photon/libc/sys/horizon/init.c

#include <magenta/task.h>
#include <magenta/tunnel.h>
#include <magenta/bootstrap.h>
#include <magenta/signals.h>
#include <magenta/errors.h>
#include <magenta/handle.h>
#include <magenta/misc.h>
#include <magenta/object.h>
#include <mio/object.h>
#include <mio/fd.h>
#include <mio/fs.h>
#include <mio/namespace.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "__init.h"
#include "__heap.h"
#include "__fio.h"

/* maximum of 32 handles can be received sent as arguments */
#define MAX_HANDLE_ARGS 32

/* maximum size of bootstrap message that can be received */
#define MAX_MSG_SIZE 0x2000

#if 1
#define dbg_log(...)
#else
static void dbg_log(const char *format, ...)
{
    char buf[1024];

    va_list arg;
    va_start(arg, format);

    int r = vsnprintf(buf, sizeof buf, format, arg);
    va_end(arg);

    mx_console_write(buf, r);
}
#endif

#ifdef DYLD_PARENT_IMAGE
extern mx_vaddr_t dyld_load_exec(int argc, const char **argv);
#endif

static const char **environ = NULL;
static char arg_msg_buf[MAX_MSG_SIZE];
static mx_bootstrap_handle_t arg_handles[MAX_HANDLE_ARGS];

const char **__crt_environ()
{
    return environ;
}

extern int main(int, const char **);
extern void __crt_run_atexit();

static void extract_arg_handles(mx_bootstrap_msg_t *args,
        mx_handle_t *handles, int hndc, mx_bootstrap_handle_t *out)
{
    uint32_t *hent = (uint32_t *)((char *)args + args->handle_info_off);

    for (int i = 0; i < hndc; i++) {
        out[i].info = hent[i];
        out[i].handle = handles[i];
    }
}

static void parse_args(mx_bootstrap_msg_t *args,
        const char **argv, const char **envp, const char **namep)
{
    if (args->args_num > 0) {
        char *arg_buf = (char *)args + args->args_off;
        int arg_i = 0;
        int arg_off = 0;

        for (int i = 0; ; i++) {
            if (arg_buf[i] == '\0') {
                argv[arg_i++] = arg_buf + arg_off;
                arg_off = i + 1;
            }

            if (arg_i == (int)args->args_num) {
                break;
            }
        }
    }

    if (args->environ_num > 0) {
        char *env_buf = (char *)args + args->environ_off;
        int env_i = 0;
        int env_off = 0;

        for (int i = 0; ; i++) {
            if (env_buf[i] == '\0') {
                envp[env_i++] = env_buf + env_off;
                env_off = i + 1;
            }

            if (env_i == (int)args->environ_num) {
                break;
            }
        }
    }

    if (args->names_num) {
        char *name_buf = (char *)args + args->names_off;
        int name_i = 0;
        int name_off = 0;

        for (int i = 0; ; i++) {
            if (name_buf[i] == '\0') {
                namep[name_i++] = name_buf + name_off;
                name_off = i + 1;
            }

            if (name_i == (int)args->names_num) {
                break;
            }
        }
    }
}

static void hang()
{
    while (1) {
        mx_nanosleep(mx_deadline_after(MX_SEC(1)));
    }
}

static void init_stdio_fd(int fd, mx_handle_t *handles, size_t nhandles)
{
    if (handles[0] == MX_NULL_HANDLE) {
        dbg_log("** photon: FD %d is closed\n", fd);
        return;
    }

    mx_info_basic_t handle0_info;
    mx_status_t err = mx_object_get_info(handles[0], MX_INFO_HANDLE_BASIC, &handle0_info, sizeof(handle0_info));
    if (err != MX_OK) {
        /* bad handle. TODO report error somehow */
        return;
    }

    mio_object *obj = NULL;

    if (handle0_info.type == MX_OBJECT_PIPE) {
        obj = mio_pipe_create(handles[0]);
        dbg_log("** photon: FD %d is a pipe\n", fd);
    } else {
        /* just assume all other stdio handles implement the file protocol over a tunnel */
        obj = mio_file_create(handles[0]);
        dbg_log("** photon: FD %d is a file\n", fd);
    }

    mio_fd_list_alloc_at(mio_global_fd_list(), obj, fd);
}

static void init_stdio(mx_bootstrap_handle_t *handles, size_t nhandles)
{
    dbg_log("** photon: initialising stdio\n");
    bool no_fds = true;
    int max_fd = 0;
    for (size_t i = 0; i < nhandles; i++) {
        uint32_t info = handles[i].info;
        if (MX_B_HND_TYPE(info) != MX_B_FD) {
            continue;
        }

        no_fds = false;
        int fd = MX_B_HND_ARG(info);
        if (fd > max_fd) {
            max_fd = fd;
        }
    }

    if (no_fds) {
        dbg_log("** photon: we've been given no FDs\n");
        return;
    }

    int nfds = max_fd + 1;
    dbg_log("** photon: we've been given up to %d FDs\n", nfds);

    /* Supports up to two handles per FD */
    mx_handle_t fd_handles[nfds][2];
    memset(fd_handles, 0x0, sizeof(mx_handle_t) * 2 * nfds);

    for (size_t i = 0; i < nhandles; i++) {
        uint32_t info = handles[i].info;
        if (MX_B_HND_TYPE(info) != MX_B_FD) {
            continue;
        }

        int fd = MX_B_HND_ARG(info);
        mx_handle_t *this_fd_handles = fd_handles[fd];

        if (this_fd_handles[0] != MX_NULL_HANDLE) {
            this_fd_handles[1] = handles[i].handle;
        } else {
            this_fd_handles[0] = handles[i].handle;
        }
    }

    for (int i = 0; i < nfds; i++) {
        size_t n = 1;
        if (fd_handles[i][1] != MX_NULL_HANDLE) {
            n++;
        }

