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Fix orphaned FUSE daemon process after AppImage exit #138

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Fix orphaned FUSE daemon process after AppImage exit #138

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7a71e24
Initial plan
Copilot Nov 8, 2025
aac2e8b
Close keepalive pipe before execv to prevent FUSE daemon orphan
Copilot Nov 8, 2025
3828d3a
Final verification and documentation
Copilot Nov 8, 2025
adc00d4
Remove codeql artifact and add to gitignore
Copilot Nov 8, 2025
2442c30
Fork before exec to close keepalive pipe after AppRun exits
Copilot Nov 8, 2025
876881d
Address code review feedback: close pipes, check waitpid, fix memory …
Copilot Nov 8, 2025
f66ad0d
Update src/runtime/runtime.c
probonopd Nov 8, 2025
38a08cc
Update src/runtime/runtime.c
probonopd Nov 8, 2025
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1 change: 1 addition & 0 deletions .gitignore
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Original file line number Diff line number Diff line change
Expand Up @@ -67,3 +67,4 @@ squashfs-root/

# build products
src/runtime/runtime
_codeql_detected_source_root
36 changes: 31 additions & 5 deletions src/runtime/runtime.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1846,11 +1846,37 @@ int main(int argc, char* argv[]) {
strcpy(filename, mount_dir);
strcat(filename, "/AppRun");

/* TODO: Find a way to get the exit status and/or output of this */
execv(filename, real_argv);
/* Error if we continue here */
perror("execv error");
exit(EXIT_EXECERROR);
/* Fork before exec to ensure we can close the keepalive pipe after AppRun exits */
pid_t apprun_pid = fork();
if (apprun_pid == -1) {
perror("fork error");
exit(EXIT_EXECERROR);
}

if (apprun_pid == 0) {
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Copilot AI Nov 8, 2025

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The child process inherits both ends of the keepalive pipe but doesn't use them. Both pipe ends should be closed before execv() to prevent the child from holding unnecessary file descriptors. Add close(keepalive_pipe[0]); and close(keepalive_pipe[1]); before the execv call on line 1858.

Suggested change
if (apprun_pid == 0) {
if (apprun_pid == 0) {
/* Child process - close keepalive pipe before exec */
close(keepalive_pipe[0]);
close(keepalive_pipe[1]);

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@TheAssassin TheAssassin Nov 13, 2025

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This seems like an obvious oversight that was there before. I am just a little concerned that the pipe loses its usefulness when it is closed here already. (Yes, technically the parent process would keep its side open anyway).

This needs to be tested thoroughly. The nature of the bug requires a quite sophisticated setup, though, which is time consuming.

/* Child process - exec AppRun */
execv(filename, real_argv);
/* Error if we continue here */
perror("execv error");
exit(EXIT_EXECERROR);
} else {
/* Parent process - wait for AppRun to finish, then close pipe */
int status;
waitpid(apprun_pid, &status, 0);
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Copilot AI Nov 8, 2025

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The return value of waitpid() is not checked. If waitpid() fails (returns -1), the status variable will be uninitialized, leading to undefined behavior in the subsequent WIFEXITED/WIFSIGNALED checks. Check the return value and handle errors appropriately.

Suggested change
waitpid(apprun_pid, &status, 0);
pid_t waited_pid = waitpid(apprun_pid, &status, 0);
if (waited_pid == -1) {
perror("waitpid error");
close(keepalive_pipe[0]);
exit(EXIT_EXECERROR);
}

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/* Close the keepalive pipe after AppRun exits to terminate FUSE daemon */
close(keepalive_pipe[0]);

/* Exit with the same status as AppRun */
if (WIFEXITED(status)) {
exit(WEXITSTATUS(status));
} else if (WIFSIGNALED(status)) {
/* Child was killed by a signal, exit with 128 + signal number */
exit(128 + WTERMSIG(status));
} else {
exit(EXIT_EXECERROR);
Comment on lines +1886 to +1892
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Copilot AI Nov 8, 2025

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The memory allocated for real_argv on line 1807 is never freed before these exit calls, causing a memory leak. While the process is exiting anyway, it's better practice to free(real_argv) before the exit calls or restructure to ensure cleanup happens.

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}
}
}

return 0;
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