user: implement mlibc as the libc, finally.

It's finally done.. Signed-off-by: kaguya <vpshinomiya@protonmail.com>
2026-05-02 03:31:49 -04:00
parent 2fa39ad85a
commit 9a9b91c940
2387 changed files with 152741 additions and 315 deletions
@@ -0,0 +1,376 @@
+
+#include <spawn.h>
+#include <errno.h>
+#include <pthread.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <limits.h>
+#include <sched.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <sys/wait.h>
+
+#include <bits/ensure.h>
+#include <mlibc/debug.hpp>
+
+/*
+ * Musl places this in a seperate header called fdop.h
+ * This header isn't present in glibc, or on my host, so I
+ * include it's contents here
+ */
+
+#define FDOP_CLOSE 1
+#define FDOP_DUP2 2
+#define FDOP_OPEN 3
+#define FDOP_CHDIR 4
+#define FDOP_FCHDIR 5
+
+struct fdop {
+	struct fdop *next, *prev;
+	int cmd, fd, srcfd, oflag;
+	mode_t mode;
+	char path[];
+};
+
+/*
+ * This posix_spawn implementation is taken from musl
+ */
+
+static unsigned long handler_set[NSIG / (8 * sizeof(long))];
+
+static void __get_handler_set(sigset_t *set) {
+	memcpy(set, handler_set, sizeof handler_set);
+}
+
+struct args {
+	int p[2];
+	sigset_t oldmask;
+	const char *path;
+	const posix_spawn_file_actions_t *fa;
+	const posix_spawnattr_t *__restrict attr;
+	char *const *argv, *const *envp;
+};
+
+static int child(void *args_vp) {
+	int i, ret;
+	struct sigaction sa = {};
+	struct args *args = (struct args *)args_vp;
+	int p = args->p[1];
+	const posix_spawn_file_actions_t *fa = args->fa;
+	const posix_spawnattr_t *__restrict attr = args->attr;
+	sigset_t hset;
+	bool use_execvpe = false;
+
+	if(attr->__fn)
+		use_execvpe = true;
+
+	close(args->p[0]);
+
+	/* All signal dispositions must be either SIG_DFL or SIG_IGN
+	 * before signals are unblocked. Otherwise a signal handler
+	 * from the parent might get run in the child while sharing
+	 * memory, with unpredictable and dangerous results. To
+	 * reduce overhead, sigaction has tracked for us which signals
+	 * potentially have a signal handler. */
+	__get_handler_set(&hset);
+	for(i = 1; i < NSIG; i++) {
+		if((attr->__flags & POSIX_SPAWN_SETSIGDEF) && sigismember(&attr->__def, i)) {
+			sa.sa_handler = SIG_DFL;
+		} else if(sigismember(&hset, i)) {
+			if (i - 32 < 3) {
+				sa.sa_handler = SIG_IGN;
+			} else {;
+				sigaction(i, nullptr, &sa);
+				if(sa.sa_handler == SIG_IGN)
+					continue;
+				sa.sa_handler = SIG_DFL;
+			}
+		} else {
+			continue;
+		}
+		sigaction(i, &sa, nullptr);
+	}
+
+	if(attr->__flags & POSIX_SPAWN_SETSID) {
+		if((ret = setsid()) < 0)
+			goto fail;
+	}
+
+	if(attr->__flags & POSIX_SPAWN_SETPGROUP) {
+		mlibc::infoLogger() << "mlibc: posix_spawn: ignoring SETPGROUP" << frg::endlog;
+		//if((ret = setpgid(0, attr->__pgrp)))
+		//	goto fail;
+	}
+
+	if(attr->__flags & POSIX_SPAWN_RESETIDS) {
