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108 lines
2.6 KiB
C
108 lines
2.6 KiB
C
/// Very limited implementation. Half of code from Musl was cut.
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/// This is Ok, because for now, this function is used only from clang driver.
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#define _GNU_SOURCE
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#include <spawn.h>
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#include <sched.h>
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#include <unistd.h>
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#include <signal.h>
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#include <fcntl.h>
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#include <sys/wait.h>
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#include <syscall.h>
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#include <sys/signal.h>
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#include <pthread.h>
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#include <spawn.h>
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#include <errno.h>
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#include "syscall.h"
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struct args {
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int p[2];
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sigset_t oldmask;
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const char *path;
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int (*exec)(const char *, char *const *, char *const *);
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const posix_spawn_file_actions_t *fa;
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const posix_spawnattr_t *restrict attr;
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char *const *argv, *const *envp;
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};
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void __get_handler_set(sigset_t *);
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static int child(void *args_vp)
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{
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int ret;
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struct args *args = args_vp;
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int p = args->p[1];
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const posix_spawnattr_t *restrict attr = args->attr;
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close(args->p[0]);
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/* Close-on-exec flag may have been lost if we moved the pipe
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* to a different fd. We don't use F_DUPFD_CLOEXEC above because
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* it would fail on older kernels and atomicity is not needed --
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* in this process there are no threads or signal handlers. */
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__syscall(SYS_fcntl, p, F_SETFD, FD_CLOEXEC);
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pthread_sigmask(SIG_SETMASK, (attr->__flags & POSIX_SPAWN_SETSIGMASK)
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? &attr->__ss : &args->oldmask, 0);
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args->exec(args->path, args->argv, args->envp);
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ret = -errno;
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/* Since sizeof errno < PIPE_BUF, the write is atomic. */
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ret = -ret;
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if (ret) while (__syscall(SYS_write, p, &ret, sizeof ret) < 0);
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_exit(127);
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}
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int __posix_spawnx(pid_t *restrict res, const char *restrict path,
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int (*exec)(const char *, char *const *, char *const *),
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const posix_spawn_file_actions_t *fa,
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const posix_spawnattr_t *restrict attr,
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char *const argv[restrict], char *const envp[restrict])
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{
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pid_t pid;
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char stack[1024];
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int ec=0, cs;
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struct args args;
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if (pipe2(args.p, O_CLOEXEC))
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return errno;
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pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
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args.path = path;
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args.exec = exec;
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args.fa = fa;
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args.attr = attr ? attr : &(const posix_spawnattr_t){0};
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args.argv = argv;
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args.envp = envp;
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pid = clone(child, stack+sizeof stack,
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CLONE_VM|CLONE_VFORK|SIGCHLD, &args);
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close(args.p[1]);
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if (pid > 0) {
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if (read(args.p[0], &ec, sizeof ec) != sizeof ec) ec = 0;
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else waitpid(pid, &(int){0}, 0);
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} else {
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ec = -pid;
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}
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close(args.p[0]);
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if (!ec && res) *res = pid;
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pthread_setcancelstate(cs, 0);
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return ec;
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}
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int posix_spawn(pid_t *restrict res, const char *restrict path,
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const posix_spawn_file_actions_t *fa,
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const posix_spawnattr_t *restrict attr,
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char *const argv[restrict], char *const envp[restrict])
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{
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return __posix_spawnx(res, path, execve, fa, attr, argv, envp);
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}
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