/*
 * Mini xargs implementation for busybox
 * Only "-prt" options are supported in this version of xargs.
 *
 * (C) 2002 by Vladimir Oleynik <dzo@simtreas.ru>
 * (C) 2003 by Glenn McGrath <bug1@optushome.com.au>
 *
 * Special thanks Mark Whitley for stimul to rewrote :)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 *
 * Reference:
 *	http://www.opengroup.org/onlinepubs/007904975/utilities/xargs.html
 *
 *
 * BUGS:
 *      - E option doesnt allow spaces before argument
 *      - exit value of isnt correct 
 *      - doesnt print quoted string properly
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <getopt.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/wait.h>

#include "busybox.h"

/*
   This function have special algorithm.
   Don`t use fork and include to main!
*/
static int xargs_exec(char **args)
{
	pid_t p;
	volatile int exec_errno;	/* shared vfork stack */
	
	exec_errno = 0;
	p = vfork();
	if (p < 0) {
		bb_perror_msg_and_die("vfork");
	} else if (p == 0) {
		/* vfork -- child */
		execvp(args[0], args);
		exec_errno = errno;	/* set error to shared stack */
		_exit(1);
	} else {
		/* vfork -- parent */
		int status;

		while (wait(&status) == (pid_t) - 1) {
			if (errno != EINTR) {
				break;
			}
		}

		if (exec_errno) {
			errno = exec_errno;
			bb_perror_msg("%s", args[0]);
			return exec_errno == ENOENT ? 127 : 126;
		} else if (WEXITSTATUS(status) == 255) {
			bb_error_msg("%s: exited with status 255; aborting", args[0]);
			return 124;
		} else if (WIFSTOPPED(status)) {
			bb_error_msg("%s: stopped by signal %d", args[0],
						 WSTOPSIG(status));
			return 125;
		} else if (WIFSIGNALED(status)) {
			bb_error_msg("%s: terminated by signal %d", args[0],
						 WTERMSIG(status));
			return 125;
		} else if (WEXITSTATUS(status)) {
			return 123;
		} else {
			return 0;
		}
	}
}

#define OPT_VERBOSE	0x1
#define OPT_TERMINATE	0x2
#define OPT_UPTO_NUMBER	0x4
#define OPT_UPTO_SIZE	0x8
#define OPT_EOF_STRING	0x10

int xargs_main(int argc, char **argv)
{
#ifdef CONFIG_FEATURE_XARGS_FANCY
	char *s_max_args = NULL;
	char *s_line_size = NULL;
#endif
	char *eof_string = "_";
	unsigned long flg;

	int line_size;
	unsigned int max_args = LINE_MAX;

	char *line_buffer = NULL;
	char *line_buffer_ptr_ptr;
	char *old_arg = NULL;

	char **args;
	char *args_entry_ptr;

	int i;
	int a;

#if 0
	/* Default to maximum line length */
	if (LINE_MAX > ARG_MAX - 2048) {
		/* Minimum command line length */
		line_size = LINE_MAX;
	} else {
		/* Maximum command line length */
		line_size = ARG_MAX = 2048;
	}
#else
	line_size = LINE_MAX;
#endif
	
#ifndef CONFIG_FEATURE_XARGS_FANCY
	flg = bb_getopt_ulflags(argc, argv, "+t");
#else
	flg = bb_getopt_ulflags(argc, argv, "+txn:s:E::", &s_max_args, &s_line_size, &eof_string);

	if (s_line_size) {
		line_size =	bb_xgetularg10_bnd(s_max_args, 1, line_size);
	}
	if (s_max_args) {
		max_args = bb_xgetularg10(s_max_args);
	}
#endif

	a = argc - optind;
	argv += optind;
	if (a == 0) {
		/* default behavior is to echo all the filenames */
		*argv = "echo";
		a++;
	}
	/* allocating pointers for execvp: a*arg, arg from stdin, NULL */
	args = xcalloc(a + 2, sizeof(char *));

	/* Store the command to be executed (taken from the command line) */
	for (i = 0; i < a; i++) {
		line_size -= strlen(*argv) + 1;
		args[i] = *argv++;
	}
	if (line_size < 1) {
		bb_error_msg_and_die("can not fit single argument within argument list size limit");
	}

	args[i] = xmalloc(line_size);
	args_entry_ptr = args[i];

	/* Now, read in one line at a time from stdin, and store this 
	 * line to be used later as an argument to the command */
	do {
		char *line_buffer_ptr = NULL;
		unsigned int arg_count = 0;
		unsigned int arg_size = 0;

		*args_entry_ptr = '\0';

		/* Get the required number of entries from stdin */
		do {
			/* (Re)fill the line buffer */
			if (line_buffer == NULL) {
				line_buffer = bb_get_chomped_line_from_file(stdin);
				if (line_buffer == NULL) {
					/* EOF, exit outer loop */
					break;
				}
				line_buffer_ptr =
					strtok_r(line_buffer, " \t", &line_buffer_ptr_ptr);
			} else {
				if (old_arg) {
					line_buffer_ptr = old_arg;
					old_arg = NULL;
				} else {
					line_buffer_ptr =
						strtok_r(NULL, " \t", &line_buffer_ptr_ptr);
				}
			}
			/* If no arguments left go back and get another line */
			if (line_buffer_ptr == NULL) {
				free(line_buffer);
				line_buffer = NULL;
				continue;
			}

#ifdef CONFIG_FEATURE_XARGS_FANCY
			if (eof_string && (strcmp(line_buffer_ptr, eof_string) == 0)) {
#else
			if (strcmp(line_buffer_ptr, eof_string) == 0) {
#endif
				/* logical EOF, exit outer loop */
				line_buffer = NULL;
				break;
			}

			/* Check the next argument will fit */
			arg_size += 1 + strlen(line_buffer_ptr);
			if (arg_size > line_size) {
				if ((arg_count == 0)
#ifdef CONFIG_FEATURE_XARGS_FANCY
					|| ((flg & OPT_TERMINATE) && (arg_count != max_args))) {
#else
					) {
#endif
					bb_error_msg_and_die("argument line too long");
				}
				old_arg = line_buffer_ptr;
				break;
			}

			/* Add the entry to our pre-allocated space */
			strcat(args_entry_ptr, line_buffer_ptr);
			strcat(args_entry_ptr, " ");
			arg_count++;
		} while (arg_count < max_args);

		/* Remove the last space */
		args_entry_ptr[arg_size - 1] = '\0';

		if (*args_entry_ptr != '\0') {
			if (flg & OPT_VERBOSE) {
				for (i = 0; args[i]; i++) {
					if (i) {
						fputc(' ', stderr);
					}
					fputs(args[i], stderr);
				}
				fputc('\n', stderr);
			}
			xargs_exec(args);
		}
	} while (line_buffer);

#ifdef CONFIG_FEATURE_CLEAN_UP
	free(args);
#endif
	return 0;
}