// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *
 *   Copyright (c) International Business Machines  Corp., 2000,2009
 *   Modified by Steve French (sfrench@us.ibm.com)
 */
#include <linux/fs.h>
#include <linux/slab.h>
#include "cifs_fs_sb.h"
#include "cifs_unicode.h"
#include "cifsglob.h"
#include "cifs_debug.h"

/* Convert character using the SFU - "Services for Unix" remapping range */
static bool
convert_sfu_char(const __u16 src_char, char *target)
{
        /*
         * BB: Cannot handle remapping UNI_SLASH until all the calls to
         *     build_path_from_dentry are modified, as they use slash as
         *     separator.
         */
        switch (src_char) {
        case UNI_COLON:
                *target = ':';
                break;
        case UNI_ASTERISK:
                *target = '*';
                break;
        case UNI_QUESTION:
                *target = '?';
                break;
        case UNI_PIPE:
                *target = '|';
                break;
        case UNI_GRTRTHAN:
                *target = '>';
                break;
        case UNI_LESSTHAN:
                *target = '<';
                break;
        default:
                return false;
        }
        return true;
}

/* Convert character using the SFM - "Services for Mac" remapping range */
static bool
convert_sfm_char(const __u16 src_char, char *target)
{
        if (src_char >= 0xF001 && src_char <= 0xF01F) {
                *target = src_char - 0xF000;
                return true;
        }
        switch (src_char) {
        case SFM_COLON:
                *target = ':';
                break;
        case SFM_DOUBLEQUOTE:
                *target = '"';
                break;
        case SFM_ASTERISK:
                *target = '*';
                break;
        case SFM_QUESTION:
                *target = '?';
                break;
        case SFM_PIPE:
                *target = '|';
                break;
        case SFM_GRTRTHAN:
                *target = '>';
                break;
        case SFM_LESSTHAN:
                *target = '<';
                break;
        case SFM_SPACE:
                *target = ' ';
                break;
        case SFM_PERIOD:
                *target = '.';
                break;
        default:
                return false;
        }
        return true;
}


/*
 * cifs_mapchar - convert a host-endian char to proper char in codepage
 * @target - where converted character should be copied
 * @src_char - 2 byte host-endian source character
 * @cp - codepage to which character should be converted
 * @map_type - How should the 7 NTFS/SMB reserved characters be mapped to UCS2?
 *
 * This function handles the conversion of a single character. It is the
 * responsibility of the caller to ensure that the target buffer is large
 * enough to hold the result of the conversion (at least NLS_MAX_CHARSET_SIZE).
 */
static int
cifs_mapchar(char *target, const __u16 *from, const struct nls_table *cp,
             int maptype)
{
        int len = 1;
        __u16 src_char;

        src_char = *from;

        if ((maptype == SFM_MAP_UNI_RSVD) && convert_sfm_char(src_char, target))
                return len;
        else if ((maptype == SFU_MAP_UNI_RSVD) &&
                  convert_sfu_char(src_char, target))
                return len;

        /* if character not one of seven in special remap set */
        len = cp->uni2char(src_char, target, NLS_MAX_CHARSET_SIZE);
        if (len <= 0)
                goto surrogate_pair;

        return len;

surrogate_pair:
        /* convert SURROGATE_PAIR and IVS */
        if (strcmp(cp->charset, "utf8"))
                goto unknown;
        len = utf16s_to_utf8s(from, 3, UTF16_LITTLE_ENDIAN, target, 6);
        if (len <= 0)
                goto unknown;
        return len;

unknown:
        *target = '?';
        len = 1;
        return len;
}

/*
 * cifs_from_utf16 - convert utf16le string to local charset
 * @to - destination buffer
 * @from - source buffer
 * @tolen - destination buffer size (in bytes)
 * @fromlen - source buffer size (in bytes)
 * @codepage - codepage to which characters should be converted
 * @mapchar - should characters be remapped according to the mapchars option?
 *
 * Convert a little-endian utf16le string (as sent by the server) to a string
 * in the provided codepage. The tolen and fromlen parameters are to ensure
 * that the code doesn't walk off of the end of the buffer (which is always
 * a danger if the alignment of the source buffer is off). The destination
 * string is always properly null terminated and fits in the destination
 * buffer. Returns the length of the destination string in bytes (including
 * null terminator).
 *
 * Note that some windows versions actually send multiword UTF-16 characters
 * instead of straight UTF16-2. The linux nls routines however aren't able to
 * deal with those characters properly. In the event that we get some of
 * those characters, they won't be translated properly.
 */
int
cifs_from_utf16(char *to, const __le16 *from, int tolen, int fromlen,
                const struct nls_table *codepage, int map_type)
{
        int i, charlen, safelen;
        int outlen = 0;
        int nullsize = nls_nullsize(codepage);
        int fromwords = fromlen / 2;
        char tmp[NLS_MAX_CHARSET_SIZE];
        __u16 ftmp[3];          /* ftmp[3] = 3array x 2bytes = 6bytes UTF-16 */

