/*
   * Copyright 2008 Freescale Semiconductor, Inc.
   * Copyright 2013 Wolfgang Denk <wd@denx.de>
   *
   * SPDX-License-Identifier:	GPL-2.0+
   */
  
  /*
   * This file provides a shell like 'expr' function to return.
   */
  
  #include <common.h>
  #include <config.h>
  #include <command.h>
  
  static ulong get_arg(char *s, int w)
  {
  	ulong *p;
  
  	/*
  	 * if the parameter starts with a '*' then assume
  	 * it is a pointer to the value we want
  	 */
  
  	if (s[0] == '*') {
  		p = (ulong *)simple_strtoul(&s[1], NULL, 16);
  		switch (w) {
  		case 1: return((ulong)(*(uchar *)p));
  		case 2: return((ulong)(*(ushort *)p));
  		case 4:
  		default: return(*p);
  		}
  	} else {
  		return simple_strtoul(s, NULL, 16);
  	}
  }
  
  #ifdef CONFIG_REGEX
  
  #include <slre.h>
  
  #define SLRE_BUFSZ	16384
  #define SLRE_PATSZ	4096
  
  /*
   * memstr - Find the first substring in memory
   * @s1: The string to be searched
   * @s2: The string to search for
   *
   * Similar to and based on strstr(),
   * but strings do not need to be NUL terminated.
   */
  static char *memstr(const char *s1, int l1, const char *s2, int l2)
  {
  	if (!l2)
  		return (char *)s1;
  
  	while (l1 >= l2) {
  		l1--;
  		if (!memcmp(s1, s2, l2))
  			return (char *)s1;
  		s1++;
  	}
  	return NULL;
  }
  
  static char *substitute(char *string,	/* string buffer */
  			int *slen,	/* current string length */
  			int ssize,	/* string bufer size */
  			const char *old,/* old (replaced) string */
  			int olen,	/* length of old string */
  			const char *new,/* new (replacement) string */
  			int nlen)	/* length of new string */
  {
  	char *p = memstr(string, *slen, old, olen);
  
  	if (p == NULL)
  		return NULL;
  
  	debug("## Match at pos %ld: match len %d, subst len %d
  ",
  		(long)(p - string), olen, nlen);
  
  	/* make sure replacement matches */
  	if (*slen + nlen - olen > ssize) {
  		printf("## error: substitution buffer overflow
  ");
  		return NULL;
  	}
  
  	/* move tail if needed */
  	if (olen != nlen) {
  		int tail, len;
  
  		len = (olen > nlen) ? olen : nlen;
  
  		tail = ssize - (p + len - string);
  
  		debug("## tail len %d
  ", tail);
  
  		memmove(p + nlen, p + olen, tail);
  	}
  
  	/* insert substitue */
  	memcpy(p, new, nlen);
  
  	*slen += nlen - olen;
  
  	return p + nlen;
  }
  
  /*
   * Perform regex operations on a environment variable
   *
   * Returns 0 if OK, 1 in case of errors.
   */
  static int regex_sub(const char *name,
  	const char *r, const char *s, const char *t,
  	int global)
  {
  	struct slre slre;
  	char data[SLRE_BUFSZ];
  	char *datap = data;
  	const char *value;
  	int res, len, nlen, loop;
  
  	if (name == NULL)
  		return 1;
  
  	if (slre_compile(&slre, r) == 0) {
  		printf("Error compiling regex: %s
  ", slre.err_str);
  		return 1;
  	}
  
  	if (t == NULL) {
  		value = getenv(name);
  
  		if (value == NULL) {
  			printf("## Error: variable \"%s\" not defined
  ", name);
  			return 1;
  		}
  		t = value;
  	}
  
  	debug("REGEX on %s=%s
  ", name, t);
  	debug("REGEX=\"%s\", SUBST=\"%s\", GLOBAL=%d
  ",
  		r, s ? s : "<NULL>", global);
  
  	len = strlen(t);
  	if (len + 1 > SLRE_BUFSZ) {
  		printf("## error: subst buffer overflow: have %d, need %d
  ",
  			SLRE_BUFSZ, len + 1);
  		return 1;
  	}
  
  	strcpy(data, t);
  
  	if (s == NULL)
  		nlen = 0;
  	else
  		nlen = strlen(s);
  
  	for (loop = 0;; loop++) {
  		struct cap caps[slre.num_caps + 2];
  		char nbuf[SLRE_PATSZ];
  		const char *old;
  		char *np;
  		int i, olen;
  
  		(void) memset(caps, 0, sizeof(caps));
  
  		res = slre_match(&slre, datap, len, caps);
  
  		debug("Result: %d
  ", res);
  
  		for (i = 0; i < slre.num_caps; i++) {
  			if (caps[i].len > 0) {
  				debug("Substring %d: [%.*s]
  ", i,
  					caps[i].len, caps[i].ptr);
  			}
  		}
  
  		if (res == 0) {
  			if (loop == 0) {
  				printf("%s: No match
  ", t);
  				return 1;
  			} else {
  				break;
  			}
  		}
  
  		debug("## MATCH ## %s
  ", data);
  
  		if (s == NULL) {
  			printf("%s=%s
  ", name, t);
  			return 1;
  		}
  
  		old = caps[0].ptr;
  		olen = caps[0].len;
  
  		if (nlen + 1 >= SLRE_PATSZ) {
  			printf("## error: pattern buffer overflow: have %d, need %d
  ",
  				SLRE_BUFSZ, nlen + 1);
  			return 1;
  		}
  		strcpy(nbuf, s);
  
  		debug("## SUBST(1) ## %s
  ", nbuf);
  
