findutils/grep.c - codeaurora/busybox - Gitiles

 /* vi: set sw=4 ts=4: */
 /*
  * Mini grep implementation for busybox using libc regex.
  *
  * Copyright (C) 1999,2000,2001 by Lineo, inc. and Mark Whitley
  * Copyright (C) 1999,2000,2001 by Mark Whitley <markw@codepoet.org>
  *
  * Licensed under the GPL v2, see the file LICENSE in this tarball.
  */
 /* BB_AUDIT SUSv3 defects - unsupported option -x.  */
 /* BB_AUDIT GNU defects - always acts as -a.  */
 /* http://www.opengroup.org/onlinepubs/007904975/utilities/grep.html */
 /*
  * Apr 2004 by Vladimir Oleynik <dzo@simtreas.ru> -
  * correction "-e pattern1 -e pattern2" logic and more optimizations.
 */

 #include <stdio.h>
 #include <stdlib.h>
 #include <getopt.h>
 #include <string.h>
 #include <errno.h>
 #include "busybox.h"
 #include "xregex.h"


 /* options */
 static unsigned long opt;
 #define GREP_OPTS "lnqvscFiHhe:f:L"
 #define GREP_OPT_l (1<<0)
 #define PRINT_FILES_WITH_MATCHES (opt & GREP_OPT_l)
 #define GREP_OPT_n (1<<1)
 #define PRINT_LINE_NUM (opt & GREP_OPT_n)
 #define GREP_OPT_q (1<<2)
 #define BE_QUIET (opt & GREP_OPT_q)
 #define GREP_OPT_v (1<<3)
 typedef char invert_search_t;
 static invert_search_t invert_search;
 #define GREP_OPT_s (1<<4)
 #define SUPPRESS_ERR_MSGS (opt & GREP_OPT_s)
 #define GREP_OPT_c (1<<5)
 #define PRINT_MATCH_COUNTS (opt & GREP_OPT_c)
 #define GREP_OPT_F (1<<6)
 #define FGREP_FLAG (opt & GREP_OPT_F)
 #define GREP_OPT_i (1<<7)
 #define GREP_OPT_H (1<<8)
 #define GREP_OPT_h (1<<9)
 #define GREP_OPT_e (1<<10)
 #define GREP_OPT_f (1<<11)
 #define GREP_OPT_L (1<<12)
 #define PRINT_FILES_WITHOUT_MATCHES ((opt & GREP_OPT_L) != 0)
 #if ENABLE_FEATURE_GREP_CONTEXT
 #define GREP_OPT_CONTEXT "A:B:C"
 #define GREP_OPT_A (1<<13)
 #define GREP_OPT_B (1<<14)
 #define GREP_OPT_C (1<<15)
 #define GREP_OPT_E (1<<16)
 #else
 #define GREP_OPT_CONTEXT ""
 #define GREP_OPT_A (0)
 #define GREP_OPT_B (0)
 #define GREP_OPT_C (0)
 #define GREP_OPT_E (1<<13)
 #endif
 #if ENABLE_FEATURE_GREP_EGREP_ALIAS
 # define OPT_EGREP "E"
 #else
 # define OPT_EGREP ""
 #endif

 static int reflags;
 static int print_filename;

 #if ENABLE_FEATURE_GREP_CONTEXT
 static int lines_before;
 static int lines_after;
 static char **before_buf;
 static int last_line_printed;
 #endif /* ENABLE_FEATURE_GREP_CONTEXT */