        /*
         * because the chars can be of varying widths, we need to take care
         * not to overflow the destination buffer when we get close to the
         * end of it. Until we get to this offset, we don't need to check
         * for overflow however.
         */
        safelen = tolen - (NLS_MAX_CHARSET_SIZE + nullsize);

        for (i = 0; i < fromwords; i++) {
                ftmp[0] = get_unaligned_le16(&from[i]);
                if (ftmp[0] == 0)
                        break;
                if (i + 1 < fromwords)
                        ftmp[1] = get_unaligned_le16(&from[i + 1]);
                else
                        ftmp[1] = 0;
                if (i + 2 < fromwords)
                        ftmp[2] = get_unaligned_le16(&from[i + 2]);
                else
                        ftmp[2] = 0;

                /*
                 * check to see if converting this character might make the
                 * conversion bleed into the null terminator
                 */
                if (outlen >= safelen) {
                        charlen = cifs_mapchar(tmp, ftmp, codepage, map_type);
                        if ((outlen + charlen) > (tolen - nullsize))
                                break;
                }

                /* put converted char into 'to' buffer */
                charlen = cifs_mapchar(&to[outlen], ftmp, codepage, map_type);
                outlen += charlen;

                /* charlen (=bytes of UTF-8 for 1 character)
                 * 4bytes UTF-8(surrogate pair) is charlen=4
                 *   (4bytes UTF-16 code)
                 * 7-8bytes UTF-8(IVS) is charlen=3+4 or 4+4
                 *   (2 UTF-8 pairs divided to 2 UTF-16 pairs) */
                if (charlen == 4)
                        i++;
                else if (charlen >= 5)
                        /* 5-6bytes UTF-8 */
                        i += 2;
        }

        /* properly null-terminate string */
        for (i = 0; i < nullsize; i++)
                to[outlen++] = 0;

        return outlen;
}

/*
 * NAME:        cifs_strtoUTF16()
 *
 * FUNCTION:    Convert character string to unicode string
 *
 */
int
cifs_strtoUTF16(__le16 *to, const char *from, int len,
              const struct nls_table *codepage)
{
        int charlen;
        int i;
        wchar_t wchar_to; /* needed to quiet sparse */

        /* special case for utf8 to handle no plane0 chars */
        if (!strcmp(codepage->charset, "utf8")) {
                /*
                 * convert utf8 -> utf16, we assume we have enough space
                 * as caller should have assumed conversion does not overflow
                 * in destination len is length in wchar_t units (16bits)
                 */
                i  = utf8s_to_utf16s(from, len, UTF16_LITTLE_ENDIAN,
                                       (wchar_t *) to, len);

                /* if success terminate and exit */
                if (i >= 0)
                        goto success;
                /*
                 * if fails fall back to UCS encoding as this
                 * function should not return negative values
                 * currently can fail only if source contains
                 * invalid encoded characters
                 */
        }

        for (i = 0; len && *from; i++, from += charlen, len -= charlen) {
                charlen = codepage->char2uni(from, len, &wchar_to);
                if (charlen < 1) {
                        cifs_dbg(VFS, "strtoUTF16: char2uni of 0x%x returned %d\n",
                                 *from, charlen);
                        /* A question mark */
                        wchar_to = 0x003f;
                        charlen = 1;
                }
                put_unaligned_le16(wchar_to, &to[i]);
        }

