/***************************************************************/
/*  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 "main.h"
#include "utils.h"
#include "inferior.h"
#include "gdbcore.h"
#include "gdbthread.h"
#include "inf-child.h"
#include "xml-support.h"
#include "winnt-nat.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>

#include <perk/perk.h>

#define WINNT_OUTBUF_SIZE 65536
#define X86_DR_RTM_MASK   (1 << 16)
#define X86_EFLAGS_TRACE  (1 << 8)

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

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

#define WINNT_W32_EXCEPTION_MASK ((0xe0 << 24) | ('m' << 16) | ('s' << 8) | ('c' << 0))
#define WINNT_ZED_EXCEPTION_MASK ((0x2d << 24) | ('Z' << 16) | ('E' << 8) | ('D' << 0))
#define WINNT_GCC_EXCEPTION_MASK ((0x20 << 24) | ('G' << 16) | ('C' << 8) | ('C' << 0))

static size_t          pcnt;
static winnt_process * plist;
static char *          outbuf;
static struct pe_driver_ctx * pe_dctx;

static struct winnt_exception_filter winnt_exception_filters[] = {
	{WINNT_W32_EXCEPTION_MASK,  WINNT_EXCEPTION_FIRST_CHANCE,   0},
	{WINNT_ZED_EXCEPTION_MASK,  WINNT_EXCEPTION_FIRST_CHANCE,   0},
	{WINNT_GCC_EXCEPTION_MASK,  WINNT_EXCEPTION_FIRST_CHANCE,   0},
	{0,                         WINNT_EXCEPTION_FIRST_CHANCE,   "sysfer.dll"},
	{0,                         0,                              0},
};

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_free_modules(struct winnt_process * pidinfo)
{
	struct __dbg_module_info * module;
	struct __dbg_module_info * modules_base;
	struct __dbg_module_info * modules_cap;

	if (!pidinfo->modules)
		return;

	modules_base = pidinfo->modules;
	modules_cap  = &modules_base[pidinfo->nmodules];

	for (module=modules_base; module<modules_cap; module++) {
		if (module->module_name)
			free(module->module_name);

		if (module->module_ctx)
			pe_free_unit_ctx((pe_unit_ctx *)module->module_ctx);
	}

	if (pidinfo->solibs)
		free(pidinfo->solibs);

	free(pidinfo->modules);

	pidinfo->modules  = 0;
	pidinfo->nmodules = 0;
	pidinfo->solibs   = 0;
}

static void winnt_free_threads(struct winnt_process * pidinfo)
{
	struct winnt_thread * thread;
	struct winnt_thread * next;

	next = pidinfo->threads;

	for (thread=next; thread; thread=next) {
		next = thread->next;
		free(thread);
	}
}

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) {
			close(pdbg->pfd);
			winnt_free_modules(pdbg);
			winnt_free_threads(pdbg);
			memset(pdbg,0,sizeof(*pdbg));
			return;
		}
	}
}

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

	if (!pid)
		return 0;

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

	return 0;
}

static ptid_t winnt_get_ada_task_ptid (struct target_ops * t, long lwp, long tid)
{
	ptid_t ptid;

	(void)t;

	ptid.pid = inferior_ptid.pid;
	ptid.lwp = 0;
	ptid.tid = lwp;

	return ptid;
}

static char * winnt_pid_to_exec_file (struct target_ops * t, int pid)
{
	ssize_t ret;
	struct  winnt_process * pidinfo;

