fix(v3/linux): fix OpenFileDialog crash from GTK thread violation by ddmoney420 · Pull Request #4926 · wailsapp/wails

ddmoney420 · 2026-01-29T09:16:12Z

Summary

Fixes GTK assertion failure and crash when using OpenFileDialog() on Linux.

Problem

When calling OpenFileDialog() on Linux and selecting a file, the application crashed with:

gtk_file_chooser_get_filenames: assertion 'GTK_IS_FILE_CHOOSER (chooser)' failed
signal 11 received but handler not on signal stack

Root Cause

The runChooserDialog function had a race condition and thread safety violation:

InvokeAsync scheduled gtk_dialog_run on the GTK thread
After the dialog closed, a new goroutine was spawned off the GTK thread
gtk_widget_destroy was called immediately (outside InvokeAsync)
The goroutine tried to call gtk_file_chooser_get_filenames on the destroyed widget

GTK is NOT thread-safe - all GTK operations must occur on the GTK main thread.

Solution

Extract filenames on GTK thread BEFORE destroying widget
Call gtk_widget_destroy on GTK thread AFTER extraction
Goroutine only handles sending Go strings (no GTK calls)

InvokeAsync(func() {
    response := C.gtk_dialog_run(...)
    // Extract results on GTK thread
    var results []string
    if response == C.GTK_RESPONSE_ACCEPT {
        filenames := C.gtk_file_chooser_get_filenames(...)
        // ... extract to results slice ...
    }
    // Destroy widget on GTK thread
    C.gtk_widget_destroy(...)
    // Send results from goroutine (safe - no GTK calls)
    go func() {
        for _, result := range results {
            selections <- result
        }
        close(selections)
    }()
})

Test plan

Test on Linux with GTK
Call OpenFileDialog() from a service binding
Select a file and verify no crash occurs
Verify selected filename is returned correctly

Fixes #3683

🤖 Generated with Claude Code

Summary by CodeRabbit

Bug Fixes
- Fixed a crash on Linux when opening the file chooser by ensuring selected files are collected on the UI thread before the dialog closes, preserving selections reliably and preventing thread-safety issues.

The runChooserDialog function had a race condition that caused GTK assertion failures and crashes on Linux: 1. InvokeAsync scheduled gtk_dialog_run on the GTK thread 2. After dialog closed, a goroutine was spawned OFF the GTK thread 3. gtk_widget_destroy was called immediately (before goroutine ran) 4. Goroutine tried to call gtk_file_chooser_get_filenames on destroyed widget Fix: - Extract filenames on GTK thread BEFORE destroying widget - Call gtk_widget_destroy on GTK thread AFTER extraction - Goroutine only handles sending Go strings (no GTK calls) Fixes wailsapp#3683 Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

coderabbitai · 2026-01-29T09:16:36Z

Walkthrough

Collect GTK file-chooser results on the GTK thread: retrieve filenames via gtk_file_chooser_get_filenames and buildStringAndFree into a local slice before destroying the widget; the background goroutine iterates that slice and sends selections over the channel (no artificial result cap).

Changes

Cohort / File(s)	Summary
GTK File Dialog Thread Safety `v3/pkg/application/linux_cgo.go`	Move all GTK calls to the GTK thread: collect filenames with `gtk_file_chooser_get_filenames` and `buildStringAndFree` into a local results slice (removed artificial 1024 cap), destroy the widget on the GTK thread, then have the goroutine iterate the local slice to send selections over the channel.
Changelog `v3/UNRELEASED_CHANGELOG.md`	Add Fixed entry documenting "Fix OpenFileDialog crash on Linux due to GTK thread safety violation" referencing issue `#3683`.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

[v3] Fix save dialog filename not pre-populated on Linux (#4841) #4842: Modifies runChooserDialog in v3/pkg/application/linux_cgo.go (related GTK/file-chooser changes and save-dialog filename handling).
[v3 alpha] Fix deadlock of linux dialog for multiple selections #3925: Adjusts runChooserDialog and multi-selection handling; addresses threading/deadlock concerns.
[v3] Make filtered dialog examples code work for linux #4287: Edits runChooserDialog and file-filter handling in the GTK file chooser.

Suggested labels

Linux, v3-alpha, size:S, lgtm

Poem

🐰 I hopped onto GTK with careful paws,
Gathered filenames without a pause,
Built each string and freed the rest,
Closed the chooser — now all is best.
Hooray for safe threads and fewer straws! 🥕

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main fix: addressing an OpenFileDialog crash on Linux caused by GTK thread safety violations.
Description check	✅ Passed	The description covers the problem, root cause, solution, and test plan, but the PR description template checklist items are not explicitly marked as completed in the provided description.
Linked Issues check	✅ Passed	The PR directly addresses issue `#3683` by ensuring all GTK operations execute on the GTK thread, preventing the assertion failures and crashes from thread safety violations that caused OpenFileDialog to fail.
Out of Scope Changes check	✅ Passed	All changes are focused on fixing the GTK thread safety issue in runChooserDialog and documenting the fix in the changelog; no unrelated modifications are present.