success:
        put_unaligned_le16(0, &to[i]);
        return i;
}

/*
 * cifs_utf16_bytes - how long will a string be after conversion?
 * @utf16 - pointer to input string
 * @maxbytes - don't go past this many bytes of input string
 * @codepage - destination codepage
 *
 * Walk a utf16le string and return the number of bytes that the string will
 * be after being converted to the given charset, not including any null
 * termination required. Don't walk past maxbytes in the source buffer.
 */
int
cifs_utf16_bytes(const __le16 *from, int maxbytes,
                const struct nls_table *codepage)
{
        int i;
        int charlen, outlen = 0;
        int maxwords = maxbytes / 2;
        char tmp[NLS_MAX_CHARSET_SIZE];
        __u16 ftmp[3];

        for (i = 0; i < maxwords; i++) {
                ftmp[0] = get_unaligned_le16(&from[i]);
                if (ftmp[0] == 0)
                        break;
                if (i + 1 < maxwords)
                        ftmp[1] = get_unaligned_le16(&from[i + 1]);
                else
                        ftmp[1] = 0;
                if (i + 2 < maxwords)
                        ftmp[2] = get_unaligned_le16(&from[i + 2]);
                else
                        ftmp[2] = 0;

                charlen = cifs_mapchar(tmp, ftmp, codepage, NO_MAP_UNI_RSVD);
                outlen += charlen;
        }

        return outlen;
}

/*
 * cifs_strndup_from_utf16 - copy a string from wire format to the local
 * codepage
 * @src - source string
 * @maxlen - don't walk past this many bytes in the source string
 * @is_unicode - is this a unicode string?
 * @codepage - destination codepage
 *
 * Take a string given by the server, convert it to the local codepage and
 * put it in a new buffer. Returns a pointer to the new string or NULL on
 * error.
 */
char *
cifs_strndup_from_utf16(const char *src, const int maxlen,
                        const bool is_unicode, const struct nls_table *codepage)
{
        int len;
        char *dst;

        if (is_unicode) {
                len = cifs_utf16_bytes((__le16 *) src, maxlen, codepage);
                len += nls_nullsize(codepage);
                dst = kmalloc(len, GFP_KERNEL);
                if (!dst)
                        return NULL;
                cifs_from_utf16(dst, (__le16 *) src, len, maxlen, codepage,
                                NO_MAP_UNI_RSVD);
        } else {
                dst = kstrndup(src, maxlen, GFP_KERNEL);
        }

        return dst;
}

static __le16 convert_to_sfu_char(char src_char)
{
        __le16 dest_char;

        switch (src_char) {
        case ':':
                dest_char = cpu_to_le16(UNI_COLON);
                break;
        case '*':
                dest_char = cpu_to_le16(UNI_ASTERISK);
                break;
        case '?':
                dest_char = cpu_to_le16(UNI_QUESTION);
                break;
        case '<':
                dest_char = cpu_to_le16(UNI_LESSTHAN);
                break;
        case '>':
                dest_char = cpu_to_le16(UNI_GRTRTHAN);
                break;
        case '|':
                dest_char = cpu_to_le16(UNI_PIPE);
                break;
        default:
                dest_char = 0;
        }

        return dest_char;
}

static __le16 convert_to_sfm_char(char src_char, bool end_of_string)
{
        __le16 dest_char;

        if (src_char >= 0x01 && src_char <= 0x1F) {
                dest_char = cpu_to_le16(src_char + 0xF000);
                return dest_char;
        }
        switch (src_char) {
        case ':':
                dest_char = cpu_to_le16(SFM_COLON);
                break;
        case '"':
                dest_char = cpu_to_le16(SFM_DOUBLEQUOTE);
                break;
        case '*':
                dest_char = cpu_to_le16(SFM_ASTERISK);
                break;
        case '?':
                dest_char = cpu_to_le16(SFM_QUESTION);
                break;
        case '<':
                dest_char = cpu_to_le16(SFM_LESSTHAN);
                break;
        case '>':
                dest_char = cpu_to_le16(SFM_GRTRTHAN);
                break;
        case '|':
                dest_char = cpu_to_le16(SFM_PIPE);
                break;
        case '.':
                if (end_of_string)
                        dest_char = cpu_to_le16(SFM_PERIOD);
                else
                        dest_char = 0;
                break;
        case ' ':
                if (end_of_string)
                        dest_char = cpu_to_le16(SFM_SPACE);
                else
                        dest_char = 0;
                break;
        default:
                dest_char = 0;
        }

