Add SLRE - Super Light Regular Expression library

Downloaded from http://slre.sourceforge.net/
and adapted for U-Boot environment.

Used to implement regex operations on environment variables.
Code size is ~ 3.5 KiB on PPC.

To enable this code, define the  CONFIG_REGEX  option in your board
config file.

Note:  There are more recent versions of the SLRE library available at
http://slre.googlecode.com ; unfortunately, the new code has a heavily
reorked API which makes it less usable for our purposes:
- the return code is strings, which are more difficult to process
- we don't get any information any more which sub-string of the data
  was matched by the given regex
- it is much more cumbersome to work with arbitrary expressions, where
  for example the number of substrings for capturing are not known at
  compile time
Also, there does not seem to be any real changes or improvements of
the functionality.

Because of this, we deliberately stick with the older code.

Note 2: the test code (built when SLRE_TEST is defined) was modified
to allow for more extensive testing; now we can test the regexp
matching on all lines on a text file (instead of the whole data in the
file as a single block).

Signed-off-by: Wolfgang Denk <wd@denx.de>

2 files changed, 725 insertions, 0 deletions

diff --git a/lib/Makefile b/lib/Makefile
index e901cc7..a3131d8 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -72,6 +72,7 @@ COBJS-y += crc32.o
 COBJS-y += ctype.o
 COBJS-y += div64.o
 COBJS-y += linux_string.o
+COBJS-$(CONFIG_REGEX) += slre.o
 COBJS-y += string.o
 COBJS-y += time.o
 COBJS-$(CONFIG_BOOTP_PXE) += uuid.o
diff --git a/lib/slre.c b/lib/slre.c
new file mode 100644
index 0000000..8cdd192
--- /dev/null
+++ b/lib/slre.c
@@ -0,0 +1,724 @@
+/*
+ * Copyright (c) 2004-2005 Sergey Lyubka <valenok@gmail.com>
+ * All rights reserved
+ *
+ * "THE BEER-WARE LICENSE" (Revision 42):
+ * Sergey Lyubka wrote this file.  As long as you retain this notice you
+ * can do whatever you want with this stuff. If we meet some day, and you think
+ * this stuff is worth it, you can buy me a beer in return.
+ */
+
+/*
+ * Downloaded Sat Nov  5 17:43:06 CET 2011 at
+ * http://slre.sourceforge.net/1.0/slre.c
+ */
+
+#ifdef SLRE_TEST
+#include <stdio.h>
+#include <assert.h>
+#include <ctype.h>
+#include <stdlib.h>
+#include <string.h>
+#else
+#include <common.h>
+#include <linux/ctype.h>
+#endif /* SLRE_TEST */
+
+#include <errno.h>
+
+#include <slre.h>
+
+enum {END, BRANCH, ANY, EXACT, ANYOF, ANYBUT, OPEN, CLOSE, BOL, EOL,
+	STAR, PLUS, STARQ, PLUSQ, QUEST, SPACE, NONSPACE, DIGIT};
+
+#ifdef SLRE_TEST
+static struct {
+	const char	*name;
+	int		narg;
+	const char	*flags;
+} opcodes[] = {
+	{"END",		0, ""},		/* End of code block or program	*/
+	{"BRANCH",	2, "oo"},	/* Alternative operator, "|"	*/
+	{"ANY",		0, ""},		/* Match any character, "."	*/
