diff --git a/regexp.c b/regexp.c
new file mode 100644
index 0000000..6017d79
--- /dev/null
+++ b/regexp.c
@@ -0,0 +1,826 @@
+/* regexp.c */
+
+#include "internal.h"
+#include "regexp.h"
+#include <setjmp.h>
+#include <stdio.h>
+#include <ctype.h>
+
+
+#if ( defined BB_GREP || defined BB_FIND )
+
+/* This also tries to find a needle in a haystack, but uses
+ * real regular expressions....  The fake regular expression
+ * version of find_match lives in utility.c.  Using this version
+ * will add 3.9k to busybox...
+ *  -Erik Andersen
+ */
+extern int find_match(char *haystack, char *needle, int ignoreCase)
+{
+    int status;
+    struct regexp*  re;
+    re = regcomp( needle);
+    status = regexec(re, haystack, FALSE, ignoreCase);
+    free( re);
+    return( status);
+}
+
+
+/* code swiped from elvis-tiny 1.4 (a clone of vi) and adjusted to 
+ * suit the needs of busybox by Erik Andersen.
+ *
+ * From the README:
+ * "Elvis is freely redistributable, in either source form or executable form.
+ * There are no restrictions on how you may use it".
+ * Elvis was written by Steve Kirkendall <kirkenda@cs.pdx.edu>
+ *
+ *
+ * This file contains the code that compiles regular expressions and executes
+ * them.  It supports the same syntax and features as vi's regular expression
+ * code.  Specifically, the meta characters are:
+ *	^	matches the beginning of a line
+ *	$	matches the end of a line
+ *	\<	matches the beginning of a word
+ *	\>	matches the end of a word
+ *	.	matches any single character
+ *	[]	matches any character in a character class
+ *	\(	delimits the start of a subexpression
+ *	\)	delimits the end of a subexpression
+ *	*	repeats the preceding 0 or more times
+ * NOTE: You cannot follow a \) with a *.
+ *
+ * The physical structure of a compiled RE is as follows:
+ *	- First, there is a one-byte value that says how many character classes
+ *	  are used in this regular expression
+ *	- Next, each character class is stored as a bitmap that is 256 bits
+ *	  (32 bytes) long.
+ *	- A mixture of literal characters and compiled meta characters follows.
+ *	  This begins with M_BEGIN(0) and ends with M_END(0).  All meta chars
+ *	  are stored as a \n followed by a one-byte code, so they take up two
+ *	  bytes apiece.  Literal characters take up one byte apiece.  \n can't
+ *	  be used as a literal character.
+ *
+ */
+
+
+
+static char *previous;	/* the previous regexp, used when null regexp is given */
+static char *previous1;	/* a copy of the text from the previous substitution for regsub()*/
+
+
+/* These are used to classify or recognize meta-characters */
+#define META		'\0'
+#define BASE_META(m)	((m) - 256)
+#define INT_META(c)	((c) + 256)
+#define IS_META(m)	((m) >= 256)
+#define IS_CLASS(m)	((m) >= M_CLASS(0) && (m) <= M_CLASS(9))
+#define IS_START(m)	((m) >= M_START(0) && (m) <= M_START(9))
+#define IS_END(m)	((m) >= M_END(0) && (m) <= M_END(9))
+#define IS_CLOSURE(m)	((m) >= M_SPLAT && (m) <= M_QMARK)
+#define ADD_META(s,m)	(*(s)++ = META, *(s)++ = BASE_META(m))
+#define GET_META(s)	(*(s) == META ? INT_META(*++(s)) : *s)
+
+/* These are the internal codes used for each type of meta-character */
+#define M_BEGLINE	256		/* internal code for ^ */
+#define M_ENDLINE	257		/* internal code for $ */
+#define M_BEGWORD	258		/* internal code for \< */
+#define M_ENDWORD	259		/* internal code for \> */
+#define M_ANY		260		/* internal code for . */
+#define M_SPLAT		261		/* internal code for * */
+#define M_PLUS		262		/* internal code for \+ */
+#define M_QMARK		263		/* internal code for \? */
+#define M_CLASS(n)	(264+(n))	/* internal code for [] */
+#define M_START(n)	(274+(n))	/* internal code for \( */
+#define M_END(n)	(284+(n))	/* internal code for \) */