 /* globals used internally */
 static llist_t *pattern_head;   /* growable list of patterns to match */
 static char *cur_file;          /* the current file we are reading */


 static void print_line(const char *line, int linenum, char decoration)
 {
 #if ENABLE_FEATURE_GREP_CONTEXT
 	/* possibly print the little '--' separator */
 	if ((lines_before || lines_after) && last_line_printed &&
 			last_line_printed < linenum - 1) {
 		puts("--");
 	}
 	last_line_printed = linenum;
 #endif
 	if (print_filename > 0)
 		printf("%s%c", cur_file, decoration);
 	if (PRINT_LINE_NUM)
 		printf("%i%c", linenum, decoration);
 	puts(line);
 }


 static int grep_file(FILE *file)
 {
 	char *line;
 	invert_search_t ret;
 	int linenum = 0;
 	int nmatches = 0;
 #if ENABLE_FEATURE_GREP_CONTEXT
 	int print_n_lines_after = 0;
 	int curpos = 0; /* track where we are in the circular 'before' buffer */
 	int idx = 0; /* used for iteration through the circular buffer */
 #endif /* ENABLE_FEATURE_GREP_CONTEXT */

 	while ((line = bb_get_chomped_line_from_file(file)) != NULL) {
 		llist_t *pattern_ptr = pattern_head;

 		linenum++;
 		ret = 0;
 		while (pattern_ptr) {
 			if (FGREP_FLAG) {
 				ret = strstr(line, pattern_ptr->data) != NULL;
 			} else {
 				/*
 				 * test for a postitive-assertion match (regexec returns success (0)
 				 * and the user did not specify invert search), or a negative-assertion
 				 * match (regexec returns failure (REG_NOMATCH) and the user specified
 				 * invert search)
 				 */
 				regex_t regex;
 				xregcomp(&regex, pattern_ptr->data, reflags);
 				ret |= regexec(&regex, line, 0, NULL, 0) == 0;
 				regfree(&regex);
 			}
 			pattern_ptr = pattern_ptr->link;
 		} /* while (pattern_ptr) */

 		if ((ret ^ invert_search)) {

 			if (PRINT_FILES_WITH_MATCHES || BE_QUIET)
 				free(line);

 			/* if we found a match but were told to be quiet, stop here */
 			if (BE_QUIET || PRINT_FILES_WITHOUT_MATCHES)
 				return -1;

 				/* keep track of matches */
 				nmatches++;

 				/* if we're just printing filenames, we stop after the first match */
 				if (PRINT_FILES_WITH_MATCHES)
 					break;

 				/* print the matched line */
 				if (PRINT_MATCH_COUNTS == 0) {
 #if ENABLE_FEATURE_GREP_CONTEXT
 					int prevpos = (curpos == 0) ? lines_before - 1 : curpos - 1;

 					/* if we were told to print 'before' lines and there is at least
 					 * one line in the circular buffer, print them */
 					if (lines_before && before_buf[prevpos] != NULL) {
 						int first_buf_entry_line_num = linenum - lines_before;

 						/* advance to the first entry in the circular buffer, and
 						 * figure out the line number is of the first line in the
 						 * buffer */
 						idx = curpos;
 						while (before_buf[idx] == NULL) {
 							idx = (idx + 1) % lines_before;
 							first_buf_entry_line_num++;
 						}

 						/* now print each line in the buffer, clearing them as we go */
 						while (before_buf[idx] != NULL) {
 							print_line(before_buf[idx], first_buf_entry_line_num, '-');
 							free(before_buf[idx]);
 							before_buf[idx] = NULL;
 							idx = (idx + 1) % lines_before;
 							first_buf_entry_line_num++;
 						}
 					}

 					/* make a note that we need to print 'after' lines */
 					print_n_lines_after = lines_after;
 #endif
 					print_line(line, linenum, ':');
 				}
 			}
 #if ENABLE_FEATURE_GREP_CONTEXT
 			else { /* no match */
 				/* Add the line to the circular 'before' buffer */
 				if(lines_before) {
 					free(before_buf[curpos]);
 					before_buf[curpos] = bb_xstrdup(line);
 					curpos = (curpos + 1) % lines_before;
 				}
 			}

 			/* if we need to print some context lines after the last match, do so */
 			if (print_n_lines_after && (last_line_printed != linenum)) {
 				print_line(line, linenum, '-');
 				print_n_lines_after--;
 			}
 #endif /* ENABLE_FEATURE_GREP_CONTEXT */
 		free(line);
 	}


 	/* special-case file post-processing for options where we don't print line
 	 * matches, just filenames and possibly match counts */