+	{"EXACT",	2, "d"},	/* Match exact string		*/
+	{"ANYOF",	2, "D"},	/* Match any from set, "[]"	*/
+	{"ANYBUT",	2, "D"},	/* Match any but from set, "[^]"*/
+	{"OPEN ",	1, "i"},	/* Capture start, "("		*/
+	{"CLOSE",	1, "i"},	/* Capture end, ")"		*/
+	{"BOL",		0, ""},		/* Beginning of string, "^"	*/
+	{"EOL",		0, ""},		/* End of string, "$"		*/
+	{"STAR",	1, "o"},	/* Match zero or more times "*"	*/
+	{"PLUS",	1, "o"},	/* Match one or more times, "+"	*/
+	{"STARQ",	1, "o"},	/* Non-greedy STAR,  "*?"	*/
+	{"PLUSQ",	1, "o"},	/* Non-greedy PLUS, "+?"	*/
+	{"QUEST",	1, "o"},	/* Match zero or one time, "?"	*/
+	{"SPACE",	0, ""},		/* Match whitespace, "\s"	*/
+	{"NONSPACE",	0, ""},		/* Match non-space, "\S"	*/
+	{"DIGIT",	0, ""}		/* Match digit, "\d"		*/
+};
+#endif /* SLRE_TEST */
+
+/*
+ * Commands and operands are all unsigned char (1 byte long). All code offsets
+ * are relative to current address, and positive (always point forward). Data
+ * offsets are absolute. Commands with operands:
+ *
+ * BRANCH offset1 offset2
+ *	Try to match the code block that follows the BRANCH instruction
+ *	(code block ends with END). If no match, try to match code block that
+ *	starts at offset1. If either of these match, jump to offset2.
+ *
+ * EXACT data_offset data_length
+ *	Try to match exact string. String is recorded in data section from
+ *	data_offset, and has length data_length.
+ *
+ * OPEN capture_number
+ * CLOSE capture_number
+ *	If the user have passed 'struct cap' array for captures, OPEN
+ *	records the beginning of the matched substring (cap->ptr), CLOSE
+ *	sets the length (cap->len) for respective capture_number.
+ *
+ * STAR code_offset
+ * PLUS code_offset
+ * QUEST code_offset
+ *	*, +, ?, respectively. Try to gobble as much as possible from the
+ *	matched buffer, until code block that follows these instructions
+ *	matches. When the longest possible string is matched,
+ *	jump to code_offset
+ *
+ * STARQ, PLUSQ are non-greedy versions of STAR and PLUS.
+ */
+
+static const char *meta_chars = "|.^$*+?()[\\";
+
+#ifdef SLRE_TEST
+
+static void
+print_character_set(FILE *fp, const unsigned char *p, int len)
+{
+	int	i;
+
+	for (i = 0; i < len; i++) {
+		if (i > 0)
+			(void) fputc(',', fp);
+		if (p[i] == 0) {
+			i++;
+			if (p[i] == 0)
+				(void) fprintf(fp, "\\x%02x", p[i]);
+			else
+				(void) fprintf(fp, "%s", opcodes[p[i]].name);
+		} else if (isprint(p[i])) {
+			(void) fputc(p[i], fp);
+		} else {
+			(void) fprintf(fp, "\\x%02x", p[i]);
+		}
+	}
+}
+
+void
+slre_dump(const struct slre *r, FILE *fp)
+{
+	int	i, j, ch, op, pc;
+
+	for (pc = 0; pc < r->code_size; pc++) {
+
+		op = r->code[pc];
+		(void) fprintf(fp, "%3d %s ", pc, opcodes[op].name);
+
+		for (i = 0; opcodes[op].flags[i] != '\0'; i++)
+			switch (opcodes[op].flags[i]) {
+			case 'i':