+
+/* These are used during compilation */
+static int	class_cnt;	/* used to assign class IDs */
+static int	start_cnt;	/* used to assign start IDs */
+static int	end_stk[NSUBEXP];/* used to assign end IDs */
+static int	end_sp;
+static char	*retext;	/* points to the text being compiled */
+
+/* error-handling stuff */
+jmp_buf	errorhandler;
+#define FAIL(why)	fprintf(stderr, why); longjmp(errorhandler, 1)
+
+
+
+
+/* This function builds a bitmap for a particular class */
+/* text -- start of the class */
+/* bmap -- the bitmap */
+static char *makeclass(char* text, char* bmap)
+{
+	int		i;
+	int		complement = 0;
+
+
+	/* zero the bitmap */
+	for (i = 0; bmap && i < 32; i++)
+	{
+		bmap[i] = 0;
+	}
+
+	/* see if we're going to complement this class */
+	if (*text == '^')
+	{
+		text++;
+		complement = 1;
+	}
+
+	/* add in the characters */
+	while (*text && *text != ']')
+	{
+		/* is this a span of characters? */
+		if (text[1] == '-' && text[2])
+		{
+			/* spans can't be backwards */
+			if (text[0] > text[2])
+			{
+				FAIL("Backwards span in []");
+			}
+
+			/* add each character in the span to the bitmap */
+			for (i = text[0]; bmap && i <= text[2]; i++)
+			{
+				bmap[i >> 3] |= (1 << (i & 7));
+			}
+
+			/* move past this span */
+			text += 3;
+		}
+		else
+		{
+			/* add this single character to the span */
+			i = *text++;
+			if (bmap)
+			{
+				bmap[i >> 3] |= (1 << (i & 7));
+			}
+		}
+	}
+
+	/* make sure the closing ] is missing */
+	if (*text++ != ']')
+	{
+		FAIL("] missing");
+	}
+
+	/* if we're supposed to complement this class, then do so */
+	if (complement && bmap)
+	{
+		for (i = 0; i < 32; i++)
+		{
+			bmap[i] = ~bmap[i];
+		}
+	}
+
+	return text;
+}
+
+
+
+
+/* This function gets the next character or meta character from a string.
+ * The pointer is incremented by 1, or by 2 for \-quoted characters.  For [],
+ * a bitmap is generated via makeclass() (if re is given), and the
+ * character-class text is skipped.
+ */
+static int gettoken(sptr, re)
+	char	**sptr;
+	regexp	*re;
+{
+	int	c;
+
+	c = **sptr;
+	++*sptr;
+	if (c == '\\')
+	{
+		c = **sptr;
+		++*sptr;
+		switch (c)
+		{
+		  case '<':
+			return M_BEGWORD;
+
+		  case '>':
+			return M_ENDWORD;
+
+		  case '(':
+			if (start_cnt >= NSUBEXP)
+			{
+				FAIL("Too many \\(s");
+			}
+			end_stk[end_sp++] = start_cnt;
+			return M_START(start_cnt++);
+
+		  case ')':
+			if (end_sp <= 0)
+			{
+				FAIL("Mismatched \\)");
+			}
+			return M_END(end_stk[--end_sp]);
+
+		  case '*':
+			return M_SPLAT;
+
+		  case '.':
+			return M_ANY;
+
+		  case '+':
+			return M_PLUS;
+
+		  case '?':
+			return M_QMARK;
+
+		  default:
+			return c;
+		}
+	}
+	else {
+		switch (c)
+		{
+		  case '^':
+			if (*sptr == retext + 1)
+			{
+				return M_BEGLINE;
+			}
+			return c;
+
+		  case '$':
+			if (!**sptr)
+			{
+				return M_ENDLINE;
+			}
+			return c;
+
+		  case '.':
+			return M_ANY;
+
+		  case '*':
+			return M_SPLAT;
+
+		  case '[':
+			/* make sure we don't have too many classes */
+			if (class_cnt >= 10)
+			{
+				FAIL("Too many []s");
+			}
+
+			/* process the character list for this class */
+			if (re)
+			{
+				/* generate the bitmap for this class */
+				*sptr = makeclass(*sptr, re->program + 1 + 32 * class_cnt);
+			}
+			else
+			{
+				/* skip to end of the class */
+				*sptr = makeclass(*sptr, (char *)0);
+			}
+			return M_CLASS(class_cnt++);
+
+		  default:
+			return c;
+		}
+	}
+	/*NOTREACHED*/
+}
+
+
+
+
+/* This function calculates the number of bytes that will be needed for a
+ * compiled RE.  Its argument is the uncompiled version.  It is not clever
+ * about catching syntax errors; that is done in a later pass.