 	/* grep -c: print [filename:]count, even if count is zero */
 	if (PRINT_MATCH_COUNTS) {
 		if (print_filename > 0)
 			printf("%s:", cur_file);
 		    printf("%d\n", nmatches);
 	}

 	/* grep -l: print just the filename, but only if we grepped the line in the file  */
 	if (PRINT_FILES_WITH_MATCHES && nmatches > 0) {
 		puts(cur_file);
 	}

 	/* grep -L: print just the filename, but only if we didn't grep the line in the file  */
 	if (PRINT_FILES_WITHOUT_MATCHES && nmatches == 0) {
 		puts(cur_file);
 	}

 	return nmatches;
 }

 static void load_regexes_from_file(llist_t *fopt)
 {
 	char *line;
 	FILE *f;

 	while(fopt) {
 		llist_t *cur = fopt;
 		char *ffile = cur->data;

 		fopt = cur->link;
 		free(cur);
 		f = bb_xfopen(ffile, "r");
 		while ((line = bb_get_chomped_line_from_file(f)) != NULL) {
 			pattern_head = llist_add_to(pattern_head, line);
 		}
 	}
 }


 extern int grep_main(int argc, char **argv)
 {
 	FILE *file;
 	int matched;
 	llist_t *fopt = NULL;
 	int error_open_count = 0;

 	/* do normal option parsing */
 #if ENABLE_FEATURE_GREP_CONTEXT
   {
 	char *junk;
 	char *slines_after;
 	char *slines_before;
 	char *Copt;

 	bb_opt_complementally = "H-h:e*:f*:C-AB";
 	opt = bb_getopt_ulflags(argc, argv,
 		GREP_OPTS GREP_OPT_CONTEXT OPT_EGREP,
 		&pattern_head, &fopt,
 		&slines_after, &slines_before, &Copt);

 	if(opt & GREP_OPT_C) {
 		/* C option unseted A and B options, but next -A or -B
 		   may be ovewrite own option */
 		if(!(opt & GREP_OPT_A))         /* not overwtited */
 			slines_after = Copt;
 		if(!(opt & GREP_OPT_B))         /* not overwtited */
 			slines_before = Copt;
 		opt |= GREP_OPT_A|GREP_OPT_B;   /* set for parse now */
 	}
 	if(opt & GREP_OPT_A) {
 		lines_after = strtoul(slines_after, &junk, 10);
 		if(*junk != '\0')
 			bb_error_msg_and_die("invalid context length argument");
 	}
 	if(opt & GREP_OPT_B) {
 		lines_before = strtoul(slines_before, &junk, 10);
 		if(*junk != '\0')
 			bb_error_msg_and_die("invalid context length argument");
 	}
 	/* sanity checks after parse may be invalid numbers ;-) */
 	if ((opt & (GREP_OPT_c|GREP_OPT_q|GREP_OPT_l|GREP_OPT_L))) {
 		opt &= ~GREP_OPT_n;
 		lines_before = 0;
 		lines_after = 0;
 	} else if(lines_before > 0)
 		before_buf = (char **)xcalloc(lines_before, sizeof(char *));
 	}
 #else
 	/* with auto sanity checks */
 	bb_opt_complementally = "H-h:e*:f*:c-n:q-n:l-n";
 	opt = bb_getopt_ulflags(argc, argv, GREP_OPTS OPT_EGREP,
 		&pattern_head, &fopt);
 #endif
 	invert_search = (opt & GREP_OPT_v) != 0;        /* 0 | 1 */

 	if(opt & GREP_OPT_H)
 		print_filename++;
 	if(opt & GREP_OPT_h)
 		print_filename--;
 	if(opt & GREP_OPT_f)
 		load_regexes_from_file(fopt);

 	if(ENABLE_FEATURE_GREP_FGREP_ALIAS && bb_applet_name[0] == 'f')
 		opt |= GREP_OPT_F;

 	if(ENABLE_FEATURE_GREP_EGREP_ALIAS &&
 			(bb_applet_name[0] == 'e' || (opt & GREP_OPT_E)))
 		reflags = REG_EXTENDED | REG_NOSUB;
 	else
 		reflags = REG_NOSUB;

 	if(opt & GREP_OPT_i)
 		reflags |= REG_ICASE;

 	argv += optind;
 	argc -= optind;