+				(void) fprintf(fp, "%d ", r->code[pc + 1]);
+				pc++;
+				break;
+			case 'o':
+				(void) fprintf(fp, "%d ",
+				    pc + r->code[pc + 1] - i);
+				pc++;
+				break;
+			case 'D':
+				print_character_set(fp, r->data +
+				    r->code[pc + 1], r->code[pc + 2]);
+				pc += 2;
+				break;
+			case 'd':
+				(void) fputc('"', fp);
+				for (j = 0; j < r->code[pc + 2]; j++) {
+					ch = r->data[r->code[pc + 1] + j];
+					if (isprint(ch)) {
+						(void) fputc(ch, fp);
+					} else {
+						(void) fprintf(fp,
+							"\\x%02x", ch);
+					}
+				}
+				(void) fputc('"', fp);
+				pc += 2;
+				break;
+			}
+
+		(void) fputc('\n', fp);
+	}
+}
+#endif /* SLRE_TEST */
+
+static void
+set_jump_offset(struct slre *r, int pc, int offset)
+{
+	assert(offset < r->code_size);
+
+	if (r->code_size - offset > 0xff)
+		r->err_str = "Jump offset is too big";
+	else
+		r->code[pc] = (unsigned char) (r->code_size - offset);
+}
+
+static void
+emit(struct slre *r, int code)
+{
+	if (r->code_size >= (int) (sizeof(r->code) / sizeof(r->code[0])))
+		r->err_str = "RE is too long (code overflow)";
+	else
+		r->code[r->code_size++] = (unsigned char) code;
+}
+
+static void
+store_char_in_data(struct slre *r, int ch)
+{
+	if (r->data_size >= (int) sizeof(r->data))
+		r->err_str = "RE is too long (data overflow)";
+	else
+		r->data[r->data_size++] = ch;
+}
+
+static void
+exact(struct slre *r, const char **re)
+{
+	int	old_data_size = r->data_size;
+
+	while (**re != '\0' && (strchr(meta_chars, **re)) == NULL)
+		store_char_in_data(r, *(*re)++);
+
+	emit(r, EXACT);
+	emit(r, old_data_size);
+	emit(r, r->data_size - old_data_size);
+}
+
+static int
+get_escape_char(const char **re)
+{
+	int	res;
+
+	switch (*(*re)++) {
+	case 'n':
+		res = '\n';
+		break;
+	case 'r':
+		res = '\r';
+		break;
+	case 't':
+		res = '\t';
+		break;
+	case '0':
+		res = 0;
+		break;
+	case 'S':
+		res = NONSPACE << 8;
+		break;
+	case 's':
+		res = SPACE << 8;
+		break;
+	case 'd':
+		res = DIGIT << 8;
+		break;
+	default:
+		res = (*re)[-1];
+		break;
+	}
+
+	return res;
+}
+
+static void
+anyof(struct slre *r, const char **re)
+{
+	int	esc, old_data_size = r->data_size, op = ANYOF;
+
+	if (**re == '^') {
+		op = ANYBUT;
+		(*re)++;
+	}
+
+	while (**re != '\0')
+
+		switch (*(*re)++) {
+		case ']':
+			emit(r, op);
+			emit(r, old_data_size);
+			emit(r, r->data_size - old_data_size);
+			return;
+			/* NOTREACHED */
+			break;
+		case '\\':
+			esc = get_escape_char(re);
+			if ((esc & 0xff) == 0) {
+				store_char_in_data(r, 0);
+				store_char_in_data(r, esc >> 8);
+			} else {
+				store_char_in_data(r, esc);
+			}
+			break;
+		default:
+			store_char_in_data(r, (*re)[-1]);
+			break;
+		}
+
+	r->err_str = "No closing ']' bracket";
+}
+
+static void
+relocate(struct slre *r, int begin, int shift)
+{
+	emit(r, END);
