/***************************************************************/
/*  mgdb: midipix-specific bits for gdb                        */
/*  Copyright (C) 2019  Z. Gilboa                              */
/*  Released under GPLv2 and GPLv3; see COPYING.MGDB.          */
/***************************************************************/

#include "defs.h"
#include "osabi.h"
#include "config.h"
#include "target.h"
#include "utils.h"
#include "inferior.h"
#include "gdbthread.h"
#include "inf-child.h"
#include "x86-nat.h"

#include <poll.h>
#include <unistd.h>
#include <stdint.h>
#include <stddef.h>
#include <pthread.h>
#include <sys/cmd.h>
#include <sys/debug.h>

#define WINNT_OUTBUF_SIZE 65536

#define winnt_error(msg) \
	error("%s(): %s.",__FUNCTION__,msg)

#define winnt_perror(msg,pid) \
	error("%s(): %s (pid %d).",__FUNCTION__,msg,pid)

struct regcache;

struct winnt_process {
	int			pfd;
	pid_t			pid;
	pid_t			syspid;
	pid_t			systid;
	pid_t			flags;
	struct __dbg_event	event;
};

static size_t          pcnt;
static winnt_process * plist;
static char *          outbuf;

extern void amd64_winnt_fetch_registers(
	int pfd, struct regcache * rcache,
	int regnum, pid_t tid);

extern void i386_winnt_fetch_registers(
	int pfd, struct regcache * rcache,
	int regnum, pid_t tid);

static winnt_process * winnt_plist_expand (void)
{
	struct winnt_process * pnew;
	struct winnt_process * pold;
	size_t                 idx;

	if (!(pnew = (struct winnt_process *)calloc(pcnt+32, sizeof(*pnew))))
		return 0;

	memcpy(
		pnew,plist,
		pcnt*sizeof(*plist));

	pold  = plist;
	plist = pnew;
	pcnt += 32;

	free(pold);

	return pnew;
}

static int winnt_plist_add (pid_t pid, int pfd)
{
	struct winnt_process * pdbg;
	struct winnt_process * pcap;

	for (pdbg=plist, pcap=&plist[pcnt]; pdbg<pcap; pdbg++) {
		if (!pdbg->pid) {
			pdbg->pid = pid;
			pdbg->pfd = pfd;
			return 0;
		}
	}

	return winnt_plist_expand()
		? winnt_plist_add(pid,pfd)
		: -1;
}

static void winnt_plist_remove (pid_t pid)
{
	struct winnt_process * pdbg;
	struct winnt_process * pcap;

	for (pdbg=plist, pcap=&plist[pcnt]; pdbg<pcap; pdbg++) {
		if (pdbg->pid == pid) {
			pdbg->pid = 0;
			return;
		}
	}
}

static struct winnt_process * winnt_process_record(pid_t pid)
{
	winnt_process * pdbg;
	winnt_process * pcap;

	for (pdbg=plist, pcap=&plist[pcnt]; pdbg<pcap; pdbg++)
		if (pdbg->pid == pid)
			return pdbg;

	return 0;
}

static char * winnt_pid_to_exec_file (struct target_ops * t, int pid)
{
	(void)t;
	(void)pid;

	outbuf[0] = 0;

	return outbuf;
}

static void winnt_fetch_registers (
	struct target_ops * t,
	struct regcache *   rcache,
	int                 regnum)
{
	pid_t pid;
	pid_t tid;
	struct winnt_process * pidinfo;

	pid = inferior_ptid.pid;
	tid = inferior_ptid.tid;

	if (!(pidinfo = winnt_process_record(pid)))
		winnt_perror("internal error: record not found",pid);

	if (sizeof(uintptr_t) == 8)
		amd64_winnt_fetch_registers(
			pidinfo->pfd,
			rcache,regnum,
			tid);
	else
		i386_winnt_fetch_registers(
			pidinfo->pfd,
			rcache,regnum,
			tid);
}

static void winnt_store_registers (
	struct target_ops * t,
	struct regcache *   rcache,
	int                 regnum)
{
	(void)t;
	(void)rcache;
	(void)regnum;
}

static enum target_xfer_status winnt_xfer_partial(
	struct target_ops * t,
	enum target_object  object,
	const char *        annex,
	gdb_byte *          readbuf,
	const gdb_byte *    writebuf,
	ULONGEST            offset,
	ULONGEST            len,
	ULONGEST *          nxfered)
{
	(void)t;
	(void)object;
	(void)annex;
	(void)offset;
	(void)len;