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Post copyable unit tests in a comment

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coderabbitai

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@v3/pkg/application/linux_cgo.go`:
- Around line 2109-2129: The loop over filenames from
gtk_file_chooser_get_filenames stops at 1024 and only calls buildStringAndFree
for those items, causing any remaining filename strings to leak because
g_slist_free only frees nodes; modify the extraction logic in the block that
uses filenames, iter and count so you iterate the entire list: for the first up
to 1024 entries call buildStringAndFree and append into results, and for any
remaining entries call C.g_free on the gpointer(iter.data) to free the string;
after finishing the full traversal still call C.g_slist_free(filenames), then
destroy the widget and send results to selections as before (referencing
gtk_file_chooser_get_filenames, buildStringAndFree, C.g_free, C.g_slist_free,
filenames, iter, results, selections).

leaanthony

LGTM! This correctly fixes the GTK thread safety violation. All GTK operations now happen on the GTK thread inside InvokeAsync, and the widget is properly destroyed after extracting results.

The coderabbit comment about the 1024 limit leaking memory is technically valid but a pre-existing edge case (the limit was already there). The main crash fix is correct.

Please add an UNRELEASED_CHANGELOG.md entry for this bug fix.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

When more than 1024 files are selected, the previous code leaked memory because g_slist_free() only frees list nodes, not the data pointers. Now we iterate through ALL entries, freeing each filename string. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

GTK's gtk_file_chooser_get_filenames() has no documented maximum. The limit was arbitrary and unnecessary. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Consistent with Windows/macOS behavior. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

sonarqubecloud · 2026-02-02T18:59:31Z

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

…ilsapp#4926) * fix(v3/linux): fix OpenFileDialog crash from GTK thread violation The runChooserDialog function had a race condition that caused GTK assertion failures and crashes on Linux: 1. InvokeAsync scheduled gtk_dialog_run on the GTK thread 2. After dialog closed, a goroutine was spawned OFF the GTK thread 3. gtk_widget_destroy was called immediately (before goroutine ran) 4. Goroutine tried to call gtk_file_chooser_get_filenames on destroyed widget Fix: - Extract filenames on GTK thread BEFORE destroying widget - Call gtk_widget_destroy on GTK thread AFTER extraction - Goroutine only handles sending Go strings (no GTK calls) Fixes wailsapp#3683 Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com> * docs: add changelog entry for OpenFileDialog crash fix Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com> * fix: properly free all filenames to prevent memory leak When more than 1024 files are selected, the previous code leaked memory because g_slist_free() only frees list nodes, not the data pointers. Now we iterate through ALL entries, freeing each filename string. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com> * refactor: remove arbitrary 1024 file selection limit GTK's gtk_file_chooser_get_filenames() has no documented maximum. The limit was arbitrary and unnecessary. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com> * docs: add comment about no file selection limit Consistent with Windows/macOS behavior. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com> --------- Co-authored-by: ddmoney420 <ddmoney420@users.noreply.github.com> Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com> Co-authored-by: Lea Anthony <lea.anthony@gmail.com>

coderabbitai Bot reviewed Jan 29, 2026

View reviewed changes

Comment thread v3/pkg/application/linux_cgo.go

leaanthony approved these changes Feb 2, 2026

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leaanthony mentioned this pull request Feb 2, 2026

fix(generator): add defensive checks for cross-package type alias namespace resolution #4931

Closed

2 tasks

leaanthony and others added 5 commits February 2, 2026 23:16

docs: add changelog entry for OpenFileDialog crash fix

ad1fcee

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

refactor: remove arbitrary 1024 file selection limit

eb40f75

GTK's gtk_file_chooser_get_filenames() has no documented maximum. The limit was arbitrary and unnecessary. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs: add comment about no file selection limit

650db07

Consistent with Windows/macOS behavior. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Merge branch 'v3-alpha' into fix/3683-linux-dialog-crash

292f7bf

leaanthony merged commit 1f45359 into wailsapp:v3-alpha Feb 2, 2026
48 checks passed

This was referenced May 5, 2026

fix(linux): dispatch dialog GTK calls via InvokeAsync to fix GTK3 segfault #5339

Merged

fix(linux): split dialog dispatch between GTK3 and GTK4 #5340

Merged

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fix(v3/linux): fix OpenFileDialog crash from GTK thread violation#4926

fix(v3/linux): fix OpenFileDialog crash from GTK thread violation#4926
leaanthony merged 6 commits into
wailsapp:v3-alphafrom
ddmoney420:fix/3683-linux-dialog-crash

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