+		if((ret = setgid(getgid())) || (ret = setuid(getuid())) )
+			goto fail;
+	}
+
+	if(fa && fa->__actions) {
+		struct fdop *op;
+		int fd;
+		for(op = (struct fdop *)fa->__actions; op->next; op = op->next);
+		for(; op; op = op->prev) {
+			/* It's possible that a file operation would clobber
+			 * the pipe fd used for synchronizing with the
+			 * parent. To avoid that, we dup the pipe onto
+			 * an unoccupied fd. */
+			if(op->fd == p) {
+				ret = dup(p);
+				if(ret < 0)
+					goto fail;
+				close(p);
+				p = ret;
+			}
+			switch(op->cmd) {
+			case FDOP_CLOSE:
+				close(op->fd);
+				break;
+			case FDOP_DUP2:
+				fd = op->srcfd;
+				if(fd == p) {
+					ret = -EBADF;
+					goto fail;
+				}
+				if(fd != op->fd) {
+					if((ret = dup2(fd, op->fd)) < 0)
+						goto fail;
+				} else {
+					ret = fcntl(fd, F_GETFD);
+					ret = fcntl(fd, F_SETFD, ret & ~FD_CLOEXEC);
+					if(ret < 0)
+						goto fail;
+				}
+				break;
+			case FDOP_OPEN:
+				fd = open(op->path, op->oflag, op->mode);
+				if((ret = fd) < 0)
+					goto fail;
+				if(fd != op->fd) {
+					if((ret = dup2(fd, op->fd)) < 0)
+						goto fail;
+					close(fd);
+				}
+				break;
+			case FDOP_CHDIR:
+				ret = chdir(op->path);
+				if(ret < 0)
+					goto fail;
+				break;
+			case FDOP_FCHDIR:
+				ret = fchdir(op->fd);
+				if(ret < 0)
+					goto fail;
+				break;
+			}
+		}
+	}
+
+	/* Close-on-exec flag may have been lost if we moved the pipe
+	 * to a different fd. */
+	fcntl(p, F_SETFD, FD_CLOEXEC);
+
+	pthread_sigmask(SIG_SETMASK, (attr->__flags & POSIX_SPAWN_SETSIGMASK)
+		? &attr->__mask : &args->oldmask, nullptr);
+
+	if(use_execvpe)
+		execvpe(args->path, args->argv, args->envp);
+	else
+		execve(args->path, args->argv, args->envp);
+	ret = -errno;
+
+fail:
+	/* Since sizeof errno < PIPE_BUF, the write is atomic. */
+	ret = -ret;
+	if(ret)
+		while(write(p, &ret, sizeof ret) < 0);
+	_exit(127);
+}
+
+int posix_spawn(pid_t *__restrict res, const char *__restrict path,
+		const posix_spawn_file_actions_t *file_actions,
+		const posix_spawnattr_t *__restrict attrs,
+		char *const argv[], char *const envp[]) {
+	pid_t pid;
+	int ec = 0, cs;
+	struct args args;
+	const posix_spawnattr_t empty_attr = {};
+	sigset_t full_sigset;
+	sigfillset(&full_sigset);
+
+	pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
+
+	args.path = path;
+	args.fa = file_actions;
+	args.attr = attrs ? attrs : &empty_attr;
+	args.argv = argv;
+	args.envp = envp;
+	pthread_sigmask(SIG_BLOCK, &full_sigset, &args.oldmask);
+
+	/* The lock guards both against seeing a SIGABRT disposition change
+	 * by abort and against leaking the pipe fd to fork-without-exec. */
+	//LOCK(__abort_lock);
+
+	if(pipe2(args.p, O_CLOEXEC)) {
+		//UNLOCK(__abort_lock);
+		ec = errno;
+		goto fail;
+	}
+
+	/* Mlibc change: We use fork + execve, as clone is not implemented.