	if (readbuf && writebuf)
		winnt_error("internal error: both readbuf and writebuf are non-null.");

	if (!readbuf && !writebuf)
		winnt_error("internal error: both readbuf and writebuf are null.");

	if (!nxfered)
		winnt_error("internal error: nxfered is null.");

	return TARGET_XFER_E_IO;
}

static int winnt_thread_alive (struct target_ops * t, ptid_t ptid)
{
	(void)t;
	(void)ptid;

	return true;
}

static void winnt_interrupt (struct target_ops * t, ptid_t ptid)
{
	(void)t;
	(void)ptid;
}

static void winnt_files_info (struct target_ops * t)
{
	(void)t;
}

static nfds_t winnt_poll_one_init (struct pollfd * pfds, pid_t pid)
{
	winnt_process * pdbg;
	winnt_process * pcap;

	for (pdbg=plist, pcap=&plist[pcnt]; pdbg<pcap; pdbg++) {
		if (pdbg->pid == pid) {
			pfds->fd     = pdbg->pfd;
			pfds->events = POLLIN;

			return 1;
		}
	}

	return 0;
}

static nfds_t winnt_poll_init (struct pollfd * pfds)
{
	winnt_process * pdbg;
	winnt_process * pcap;
	struct pollfd * pfd;

	for (pfd=pfds, pdbg=plist, pcap=&plist[pcnt]; pdbg<pcap; pdbg++) {
		if (pdbg->pid) {
			pfd->fd     = pdbg->pfd;
			pfd->events = POLLIN;
			pfd++;
		}
	}

	return pfd - pfds;
}

static void winnt_close (struct target_ops * t)
{
}

static void winnt_xclose (struct target_ops * t)
{
}

static void winnt_respond (int pfd, struct __dbg_event * event, int response)
{
	ptid_t ptid;

	event->eresponse = response;

	switch (event->evttype) {
		case __DBG_STATE_CREATE_PROCESS:
			ptid = ptid_build(event->syspid,0,0);
			add_thread(ptid);
			ptid = ptid_build(event->syspid,0,event->systid);
			add_thread(ptid);
			break;

		case __DBG_STATE_CREATE_THREAD:
			ptid = ptid_build(event->syspid,0,event->systid);
			add_thread(ptid);
			break;

		default:
			break;
	}

	if (__dbg_event_respond(pfd,event) < 0)
		winnt_perror("failed to respond to debug event",pfd);

	event->syspid = 0;
	event->systid = 0;
}

static void winnt_prepare (struct target_ops * t, pid_t pid, int pfd, int attached)
{
	int			ret;
	struct inferior *	cinf;
	struct __dbg_event *	event;
	struct winnt_process *	pidinfo;

	if (!target_is_pushed(t))
		push_target(t);

	clear_proceed_status(0);
	init_wait_for_inferior();

	if (!(cinf = current_inferior()))
		winnt_error("failed to obtain current inferior");

	if (!(pidinfo = winnt_process_record(pid)))
		winnt_perror("internal error: record not found",pid);

	event             = &pidinfo->event;
	inferior_ptid     = pid_to_ptid (pid);
	cinf->attach_flag = attached;

	inferior_appeared(cinf,pid);
	init_thread_list();

	target_terminal_init();
	target_terminal_inferior();

	while (1) {
		do {
			ret = __dbg_event_acquire(pfd,event);
		} while ((ret < 0) && (errno == EAGAIN));

		if (ret < 0)
			winnt_perror("failed to acquire preliminary debug event",pid);

		if ((event->evttype == __DBG_STATE_CREATE_PROCESS) && !attached)
			if (__dbg_resume_thread(pfd,event->systid) < 0)
				winnt_perror("failed to resume first thread",pid);

		inferior_ptid.pid = event->syspid;
		inferior_ptid.tid = event->systid;

		switch (event->evttype) {
			case __DBG_STATE_EXCEPTION:
			case __DBG_STATE_BREAKPOINT:
			case __DBG_STATE_SINGLE_STEP:
				pidinfo->syspid = event->syspid;
				pidinfo->systid = event->systid;
				target_terminal_ours();
				return;