  		/*
  		 * Handle back references
  		 *
  		 * Support for \0 ... \9, where \0 is the
  		 * whole matched pattern (similar to &).
  		 *
  		 * Implementation is a bit simpleminded as
  		 * backrefs are substituted sequentially, one
  		 * by one.  This will lead to somewhat
  		 * unexpected results if the replacement
  		 * strings contain any \N strings then then
  		 * may get substitued, too.  We accept this
  		 * restriction for the sake of simplicity.
  		 */
  		for (i = 0; i < 10; ++i) {
  			char backref[2] = {
  				'\\',
  				'0',
  			};
  
  			if (caps[i].len == 0)
  				break;
  
  			backref[1] += i;
  
  			debug("## BACKREF %d: replace \"%.*s\" by \"%.*s\" in \"%s\"
  ",
  				i,
  				2, backref,
  				caps[i].len, caps[i].ptr,
  				nbuf);
  
  			for (np = nbuf;;) {
  				char *p = memstr(np, nlen, backref, 2);
  
  				if (p == NULL)
  					break;
  
  				np = substitute(np, &nlen,
  					SLRE_PATSZ,
  					backref, 2,
  					caps[i].ptr, caps[i].len);
  
  				if (np == NULL)
  					return 1;
  			}
  		}
  		debug("## SUBST(2) ## %s
  ", nbuf);
  
  		datap = substitute(datap, &len, SLRE_BUFSZ,
  				old, olen,
  				nbuf, nlen);
  
  		if (datap == NULL)
  			return 1;
  
  		debug("## REMAINDER: %s
  ", datap);
  
  		debug("## RESULT: %s
  ", data);
  
  		if (!global)
  			break;
  	}
  	debug("## FINAL (now setenv()) :  %s
  ", data);
  
  	printf("%s=%s
  ", name, data);
  
  	return setenv(name, data);
  }
  #endif
  
  static int do_setexpr(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
  {
  	ulong a, b;
  	ulong value;
  	int w;
  
  	/*
  	 * We take 3, 5, or 6 arguments:
  	 * 3 : setexpr name value
  	 * 5 : setexpr name val1 op val2
  	 *     setexpr name [g]sub r s
  	 * 6 : setexpr name [g]sub r s t
  	 */
  
  	/* > 6 already tested by max command args */
  	if ((argc < 3) || (argc == 4))
  		return CMD_RET_USAGE;
  
  	w = cmd_get_data_size(argv[0], 4);
  
  	a = get_arg(argv[2], w);
  
  	/* plain assignment: "setexpr name value" */
  	if (argc == 3) {
  		setenv_hex(argv[1], a);
  		return 0;
  	}
  
  	/* 5 or 6 args (6 args only with [g]sub) */
  #ifdef CONFIG_REGEX
  	/*
  	 * rexep handling: "setexpr name [g]sub r s [t]"
  	 * with 5 args, "t" will be NULL
  	 */
  	if (strcmp(argv[2], "gsub") == 0)
  		return regex_sub(argv[1], argv[3], argv[4], argv[5], 1);
  
  	if (strcmp(argv[2], "sub") == 0)
  		return regex_sub(argv[1], argv[3], argv[4], argv[5], 0);
  #endif
  
  	/* standard operators: "setexpr name val1 op val2" */
  	if (argc != 5)
  		return CMD_RET_USAGE;
  
  	if (strlen(argv[3]) != 1)
  		return CMD_RET_USAGE;
  
  	b = get_arg(argv[4], w);
  
  	switch (argv[3][0]) {
  	case '|':
  		value = a | b;
  		break;
  	case '&':
  		value = a & b;
  		break;
  	case '+':
  		value = a + b;
  		break;
  	case '^':
  		value = a ^ b;
  		break;
  	case '-':
  		value = a - b;
  		break;
  	case '*':
  		value = a * b;
  		break;
  	case '/':
  		value = a / b;
  		break;
  	case '%':
  		value = a % b;
  		break;
  	default:
  		printf("invalid op
  ");
  		return 1;
  	}
  
  	setenv_hex(argv[1], value);
  
  	return 0;
  }
  
  U_BOOT_CMD(
  	setexpr, 6, 0, do_setexpr,
  	"set environment variable as the result of eval expression",
  	"[.b, .w, .l] name [*]value1 <op> [*]value2
  "
  	"    - set environment variable 'name' to the result of the evaluated
  "
  	"      expression specified by <op>.  <op> can be &, |, ^, +, -, *, /, %
  "
  	"      size argument is only meaningful if value1 and/or value2 are
  "
  	"      memory addresses (*)
  "
  	"setexpr[.b, .w, .l] name [*]value
  "
  	"    - load a value into a variable"
  #ifdef CONFIG_REGEX
  	"
  "
  	"setexpr name gsub r s [t]
  "
  	"    - For each substring matching the regular expression <r> in the
  "
  	"      string <t>, substitute the string <s>.  The result is
  "
  	"      assigned to <name>.  If <t> is not supplied, use the old
  "
  	"      value of <name>
  "
  	"setexpr name sub r s [t]
  "
  	"    - Just like gsub(), but replace only the first matching substring"
  #endif
  );