// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright 2008 Freescale Semiconductor, Inc.
 * Copyright 2013 Wolfgang Denk <wd@denx.de>
 */

/*
 * This file provides a shell like 'expr' function to return.
 */

#include <common.h>
#include <config.h>
#include <command.h>
#include <ctype.h>
#include <env.h>
#include <log.h>
#include <malloc.h>
#include <mapmem.h>
#include <linux/sizes.h>
#include "printf.h"

#define MAX_STR_LEN 128

/**
 * struct expr_arg: Holds an argument to an expression
 *
 * @ival: Integer value (if width is not CMD_DATA_SIZE_STR)
 * @sval: String value (if width is CMD_DATA_SIZE_STR)
 */
struct expr_arg {
        union {
                ulong ival;
                char *sval;
        };
};

static int get_arg(char *s, int w, struct expr_arg *argp)
{
        struct expr_arg arg;

        /*
         * If the parameter starts with a '*' then assume it is a pointer to
         * the value we want.
         */
        if (s[0] == '*') {
                ulong *p;
                ulong addr;
                ulong val;
                int len;
                char *str;

                addr = hextoul(&s[1], NULL);
                switch (w) {
                case 1:
                        p = map_sysmem(addr, sizeof(uchar));
                        val = (ulong)*(uchar *)p;
                        unmap_sysmem(p);
                        arg.ival = val;
                        break;
                case 2:
                        p = map_sysmem(addr, sizeof(ushort));
                        val = (ulong)*(ushort *)p;
                        unmap_sysmem(p);
                        arg.ival = val;
                        break;
                case CMD_DATA_SIZE_STR:
                        p = map_sysmem(addr, SZ_64K);

                        /* Maximum string length of 64KB plus terminator */
                        len = strnlen((char *)p, SZ_64K) + 1;
                        str = malloc(len);
                        if (!str) {
                                printf("Out of memory\n");
                                return -ENOMEM;
                        }
                        memcpy(str, p, len);
                        str[len - 1] = '\0';
                        unmap_sysmem(p);
                        arg.sval = str;
                        break;
                case 4:
                        p = map_sysmem(addr, sizeof(u32));
                        val = *(u32 *)p;
                        unmap_sysmem(p);
                        arg.ival = val;
                        break;
                default:
                        p = map_sysmem(addr, sizeof(ulong));
                        val = *p;
                        unmap_sysmem(p);
                        arg.ival = val;
                        break;
                }
        } else {
                if (w == CMD_DATA_SIZE_STR)
                        return -EINVAL;
                arg.ival = hextoul(s, NULL);
        }
        *argp = arg;

        return 0;
}

#ifdef CONFIG_REGEX

#include <slre.h>

/*
 * 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;
}

/**
 * substitute() - Substitute part of one string with another
 *
 * This updates @string so that the first occurrence of @old is replaced with
 * @new
 *
 * @string: String buffer containing string to update at the start
 * @slen: Pointer to current string length, updated on success
 * @ssize: Size of string buffer
 * @old: Old string to find in the buffer (no terminator needed)
 * @olen: Length of @old excluding terminator
 * @new: New string to replace @old with
 * @nlen: Length of @new excluding terminator
 * @return pointer to immediately after the copied @new in @string, or NULL if
 *      no replacement took place
 */
static char *substitute(char *string, int *slen, int ssize,
                        const char *old, int olen, const char *new, int nlen)
{
        char *p = memstr(string, *slen, old, olen);

        if (p == NULL)
                return NULL;

        debug("## Match at pos %ld: match len %d, subst len %d\n",
                (long)(p - string), olen, nlen);

        /* make sure replacement matches */
        if (*slen + nlen - olen > ssize) {
                printf("## error: substitution buffer overflow\n");
                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\n", tail);

                memmove(p + nlen, p + olen, tail);
        }

        /* insert substitute */
        memcpy(p, new, nlen);

