/*-
 * Copyright (c) 2015, 2017, 2020
 *	KO Myung-Hun <komh@chollian.net>
 * Copyright (c) 2017, 2020
 *	mirabilos <m@mirbsd.org>
 *
 * Provided that these terms and disclaimer and all copyright notices
 * are retained or reproduced in an accompanying document, permission
 * is granted to deal in this work without restriction, including un-
 * limited rights to use, publicly perform, distribute, sell, modify,
 * merge, give away, or sublicence.
 *
 * This work is provided "AS IS" and WITHOUT WARRANTY of any kind, to
 * the utmost extent permitted by applicable law, neither express nor
 * implied; without malicious intent or gross negligence. In no event
 * may a licensor, author or contributor be held liable for indirect,
 * direct, other damage, loss, or other issues arising in any way out
 * of dealing in the work, even if advised of the possibility of such
 * damage or existence of a defect, except proven that it results out
 * of said person's immediate fault when using the work as intended.
 */

#define INCL_KBD
#define INCL_DOS
#include <os2.h>

#include "sh.h"

#include <klibc/startup.h>
#include <errno.h>
#include <io.h>
#include <unistd.h>
#include <process.h>

__RCSID("$MirOS: src/bin/mksh/os2.c,v 1.11 2020/10/01 21:13:45 tg Exp $");

struct a_s_arg {
	union {
		int (*i)(const char *, int);
		int (*p)(const char *, void *);
	} fn;
	union {
		int i;
		void *p;
	} arg;
	bool isint;
};

static void remove_trailing_dots(char *, size_t);
static int access_stat_ex(const char *, struct a_s_arg *);
static int test_exec_exist(const char *, void *);
static void response(int *, const char ***);
static char *make_response_file(char * const *);
static void add_temp(const char *);
static void cleanup_temps(void);
static void cleanup(void);

#define RPUT(x) do {					\
	if (new_argc >= new_alloc) {			\
		new_alloc += 20;			\
		if (!(new_argv = realloc(new_argv,	\
		    new_alloc * sizeof(char *))))	\
			goto exit_out_of_memory;	\
	}						\
	new_argv[new_argc++] = (x);			\
} while (/* CONSTCOND */ 0)

#define KLIBC_ARG_RESPONSE_EXCLUDE	\
	(__KLIBC_ARG_DQUOTE | __KLIBC_ARG_WILDCARD | __KLIBC_ARG_SHELL)

static void
response(int *argcp, const char ***argvp)
{
	int i, old_argc, new_argc, new_alloc = 0;
	const char **old_argv, **new_argv;
	char *line, *l, *p;
	FILE *f;

	old_argc = *argcp;
	old_argv = *argvp;
	for (i = 1; i < old_argc; ++i)
		if (old_argv[i] &&
		    !(old_argv[i][-1] & KLIBC_ARG_RESPONSE_EXCLUDE) &&
		    old_argv[i][0] == '@')
			break;

	if (i >= old_argc)
		/* do nothing */
		return;

	new_argv = NULL;
	new_argc = 0;
	for (i = 0; i < old_argc; ++i) {
		if (i == 0 || !old_argv[i] ||
		    (old_argv[i][-1] & KLIBC_ARG_RESPONSE_EXCLUDE) ||
		    old_argv[i][0] != '@' ||
		    !(f = fopen(old_argv[i] + 1, "rt")))
			RPUT(old_argv[i]);
		else {
			long filesize;

			fseek(f, 0, SEEK_END);
			filesize = ftell(f);
			fseek(f, 0, SEEK_SET);

			line = malloc(filesize + /* type */ 1 + /* NUL */ 1);
			if (!line) {
 exit_out_of_memory:
				fputs("Out of memory while reading response file\n", stderr);
				exit(255);
			}

			line[0] = __KLIBC_ARG_NONZERO | __KLIBC_ARG_RESPONSE;
			l = line + 1;
			while (fgets(l, (filesize + 1) - (l - (line + 1)), f)) {
				p = strchr(l, '\n');
				if (p) {
					/*
					 * if a line ends with a backslash,
					 * concatenate with the next line
					 */
					if (p > l && p[-1] == '\\') {
						char *p1;
						int count = 0;

						for (p1 = p - 1; p1 >= l &&
						    *p1 == '\\'; p1--)
							count++;

						if (count & 1) {
							l = p + 1;

							continue;
						}
					}

					*p = 0;
				}
				p = strdup(line);
				if (!p)
					goto exit_out_of_memory;