+ */
+static unsigned calcsize(text)
+	char		*text;
+{
+	unsigned	size;
+	int		token;
+
+	retext = text;
+	class_cnt = 0;
+	start_cnt = 1;
+	end_sp = 0;
+	size = 5;
+	while ((token = gettoken(&text, (regexp *)0)) != 0)
+	{
+		if (IS_CLASS(token))
+		{
+			size += 34;
+		}
+		else if (IS_META(token))
+		{
+			size += 2;
+		}
+		else
+		{
+			size++;
+		}
+	}
+
+	return size;
+}
+
+
+
+/*---------------------------------------------------------------------------*/
+
+
+/* This function checks for a match between a character and a token which is
+ * known to represent a single character.  It returns 0 if they match, or
+ * 1 if they don't.
+ */
+static int match1(regexp* re, char ch, int token, int ignoreCase)
+{
+	if (!ch)
+	{
+		/* the end of a line can't match any RE of width 1 */
+		return 1;
+	}
+	if (token == M_ANY)
+	{
+		return 0;
+	}
+	else if (IS_CLASS(token))
+	{
+		if (re->program[1 + 32 * (token - M_CLASS(0)) + (ch >> 3)] & (1 << (ch & 7)))
+			return 0;
+	}
+	else if (ch == token
+		|| (ignoreCase==TRUE && isupper(ch) && tolower(ch) == token))
+	{
+		return 0;
+	}
+	return 1;
+}
+
+
+
+/* This function checks characters up to and including the next closure, at
+ * which point it does a recursive call to check the rest of it.  This function
+ * returns 0 if everything matches, or 1 if something doesn't match.
+ */
+/* re   -- the regular expression */
+/* str  -- the string */
+/* prog -- a portion of re->program, an compiled RE */
+/* here -- a portion of str, the string to compare it to */
+static int match(regexp* re, char* str, char* prog, char* here, int ignoreCase)
+{
+	int		token;
+	int		nmatched;
+	int		closure;
+
+	for (token = GET_META(prog); !IS_CLOSURE(token); prog++, token = GET_META(prog))
+	{
+		switch (token)
+		{
+		/*case M_BEGLINE: can't happen; re->bol is used instead */
+		  case M_ENDLINE:
+			if (*here)
+				return 1;
+			break;
+
+		  case M_BEGWORD:
+			if (here != str &&
+			   (here[-1] == '_' ||
+			     (isascii(here[-1]) && isalnum(here[-1]))))
+				return 1;
+			break;
+
+		  case M_ENDWORD:
+			if ((here[0] == '_' || isascii(here[0])) && isalnum(here[0]))
+				return 1;
+			break;
+
+		  case M_START(0):
+		  case M_START(1):
+		  case M_START(2):
+		  case M_START(3):
+		  case M_START(4):
+		  case M_START(5):
+		  case M_START(6):
+		  case M_START(7):
+		  case M_START(8):
+		  case M_START(9):
+			re->startp[token - M_START(0)] = (char *)here;
+			break;
+
+		  case M_END(0):
+		  case M_END(1):
+		  case M_END(2):
+		  case M_END(3):
+		  case M_END(4):
+		  case M_END(5):
+		  case M_END(6):
+		  case M_END(7):
+		  case M_END(8):
+		  case M_END(9):
+			re->endp[token - M_END(0)] = (char *)here;
+			if (token == M_END(0))
+			{
+				return 0;
+			}
+			break;
+
+		  default: /* literal, M_CLASS(n), or M_ANY */
+			if (match1(re, *here, token, ignoreCase) != 0)
+				return 1;
+			here++;
+		}
+	}
+
+	/* C L O S U R E */
+
+	/* step 1: see what we have to match against, and move "prog" to point
+	 * the the remainder of the compiled RE.