+	memmove(r->code + begin + shift, r->code + begin, r->code_size - begin);
+	r->code_size += shift;
+}
+
+static void
+quantifier(struct slre *r, int prev, int op)
+{
+	if (r->code[prev] == EXACT && r->code[prev + 2] > 1) {
+		r->code[prev + 2]--;
+		emit(r, EXACT);
+		emit(r, r->code[prev + 1] + r->code[prev + 2]);
+		emit(r, 1);
+		prev = r->code_size - 3;
+	}
+	relocate(r, prev, 2);
+	r->code[prev] = op;
+	set_jump_offset(r, prev + 1, prev);
+}
+
+static void
+exact_one_char(struct slre *r, int ch)
+{
+	emit(r, EXACT);
+	emit(r, r->data_size);
+	emit(r, 1);
+	store_char_in_data(r, ch);
+}
+
+static void
+fixup_branch(struct slre *r, int fixup)
+{
+	if (fixup > 0) {
+		emit(r, END);
+		set_jump_offset(r, fixup, fixup - 2);
+	}
+}
+
+static void
+compile(struct slre *r, const char **re)
+{
+	int	op, esc, branch_start, last_op, fixup, cap_no, level;
+
+	fixup = 0;
+	level = r->num_caps;
+	branch_start = last_op = r->code_size;
+
+	for (;;)
+		switch (*(*re)++) {
+		case '\0':
+			(*re)--;
+			return;
+			/* NOTREACHED */
+			break;
+		case '^':
+			emit(r, BOL);
+			break;
+		case '$':
+			emit(r, EOL);
+			break;
+		case '.':
+			last_op = r->code_size;
+			emit(r, ANY);
+			break;
+		case '[':
+			last_op = r->code_size;
+			anyof(r, re);
+			break;
+		case '\\':
+			last_op = r->code_size;
+			esc = get_escape_char(re);
+			if (esc & 0xff00)
+				emit(r, esc >> 8);
+			else
+				exact_one_char(r, esc);
+			break;
+		case '(':
+			last_op = r->code_size;
+			cap_no = ++r->num_caps;
+			emit(r, OPEN);
+			emit(r, cap_no);
+
+			compile(r, re);
+			if (*(*re)++ != ')') {
+				r->err_str = "No closing bracket";
+				return;
+			}
+
+			emit(r, CLOSE);
+			emit(r, cap_no);
+			break;
+		case ')':
+			(*re)--;
+			fixup_branch(r, fixup);
+			if (level == 0) {
+				r->err_str = "Unbalanced brackets";
+				return;
+			}
+			return;
+			/* NOTREACHED */
+			break;
+		case '+':
+		case '*':
+			op = (*re)[-1] == '*' ? STAR : PLUS;
+			if (**re == '?') {
+				(*re)++;
+				op = op == STAR ? STARQ : PLUSQ;
+			}
+			quantifier(r, last_op, op);
+			break;
+		case '?':
+			quantifier(r, last_op, QUEST);
+			break;
+		case '|':
+			fixup_branch(r, fixup);
+			relocate(r, branch_start, 3);
+			r->code[branch_start] = BRANCH;
+			set_jump_offset(r, branch_start + 1, branch_start);
+			fixup = branch_start + 2;
+			r->code[fixup] = 0xff;
+			break;
+		default:
+			(*re)--;
+			last_op = r->code_size;
+			exact(r, re);
+			break;
+		}
+}
+
+int
+slre_compile(struct slre *r, const char *re)
+{
+	r->err_str = NULL;
+	r->code_size = r->data_size = r->num_caps = r->anchored = 0;
+
+	if (*re == '^')
+		r->anchored++;
+
+	emit(r, OPEN);	/* This will capture what matches full RE */
+	emit(r, 0);
+
+	while (*re != '\0')
+		compile(r, &re);
+
+	if (r->code[2] == BRANCH)
+		fixup_branch(r, 4);
+
+	emit(r, CLOSE);
+	emit(r, 0);
+	emit(r, END);
+