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

	ret = __dbg_info_get(
		pidinfo->pfd,0,
		__DBG_INFO_IMAGE_RPATH,
		outbuf,WINNT_OUTBUF_SIZE);

	if (ret < 0)
		ret = __dbg_info_get(
			pidinfo->pfd,0,
			__DBG_INFO_REPORTED_IMAGE_RPATH,
			outbuf,WINNT_OUTBUF_SIZE);

	if (ret < 0)
		outbuf[0] = 0;

	return outbuf;
}

static void winnt_get_modules(struct winnt_process * pidinfo)
{
	void *                     addr;
	char *                     xmlstr;
	char *                     mark;
	char *                     text;
	struct pe_unit_ctx *       uctx;
	struct pe_meta_sec_hdr *   sechdr;
	struct __dbg_module_info * module;
	struct __dbg_module_info * modules;
	struct __dbg_module_info * modules_cap;
	ssize_t                    nbytes;
	size_t                     nmodules;
	size_t                     buflen;
	int                        secidx;

	winnt_free_modules(pidinfo);

	if (!(addr = calloc(2048,sizeof(*modules))))
		return;

	nbytes = __dbg_info_get(
		pidinfo->pfd,0,
		__DBG_INFO_CACHED_MODULE_LIST,
		addr,2048*sizeof(*modules));

	if (nbytes < 0) {
		free(addr);
		return;
	};

	nmodules = nbytes / sizeof(*modules);
	modules  = (struct __dbg_module_info *)calloc(nmodules,sizeof(*modules));

	if (!modules) {
		free(addr);
		return;
	}

	memcpy(modules,addr,nmodules*sizeof(*modules));
	free(addr);

	buflen      = 64;
	module      = modules;
	modules_cap = &modules[nmodules];

	for (; module<modules_cap; ) {
		nbytes = __dbg_info_get(
			pidinfo->pfd,module->module_key,
			__DBG_INFO_MODULE_RPATH,
			outbuf,WINNT_OUTBUF_SIZE);

		if (nbytes > 0) {
			module->module_name = strdup(outbuf);
			xmlstr = xml_escape_text(outbuf);

			if (xmlstr) {
				buflen += strlen(xmlstr) + 128;
				xfree(xmlstr);
			}

			pe_get_unit_ctx(
				pe_dctx,
				module->module_name,
				(pe_unit_ctx **)&module->module_ctx);
		}

		module++;
	}

	module            = modules;
	pidinfo->modules  = modules;
	pidinfo->nmodules = nmodules;

	if (!(pidinfo->solibs = (char *)calloc(1,buflen)))
		return;

	mark  = pidinfo->solibs;
	mark += sprintf(mark,"<library-list>\n");

	for (; module<modules_cap; ) {
		uctx = 0;
		text = 0;

		if (module->module_name) {
			if ((xmlstr = xml_escape_text(module->module_name))) {
				mark += sprintf(mark,"<library name=");
				mark += sprintf(mark,"\"%s\">",xmlstr);
				xfree(xmlstr);
			}

			/* text */
			if ((uctx = (pe_unit_ctx *)module->module_ctx)) {
				secidx = pe_get_named_section_index(
					uctx->meta,".text");

				if (secidx >= 0) {
					sechdr = &uctx->meta->m_sectbl[secidx];
					text   = (char *)module->module_base;
					text  += sechdr->sh_virtual_addr;
				}
			}

			mark += sprintf(mark,"<segment address=");
			mark += sprintf(mark,"\"%p\"/>",(void *)text);

			mark += sprintf(mark,"</library>");
		}
		module++;
	}

	mark += sprintf(mark,"</library-list>\n");
}

static void winnt_mourn_inferior (struct target_ops * t)
{
	if (inferior_ptid.pid)
		winnt_plist_remove(inferior_ptid.pid);

	x86_cleanup_dregs();
	inf_child_maybe_unpush_target(t);
	inf_child_mourn_inferior(t);
}

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

ssize_t winnt_xfer_solibs(
	struct winnt_process * pidinfo,
	gdb_byte *             readbuf,
	ULONGEST               offset,
	ULONGEST               len)
{
	size_t buflen;

	if (!pidinfo->solibs)
		return -1;

	buflen = strlen(pidinfo->solibs);

	if (offset >= buflen)
		return 0;

	if (len > (buflen - offset))
		len = buflen - offset;

	memcpy(readbuf,pidinfo->solibs + offset,len);

	return len;
}

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)
{
	ssize_t ret;
	struct  winnt_process * pidinfo;

	pidinfo = winnt_process_record(inferior_ptid.pid);