+	 */
+	closure = token;
+	prog++, token = GET_META(prog);
+	prog++;
+
+	/* step 2: see how many times we can match that token against the string */
+	for (nmatched = 0;
+	     (closure != M_QMARK || nmatched < 1) && *here && match1(re, *here, token, ignoreCase) == 0;
+	     nmatched++, here++)
+	{
+	}
+
+	/* step 3: try to match the remainder, and back off if it doesn't */
+	while (nmatched >= 0 && match(re, str, prog, here, ignoreCase) != 0)
+	{
+		nmatched--;
+		here--;
+	}
+
+	/* so how did it work out? */
+	if (nmatched >= ((closure == M_PLUS) ? 1 : 0))
+		return 0;
+	return 1;
+}
+
+
+/* This function compiles a regexp. */
+extern regexp *regcomp(char* text)
+{
+	int		needfirst;
+	unsigned	size;
+	int		token;
+	int		peek;
+	char		*build;
+	regexp		*re;
+
+
+	/* prepare for error handling */
+	re = (regexp *)0;
+	if (setjmp(errorhandler))
+	{
+		if (re)
+		{
+			free(re);
+		}
+		return (regexp *)0;
+	}
+
+	/* if an empty regexp string was given, use the previous one */
+	if (*text == 0)
+	{
+		if (!previous)
+		{
+			FAIL("No previous RE");
+		}
+		text = previous;
+	}
+	else /* non-empty regexp given, so remember it */
+	{
+		if (previous)
+			free(previous);
+		previous = (char *)malloc((unsigned)(strlen(text) + 1));
+		if (previous)
+			strcpy(previous, text);
+	}
+
+	/* allocate memory */
+	class_cnt = 0;
+	start_cnt = 1;
+	end_sp = 0;
+	retext = text;
+	size = calcsize(text) + sizeof(regexp);
+	re = (regexp *)malloc((unsigned)size);
+
+	if (!re)
+	{
+		FAIL("Not enough memory for this RE");
+	}
+
+	/* compile it */
+	build = &re->program[1 + 32 * class_cnt];
+	re->program[0] = class_cnt;
+	for (token = 0; token < NSUBEXP; token++)
+	{
+		re->startp[token] = re->endp[token] = (char *)0;
+	}
+	re->first = 0;
+	re->bol = 0;
+	re->minlen = 0;
+	needfirst = 1;
+	class_cnt = 0;
+	start_cnt = 1;
+	end_sp = 0;
+	retext = text;
+	for (token = M_START(0), peek = gettoken(&text, re);
+	     token;
+	     token = peek, peek = gettoken(&text, re))
+	{
+		/* special processing for the closure operator */
+		if (IS_CLOSURE(peek))
+		{
+			/* detect misuse of closure operator */
+			if (IS_START(token))
+			{
+				FAIL("* or \\+ or \\? follows nothing");
+			}
+			else if (IS_META(token) && token != M_ANY && !IS_CLASS(token))
+			{
+				FAIL("* or \\+ or \\? can only follow a normal character or . or []");
+			}
+
+			/* it is okay -- make it prefix instead of postfix */
+			ADD_META(build, peek);
+
+			/* take care of "needfirst" - is this the first char? */
+			if (needfirst && peek == M_PLUS && !IS_META(token))
+			{
+				re->first = token;
+			}
+			needfirst = 0;
+
+			/* we used "peek" -- need to refill it */
+			peek = gettoken(&text, re);
+			if (IS_CLOSURE(peek))
+			{
+				FAIL("* or \\+ or \\? doubled up");
+			}
+		}
+		else if (!IS_META(token))
+		{
+			/* normal char is NOT argument of closure */
+			if (needfirst)
+			{
+				re->first = token;
+				needfirst = 0;
+			}
+			re->minlen++;
+		}
+		else if (token == M_ANY || IS_CLASS(token))
+		{
+			/* . or [] is NOT argument of closure */
+			needfirst = 0;
+			re->minlen++;
+		}
+
+		/* the "token" character is not closure -- process it normally */
+		if (token == M_BEGLINE)
+		{
+			/* set the BOL flag instead of storing M_BEGLINE */
+			re->bol = 1;
+		}
+		else if (IS_META(token))
+		{
+			ADD_META(build, token);
+		}
+		else
+		{
+			*build++ = token;
+		}
+	}
+
+	/* end it with a \) which MUST MATCH the opening \( */
+	ADD_META(build, M_END(0));
+	if (end_sp > 0)
+	{
+		FAIL("Not enough \\)s");
+	}
+
+	return re;
+}
+
+
+
+
+/* This function searches through a string for text that matches an RE. */
+/* re  -- the compiled regexp to search for */
+/* str -- the string to search through */
+/* bol -- does str start at the beginning of a line? (boolean) */
+/* ignoreCase -- ignoreCase or not */
+extern int regexec(struct regexp* re, char* str, int bol, int ignoreCase)
+{
+	char	*prog;	/* the entry point of re->program */
+	int	len;	/* length of the string */