+	 * This yields the same result in the end. */
+	//pid = clone(child, stack + sizeof stack, CLONE_VM | CLONE_VFORK | SIGCHLD, &args);
+	pid = fork();
+	if(!pid) {
+		child(&args);
+	}
+	close(args.p[1]);
+	//UNLOCK(__abort_lock);
+
+	if(pid > 0) {
+		if(read(args.p[0], &ec, sizeof ec) != sizeof ec)
+			ec = 0;
+		else
+			waitpid(pid, nullptr, 0);
+	} else {
+		ec = -pid;
+	}
+
+	close(args.p[0]);
+
+	if(!ec && res)
+		*res = pid;
+
+fail:
+	pthread_sigmask(SIG_SETMASK, &args.oldmask, nullptr);
+	pthread_setcancelstate(cs, nullptr);
+
+	return ec;
+}
+
+int posix_spawnattr_init(posix_spawnattr_t *attr) {
+	*attr = (posix_spawnattr_t){};
+	return 0;
+}
+
+int posix_spawnattr_destroy(posix_spawnattr_t *) {
+	return 0;
+}
+
+int posix_spawnattr_setflags(posix_spawnattr_t *attr, short flags) {
+	const unsigned all_flags = 
+			POSIX_SPAWN_RESETIDS |
+			POSIX_SPAWN_SETPGROUP |
+			POSIX_SPAWN_SETSIGDEF |
+			POSIX_SPAWN_SETSIGMASK |
+			POSIX_SPAWN_SETSCHEDPARAM |
+			POSIX_SPAWN_SETSCHEDULER |
+			POSIX_SPAWN_USEVFORK |
+			POSIX_SPAWN_SETSID;
+	if(flags & ~all_flags)
+		return EINVAL;
+	attr->__flags = flags;
+	return 0;
+}
+
+int posix_spawnattr_setsigdefault(posix_spawnattr_t *__restrict attr,
+		const sigset_t *__restrict sigdefault) {
+	attr->__def = *sigdefault;
+	return 0;
+}
+
+int posix_spawnattr_setschedparam(posix_spawnattr_t *__restrict,
+		const struct sched_param *__restrict) {
+	__ensure(!"Not implemented");
+	__builtin_unreachable();
+}
+
+int posix_spawnattr_setschedpolicy(posix_spawnattr_t *, int) {
+	__ensure(!"Not implemented");
+	__builtin_unreachable();
+}
+
+int posix_spawnattr_setsigmask(posix_spawnattr_t *__restrict attr,
+		const sigset_t *__restrict sigmask) {
+	attr->__mask = *sigmask;
+	return 0;
+}
+
+int posix_spawnattr_setpgroup(posix_spawnattr_t *attr, pid_t pgroup) {
+	attr->__pgrp = pgroup;
+	return 0;
+}
+
+int posix_spawn_file_actions_init(posix_spawn_file_actions_t *file_actions) {
+	file_actions->__actions = nullptr;
+	return 0;
+}
+
+int posix_spawn_file_actions_destroy(posix_spawn_file_actions_t *file_actions) {
+	struct fdop *op = (struct fdop *)file_actions->__actions, *next;
+	while(op) {
+		next = op->next;
+		free(op);
+		op = next;
+	}
+	return 0;
+}
+
+int posix_spawn_file_actions_adddup2(posix_spawn_file_actions_t *file_actions,
+		int fildes, int newfildes) {
+	struct fdop *op = (struct fdop *)malloc(sizeof *op);
+	if(!op)
+		return ENOMEM;
+	op->cmd = FDOP_DUP2;
+	op->srcfd = fildes;
+	op->fd = newfildes;
+	if((op->next = (struct fdop *)file_actions->__actions))
+		op->next->prev = op;
+	op->prev = nullptr;
+	file_actions->__actions = op;
+	return 0;
+}
+
+int posix_spawn_file_actions_addclose(posix_spawn_file_actions_t *file_actions,
+		int fildes) {
+	struct fdop *op = (struct fdop *)malloc(sizeof *op);
+	if(!op)
+		return ENOMEM;
+	op->cmd = FDOP_CLOSE;
+	op->fd = fildes;
+	if((op->next = (struct fdop *)file_actions->__actions))
+		op->next->prev = op;
+	op->prev = nullptr;
+	file_actions->__actions = op;
+	return 0;
+}
+
+int posix_spawn_file_actions_addopen(posix_spawn_file_actions_t *__restrict file_actions,
+		int fildes, const char *__restrict path, int oflag, mode_t mode) {
+	struct fdop *op = (struct fdop *)malloc(sizeof *op + strlen(path) + 1);
+	if(!op)
+		return ENOMEM;
+	op->cmd = FDOP_OPEN;
+	op->fd = fildes;
+	op->oflag = oflag;
+	op->mode = mode;
+	strcpy(op->path, path);
+	if((op->next = (struct fdop *)file_actions->__actions))
+		op->next->prev = op;
+	op->prev = nullptr;
+	file_actions->__actions = op;
+	return 0;
+}
+
+int posix_spawnp(pid_t *__restrict pid, const char *__restrict file,
+		const posix_spawn_file_actions_t *file_actions,
+		const posix_spawnattr_t *__restrict attrp,
+		char *const argv[], char *const envp[]) {
+	posix_spawnattr_t spawnp_attr = {};
+	if(attrp)
+		spawnp_attr = *attrp;
+	spawnp_attr.__fn = (void *)execvpe;	
+	return posix_spawn(pid, file, file_actions, &spawnp_attr, argv, envp);
+}
+