rosetta/lib/libc/exec/spawn/posix-spawn.c

#include "file-actions.h"

#include <errno.h>
#include <fcntl.h>
#include <launch.h>
#include <magenta/handle.h>
#include <magenta/log.h>
#include <magenta/task.h>
#include <rosetta/fs.h>
#include <spawn.h>
#include <stdio.h>
#include <sys/mman.h>
#include <unistd.h>

static enum launch_status resolve_dependency(
	struct launch_ctx *ctx,
	const char *name,
	kern_handle_t *out,
	void *arg)
{
	int fd = open(name, O_RDONLY);
	if (fd < 0) {
		return fd;
	}

	int err = 0;
	kern_handle_t image = KERN_HANDLE_INVALID;
	kern_status_t status = fs_map(
		fd,
		PROT_READ | PROT_EXEC,
		MAP_SHARED | MAP_EXECUTABLE,
		&err,
		&image);
	close(fd);

	if (status != KERN_OK || err != SUCCESS) {
		return LAUNCH_ERR_CANNOT_RESOLVE_DEPENDENCY;
	}

	*out = image;
	return LAUNCH_OK;
}

static size_t count_array_items(char *const items[])
{
	size_t i;
	for (i = 0; items[i]; i++)
		;
	return i;
}

static const char *get_task_name(const char *path)
{
	const char *name = path;
	for (size_t i = 0; path[i]; i++) {
		char c = path[i];
		char c2 = path[i + 1];
		if (c != '/') {
			continue;
		}

		if (c2 == '\0' || c2 == '/') {
			continue;
		}

		name = path + i + 1;
	}

	return name;
}

int posix_spawn(
	pid_t *restrict pid,
	const char *restrict path,
	const posix_spawn_file_actions_t *restrict file_actions,
	const posix_spawnattr_t *restrict attrp,
	char *const argv[],
	char *const envp[])
{
	int fd = open(path, O_RDONLY);
	if (fd < 0) {
		return fd;
	}

	int err = 0;
	kern_handle_t image = KERN_HANDLE_INVALID;
	kern_status_t status = fs_map(
		fd,
		PROT_READ | PROT_EXEC,
		MAP_SHARED | MAP_EXECUTABLE,
		&err,
		&image);
	close(fd);

	if (status != KERN_OK) {
		return __set_errno(__errno_from_kern_status(status));
	}

	if (err != SUCCESS) {
		return __set_errno(err);
	}

	struct launch_ctx launch;
	struct launch_result result;

	size_t argc = 0, envc = 0;
	if (argv) {
		argc = count_array_items(argv);
	}

	if (envp) {
		envc = count_array_items(envp);
	}

	kern_handle_t self = KERN_HANDLE_INVALID,
		      address_space = KERN_HANDLE_INVALID;

	task_self(&self);
	task_get_address_space(self, &address_space);

	struct launch_parameters params = {
		.p_exec_image = image,
		.p_exec_path = path,
		.p_parent_task = self,
		.p_task_name = get_task_name(path),
		.p_local_address_space = address_space,
		.p_resolver_arg = NULL,
		.p_argc = argc,
		.p_argv = (const char **)argv,
		.p_envc = envc,
		.p_envp = (const char **)envp,
		.p_channel_count = 0,
		.p_channels = NULL,
		.p_stdio = {
			KERN_HANDLE_INVALID,
			KERN_HANDLE_INVALID,
			KERN_HANDLE_INVALID,
		},
	};

	launch_ctx_init(&launch);
	launch.ctx_resolve_library = resolve_dependency;

	enum launch_status launch_status = launch_ctx_execute(
		&launch,
		&params,
		LAUNCH_F_CLONE_ALL_HANDLES,
		&result);
	kern_handle_close(address_space);
	kern_handle_close(self);
	kern_handle_close(image);

	switch (launch_status) {
	case LAUNCH_OK:
		break;
	case LAUNCH_ERR_NO_MEMORY:
		return __set_errno(ENOMEM);
	case LAUNCH_ERR_INVALID_EXECUTABLE:
	case LAUNCH_ERR_UNSUPPORTED_EXECUTABLE:
	case LAUNCH_ERR_MISSING_SYMBOL:
	case LAUNCH_ERR_INTERPRETER_REQUIRED:
		return __set_errno(ENOEXEC);
	case LAUNCH_ERR_CANNOT_RESOLVE_DEPENDENCY:
		return __set_errno(ENOENT);
	default:
		/* TODO */
		return __set_errno(EPERM);
	}

	tid_t child_id = 0;
	task_config_get(result.r_task, TASK_CFG_ID, &child_id, sizeof child_id);

	*pid = child_id;

	return __set_errno(SUCCESS);
}