        *slen += nlen - olen;

        return p + nlen;
}

int setexpr_regex_sub(char *data, uint data_size, char *nbuf, uint nbuf_size,
                      const char *r, const char *s, bool global)
{
        struct slre slre;
        char *datap = data;
        int res, len, nlen, loop;

        if (slre_compile(&slre, r) == 0) {
                printf("Error compiling regex: %s\n", slre.err_str);
                return 1;
        }

        len = strlen(data);
        for (loop = 0;; loop++) {
                struct cap caps[slre.num_caps + 2];
                const char *old;
                char *np;
                int i, olen;

                (void) memset(caps, 0, sizeof(caps));

                res = slre_match(&slre, datap, len - (datap - data), caps);

                debug("Result: %d\n", res);

                for (i = 0; i <= slre.num_caps; i++) {
                        if (caps[i].len > 0) {
                                debug("Substring %d: [%.*s]\n", i,
                                        caps[i].len, caps[i].ptr);
                        }
                }

                if (res == 0) {
                        if (loop == 0) {
                                printf("%s: No match\n", data);
                                return 1;
                        } else {
                                break;
                        }
                }

                debug("## MATCH ## %s\n", data);

                if (!s)
                        return 1;

                old = caps[0].ptr;
                olen = caps[0].len;
                nlen = strlen(s);

                if (nlen + 1 >= nbuf_size) {
                        printf("## error: pattern buffer overflow: have %d, need %d\n",
                               nbuf_size, nlen + 1);
                        return 1;
                }
                strcpy(nbuf, s);

                debug("## SUBST(1) ## %s\n", 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\"\n",
                                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,
                                        nbuf_size - (np - nbuf),
                                        backref, 2,
                                        caps[i].ptr, caps[i].len);

                                if (np == NULL)
                                        return 1;
                        }
                }
                debug("## SUBST(2) ## %s\n", nbuf);

                datap = substitute(datap, &len, data_size - (datap - data),
                                   old, olen, nbuf, nlen);

                if (datap == NULL)
                        return 1;

                debug("## REMAINDER: %s\n", datap);

                debug("## RESULT: %s\n", data);

                if (!global)
                        break;
        }
        debug("## FINAL (now env_set()) :  %s\n", data);

        return 0;
}

#define SLRE_BUFSZ      16384
#define SLRE_PATSZ      4096

/*
 * Perform regex operations on a environment variable
 *
 * Returns 0 if OK, 1 in case of errors.
 */
static int regex_sub_var(const char *name, const char *r, const char *s,
                         const char *t, int global)
{
        struct slre slre;
        char data[SLRE_BUFSZ];
        char nbuf[SLRE_PATSZ];
        const char *value;
        int len;
        int ret;

        if (!name)
                return 1;

        if (slre_compile(&slre, r) == 0) {
                printf("Error compiling regex: %s\n", slre.err_str);
                return 1;
        }

        if (!t) {
                value = env_get(name);
                if (!value) {
                        printf("## Error: variable \"%s\" not defined\n", name);
                        return 1;
                }
                t = value;
        }

        debug("REGEX on %s=%s\n", name, t);
        debug("REGEX=\"%s\", SUBST=\"%s\", GLOBAL=%d\n", r, s ? s : "<NULL>",
              global);

        len = strlen(t);
        if (len + 1 > SLRE_BUFSZ) {
                printf("## error: subst buffer overflow: have %d, need %d\n",
                       SLRE_BUFSZ, len + 1);
                return 1;
        }

        strcpy(data, t);

        ret = setexpr_regex_sub(data, SLRE_BUFSZ, nbuf, SLRE_PATSZ, r, s,
                                global);
        if (ret)
                return 1;

        printf("%s=%s\n", name, data);

        return env_set(name, data);
}
#endif

static int do_setexpr(struct cmd_tbl *cmdtp, int flag, int argc,
                      char *const argv[])
{
        struct expr_arg aval, bval;
        ulong value;
        int ret = 0;
        int w;