				RPUT(p + 1);

				l = line + 1;
			}

			free(line);

			if (ferror(f)) {
				fputs("Cannot read response file\n", stderr);
				exit(255);
			}

			fclose(f);
		}
	}

	RPUT(NULL);
	--new_argc;

	*argcp = new_argc;
	*argvp = new_argv;
}

static void
init_extlibpath(void)
{
	const char *vars[] = {
		"BEGINLIBPATH",
		"ENDLIBPATH",
		"LIBPATHSTRICT",
		NULL
	};
	char val[512];
	int flag;

	for (flag = 0; vars[flag]; flag++) {
		DosQueryExtLIBPATH(val, flag + 1);
		if (val[0])
			setenv(vars[flag], val, 1);
	}
}

void
os2_init(int *argcp, const char ***argvp)
{
	KBDINFO ki;

	response(argcp, argvp);

	init_extlibpath();

	if (!isatty(STDIN_FILENO))
		setmode(STDIN_FILENO, O_BINARY);
	if (!isatty(STDOUT_FILENO))
		setmode(STDOUT_FILENO, O_BINARY);
	if (!isatty(STDERR_FILENO))
		setmode(STDERR_FILENO, O_BINARY);

	/* ensure ECHO mode is ON so that read command echoes. */
	memset(&ki, 0, sizeof(ki));
	ki.cb = sizeof(ki);
	ki.fsMask |= KEYBOARD_ECHO_ON;
	KbdSetStatus(&ki, 0);

	atexit(cleanup);
}

void
setextlibpath(const char *name, const char *val)
{
	int flag;
	char *p, *cp;

	if (!strcmp(name, "BEGINLIBPATH"))
		flag = BEGIN_LIBPATH;
	else if (!strcmp(name, "ENDLIBPATH"))
		flag = END_LIBPATH;
	else if (!strcmp(name, "LIBPATHSTRICT"))
		flag = LIBPATHSTRICT;
	else
		return;

	/* convert slashes to backslashes */
	strdupx(cp, val, ATEMP);
	for (p = cp; *p; p++) {
		if (*p == '/')
			*p = '\\';
	}

	DosSetExtLIBPATH(cp, flag);

	afree(cp, ATEMP);
}

/* remove trailing dots */
static void
remove_trailing_dots(char *name, size_t namelen)
{
	char *p = name + namelen;

	while (--p > name && *p == '.')
		/* nothing */;

	if (*p != '.' && *p != '/' && *p != '\\' && *p != ':')
		p[1] = '\0';
}

/* alias of stat() */
extern int _std_stat(const char *, struct stat *);

/* replacement for stat() of kLIBC which fails if there are trailing dots */
int
stat(const char *name, struct stat *buffer)
{
	size_t namelen = strlen(name) + 1;
	char nodots[namelen];

	memcpy(nodots, name, namelen);
	remove_trailing_dots(nodots, namelen);
	return (_std_stat(nodots, buffer));
}

/* alias of access() */
extern int _std_access(const char *, int);

/* replacement for access() of kLIBC which fails if there are trailing dots */
int
access(const char *name, int mode)
{
	size_t namelen = strlen(name) + 1;
	char nodots[namelen];

	/*
	 * On OS/2 kLIBC, X_OK is set only for executable files.
	 * This prevents scripts from being executed.
	 */
	if (mode & X_OK)
		mode = (mode & ~X_OK) | R_OK;

	memcpy(nodots, name, namelen);
	remove_trailing_dots(nodots, namelen);
	return (_std_access(nodots, mode));
}

#define MAX_X_SUFFIX_LEN	4

static const char *x_suffix_list[] =
    { "", ".ksh", ".exe", ".sh", ".cmd", ".com", ".bat", NULL };

/* call fn() by appending executable extensions */
static int
access_stat_ex(const char *name, struct a_s_arg *action)
{
	char *x_name;
	const char **x_suffix;
	int rc = -1;
	size_t x_namelen = strlen(name) + MAX_X_SUFFIX_LEN + 1;