+	return (r->err_str == NULL ? 1 : 0);
+}
+
+static int match(const struct slre *, int,
+		const char *, int, int *, struct cap *);
+
+static void
+loop_greedy(const struct slre *r, int pc, const char *s, int len, int *ofs)
+{
+	int	saved_offset, matched_offset;
+
+	saved_offset = matched_offset = *ofs;
+
+	while (match(r, pc + 2, s, len, ofs, NULL)) {
+		saved_offset = *ofs;
+		if (match(r, pc + r->code[pc + 1], s, len, ofs, NULL))
+			matched_offset = saved_offset;
+		*ofs = saved_offset;
+	}
+
+	*ofs = matched_offset;
+}
+
+static void
+loop_non_greedy(const struct slre *r, int pc, const char *s, int len, int *ofs)
+{
+	int	saved_offset = *ofs;
+
+	while (match(r, pc + 2, s, len, ofs, NULL)) {
+		saved_offset = *ofs;
+		if (match(r, pc + r->code[pc + 1], s, len, ofs, NULL))
+			break;
+	}
+
+	*ofs = saved_offset;
+}
+
+static int
+is_any_of(const unsigned char *p, int len, const char *s, int *ofs)
+{
+	int	i, ch;
+
+	ch = s[*ofs];
+
+	for (i = 0; i < len; i++)
+		if (p[i] == ch) {
+			(*ofs)++;
+			return 1;
+		}
+
+	return 0;
+}
+
+static int
+is_any_but(const unsigned char *p, int len, const char *s, int *ofs)
+{
+	int	i, ch;
+
+	ch = s[*ofs];
+
+	for (i = 0; i < len; i++) {
+		if (p[i] == ch)
+			return 0;
+	}
+
+	(*ofs)++;
+	return 1;
+}
+
+static int
+match(const struct slre *r, int pc, const char *s, int len,
+		int *ofs, struct cap *caps)
+{
+	int	n, saved_offset, res = 1;
+
+	while (res && r->code[pc] != END) {
+
+		assert(pc < r->code_size);
+		assert(pc < (int) (sizeof(r->code) / sizeof(r->code[0])));
+
+		switch (r->code[pc]) {
+		case BRANCH:
+			saved_offset = *ofs;
+			res = match(r, pc + 3, s, len, ofs, caps);
+			if (res == 0) {
+				*ofs = saved_offset;
+				res = match(r, pc + r->code[pc + 1],
+				    s, len, ofs, caps);
+			}
+			pc += r->code[pc + 2];
+			break;
+		case EXACT:
+			res = 0;
+			n = r->code[pc + 2];	/* String length */
+			if (n <= len - *ofs && !memcmp(s + *ofs, r->data +
+			    r->code[pc + 1], n)) {
+				(*ofs) += n;
+				res = 1;
+			}
+			pc += 3;
+			break;
+		case QUEST:
+			res = 1;
+			saved_offset = *ofs;
+			if (!match(r, pc + 2, s, len, ofs, caps))
+				*ofs = saved_offset;
+			pc += r->code[pc + 1];
+			break;
+		case STAR:
+			res = 1;
+			loop_greedy(r, pc, s, len, ofs);
+			pc += r->code[pc + 1];
+			break;
+		case STARQ:
+			res = 1;
+			loop_non_greedy(r, pc, s, len, ofs);
+			pc += r->code[pc + 1];
+			break;
+		case PLUS:
+			res = match(r, pc + 2, s, len, ofs, caps);
+			if (res == 0)
+				break;
+
+			loop_greedy(r, pc, s, len, ofs);
+			pc += r->code[pc + 1];
+			break;
+		case PLUSQ:
+			res = match(r, pc + 2, s, len, ofs, caps);
+			if (res == 0)
+				break;
+
+			loop_non_greedy(r, pc, s, len, ofs);
+			pc += r->code[pc + 1];
+			break;
+		case SPACE:
+			res = 0;
+			if (*ofs < len && isspace(((unsigned char *)s)[*ofs])) {
+				(*ofs)++;