 	/* if we didn't get a pattern from a -e and no command file was specified,
 	 * argv[optind] should be the pattern. no pattern, no worky */
 	if (pattern_head == NULL) {
 		if (*argv == NULL)
 			bb_show_usage();
 		else {
 			pattern_head = llist_add_to(pattern_head, *argv++);
 			argc--;
 		}
 	}

 	/* argv[(optind)..(argc-1)] should be names of file to grep through. If
 	 * there is more than one file to grep, we will print the filenames */
 	if (argc > 1) {
 		print_filename++;

 	/* If no files were specified, or '-' was specified, take input from
 	 * stdin. Otherwise, we grep through all the files specified. */
 	} else if (argc == 0) {
 		argc++;
 	}
 	matched = 0;
 	while (argc--) {
 		cur_file = *argv++;
 		if(!cur_file || (*cur_file == '-' && !cur_file[1])) {
 			cur_file = "(standard input)";
 			file = stdin;
 		} else {
 			file = fopen(cur_file, "r");
 		}
 		if (file == NULL) {
 			if (!SUPPRESS_ERR_MSGS)
 				bb_perror_msg("%s", cur_file);
 			error_open_count++;
 		} else {
 			matched += grep_file(file);
 			if(matched < 0) {
 				/* we found a match but were told to be quiet, stop here and
 				* return success */
 				break;
 			}
 			fclose(file);
 		}
 	}

 	/* destroy all the elments in the pattern list */
 	if (ENABLE_FEATURE_CLEAN_UP)
 	while (pattern_head) {
 		llist_t *pattern_head_ptr = pattern_head;

 		pattern_head = pattern_head->link;
 		free(pattern_head_ptr);
 	}

 	/* 0 = success, 1 = failed, 2 = error */
 	/* If the -q option is specified, the exit status shall be zero
 	 * if an input line is selected, even if an error was detected.  */
 	if(BE_QUIET && matched)
 		return 0;
 	if(error_open_count)
 		return 2;
 	return !matched; /* invert return value 0 = success, 1 = failed */
 }
	/* vi: set sw=4 ts=4: */
	/*
	* Mini grep implementation for busybox using libc regex.
	*
	* Copyright (C) 1999,2000,2001 by Lineo, inc. and Mark Whitley
	* Copyright (C) 1999,2000,2001 by Mark Whitley <markw@codepoet.org>
	*
	* Licensed under the GPL v2, see the file LICENSE in this tarball.
	*/
	/* BB_AUDIT SUSv3 defects - unsupported option -x. */
	/* BB_AUDIT GNU defects - always acts as -a. */
	/* http://www.opengroup.org/onlinepubs/007904975/utilities/grep.html */
	/*
	* Apr 2004 by Vladimir Oleynik <dzo@simtreas.ru> -
	* correction "-e pattern1 -e pattern2" logic and more optimizations.
	*/

	#include <stdio.h>
	#include <stdlib.h>
	#include <getopt.h>
	#include <string.h>
	#include <errno.h>
	#include "busybox.h"
	#include "xregex.h"