        //dbg_log("** photon: handles for FD %d = { %x, %x }\n", i, fd_handles[i][0], fd_handles[i][1]);

        init_stdio_fd(i, fd_handles[i], n);
    }

    __fio_init(0, 1, 2);
    dbg_log("** photon: stdio init finished\n");
}

static int do_init(mx_handle_t bootstrap, bool enable_fs, bool enable_stdio, int *out_argc, const char ***out_argv)
{
    dbg_log("reading bootstrap message from %x\n", bootstrap);
    mx_signals_t sig = 0;
    mx_object_wait(bootstrap, MX_TUNNEL_READABLE, 0, &sig);
    if (!(sig & MX_TUNNEL_READABLE)) {
        dbg_log("no bootstrap message!\n");
        return -1;
    }

    size_t msg_size = 0;
    size_t nr_handles = 0;

    mx_handle_t handles[MAX_HANDLE_ARGS + 1];

    dbg_log("receiving message from handle %lx\n", bootstrap);
    mx_status_t err = mx_tunnel_read(bootstrap,
            arg_msg_buf, MAX_MSG_SIZE,
            handles, MAX_HANDLE_ARGS,
            &msg_size, &nr_handles);

    if (err != MX_OK) {
        dbg_log("error: cannot read bootstrap message from handle %lx (error %d)\n",
                bootstrap, err);
        return -1;
    }

    mx_bootstrap_msg_t *msg = (mx_bootstrap_msg_t *)arg_msg_buf;

    dbg_log("extracting handles\n");
    extract_arg_handles(msg, handles, nr_handles, arg_handles);
#if 0
    arg_handles[nr_handles].handle = bootstrap;
    arg_handles[nr_handles].info = MX_B_HND(MX_B_TUNNEL_BTSTP, 0);
    nr_handles++;
#endif

    dbg_log("extracted %zu handles\n", nr_handles);

    mx_bootstrap_handle_init(arg_handles, nr_handles);

    const char **argv = NULL, **envp = NULL, **namep = NULL;

    dbg_log("allocating buffers (%u, %u, %u)\n", msg->args_num, msg->environ_num, msg->names_num);

    argv =  calloc(sizeof *argv,  msg->args_num    + 1);
    envp =  calloc(sizeof *envp,  msg->environ_num + 1);
    namep = calloc(sizeof *namep, msg->names_num   + 1);

    environ = envp;

    parse_args(msg, argv, envp, namep);

    *out_argc = msg->args_num;
    *out_argv = argv;

    if (enable_stdio) {
        init_stdio(arg_handles, nr_handles);
    } else {
        __fio_init(-1, -1, -1);
    }

    if (!enable_fs) {
        return 0;
    }

    mio_namespace *ns = mio_namespace_create();

    dbg_log("received %u names/%zu handles\n", msg->names_num, nr_handles);
    if (msg->names_num > 0) {
        for (size_t i = 0; i < nr_handles; i++) {
            int type = MX_B_HND_TYPE(arg_handles[i].info);
            int arg = MX_B_HND_ARG(arg_handles[i].info);

            if (type != MX_B_NS_DIR && type != MX_B_TUNNEL_CWD) {
                dbg_log(" * wrong type %x\n", type);
                continue;
            }

            const char *path = namep[arg];
            dbg_log(" * %s = %x\n", path, arg_handles[i].handle);

            if (type == MX_B_TUNNEL_CWD) {
                mio_set_cwd(arg_handles[i].handle, path);
            } else {
                mio_namespace_add_entry(ns, path, arg_handles[i].handle);
            }
        }
    }

    mio_set_global_namespace(ns);
    return 0;
}

static int do_run(mx_handle_t bootstrap)
{
    int argc;
    const char **argv;

    int err = do_init(bootstrap, true, true, &argc, &argv);
    if (err != 0) {
        return err;
    }

    return main(argc, argv);
}

#ifdef DYLD_PARENT_IMAGE
static int do_load_and_run(mx_handle_t bootstrap)
{
    int argc;
    const char **argv;

    int err = do_init(bootstrap, false, true, &argc, &argv);
    if (err != 0) {
        return err;
    }

    mx_vaddr_t main_ptr = dyld_load_exec(argc, argv);
    if (!main_ptr) {
        return -1;
    }

    mx_bootstrap_handle_cleanup();

    err = do_init(bootstrap, true, true, &argc, &argv);
    if (err != 0) {
        return err;
    }

    int(*main_func)(int, const char **) = (int(*)(int, const char **))main_ptr;
    if (!main_func) {
        return -1;
    }

    return main_func(argc, argv);
}
#endif

int __crt_init(mx_handle_t bootstrap, mx_vaddr_t arg2)
{
#ifndef DYLD_PARENT_IMAGE
    int ret = do_run(bootstrap);
#else
    int ret = do_load_and_run(bootstrap);
#endif

    fflush(stdout);
    fflush(stderr);
    __crt_run_atexit();
    mio_fd_cleanup();
    mio_fs_cleanup();
    mx_task_kill(mx_bootstrap_handle_get(MX_B_TASK_SELF), ret);

    /* unreachable */
    hang();
    return 0;
}