// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 */

#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <termios.h>
#include <sys/wait.h>
#include <sys/mman.h>
#include <sys/utsname.h>
#include <sys/random.h>
#include <init.h>
#include <os.h>

void stack_protections(unsigned long address)
{
        if (mprotect((void *) address, UM_THREAD_SIZE, PROT_READ | PROT_WRITE) < 0)
                panic("protecting stack failed, errno = %d", errno);
}

int raw(int fd)
{
        struct termios tt;
        int err;

        CATCH_EINTR(err = tcgetattr(fd, &tt));
        if (err < 0)
                return -errno;

        cfmakeraw(&tt);

        CATCH_EINTR(err = tcsetattr(fd, TCSADRAIN, &tt));
        if (err < 0)
                return -errno;

        /*
         * XXX tcsetattr could have applied only some changes
         * (and cfmakeraw() is a set of changes)
         */
        return 0;
}

void setup_machinename(char *machine_out)
{
        struct utsname host;

        uname(&host);
#if IS_ENABLED(CONFIG_UML_X86)
# if !IS_ENABLED(CONFIG_64BIT)
        if (!strcmp(host.machine, "x86_64")) {
                strcpy(machine_out, "i686");
                return;
        }
# else
        if (!strcmp(host.machine, "i686")) {
                strcpy(machine_out, "x86_64");
                return;
        }
# endif
#endif
        strcpy(machine_out, host.machine);
}

void setup_hostinfo(char *buf, int len)
{
        struct utsname host;

        uname(&host);
        snprintf(buf, len, "%s %s %s %s %s", host.sysname, host.nodename,
                 host.release, host.version, host.machine);
}

/*
 * We cannot use glibc's abort(). It makes use of tgkill() which
 * has no effect within UML's kernel threads.
 * After that glibc would execute an invalid instruction to kill
 * the calling process and UML crashes with SIGSEGV.
 */
static inline void __attribute__ ((noreturn)) uml_abort(void)
{
        sigset_t sig;

        fflush(NULL);

        if (!sigemptyset(&sig) && !sigaddset(&sig, SIGABRT))
                sigprocmask(SIG_UNBLOCK, &sig, 0);

        for (;;)
                if (kill(getpid(), SIGABRT) < 0)
                        exit(127);
}

ssize_t os_getrandom(void *buf, size_t len, unsigned int flags)
{
        return getrandom(buf, len, flags);
}

/*
 * UML helper threads must not handle SIGWINCH/INT/TERM
 */
void os_fix_helper_signals(void)
{
        signal(SIGWINCH, SIG_IGN);
        signal(SIGINT, SIG_DFL);
        signal(SIGTERM, SIG_DFL);
}

void os_dump_core(void)
{
        int pid;

        signal(SIGSEGV, SIG_DFL);

        /*
         * We are about to SIGTERM this entire process group to ensure that
         * nothing is around to run after the kernel exits.  The
         * kernel wants to abort, not die through SIGTERM, so we
         * ignore it here.
         */

        signal(SIGTERM, SIG_IGN);
        kill(0, SIGTERM);
        /*
         * Most of the other processes associated with this UML are
         * likely sTopped, so give them a SIGCONT so they see the
         * SIGTERM.
         */
        kill(0, SIGCONT);

        /*
         * Now, having sent signals to everyone but us, make sure they
         * die by ptrace.  Processes can survive what's been done to
         * them so far - the mechanism I understand is receiving a
         * SIGSEGV and segfaulting immediately upon return.  There is
         * always a SIGSEGV pending, and (I'm guessing) signals are
         * processed in numeric order so the SIGTERM (signal 15 vs
         * SIGSEGV being signal 11) is never handled.
         *
         * Run a waitpid loop until we get some kind of error.
         * Hopefully, it's ECHILD, but there's not a lot we can do if
         * it's something else.  Tell os_kill_ptraced_process not to
         * wait for the child to report its death because there's
         * nothing reasonable to do if that fails.
         */

        while ((pid = waitpid(-1, NULL, WNOHANG | __WALL)) > 0)
                os_kill_ptraced_process(pid, 0);

        uml_abort();
}

void um_early_printk(const char *s, unsigned int n)
{
        printf("%.*s", n, s);
}

static int quiet_info;

static int __init quiet_cmd_param(char *str, int *add)
{
        quiet_info = 1;
        return 0;
}

__uml_setup("quiet", quiet_cmd_param,
"quiet\n"
"    Turns off information messages during boot.\n\n");

/*
 * The os_info/os_warn functions will be called by helper threads. These
 * have a very limited stack size and using the libc formatting functions
 * may overflow the stack.
 * So pull in the kernel vscnprintf and use that instead with a fixed
 * on-stack buffer.
 */
int vscnprintf(char *buf, size_t size, const char *fmt, va_list args);

void os_info(const char *fmt, ...)
{
        char buf[256];
        va_list list;
        int len;

        if (quiet_info)
                return;

        va_start(list, fmt);
        len = vscnprintf(buf, sizeof(buf), fmt, list);
        fwrite(buf, len, 1, stderr);
        va_end(list);
}

void os_warn(const char *fmt, ...)
{
        char buf[256];
        va_list list;
        int len;

        va_start(list, fmt);
        len = vscnprintf(buf, sizeof(buf), fmt, list);
        fwrite(buf, len, 1, stderr);
        va_end(list);
}