	/* options */
	static unsigned long opt;
	#define GREP_OPTS "lnqvscFiHhe:f:L"
	#define GREP_OPT_l (1<<0)
	#define PRINT_FILES_WITH_MATCHES (opt & GREP_OPT_l)
	#define GREP_OPT_n (1<<1)
	#define PRINT_LINE_NUM (opt & GREP_OPT_n)
	#define GREP_OPT_q (1<<2)
	#define BE_QUIET (opt & GREP_OPT_q)
	#define GREP_OPT_v (1<<3)
	typedef char invert_search_t;
	static invert_search_t invert_search;
	#define GREP_OPT_s (1<<4)
	#define SUPPRESS_ERR_MSGS (opt & GREP_OPT_s)
	#define GREP_OPT_c (1<<5)
	#define PRINT_MATCH_COUNTS (opt & GREP_OPT_c)
	#define GREP_OPT_F (1<<6)
	#define FGREP_FLAG (opt & GREP_OPT_F)
	#define GREP_OPT_i (1<<7)
	#define GREP_OPT_H (1<<8)
	#define GREP_OPT_h (1<<9)
	#define GREP_OPT_e (1<<10)
	#define GREP_OPT_f (1<<11)
	#define GREP_OPT_L (1<<12)
	#define PRINT_FILES_WITHOUT_MATCHES ((opt & GREP_OPT_L) != 0)
	#if ENABLE_FEATURE_GREP_CONTEXT
	#define GREP_OPT_CONTEXT "A:B:C"
	#define GREP_OPT_A (1<<13)
	#define GREP_OPT_B (1<<14)
	#define GREP_OPT_C (1<<15)
	#define GREP_OPT_E (1<<16)
	#else
	#define GREP_OPT_CONTEXT ""
	#define GREP_OPT_A (0)
	#define GREP_OPT_B (0)
	#define GREP_OPT_C (0)
	#define GREP_OPT_E (1<<13)
	#endif
	#if ENABLE_FEATURE_GREP_EGREP_ALIAS
	# define OPT_EGREP "E"
	#else
	# define OPT_EGREP ""
	#endif

	static int reflags;
	static int print_filename;

	#if ENABLE_FEATURE_GREP_CONTEXT
	static int lines_before;
	static int lines_after;
	static char **before_buf;
	static int last_line_printed;
	#endif /* ENABLE_FEATURE_GREP_CONTEXT */

	/* globals used internally */
	static llist_t pattern_head; / growable list of patterns to match */
	static char cur_file; / the current file we are reading */


	static void print_line(const char *line, int linenum, char decoration)
	{
	#if ENABLE_FEATURE_GREP_CONTEXT
	/* possibly print the little '--' separator */
	if ((lines_before \|\| lines_after) && last_line_printed &&
	last_line_printed < linenum - 1) {
	puts("--");
	}
	last_line_printed = linenum;
	#endif
	if (print_filename > 0)
	printf("%s%c", cur_file, decoration);
	if (PRINT_LINE_NUM)
	printf("%i%c", linenum, decoration);
	puts(line);
	}


	static int grep_file(FILE *file)
	{
	char *line;
	invert_search_t ret;
	int linenum = 0;
	int nmatches = 0;
	#if ENABLE_FEATURE_GREP_CONTEXT
	int print_n_lines_after = 0;
	int curpos = 0; /* track where we are in the circular 'before' buffer */
	int idx = 0; /* used for iteration through the circular buffer */
	#endif /* ENABLE_FEATURE_GREP_CONTEXT */

	while ((line = bb_get_chomped_line_from_file(file)) != NULL) {
	llist_t *pattern_ptr = pattern_head;

	linenum++;
	ret = 0;
	while (pattern_ptr) {
	if (FGREP_FLAG) {
	ret = strstr(line, pattern_ptr->data) != NULL;
	} else {
	/*
	* test for a postitive-assertion match (regexec returns success (0)
	* and the user did not specify invert search), or a negative-assertion
	* match (regexec returns failure (REG_NOMATCH) and the user specified
	* invert search)
	*/
	regex_t regex;
	xregcomp(&regex, pattern_ptr->data, reflags);
	ret \|= regexec(&regex, line, 0, NULL, 0) == 0;
	regfree(&regex);
	}
	pattern_ptr = pattern_ptr->link;
	} /* while (pattern_ptr) */

	if ((ret ^ invert_search)) {

	if (PRINT_FILES_WITH_MATCHES \|\| BE_QUIET)
	free(line);

	/* if we found a match but were told to be quiet, stop here */
	if (BE_QUIET \|\| PRINT_FILES_WITHOUT_MATCHES)
	return -1;

	/* keep track of matches */
	nmatches++;