	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.");

	switch (object) {
		case TARGET_OBJECT_MEMORY:
			if (!pidinfo)
				return TARGET_XFER_E_IO;

			ret = (readbuf)
				? __dbg_vm_read(pidinfo->pfd,readbuf,len,offset)
				: __dbg_vm_write(pidinfo->pfd,writebuf,len,offset);
			break;

		case TARGET_OBJECT_LIBRARIES:
			if (!pidinfo)
				return TARGET_XFER_E_IO;

			ret = winnt_xfer_solibs(pidinfo,readbuf,offset,len);
			break;

		default:
			ret = t->beneath->to_xfer_partial(
				t,object,annex,
				readbuf,writebuf,
				offset,len,nxfered);
			break;
	}

	if (ret == 0)
		return TARGET_XFER_EOF;

	else if (ret < 0)
		return TARGET_XFER_E_IO;

	*nxfered = ret;

	return TARGET_XFER_OK;
}

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_set_thread_context_state(struct winnt_thread * thread, int state)
{
	thread->regctx.uc_context_flags = state;
}

static void winnt_add_thread(int pfd, ptid_t ptid)
{
	pid_t			pid;
	struct winnt_process *	pidinfo;
	struct winnt_thread *	thread;
	mcontext_t *		tctx;

	pid     = ptid_get_pid(ptid);
	pidinfo = winnt_process_record(pid);

	if (!(thread = (struct winnt_thread *)calloc(1,sizeof(*thread))))
		winnt_perror("could not allocate thread record.",pid);

	if (__dbg_regs_fetch(pfd,ptid.tid,&thread->regctx) < 0)
		winnt_perror("could not fetch registers for thread.",pid);

	tctx         = &thread->regctx;
	tctx->uc_dr0 = pidinfo->dr_cache[0];
	tctx->uc_dr1 = pidinfo->dr_cache[1];
	tctx->uc_dr2 = pidinfo->dr_cache[2];
	tctx->uc_dr3 = pidinfo->dr_cache[3];
	tctx->uc_dr6 = X86_DR_RTM_MASK;
	tctx->uc_dr7 = pidinfo->dr_cache[7];

	winnt_set_thread_context_state(
		thread,
		WINNT_THREAD_CONTEXT_READY);

	if (__dbg_regs_store(pfd,ptid.tid,tctx) < 0)
		winnt_perror("could not store registers for thread.",pid);

	thread->next     = pidinfo->threads;
	pidinfo->threads = thread;

	thread->process  = pidinfo;
	thread->tid      = ptid.tid;

	add_thread(ptid);
}

static struct winnt_thread * winnt_get_thread(struct winnt_process * pidinfo, pid_t tid)
{
	struct winnt_thread * thread;

	for (thread=pidinfo->threads; thread; thread=thread->next)
		if (thread->tid == tid)
			return thread;

	return 0;
}

static struct winnt_thread * winnt_get_thread_from_ptid(ptid_t ptid)
{
	struct winnt_process * pidinfo;

	if ((pidinfo = winnt_process_record(ptid.pid)))
		return winnt_get_thread(pidinfo,ptid.tid);

	return 0;
}

static void winnt_delete_thread(struct __dbg_event * event)
{
	ptid_t                 ptid;
	struct winnt_process * process;
	struct winnt_thread  * thread;
	struct winnt_thread  * prev;

	ptid.pid = event->syspid;
	ptid.tid = event->systid;
	ptid.lwp = 0;

	delete_thread(ptid);

	if (!(thread = winnt_get_thread_from_ptid(ptid)))
		return;

	process = thread->process;

	if (thread == process->threads) {
		process->threads = thread->next;
	} else {
		prev = process->threads;

		for (; prev->next != thread; )
			prev = prev->next;

		prev->next = thread->next;
	}

	if (process->threads)
		if (inferior_ptid.pid == ptid.pid)
			if (inferior_ptid.tid == ptid.tid)
				inferior_ptid.tid = process->threads->tid;

	free(thread);
}

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,event->systid);
			winnt_add_thread(pfd,ptid);
			break;