        /*
         * We take 3, 5, or 6 arguments, except fmt operation, which
         * takes 4 to 8 arguments (limited by _maxargs):
         * 3 : setexpr name value
         * 5 : setexpr name val1 op val2
         *     setexpr name [g]sub r s
         * 6 : setexpr name [g]sub r s t
         *     setexpr name fmt format [val1] [val2] [val3] [val4]
         */

        if (argc < 3)
                return CMD_RET_USAGE;

        w = cmd_get_data_size(argv[0], 4);

        if (get_arg(argv[2], w, &aval))
                return CMD_RET_FAILURE;

        /* format string assignment: "setexpr name fmt %d value" */
        if (strcmp(argv[2], "fmt") == 0 && IS_ENABLED(CONFIG_CMD_SETEXPR_FMT)) {
                char str[MAX_STR_LEN];
                int result;

                if (argc == 3)
                        return CMD_RET_USAGE;

                result = printf_setexpr(str, sizeof(str), argc - 3, &argv[3]);
                if (result)
                        return result;

                return env_set(argv[1], str);
        }

        if (argc == 4 || argc > 6)
                return CMD_RET_USAGE;

        /* plain assignment: "setexpr name value" */
        if (argc == 3) {
                if (w == CMD_DATA_SIZE_STR) {
                        ret = env_set(argv[1], aval.sval);
                        free(aval.sval);
                } else {
                        ret = env_set_hex(argv[1], aval.ival);
                }

                return ret;
        }

        /* 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_var(argv[1], argv[3], argv[4], argv[5], 1);

        if (strcmp(argv[2], "sub") == 0)
                return regex_sub_var(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;

        if (get_arg(argv[4], w, &bval)) {
                if (w == CMD_DATA_SIZE_STR)
                        free(aval.sval);
                return CMD_RET_FAILURE;
        }

        if (w == CMD_DATA_SIZE_STR) {
                int len;
                char *str;

                switch (argv[3][0]) {
                case '+':
                        len = strlen(aval.sval) + strlen(bval.sval) + 1;
                        str = malloc(len);
                        if (!str) {
                                printf("Out of memory\n");
                                ret = CMD_RET_FAILURE;
                        } else {
                                /* These were copied out and checked earlier */
                                strcpy(str, aval.sval);
                                strcat(str, bval.sval);
                                ret = env_set(argv[1], str);
                                if (ret)
                                        printf("Could not set var\n");
                                free(str);
                        }
                        break;
                default:
                        printf("invalid op\n");
                        ret = 1;
                }
        } else {
                ulong a = aval.ival;
                ulong b = bval.ival;

                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\n");
                        return 1;
                }

                env_set_hex(argv[1], value);
        }

        if (w == CMD_DATA_SIZE_STR) {
                free(aval.sval);
                free(bval.sval);
        }

        return ret;
}

U_BOOT_CMD(
        setexpr, 8, 0, do_setexpr,
        "set environment variable as the result of eval expression",
        "[.b, .w, .l, .s] name [*]value1 <op> [*]value2\n"
        "    - set environment variable 'name' to the result of the evaluated\n"
        "      expression specified by <op>.  <op> can be &, |, ^, +, -, *, /, %\n"
        "      (for strings only + is supported)\n"
        "      size argument is only meaningful if value1 and/or value2 are\n"
        "      memory addresses (*)\n"
        "setexpr[.b, .w, .l] name [*]value\n"
        "    - load a value into a variable"
#ifdef CONFIG_CMD_SETEXPR_FMT
        "\n"
        "setexpr name fmt <format> [value1] [value2] [value3] [value4]\n"
        "    - set environment variable 'name' to the result of the bash like\n"
        "      format string evaluation of value."
#endif
#ifdef CONFIG_REGEX
        "\n"
        "setexpr name gsub r s [t]\n"
        "    - For each substring matching the regular expression <r> in the\n"
        "      string <t>, substitute the string <s>.  The result is\n"
        "      assigned to <name>.  If <t> is not supplied, use the old\n"
        "      value of <name>\n"
        "setexpr name sub r s [t]\n"
        "    - Just like gsub(), but replace only the first matching substring"
#endif
);