	/* if we're just printing filenames, we stop after the first match */
	if (PRINT_FILES_WITH_MATCHES)
	break;

	/* print the matched line */
	if (PRINT_MATCH_COUNTS == 0) {
	#if ENABLE_FEATURE_GREP_CONTEXT
	int prevpos = (curpos == 0) ? lines_before - 1 : curpos - 1;

	/* if we were told to print 'before' lines and there is at least
	* one line in the circular buffer, print them */
	if (lines_before && before_buf[prevpos] != NULL) {
	int first_buf_entry_line_num = linenum - lines_before;

	/* advance to the first entry in the circular buffer, and
	* figure out the line number is of the first line in the
	* buffer */
	idx = curpos;
	while (before_buf[idx] == NULL) {
	idx = (idx + 1) % lines_before;
	first_buf_entry_line_num++;
	}

	/* now print each line in the buffer, clearing them as we go */
	while (before_buf[idx] != NULL) {
	print_line(before_buf[idx], first_buf_entry_line_num, '-');
	free(before_buf[idx]);
	before_buf[idx] = NULL;
	idx = (idx + 1) % lines_before;
	first_buf_entry_line_num++;
	}
	}

	/* make a note that we need to print 'after' lines */
	print_n_lines_after = lines_after;
	#endif
	print_line(line, linenum, ':');
	}
	}
	#if ENABLE_FEATURE_GREP_CONTEXT
	else { /* no match */
	/* Add the line to the circular 'before' buffer */
	if(lines_before) {
	free(before_buf[curpos]);
	before_buf[curpos] = bb_xstrdup(line);
	curpos = (curpos + 1) % lines_before;
	}
	}

	/* if we need to print some context lines after the last match, do so */
	if (print_n_lines_after && (last_line_printed != linenum)) {
	print_line(line, linenum, '-');
	print_n_lines_after--;
	}
	#endif /* ENABLE_FEATURE_GREP_CONTEXT */
	free(line);
	}


	/* special-case file post-processing for options where we don't print line
	* matches, just filenames and possibly match counts */

	/* grep -c: print [filename:]count, even if count is zero */
	if (PRINT_MATCH_COUNTS) {
	if (print_filename > 0)
	printf("%s:", cur_file);
	printf("%d\n", nmatches);
	}

	/* grep -l: print just the filename, but only if we grepped the line in the file */
	if (PRINT_FILES_WITH_MATCHES && nmatches > 0) {
	puts(cur_file);
	}

	/* grep -L: print just the filename, but only if we didn't grep the line in the file */
	if (PRINT_FILES_WITHOUT_MATCHES && nmatches == 0) {
	puts(cur_file);
	}

	return nmatches;
	}

	static void load_regexes_from_file(llist_t *fopt)
	{
	char *line;
	FILE *f;

	while(fopt) {
	llist_t *cur = fopt;
	char *ffile = cur->data;

	fopt = cur->link;
	free(cur);
	f = bb_xfopen(ffile, "r");
	while ((line = bb_get_chomped_line_from_file(f)) != NULL) {
	pattern_head = llist_add_to(pattern_head, line);
	}
	}
	}


	extern int grep_main(int argc, char **argv)
	{
	FILE *file;
	int matched;
	llist_t *fopt = NULL;
	int error_open_count = 0;

	/* do normal option parsing */
	#if ENABLE_FEATURE_GREP_CONTEXT
	{
	char *junk;
	char *slines_after;
	char *slines_before;
	char *Copt;

	bb_opt_complementally = "H-h:e:f:C-AB";
	opt = bb_getopt_ulflags(argc, argv,
	GREP_OPTS GREP_OPT_CONTEXT OPT_EGREP,
	&pattern_head, &fopt,
	&slines_after, &slines_before, &Copt);