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

		case __DBG_STATE_EXIT_THREAD:
			winnt_delete_thread(event);
			break;

		case __DBG_STATE_EXIT_PROCESS:
			target_terminal_ours();
			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);

	disable_breakpoints_in_shlibs();
	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 == EINTR));

		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_EXIT_PROCESS:
				winnt_respond(pfd,event,__DBG_RESPONSE_CONTINUE);
				winnt_mourn_inferior(t);

			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:
				winnt_respond(pfd,event,__DBG_RESPONSE_CONTINUE);
		}
	}
}

static void winnt_fetch_registers (
	struct target_ops * t,
	struct regcache *   rcache,
	int                 regnum)
{
	pid_t                 tid;
	struct winnt_thread * thread;

	tid = inferior_ptid.tid;

	if (!(thread = winnt_get_thread_from_ptid(inferior_ptid)))
		winnt_perror("internal error: thread record not found",tid);

	if (sizeof(uintptr_t) == 8)
		amd64_winnt_fetch_registers(
			rcache,regnum,
			thread);
	else
		i386_winnt_fetch_registers(
			rcache,regnum,
			thread);
}

static void winnt_store_registers (
	struct target_ops * t,
	struct regcache *   rcache,
	int                 regnum)
{
	pid_t                 tid;
	struct winnt_thread * thread;

	tid = inferior_ptid.tid;

	if (!(thread = winnt_get_thread_from_ptid(inferior_ptid)))
		winnt_perror("internal error: thread record not found",tid);

	if (sizeof(uintptr_t) == 8)
		amd64_winnt_store_registers(
			rcache,regnum,
			thread);
	else
		i386_winnt_store_registers(
			rcache,regnum,
			thread);
}

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);
	winnt_get_modules(winnt_process_record(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);
	exec_file_clear(from_tty);
}

static int winnt_exception_filter_match_code(
	struct __dbg_event *		event,
	struct winnt_exception_filter *	filter)
{
	if (!filter->exception_code)
		return 1;

	if (!event->exception_record)
		return 0;

	if (filter->exception_code != event->exception_record->exception_code)
		return 0;

	if (filter->exception_flags & WINNT_EXCEPTION_FIRST_CHANCE)
		if (event->exception_priority)
			return 1;

	if (filter->exception_flags & WINNT_EXCEPTION_SECOND_CHANCE)
		if (!event->exception_priority)
			return 1;

	return 0;
}

static int winnt_exception_filter_match_module(
	struct __dbg_event *		event,
	struct winnt_exception_filter *	filter,
	struct winnt_process*		pidinfo)
{
	struct __dbg_module_info *	module;
	struct __dbg_module_info *	module_cap;
	struct winnt_thread *		thread;
	struct pe_unit_ctx *		uctx;
	struct pe_meta_sec_hdr *	sechdr;
	int				secidx;
	char *				addr;
	char *				mark;
	char *				text;
	char *				text_cap;

	thread     = winnt_get_thread(pidinfo,event->systid);
	addr       = (char *)thread->regctx.uc_rip;
	module_cap = &pidinfo->modules[pidinfo->nmodules];

	for (module=pidinfo->modules; module<module_cap; module++) {
		if ((uctx = (struct pe_unit_ctx *)module->module_ctx)) {
			secidx = pe_get_named_section_index(
				uctx->meta,".text");

