Render_Glyph_Internal( library, slot, render_mode );
           ^
/home/mj/.cache/zig/p/1220b81f6ecfb3fd222f76cf9106fecfa6554ab07ec7fdc4124b9bb063ae2adf969d/src/base/ftobjs.c:1169:17: 0x40b7136 in FT_Load_Glyph (/home/mj/.cache/zig/p/1220b81f6ecfb3fd222f76cf9106fecfa6554ab07ec7fdc4124b9bb063ae2adf969d/src/base/ftbase.c)
        error = FT_Render_Glyph( slot, mode );
                ^
/home/mj/projects/github.com/ghostty-org/ghostty/pkg/freetype/face.zig:91:42: 0x3362c9a in loadGlyph (ghostty)
        return intToError(c.FT_Load_Glyph(
                                         ^
/home/mj/projects/github.com/ghostty-org/ghostty/src/font/face/freetype.zig:282:28: 0x33644ad in isColorGlyph (ghostty)
        self.face.loadGlyph(glyph_id, .{
                           ^
/home/mj/projects/github.com/ghostty-org/ghostty/src/font/Collection.zig:600:52: 0x3268dbd in hasCodepoint (ghostty)
                        .text => !face.isColorGlyph(index),
                                                   ^
/home/mj/projects/github.com/ghostty-org/ghostty/src/font/Collection.zig:209:43: 0x32656e4 in hasCodepoint (ghostty)
    return list.at(index.idx).hasCodepoint(cp, p_mode);
                                          ^
/home/mj/projects/github.com/ghostty-org/ghostty/src/font/SharedGrid.zig:192:49: 0x354f7fe in hasCodepoint (ghostty)
    return self.resolver.collection.hasCodepoint(
                                                ^
/home/mj/projects/github.com/ghostty-org/ghostty/src/font/shaper/run.zig:374:40: 0x354f38e in indexForCell (ghostty)
            if (!self.grid.hasCodepoint(idx, primary_cp, presentation)) continue;
                                       ^
/home/mj/projects/github.com/ghostty-org/ghostty/src/font/shaper/run.zig:221:42: 0x35507ac in next (ghostty)
                if (try self.indexForCell(
                                         ^
/home/mj/projects/github.com/ghostty-org/ghostty/src/renderer/OpenGL.zig:1629:47: 0x35898bd in rebuildCells (ghostty)
                shaper_run = try run_iter.next(self.alloc);
                                              ^
/home/mj/projects/github.com/ghostty-org/ghostty/src/renderer/OpenGL.zig:867:30: 0x358d9a9 in updateFrame (ghostty)
        try self.rebuildCells(
                             ^
/home/mj/projects/github.com/ghostty-org/ghostty/src/renderer/Thread.zig:584:27: 0x34ff1c4 in renderCallback (ghostty)
    t.renderer.updateFrame(
                          ^
/home/mj/projects/github.com/ghostty-org/ghostty/src/renderer/Thread.zig:501:23: 0x34ff4be in callback (ghostty)
    _ = renderCallback(t, undefined, undefined, {});
                      ^
/home/mj/.cache/zig/p/12206029de146b685739f69b10a6f08baee86b3d0a5f9a659fa2b2b66c9602078bbf/src/backend/io_uring.zig:771:29: 0x34b4471 in invoke (ghostty)
        return self.callback(self.userdata, loop, self, result);
                            ^
/home/mj/.cache/zig/p/12206029de146b685739f69b10a6f08baee86b3d0a5f9a659fa2b2b66c9602078bbf/src/backend/io_uring.zig:160:33: 0x34b70d4 in tick___anon_131257 (ghostty)
                switch (c.invoke(self, cqe.res)) {
                                ^
/home/mj/.cache/zig/p/12206029de146b685739f69b10a6f08baee86b3d0a5f9a659fa2b2b66c9602078bbf/src/backend/io_uring.zig:61:42: 0x34b726d in run (ghostty)
            .until_done => try self.tick_(.until_done),
                                         ^
/home/mj/projects/github.com/ghostty-org/ghostty/src/renderer/Thread.zig:246:26: 0x34b755e in threadMain_ (ghostty)
    _ = try self.loop.run(.until_done);
                         ^
/home/mj/projects/github.com/ghostty-org/ghostty/src/renderer/Thread.zig:192:21: 0x346aa15 in threadMain (ghostty)
    self.threadMain_() catch |err| {
                    ^
/snap/zig/11625/lib/std/Thread.zig:408:13: 0x341b1aa in callFn__anon_128114 (ghostty)
            @call(.auto, f, args);
            ^
/snap/zig/11625/lib/std/Thread.zig:674:30: 0x338a052 in entryFn (ghostty)
                return callFn(f, args_ptr.*);
                             ^
???:?:?: 0x74856a89ca93 in ??? (libc.so.6)
???:?:?: 0x74856a929c3b in ??? (libc.so.6)
[1]    1600138 IOT instruction (core dumped)  projects/github.com/ghostty-org/ghostty/zig-out/bin/ghostty

[j5ndev]

Where the binary is called from doesn't matter.
I can call the executable from the repo directory (green dot glyph) and then cd to home directory (red x glyph) and then cause the segfault.
It is the presence of this X glyph when the git repo isn't clean that causes the issue.

[j5ndev]

These glyphs have since been removed from the ohmyzsh theme that I forked a long time ago:
https://github.com/ohmyzsh/ohmyzsh/blob/master/themes/ys.zsh-theme#L12-L13

Here is an old copy of my theme with the glyphs if you want to try to reproduce the issue:
https://github.com/j5ndev/cfg/blob/master/.oh-my-zsh/themes/majgis.zsh-theme#L15-L16
✖︎●

I replaced the glyphs in my current theme with x & o, and no more issues, so I'm happy and productive with ghostty now :-)