+	char	*here;
+
+	/* if must start at the beginning of a line, and this isn't, then fail */
+	if (re->bol && bol==TRUE)
+	{
+		return FALSE;
+	}
+
+	len = strlen(str);
+	prog = re->program + 1 + 32 * re->program[0];
+
+	/* search for the RE in the string */
+	if (re->bol)
+	{
+		/* must occur at BOL */
+		if ((re->first
+			&& match1(re, *(char *)str, re->first, ignoreCase))/* wrong first letter? */
+		 || len < re->minlen			/* not long enough? */
+		 || match(re, (char *)str, prog, str, ignoreCase))	/* doesn't match? */
+			return FALSE;			/* THEN FAIL! */
+	}
+	else if (ignoreCase == FALSE)
+	{
+		/* can occur anywhere in the line, noignorecase */
+		for (here = (char *)str;
+		     (re->first && re->first != *here)
+			|| match(re, (char *)str, prog, here, ignoreCase);
+		     here++, len--)
+		{
+			if (len < re->minlen)
+				return FALSE;
+		}
+	}
+	else
+	{
+		/* can occur anywhere in the line, ignorecase */
+		for (here = (char *)str;
+		     (re->first && match1(re, *here, (int)re->first, ignoreCase))
+			|| match(re, (char *)str, prog, here, ignoreCase);
+		     here++, len--)
+		{
+			if (len < re->minlen)
+				return FALSE;
+		}
+	}
+
+	/* if we didn't fail, then we must have succeeded */
+	return TRUE;
+}
+
+
+
+
+
+/* This performs substitutions after a regexp match has been found.  */
+extern void regsub(regexp* re, char* src, char* dst)
+{
+	char	*cpy;
+	char	*end;
+	char	c;
+	char		*start;
+	int		mod;
+
+	mod = 0;
+
+	start = src;
+	while ((c = *src++) != '\0')
+	{
+		/* recognize any meta characters */
+		if (c == '&')
+		{
+			cpy = re->startp[0];
+			end = re->endp[0];
+		}
+		else if (c == '~')
+		{
+			cpy = previous1;
+			if (cpy)
+				end = cpy + strlen(cpy);
+		}
+		else
+		if (c == '\\')
+		{
+			c = *src++;
+			switch (c)
+			{
+			  case '0':
+			  case '1':
+			  case '2':
+			  case '3':
+			  case '4':
+			  case '5':
+			  case '6':
+			  case '7':
+			  case '8':
+			  case '9':
+				/* \0 thru \9 mean "copy subexpression" */
+				c -= '0';
+				cpy = re->startp[(int)c];
+				end = re->endp[(int)c];
+				break;
+			  case 'U':
+			  case 'u':
+			  case 'L':
+			  case 'l':
+				/* \U and \L mean "convert to upper/lowercase" */
+				mod = c;
+				continue;
+
+			  case 'E':
+			  case 'e':
+				/* \E ends the \U or \L */
+				mod = 0;
+				continue;
+			  case '&':
+				/* "\&" means "original text" */
+				*dst++ = c;
+				continue;
+
+			  case '~':
+				/* "\~" means "previous text, if any" */
+				*dst++ = c;
+				continue;
+			  default:
+				/* ordinary char preceded by backslash */
+				*dst++ = c;
+				continue;
+			}
+		}
+		else
+		{
+			/* ordinary character, so just copy it */
+			*dst++ = c;
+			continue;
+		}
+
+		/* Note: to reach this point in the code, we must have evaded
+		 * all "continue" statements.  To do that, we must have hit
+		 * a metacharacter that involves copying.
+		 */
+
+		/* if there is nothing to copy, loop */
+		if (!cpy)
+			continue;
+
+		/* copy over a portion of the original */
+		while (cpy < end)
+		{
+			switch (mod)
+			{
+			  case 'U':
+			  case 'u':
+				/* convert to uppercase */
+				if (isascii(*cpy) && islower(*cpy))
+				{
+					*dst++ = toupper(*cpy);
+					cpy++;
+				}
+				else
+				{
+					*dst++ = *cpy++;
+				}
+				break;
+
+			  case 'L':
+			  case 'l':
+				/* convert to lowercase */
+				if (isascii(*cpy) && isupper(*cpy))
+				{
+					*dst++ = tolower(*cpy);
+					cpy++;
+				}
+				else
+				{
+					*dst++ = *cpy++;
+				}
+				break;
+
+			  default:
+				/* copy without any conversion */
+				*dst++ = *cpy++;
+			}
+
+			/* \u and \l end automatically after the first char */
+			if (mod && (mod == 'u' || mod == 'l'))
+			{
+				mod = 0;
+			}
+		}
+	}
+	*dst = '\0';
+
+	/* remember what text we inserted this time */
+	if (previous1)
+		free(previous1);
+	previous1 = (char *)malloc((unsigned)(strlen(start) + 1));
+	if (previous1)
+		strcpy(previous1, start);
+}
+
+
+#endif /* BB_REGEXP */
+
+