			if (secidx >= 0) {
				mark      = 0;
				sechdr    = &uctx->meta->m_sectbl[secidx];
				text      = (char *)module->module_base;
				text     += sechdr->sh_virtual_addr;
				text_cap  = text + sechdr->sh_virtual_size;

				if ((addr >= text) && (addr < text_cap))
					mark = strrchr(module->module_name,'/');

				if (mark && !filter->exception_module)
					return 1;

				if (mark && filter->exception_module)
					if (!(strcmp(++mark,filter->exception_module)))
						return 1;
			}
		}
	}

	return 0;
}

static int winnt_exception_filter_match(struct __dbg_event * event)
{
	struct winnt_process *          pidinfo;
	struct winnt_exception_filter * filter = winnt_exception_filters;

	switch (event->evttype) {
		case __DBG_STATE_EXCEPTION:
		case __DBG_STATE_BREAKPOINT:
		case __DBG_STATE_SINGLE_STEP:
			break;

		default:
			return 0;
	}

	if (!(pidinfo = winnt_process_record(event->syspid)))
		return 0;

	for (; filter->exception_flags; filter++)
		if (winnt_exception_filter_match_code(event,filter))
			if (winnt_exception_filter_match_module(event,filter,pidinfo))
				return 1;

	return 0;
}

static enum gdb_signal winnt_dbg_signal(struct __dbg_event * event)
{
	switch (event->exception_record->exception_code) {
		case WINNT_STATUS_ACCESS_VIOLATION:
			return GDB_SIGNAL_SEGV;

		default:
			return GDB_SIGNAL_UNKNOWN;
	}
}

static struct __dbg_event * winnt_wait_event(ptid_t ptid)
{
	struct __dbg_event	event;
	struct winnt_process *	pdbg;
	struct winnt_process *	pcap;
	struct winnt_process *	pidinfo;
	struct winnt_thread *	thread;
	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 &pdbg->event;

	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 &pidinfo->event;
	}

	if (pcnt*sizeof(*pfds) < sizeof(pollfdbuf))
		pfds = pollfdbuf;
	else if (!(pfds = (struct pollfd *)calloc(pcnt,sizeof(*pfds))))
		return 0;

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

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

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

	if (!pfd)
		return 0;

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

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

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

	for (thread=pidinfo->threads; thread; thread=thread->next) {
		__dbg_regs_fetch(
			pidinfo->pfd,
			thread->tid,
			&thread->regctx);

		winnt_set_thread_context_state(
			thread,
			WINNT_THREAD_CONTEXT_READY);
	}

	return &pidinfo->event;
}

static ptid_t winnt_wait(
	struct target_ops * t,
	ptid_t ptid,
	struct target_waitstatus * waitstatus,
	int target_options)
{
	int                    pfd;
	struct __dbg_event *   event;
	struct winnt_process * process;
	int                    fskip;
	int                    eresponse;

	target_terminal_ours();

	do {
		if (!(event = winnt_wait_event(ptid)))
			return null_ptid;

		if ((fskip = winnt_exception_filter_match(event))) {
			if (!(process = winnt_process_record(event->syspid)))
				return null_ptid;

			if (event->exception_priority)
				eresponse = __DBG_RESPONSE_EXCEPTION_NOT_HANDLED;
			else
				eresponse = __DBG_RESPONSE_CONTINUE;

			winnt_respond(process->pfd,event,eresponse);
		}
	} while (fskip);

	if (!(process = winnt_process_record(event->syspid)))
		return null_ptid;

	pfd = process->pfd;

