/*-
 * Copyright (c) 2015
 *	KO Myung-Hun <komh@chollian.net>
 *
 * 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_DOS
#include <os2.h>

#include "sh.h"

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

static char *remove_trailing_dots(char *);
static int access_stat_ex(int (*)(), const char *, void *);
static int test_exec_exist(const char *, char *);
static void response(int *, const char ***);
static char *make_response_file(char * const *);
static void env_slashify(void);
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;										\
			new_argv = (const char **)realloc(new_argv,				\
											  new_alloc * sizeof(char *));\
			if (!new_argv)											\
				goto exit_out_of_memory;							\
		}															\
		new_argv[new_argc++] = x;									\
	} while (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)
		return; 					/* do nothing */

	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 + 1);
			if (!line)
				goto exit_out_of_memory;

			line[0] = __KLIBC_ARG_NONZERO | __KLIBC_ARG_RESPONSE;
			l = line + 1;
			while (fgets(l, filesize - (l - line - 1), f)) {
				p = strchr(l, '\n');
				if (p) {
					/* if a line ends with '\',
					 * then concatenate a 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;
	return;

exit_out_of_memory:
	fputs("Out of memory while reading response file\n", stderr);
	exit(255);
}

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);
    }
}

/*
 * Convert backslashes of environmental variables to forward slahes.
 * A backslash may be used as an escaped character when do 'echo'. This leads
 * to an unexpected behavior.
 */
static void
env_slashify(void)
{
	/*
	 * PATH and TMPDIR are used by OS/2 as well. That is, they may have
	 * backslashes as a directory separator.
	 * BEGINLIBPATH and ENDLIBPATH are special variables on OS/2.
	 */
	const char *var_list[] = {"PATH", "TMPDIR",
	                          "BEGINLIBPATH", "ENDLIBPATH", NULL};
	const char **var;
	char *value;

	for (var = var_list; *var; var++) {
		value = getenv(*var);

		if (value)
			_fnslashify(value);
	}
}

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

	init_extlibpath();
	env_slashify();

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

	atexit(cleanup);
}

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

	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(p, val, ATEMP);
	for (val = p; *p; p++) {
		if (*p == '/')
			*p = '\\';
	}

	DosSetExtLIBPATH(val, flag);

	afree((char *)val, ATEMP);
}

/* Remove trailing dots. */
static char *
remove_trailing_dots(char *name)
{
	char *p;

	for (p = name + strlen(name); --p > name && *p == '.'; )
		/* nothing */;

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

	return name;
}

#define REMOVE_TRAILING_DOTS(name)	\
	remove_trailing_dots(strcpy(alloca(strlen(name) + 1), name))

/* Alias of stat() */
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)
{
	return _std_stat(REMOVE_TRAILING_DOTS(name), buffer);
}

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

	return _std_access(REMOVE_TRAILING_DOTS(name), 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(int (*fn)(), const char *name, void *arg)
{
	char *x_name;
	const char **x_suffix;
	int rc = -1;

	/* Otherwise, try to append executable suffixes */
	x_name = alloc(strlen(name) + MAX_X_SUFFIX_LEN + 1, ATEMP);

	for (x_suffix = x_suffix_list; rc && *x_suffix; x_suffix++) {
		strcpy(x_name, name);
		strcat(x_name, *x_suffix);

		rc = fn(x_name, arg);
	}

	afree(x_name, ATEMP);

	return rc;
}

/* access()/search_access() version */
int
access_ex(int (*fn)(const char *, int), const char *name, int mode)
{
	return access_stat_ex(fn, name, (void *)mode);
}

/* stat() version */
int
stat_ex(const char *name, struct stat *buffer)
{
	return access_stat_ex(stat, name, buffer);
}

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

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

	strcpy(real_name, name);

	return 0;
}

const char *
real_exec_name(const char *name)
{
	char x_name[strlen(name) + MAX_X_SUFFIX_LEN + 1];
	const char *real_name = name;

	if (access_stat_ex(test_exec_exist, real_name, x_name) != -1)
		strdupx(real_name, x_name, ATEMP);

	return real_name;
}

/* OS/2 can process a command line up to 32K. */
#define MAX_CMD_LINE_LEN 32768

/* 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   arg_len = 0;
	int   i;

	for (i = 0; argv[i]; i++)
		arg_len += strlen(argv[i]) + 1;

	/*
	 * If a length of command line is longer than MAX_CMD_LINE_LEN, then use
	 * a response file. OS/2 cannot process a command line longer than 32K.
	 * Of course, a response file cannot be recognized by a normal OS/2
	 * program, that is, neither non-EMX or non-kLIBC. But it cannot accept
	 * a command line longer than 32K in itself. So using a response file
	 * in this case, is an acceptable solution.
	 */
	if (arg_len > MAX_CMD_LINE_LEN) {
		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;
	}

	return NULL;
}

/* Alias of execve() */
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];
	char *rsp_argv[3];
	char *rsp_name_arg;
	int saved_stdin_mode;
	int saved_stdout_mode;
	int saved_stderr_mode;
	int pid;
	int status;
	int fd;
	int rc;

	/*
	 * #! /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;

	/*
	 * On kLIBC, a child inherits a translation mode of stdin/stdout/stderr
	 * of a parent. Set stdin/stdout/stderr to a text mode, which is default.
	 */
	saved_stdin_mode = setmode(fileno(stdin), O_TEXT);
	saved_stdout_mode = setmode(fileno(stdout), O_TEXT);
	saved_stderr_mode = setmode(fileno(stderr), O_TEXT);

	rsp_name_arg = make_response_file(argv);

	if (rsp_name_arg) {
		rsp_argv[0] = argv[0];
		rsp_argv[1] = rsp_name_arg;
		rsp_argv[2] = NULL;

		argv = rsp_argv;
	}

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

	if (rsp_name_arg)
		afree(rsp_name_arg, ATEMP);

	/* Restore a translation mode of stdin/stdout/stderr. */
	setmode(fileno(stdin), saved_stdin_mode);
	setmode(fileno(stdout), saved_stdout_mode);
	setmode(fileno(stderr), saved_stderr_mode);

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

		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;

	_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);
	strcpy(tp->tffn, name);
	tp->next = templist;
	templist = tp;
}

/* Alias of unlink() */
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();
}