			case __DBG_STATE_CREATE_PROCESS:
			case __DBG_STATE_CREATE_THREAD:
			case __DBG_STATE_IDLE:
			case __DBG_STATE_REPLY_PENDING:
			case __DBG_STATE_DLL_LOAD:
			case __DBG_STATE_DLL_UNLOAD:
			case __DBG_STATE_EXIT_THREAD:
			case __DBG_STATE_EXIT_PROCESS:
				winnt_respond(pfd,event,__DBG_RESPONSE_CONTINUE);
		}
	}
}

static void winnt_attach (struct target_ops * t, const char * args, int from_tty)
{
	pid_t	pid;
	int	pfd;

	if ((pid = parse_pid_to_attach(args)) < 0) {
		winnt_error ("cannot parse pid to attach");
	}


	if ((pfd = __dbg_attach(pid)) < 0) {
		winnt_perror ("cannot attach to process",pid);
	}


	if (__dbg_rbreak(pfd) < 0) {
		__dbg_detach(pfd);
		close(pfd);
		winnt_perror ("could not issue a breakpoint in process",pid);
	}


	if (winnt_plist_add(pid,pfd) < 0) {
		__dbg_detach(pfd);
		close(pfd);
		winnt_error ("could not expand debuggee list");
	}

	winnt_prepare(t,pid,pfd,from_tty);
}

static void winnt_mourn_inferior (struct target_ops * t)
{
	x86_cleanup_dregs();
	inf_child_maybe_unpush_target(t);
	inf_child_mourn_inferior(t);
	delete_inferior(current_inferior());
}

static void winnt_abandon (winnt_process * pidinfo)
{
	inferior_ptid = null_ptid;
	winnt_plist_remove(pidinfo->pid);
}

static void winnt_detach (struct target_ops * t, const char * args, int from_tty)
{
	pid_t		pid;
	winnt_process *	pidinfo;

	if ((pid = ptid_get_pid(inferior_ptid)) < 0)
		winnt_error ("cannot determine pid to detach");

	if (!(pidinfo = winnt_process_record(pid)))
		winnt_perror ("debuggee record does not exist",pid);

	if (__dbg_detach(pidinfo->pfd) < 0)
		winnt_perror ("could not detach from process",pid);

	if (close(pidinfo->pfd) < 0)
		winnt_perror ("failed to close process file descriptor",pid);

	detach_inferior(pidinfo->syspid);

	winnt_abandon(pidinfo);
	winnt_mourn_inferior(t);
}

static ptid_t winnt_wait(
	struct target_ops * t,
	ptid_t ptid,
	struct target_waitstatus * waitstatus,
	int target_options)
{
	struct __dbg_event	event;
	struct winnt_process *	pdbg;
	struct winnt_process *	pcap;
	struct winnt_process *	pidinfo;
	struct pollfd           pollfdbuf[512];
	struct pollfd *         pfds;
	struct pollfd *         pfd;
	nfds_t                  nfds,i;

	if (ptid.pid  < 0)
		for (pdbg=plist, pcap=&plist[pcnt]; pdbg<pcap; pdbg++)
			if (pdbg->event.systid)
				return ptid_build(
					pdbg->event.syspid,0,
					pdbg->event.systid);

	if (ptid.pid > 0) {
		if (!(pidinfo = winnt_process_record(event.syspid)))
			winnt_perror("internal error: record not found",event.syspid);

		if (pidinfo->event.systid)
			return ptid_build(
				pidinfo->event.syspid,0,
				pidinfo->event.systid);
	}

	if (pcnt*sizeof(*pfds) < sizeof(pollfdbuf))
		pfds = pollfdbuf;
	else if (!(pfds = (struct pollfd *)calloc(pcnt,sizeof(*pfds))))
		return null_ptid;

	nfds = (ptid.pid > 0)
		? winnt_poll_one_init(pfds,ptid.pid)
		: winnt_poll_init(pfds);

	if (poll(pfds,nfds,-1) < 0)
		return null_ptid;

	for (i=0, pfd=0; i<nfds && !pfd; i++)
		if (pfds[i].revents & POLLIN)
			pfd = &pfds[i];

	if (!pfd)
		return null_ptid;

	if (__dbg_event_query_one(pfd->fd,&event) < 0)
		return null_ptid;