	/* otherwise, try to append executable suffixes */
	x_name = alloc(x_namelen, ATEMP);

	for (x_suffix = x_suffix_list; rc && *x_suffix; x_suffix++) {
		strlcpy(x_name, name, x_namelen);
		strlcat(x_name, *x_suffix, x_namelen);

		rc = action->isint ? action->fn.i(x_name, action->arg.i) :
		    action->fn.p(x_name, action->arg.p);
	}

	afree(x_name, ATEMP);

	return (rc);
}

/* access()/search_access() version */
int
access_ex(int (*fn)(const char *, int), const char *name, int mode)
{
	struct a_s_arg arg;

	arg.fn.i = fn;
	arg.arg.i = mode;
	arg.isint = true;
	return (access_stat_ex(name, &arg));
}

/* stat()/lstat() version */
int
stat_ex(int (*fn)(const char *, struct stat *),
    const char *name, struct stat *buffer)
{
	struct a_s_arg arg;

	arg.fn.p = fn;
	arg.arg.p = buffer;
	arg.isint = false;
	return (access_stat_ex(name, &arg));
}

static int
test_exec_exist(const char *name, void *arg)
{
	struct stat sb;
	char *real_name;

	if (stat(name, &sb) < 0 || !S_ISREG(sb.st_mode))
		return (-1);

	/*XXX memory leak */
	strdupx(real_name, name, ATEMP);
	*((char **)arg) = real_name;
	return (0);
}

const char *
real_exec_name(const char *name)
{
	struct a_s_arg arg;
	char *real_name;

	arg.fn.p = &test_exec_exist;
	arg.arg.p = (void *)(&real_name);
	arg.isint = false;
	return (access_stat_ex(name, &arg) ? name : real_name);
}

/* make a response file to pass a very long command line */
static char *
make_response_file(char * const *argv)
{
	char rsp_name_arg[] = "@mksh-rsp-XXXXXX";
	char *rsp_name = &rsp_name_arg[1];
	int i;
	int fd;
	char *result;

	if ((fd = mkstemp(rsp_name)) == -1)
		return (NULL);

	/* write all the arguments except a 0th program name */
	for (i = 1; argv[i]; i++) {
		write(fd, argv[i], strlen(argv[i]));
		write(fd, "\n", 1);
	}

	close(fd);
	add_temp(rsp_name);
	strdupx(result, rsp_name_arg, ATEMP);

	return (result);
}

/* alias of execve() */
extern int _std_execve(const char *, char * const *, char * const *);

/* replacement for execve() of kLIBC */
int
execve(const char *name, char * const *argv, char * const *envp)
{
	const char *exec_name;
	FILE *fp;
	char sign[2];
	int pid;
	int status;
	int fd;
	int rc;
	int saved_mode;
	int saved_errno;

	/*
	 * #! /bin/sh : append .exe
	 * extproc sh : search sh.exe in PATH
	 */
	exec_name = search_path(name, path, X_OK, NULL);
	if (!exec_name) {
		errno = ENOENT;
		return (-1);
	}

	/*-
	 * kLIBC execve() has problems when executing scripts.
	 * 1. it fails to execute a script if a directory whose name
	 *    is same as an interpreter exists in a current directory.
	 * 2. it fails to execute a script not starting with sharpbang.
	 * 3. it fails to execute a batch file if COMSPEC is set to a shell
	 *    incompatible with cmd.exe, such as /bin/sh.
	 * And ksh process scripts more well, so let ksh process scripts.
	 */
	errno = 0;
	if (!(fp = fopen(exec_name, "rb")))
		errno = ENOEXEC;

	if (!errno && fread(sign, 1, sizeof(sign), fp) != sizeof(sign))
		errno = ENOEXEC;

	if (fp && fclose(fp))
		errno = ENOEXEC;

	if (!errno &&
	    !((sign[0] == 'M' && sign[1] == 'Z') ||
	      (sign[0] == 'N' && sign[1] == 'E') ||
	      (sign[0] == 'L' && sign[1] == 'X')))
		errno = ENOEXEC;

	if (errno == ENOEXEC)
		return (-1);