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

	switch (event->evttype) {
		case __DBG_STATE_EXCEPTION:
			waitstatus->kind = TARGET_WAITKIND_STOPPED;
			waitstatus->value.sig  = winnt_dbg_signal(event);
			break;

		case __DBG_STATE_BREAKPOINT:
		case __DBG_STATE_SINGLE_STEP:
			waitstatus->kind = TARGET_WAITKIND_STOPPED;
			waitstatus->value.sig  = GDB_SIGNAL_TRAP;
			break;

		case __DBG_STATE_CREATE_THREAD:
			waitstatus->kind = TARGET_WAITKIND_THREAD_CREATED;
			waitstatus->value.integer = event->systid;
			winnt_respond(pfd,event,__DBG_RESPONSE_CONTINUE);
			break;

		case __DBG_STATE_EXIT_THREAD:
			waitstatus->kind = TARGET_WAITKIND_THREAD_EXITED;
			waitstatus->value.integer = event->systid;
			winnt_respond(pfd,event,__DBG_RESPONSE_CONTINUE);
			break;

		case __DBG_STATE_CREATE_PROCESS:
			waitstatus->kind = TARGET_WAITKIND_SPURIOUS;
			waitstatus->value.integer = 0;
			break;

		case __DBG_STATE_EXIT_PROCESS:
			waitstatus->kind = TARGET_WAITKIND_EXITED;
			waitstatus->value.integer = *event->process_exit_code;
			winnt_respond(pfd,event,__DBG_RESPONSE_CONTINUE);
			break;

		case __DBG_STATE_DLL_LOAD:
			waitstatus->kind = TARGET_WAITKIND_LOADED;
			waitstatus->value.integer = 0;
			winnt_get_modules(process);
			break;

		case __DBG_STATE_DLL_UNLOAD:
			waitstatus->kind = TARGET_WAITKIND_LOADED;
			waitstatus->value.integer = 0;
			winnt_get_modules(process);
			break;

		case __DBG_STATE_IDLE:
		case __DBG_STATE_REPLY_PENDING:
			waitstatus->kind = TARGET_WAITKIND_SPURIOUS;
			waitstatus->value.integer = 0;
			break;
	}

	return inferior_ptid;
}

static void winnt_resume_one(ptid_t ptid, int step, enum gdb_signal sig)
{
	pid_t                  tid;
	struct winnt_process * process;
	struct winnt_thread *  thread;
	mcontext_t *           tctx;

	if ((tid = ptid.tid) <= 0)
		if ((process = winnt_process_record(ptid.pid)))
			tid = process->systid;

	if (!(thread = winnt_get_thread_from_ptid(ptid)))
		winnt_perror("internal error: thread record not found",tid);

	process = thread->process;
	tctx    = &thread->regctx;

	if (process->dr_state) {
		tctx->uc_dr0 = process->dr_cache[0];
		tctx->uc_dr1 = process->dr_cache[1];
		tctx->uc_dr2 = process->dr_cache[2];
		tctx->uc_dr3 = process->dr_cache[3];
		tctx->uc_dr6 = X86_DR_RTM_MASK;
		tctx->uc_dr7 = process->dr_cache[7];
	}

	if (step && !(tctx->uc_eflags & X86_EFLAGS_TRACE)) {
		tctx->uc_eflags |= X86_EFLAGS_TRACE;
		winnt_set_thread_context_state(
			thread,
			WINNT_THREAD_CONTEXT_DIRTY);
	}

	if (process->dr_state || tctx->uc_context_flags)
		__dbg_regs_store(process->pfd,tid,tctx);

	if (tid == process->event.systid) {
		process->event.eresponse = __DBG_RESPONSE_CONTINUE;

		__dbg_event_respond(
			process->pfd,
			&process->event);

		while (__dbg_resume_thread(process->pfd,tid) > 1)
			(void)0;

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

static void winnt_resume_process(pid_t pid, int step, enum gdb_signal sig)
{
	struct winnt_process * pdbg;
	struct winnt_thread *  thread;
	ptid_t                 ptid;

	if (!(pdbg = winnt_process_record(pid)))
		return;

	for (thread=pdbg->threads; thread; thread=thread->next) {
		ptid.pid = pdbg->syspid;
		ptid.tid = thread->tid;
		ptid.lwp = 0;