	if(opt & GREP_OPT_C) {
	/* C option unseted A and B options, but next -A or -B
	may be ovewrite own option */
	if(!(opt & GREP_OPT_A)) /* not overwtited */
	slines_after = Copt;
	if(!(opt & GREP_OPT_B)) /* not overwtited */
	slines_before = Copt;
	opt \|= GREP_OPT_A\|GREP_OPT_B; /* set for parse now */
	}
	if(opt & GREP_OPT_A) {
	lines_after = strtoul(slines_after, &junk, 10);
	if(*junk != '\0')
	bb_error_msg_and_die("invalid context length argument");
	}
	if(opt & GREP_OPT_B) {
	lines_before = strtoul(slines_before, &junk, 10);
	if(*junk != '\0')
	bb_error_msg_and_die("invalid context length argument");
	}
	/* sanity checks after parse may be invalid numbers ;-) */
	if ((opt & (GREP_OPT_c\|GREP_OPT_q\|GREP_OPT_l\|GREP_OPT_L))) {
	opt &= ~GREP_OPT_n;
	lines_before = 0;
	lines_after = 0;
	} else if(lines_before > 0)
	before_buf = (char *)xcalloc(lines_before, sizeof(char ));
	}
	#else
	/* with auto sanity checks */
	bb_opt_complementally = "H-h:e:f:c-n:q-n:l-n";
	opt = bb_getopt_ulflags(argc, argv, GREP_OPTS OPT_EGREP,
	&pattern_head, &fopt);
	#endif
	invert_search = (opt & GREP_OPT_v) != 0; /* 0 \| 1 */

	if(opt & GREP_OPT_H)
	print_filename++;
	if(opt & GREP_OPT_h)
	print_filename--;
	if(opt & GREP_OPT_f)
	load_regexes_from_file(fopt);

	if(ENABLE_FEATURE_GREP_FGREP_ALIAS && bb_applet_name[0] == 'f')
	opt \|= GREP_OPT_F;

	if(ENABLE_FEATURE_GREP_EGREP_ALIAS &&
	(bb_applet_name[0] == 'e' \|\| (opt & GREP_OPT_E)))
	reflags = REG_EXTENDED \| REG_NOSUB;
	else
	reflags = REG_NOSUB;

	if(opt & GREP_OPT_i)
	reflags \|= REG_ICASE;

	argv += optind;
	argc -= optind;

	/* if we didn't get a pattern from a -e and no command file was specified,
	* argv[optind] should be the pattern. no pattern, no worky */
	if (pattern_head == NULL) {
	if (*argv == NULL)
	bb_show_usage();
	else {
	pattern_head = llist_add_to(pattern_head, *argv++);
	argc--;
	}
	}

	/* argv[(optind)..(argc-1)] should be names of file to grep through. If
	* there is more than one file to grep, we will print the filenames */
	if (argc > 1) {
	print_filename++;

	/* If no files were specified, or '-' was specified, take input from
	* stdin. Otherwise, we grep through all the files specified. */
	} else if (argc == 0) {
	argc++;
	}
	matched = 0;
	while (argc--) {
	cur_file = *argv++;
	if(!cur_file \|\| (*cur_file == '-' && !cur_file[1])) {
	cur_file = "(standard input)";
	file = stdin;
	} else {
	file = fopen(cur_file, "r");
	}
	if (file == NULL) {
	if (!SUPPRESS_ERR_MSGS)
	bb_perror_msg("%s", cur_file);
	error_open_count++;
	} else {
	matched += grep_file(file);
	if(matched < 0) {
	/* we found a match but were told to be quiet, stop here and
	* return success */
	break;
	}
	fclose(file);
	}
	}

	/* destroy all the elments in the pattern list */
	if (ENABLE_FEATURE_CLEAN_UP)
	while (pattern_head) {
	llist_t *pattern_head_ptr = pattern_head;

	pattern_head = pattern_head->link;
	free(pattern_head_ptr);
	}

	/* 0 = success, 1 = failed, 2 = error */
	/* If the -q option is specified, the exit status shall be zero
	* if an input line is selected, even if an error was detected. */
	if(BE_QUIET && matched)
	return 0;
	if(error_open_count)
	return 2;
	return !matched; /* invert return value 0 = success, 1 = failed */
	}