	if (!(pidinfo = winnt_process_record(event.syspid)))
		winnt_perror("internal error: record not found",event.syspid);

	memcpy(&pidinfo->event,&event,sizeof(event));

	return ptid_build(
		event.syspid,0,
		event.systid);
}

static void winnt_resume (
	struct target_ops * t,
	ptid_t ptid, int step,
	enum gdb_signal sig)
{
}

static void winnt_kill (struct target_ops * t)
{
	struct inferior *	cinf;
	struct winnt_process *	pidinfo;

	if (!(cinf = current_inferior()))
		winnt_error("failed to obtain current inferior");

	if (!(pidinfo = winnt_process_record(cinf->pid)))
		winnt_perror("internal error: record not found",cinf->pid);

	if (__dbg_kill(pidinfo->pfd) < 0)
		winnt_perror("failed to kill current inferior",cinf->pid);

	winnt_abandon(pidinfo);
	winnt_mourn_inferior(t);
}

static void winnt_create_inferior(
	struct  target_ops * t,
	char *  exec_file,
	char *  args,
	char ** envp,
	int     from_tty)
{
	int	pfd;
	pid_t	pid;
	size_t	arglen;
	char *	argbuf;
	char **	argv;

	/* validate */
	if (!exec_file)
		winnt_error("Executable not set; use `target exec'.");

	/* assume no folded white space, add final null termination */
	arglen = strlen(args);
	arglen++;

	if (!(argbuf = (char *)calloc(arglen,1)))
		winnt_error("Failed to allocate argument string buffer.");

	/* extra pointer for exec_file (argv[0]) */
	arglen++;

	if (!(argv = (char **)calloc(arglen,sizeof(char *))))
		winnt_error("Failed to allocate argument vector buffer.");

	arglen--;

	/* argv */
	argv[0] = exec_file;

	if (__cmd_args_to_argv(args,argbuf,arglen,&argv[1],arglen) < 0)
		winnt_error("Failed to parse command-line arguments.");

	/* spawn */
	if ((pfd = __dbg_spawn(exec_file,argv,envp,0)) < 0)
		winnt_error("Failed to spawn executable.");

	/* syspid */
	if ((pid = __dbg_query_syspid(pfd)) < 0) {
		__dbg_kill(pfd);
		close(pfd);
		winnt_error("Failed to obtain syspid (should never happen).");
	}

	/* debuggee list */
	if (winnt_plist_add(pid,pfd) < 0) {
		__dbg_kill(pfd);
		close(pfd);
		winnt_error ("could not expand debuggee list");
	}

	/* init loop */
	winnt_prepare(t,pid,pfd,0);
}

static char * winnt_pid_to_str (struct target_ops * t, ptid_t ptid)
{
	if (ptid.tid)
		sprintf(outbuf,"Thread %d:%ld",ptid.pid,ptid.tid);
	else
		sprintf(outbuf,"Process %d",ptid.pid);

	return outbuf;
}

static target_ops * winnt_target_alloc (void)
{
	target_ops * t = inf_child_target();

	t->to_attach_no_wait            = 1;
	t->to_has_thread_control        = 1;

	t->to_close                     = winnt_close;
	t->to_xclose                    = winnt_xclose;

	t->to_attach                    = winnt_attach;
	t->to_detach                    = winnt_detach;

	t->to_wait                      = winnt_wait;
	t->to_resume                    = winnt_resume;

	t->to_kill                      = winnt_kill;
	t->to_mourn_inferior            = winnt_mourn_inferior;
	t->to_create_inferior           = winnt_create_inferior;

	t->to_pid_to_str                = winnt_pid_to_str;
	t->to_pid_to_exec_file          = winnt_pid_to_exec_file;

	t->to_fetch_registers           = winnt_fetch_registers;
	t->to_store_registers           = winnt_store_registers;

	t->to_xfer_partial              = winnt_xfer_partial;
	t->to_files_info                = winnt_files_info;

	t->to_thread_alive              = winnt_thread_alive;
	t->to_interrupt                 = winnt_interrupt;

	x86_use_watchpoints(t);

	return ((outbuf = (char *)calloc(1,WINNT_OUTBUF_SIZE)))
		? t : 0;
}



extern initialize_file_ftype _initialize_winnt_nat;

void
_initialize_winnt_nat(void)
{
	add_target(winnt_target_alloc());
}