+				res = 1;
+			}
+			pc++;
+			break;
+		case NONSPACE:
+			res = 0;
+			if (*ofs < len &&
+					!isspace(((unsigned char *)s)[*ofs])) {
+				(*ofs)++;
+				res = 1;
+			}
+			pc++;
+			break;
+		case DIGIT:
+			res = 0;
+			if (*ofs < len && isdigit(((unsigned char *)s)[*ofs])) {
+				(*ofs)++;
+				res = 1;
+			}
+			pc++;
+			break;
+		case ANY:
+			res = 0;
+			if (*ofs < len) {
+				(*ofs)++;
+				res = 1;
+			}
+			pc++;
+			break;
+		case ANYOF:
+			res = 0;
+			if (*ofs < len)
+				res = is_any_of(r->data + r->code[pc + 1],
+					r->code[pc + 2], s, ofs);
+			pc += 3;
+			break;
+		case ANYBUT:
+			res = 0;
+			if (*ofs < len)
+				res = is_any_but(r->data + r->code[pc + 1],
+					r->code[pc + 2], s, ofs);
+			pc += 3;
+			break;
+		case BOL:
+			res = *ofs == 0 ? 1 : 0;
+			pc++;
+			break;
+		case EOL:
+			res = *ofs == len ? 1 : 0;
+			pc++;
+			break;
+		case OPEN:
+			if (caps != NULL)
+				caps[r->code[pc + 1]].ptr = s + *ofs;
+			pc += 2;
+			break;
+		case CLOSE:
+			if (caps != NULL)
+				caps[r->code[pc + 1]].len = (s + *ofs) -
+				    caps[r->code[pc + 1]].ptr;
+			pc += 2;
+			break;
+		case END:
+			pc++;
+			break;
+		default:
+			printf("unknown cmd (%d) at %d\n", r->code[pc], pc);
+			assert(0);
+			break;
+		}
+	}
+
+	return res;
+}
+
+int
+slre_match(const struct slre *r, const char *buf, int len,
+		struct cap *caps)
+{
+	int	i, ofs = 0, res = 0;
+
+	if (r->anchored) {
+		res = match(r, 0, buf, len, &ofs, caps);
+	} else {
+		for (i = 0; i < len && res == 0; i++) {
+			ofs = i;
+			res = match(r, 0, buf, len, &ofs, caps);
+		}
+	}
+
+	return res;
+}
+
+#ifdef SLRE_TEST
+#define N_CAPS	5
+
+int main(int argc, char *argv[])
+{
+	struct slre	slre;
+	struct cap	caps[N_CAPS];
+	unsigned char	data[1 * 1024 * 1024];
+	FILE		*fp;
+	int		i, res, len;
+
+	if (argc < 2) {
+		fprintf(stderr, "Usage: %s 'slre' <file>\n", argv[0]);
+		return 1;
+	}
+
+	fp = fopen(argv[2], "rb");
+	if (fp == NULL) {
+		fprintf(stderr, "Error: cannot open %s:%s\n",
+			argv[2], strerror(errno));
+		return 1;
+	}
+
+	if (!slre_compile(&slre, argv[1])) {
+		fprintf(stderr, "Error compiling slre: %s\n", slre.err_str);
+		return 1;
+	}
+	
+	slre_dump(&slre, stderr);
+
+	while (fgets(data, sizeof(data), fp) != NULL) {
+		len = strlen(data);
+
+		if ((len > 0) && (data[len-1] == '\n')) {
+			data[len-1] = '\0';
+			--len;
+		}
+
+		printf("Data = \"%s\"\n", data);
+
+		(void) memset(caps, 0, sizeof(caps));
+
+		res = 0;
+
+		res = slre_match(&slre, data, len, caps);
+		printf("Result [%d]: %d\n", i, res);
+
+		for (i = 0; i < N_CAPS; i++) {
+			if (caps[i].len > 0) {
+				printf("Substring %d: len=%d  [%.*s]\n", i,
+					caps[i].len,
+					caps[i].len, caps[i].ptr);
+			}
+		}
+		printf("----------------------------------------------------\n");
+	}
+	(void) fclose(fp);
+
+	return 0;
+}
+#endif /* SLRE_TEST */