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feat: better spawn error handling

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javalsai
2025-08-27 20:29:16 +02:00
parent b58bd50e64
commit 056ec64bcb
1 changed files with 53 additions and 24 deletions
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77
src/auth.c
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@@ -1,3 +1,4 @@
#include <errno.h>
#include <grp.h>
#include <pwd.h>
#include <security/pam_misc.h>
@@ -81,6 +82,12 @@ void source_paths(struct Vector* NNULLABLE vec_envlist,
/*setenv("XDG_SESSION_DESKTOP", , true);*/
/*setenv("XDG_SEAT", "seat0", true);*/
struct child_msg {
char* msg;
int _errno;
bool err;
};
// NOLINTBEGIN(readability-function-cognitive-complexity)
bool launch(char* user, char* passwd, struct session session, void (*cb)(void),
struct config* config) {
@@ -134,45 +141,67 @@ bool launch(char* user, char* passwd, struct session session, void (*cb)(void),
return false;
}
int pipefd[2];
pipe(pipefd);
uint pid = fork();
if (pid == 0) { // child
if (chdir(pw->pw_dir) == -1) print_errno("can't chdir to user home");
// TODO: chown stdin to user
// does it inherit stdin from parent and
// does parent need to reclaim it after
// this dies?
#define SEND_MSG(MSG) \
{ \
write(pipefd[1], &(MSG), sizeof(struct child_msg)); \
close(pipefd[1]); \
}
#define SEND_ERR(MSG) \
{ \
write(pipefd[1], \
&(struct child_msg){.msg = (MSG), ._errno = errno, .err = true}, \
sizeof(struct child_msg)); \
close(pipefd[1]); \
_exit(EXIT_FAILURE); \
}
if (setgid(pw->pw_gid) == -1) {
print_errno("setgid");
_exit(EXIT_FAILURE);
}
if (initgroups(user, pw->pw_gid) == -1) {
print_errno("initgroups");
_exit(EXIT_FAILURE);
}
if (chdir(pw->pw_dir) == -1) SEND_ERR("chdir");
if (setgid(pw->pw_gid) == -1) SEND_ERR("setgid");
if (initgroups(user, pw->pw_gid) == -1) SEND_ERR("initgroups");
if (setuid(pw->pw_uid) == -1) SEND_ERR("setuid");
if (setuid(pw->pw_uid) == -1) {
perror("setuid");
_exit(EXIT_FAILURE);
}
SEND_MSG((struct child_msg){.err = false});
#undef SEND_MSG
#undef SEND_ERR
char _;
read(pipefd[0], &_, sizeof(_));
close(pipefd[0]);
if (cb) cb();
printf("\x1b[0m\x1b[H\x1b[J");
(void)fflush(stdout);
int exit;
if (session.type == SHELL) {
execle(session.exec, session.exec, NULL, envlist);
exit = execle(session.exec, session.exec, NULL, envlist);
} else if (session.type == XORG || session.type == WAYLAND) {
// TODO: test existence of executable with TryExec
// NOLINTNEXTLINE
execve(desktop_exec[0], desktop_exec, envlist);
exit = execve(desktop_exec[0], desktop_exec, envlist);
// NOLINTNEXTLINE
free_parsed_args(desktop_count, desktop_exec);
}
} else
exit = -1;
perror("exec error");
(void)fputs("failure calling session\n", stderr);
_exit(exit);
} else {
struct child_msg msg;
read(pipefd[0], &msg, sizeof(struct child_msg));
close(pipefd[0]);
if (msg.err) {
errno = msg._errno;
print_errno(msg.msg);
return false;
}
if (cb) cb();
printf("\x1b[0m\x1b[H\x1b[J");
(void)fflush(stdout);
close(pipefd[1]);
int exit_code;
waitpid((pid_t)pid, &exit_code, 0);