	/*
	 * Normal OS/2 programs expect that standard IOs, especially stdin,
	 * are opened in text mode at the startup. By the way, on OS/2 kLIBC
	 * child processes inherit a translation mode of a parent process.
	 * As a result, if stdin is set to binary mode in a parent process,
	 * stdin of child processes is opened in binary mode as well at the
	 * startup. In this case, some programs such as sed suffer from CR.
	 */
	saved_mode = setmode(STDIN_FILENO, O_TEXT);

	pid = spawnve(P_NOWAIT, exec_name, argv, envp);
	saved_errno = errno;

	/* arguments too long? */
	if (pid == -1 && saved_errno == EINVAL) {
		/* retry with a response file */
		char *rsp_name_arg = make_response_file(argv);

		if (rsp_name_arg) {
			char *rsp_argv[3] = { argv[0], rsp_name_arg, NULL };

			pid = spawnve(P_NOWAIT, exec_name, rsp_argv, envp);
			saved_errno = errno;

			afree(rsp_name_arg, ATEMP);
		}
	}

	/* restore translation mode of stdin */
	setmode(STDIN_FILENO, saved_mode);

	if (pid == -1) {
		cleanup_temps();

		errno = saved_errno;
		return (-1);
	}

	/* close all opened handles */
	for (fd = 0; fd < NUFILE; fd++) {
		if (fcntl(fd, F_GETFD) == -1)
			continue;

		close(fd);
	}

	while ((rc = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
		/* nothing */;

	cleanup_temps();

	/* Is this possible? And is this right? */
	if (rc == -1)
		return (-1);

	if (WIFSIGNALED(status))
		_exit(ksh_sigmask(WTERMSIG(status)));

	_exit(WEXITSTATUS(status));
}

static struct temp *templist = NULL;

static void
add_temp(const char *name)
{
	struct temp *tp;

	tp = alloc(offsetof(struct temp, tffn[0]) + strlen(name) + 1, APERM);
	memcpy(tp->tffn, name, strlen(name) + 1);
	tp->next = templist;
	templist = tp;
}

/* alias of unlink() */
extern int _std_unlink(const char *);

/*
 * Replacement for unlink() of kLIBC not supporting to remove files used by
 * another processes.
 */
int
unlink(const char *name)
{
	int rc;

	rc = _std_unlink(name);
	if (rc == -1 && errno != ENOENT)
		add_temp(name);

	return (rc);
}

static void
cleanup_temps(void)
{
	struct temp *tp;
	struct temp **tpnext;

	for (tpnext = &templist, tp = templist; tp; tp = *tpnext) {
		if (_std_unlink(tp->tffn) == 0 || errno == ENOENT) {
			*tpnext = tp->next;
			afree(tp, APERM);
		} else {
			tpnext = &tp->next;
		}
	}
}

static void
cleanup(void)
{
	cleanup_temps();
}

int
getdrvwd(char **cpp, unsigned int drvltr)
{
	PBYTE cp;
	ULONG sz;
	APIRET rc;
	ULONG drvno;

	if (DosQuerySysInfo(QSV_MAX_PATH_LENGTH, QSV_MAX_PATH_LENGTH,
	    &sz, sizeof(sz)) != 0) {
		errno = EDOOFUS;
		return (-1);
	}

	/* allocate 'X:/' plus sz plus NUL */
	checkoktoadd((size_t)sz, (size_t)4);
	cp = aresize(*cpp, (size_t)sz + (size_t)4, ATEMP);
	cp[0] = ksh_toupper(drvltr);
	cp[1] = ':';
	cp[2] = '/';
	drvno = ksh_numuc(cp[0]) + 1;
	/* NUL is part of space within buffer passed */
	++sz;
	if ((rc = DosQueryCurrentDir(drvno, cp + 3, &sz)) == 0) {
		/* success! */
		*cpp = cp;
		return (0);
	}
	afree(cp, ATEMP);
	*cpp = NULL;
	switch (rc) {
	case 15: /* invalid drive */
		errno = ENOTBLK;
		break;
	case 26: /* not dos disk */
		errno = ENODEV;
		break;
	case 108: /* drive locked */
		errno = EDEADLK;
		break;
	case 111: /* buffer overflow */
		errno = ENAMETOOLONG;
		break;
	default:
		errno = EINVAL;
	}
	return (-1);
}