		(thread->tid == inferior_ptid.tid)
			? winnt_resume_one(ptid,step,sig)
			: winnt_resume_one(ptid,0,sig);
	}
}

static void winnt_resume_all(int step, enum gdb_signal sig)
{
	struct winnt_process * pdbg;
	struct winnt_process * pcap;
	struct winnt_thread *  thread;
	ptid_t                 ptid;

	for (pdbg=plist, pcap=&plist[pcnt]; pdbg<pcap; pdbg++) {
		if (pdbg->pfd && (thread = pdbg->threads)) {
			for (; thread; ) {
				ptid.pid = pdbg->syspid;
				ptid.tid = thread->tid;
				ptid.lwp = 0;

				(thread->tid == inferior_ptid.tid)
					? winnt_resume_one(ptid,step,sig)
					: winnt_resume_one(ptid,0,sig);

				thread = thread->next;
			}
		}
	}
}

static void winnt_resume (
	struct target_ops * t,
	ptid_t ptid, int step,
	enum gdb_signal sig)
{
	ptid_equal(ptid,minus_one_ptid)
		? winnt_resume_all(step,sig)
		: ptid.tid
			? winnt_resume_one(ptid,step,sig)
			: winnt_resume_process(ptid.pid,step,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(2*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,2*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);
	winnt_get_modules(winnt_process_record(pid));
}

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 int winnt_supports_multi_process(struct target_ops * t)
{
	return 1;
}

static int winnt_perk_init(void)
{
	char * argv[2];

	if (pe_dctx)
		return 0;

	argv[0] = (char *)get_gdb_program_name();
	argv[1] = 0;

	return pe_get_driver_ctx(argv,0,0,0,&pe_dctx);
}

#define WINNT_DR_HANDLER(handler) \
	winnt_dr_ ## handler

#define WINNT_SET_DR_LOW_HANDLER(handler) \
	x86_dr_low.handler = WINNT_DR_HANDLER(handler)

static void winnt_dr_set_addr(int idx, uintptr_t any)
{
	pid_t			pid;
	struct winnt_process *	pidinfo;

	pid     = ptid_get_pid(inferior_ptid);
	pidinfo = winnt_process_record(pid);

	pidinfo->dr_cache[idx] = any;
	pidinfo->dr_state      = WINNT_DR_STATE_DIRTY;
}

static uintptr_t winnt_dr_get_addr(int idx)
{
	pid_t			pid;
	struct winnt_process *	pidinfo;

	pid     = ptid_get_pid(inferior_ptid);
	pidinfo = winnt_process_record(pid);

	return pidinfo->dr_cache[idx];
}

static void winnt_dr_set_control(unsigned long ctrl)
{
	winnt_dr_set_addr(7,ctrl);
}

static unsigned long winnt_dr_get_control(void)
{
	return winnt_dr_get_addr(7);
}

static unsigned long winnt_dr_get_status(void)
{
	return winnt_dr_get_addr(6);
}

static void winnt_init_dr_low(void)
{
	WINNT_SET_DR_LOW_HANDLER(set_control);
	WINNT_SET_DR_LOW_HANDLER(get_control);
	WINNT_SET_DR_LOW_HANDLER(get_status);
	WINNT_SET_DR_LOW_HANDLER(set_addr);
	WINNT_SET_DR_LOW_HANDLER(get_addr);

	x86_set_debug_register_length(sizeof(uintptr_t));
}

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;
	t->to_get_ada_task_ptid         = winnt_get_ada_task_ptid;

	t->to_supports_multi_process    = winnt_supports_multi_process;

	x86_use_watchpoints(t);

	winnt_init_dr_low();

	if (winnt_perk_init() < 0)
		return 0;

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



extern initialize_file_ftype _initialize_winnt_nat;

extern void amd64_winnt_init_reg_offsets(void);

void
_initialize_winnt_nat(void)
{
	add_target(winnt_target_alloc());
	amd64_winnt_init_reg_offsets();
}