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Diffstat (limited to 'regexp.c')
| -rw-r--r-- | regexp.c | 826 |
1 files changed, 826 insertions, 0 deletions
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 */ + + |