        return dest_char;
}

/*
 * Convert 16 bit Unicode pathname to wire format from string in current code
 * page. Conversion may involve remapping up the six characters that are
 * only legal in POSIX-like OS (if they are present in the string). Path
 * names are little endian 16 bit Unicode on the wire
 */
int
cifsConvertToUTF16(__le16 *target, const char *source, int srclen,
                 const struct nls_table *cp, int map_chars)
{
        int i, charlen;
        int j = 0;
        char src_char;
        __le16 dst_char;
        wchar_t tmp;
        wchar_t *wchar_to;      /* UTF-16 */
        int ret;
        unicode_t u;

        if (map_chars == NO_MAP_UNI_RSVD)
                return cifs_strtoUTF16(target, source, PATH_MAX, cp);

        wchar_to = kzalloc(6, GFP_KERNEL);

        for (i = 0; i < srclen; j++) {
                src_char = source[i];
                charlen = 1;

                /* check if end of string */
                if (src_char == 0)
                        goto ctoUTF16_out;

                /* see if we must remap this char */
                if (map_chars == SFU_MAP_UNI_RSVD)
                        dst_char = convert_to_sfu_char(src_char);
                else if (map_chars == SFM_MAP_UNI_RSVD) {
                        bool end_of_string;

                        /**
                         * Remap spaces and periods found at the end of every
                         * component of the path. The special cases of '.' and
                         * '..' are need to be handled because of symlinks.
                         * They are treated as non-end-of-string to avoid
                         * remapping and breaking symlinks pointing to . or ..
                         **/
                        if ((i == 0 || source[i-1] == '\\') &&
                            source[i] == '.' &&
                            (i == srclen-1 || source[i+1] == '\\'))
                                end_of_string = false; /* "." case */
                        else if (i >= 1 &&
                                 (i == 1 || source[i-2] == '\\') &&
                                 source[i-1] == '.' &&
                                 source[i] == '.' &&
                                 (i == srclen-1 || source[i+1] == '\\'))
                                end_of_string = false; /* ".." case */
                        else if ((i == srclen - 1) || (source[i+1] == '\\'))
                                end_of_string = true;
                        else
                                end_of_string = false;

                        dst_char = convert_to_sfm_char(src_char, end_of_string);
                } else
                        dst_char = 0;
                /*
                 * FIXME: We can not handle remapping backslash (UNI_SLASH)
                 * until all the calls to build_path_from_dentry are modified,
                 * as they use backslash as separator.
                 */
                if (dst_char == 0) {
                        charlen = cp->char2uni(source + i, srclen - i, &tmp);
                        dst_char = cpu_to_le16(tmp);

                        /*
                         * if no match, use question mark, which at least in
                         * some cases serves as wild card
                         */
                        if (charlen > 0)
                                goto ctoUTF16;

                        /* convert SURROGATE_PAIR */
                        if (strcmp(cp->charset, "utf8") || !wchar_to)
                                goto unknown;
                        if (*(source + i) & 0x80) {
                                charlen = utf8_to_utf32(source + i, 6, &u);
                                if (charlen < 0)
                                        goto unknown;
                        } else
                                goto unknown;
                        ret  = utf8s_to_utf16s(source + i, charlen,
                                               UTF16_LITTLE_ENDIAN,
                                               wchar_to, 6);
                        if (ret < 0)
                                goto unknown;

                        i += charlen;
                        dst_char = cpu_to_le16(*wchar_to);
                        if (charlen <= 3)
                                /* 1-3bytes UTF-8 to 2bytes UTF-16 */
                                put_unaligned(dst_char, &target[j]);
                        else if (charlen == 4) {
                                /* 4bytes UTF-8(surrogate pair) to 4bytes UTF-16
                                 * 7-8bytes UTF-8(IVS) divided to 2 UTF-16
                                 *   (charlen=3+4 or 4+4) */
                                put_unaligned(dst_char, &target[j]);
                                dst_char = cpu_to_le16(*(wchar_to + 1));
                                j++;
                                put_unaligned(dst_char, &target[j]);
                        } else if (charlen >= 5) {
                                /* 5-6bytes UTF-8 to 6bytes UTF-16 */
                                put_unaligned(dst_char, &target[j]);
                                dst_char = cpu_to_le16(*(wchar_to + 1));
                                j++;
                                put_unaligned(dst_char, &target[j]);
                                dst_char = cpu_to_le16(*(wchar_to + 2));
                                j++;
                                put_unaligned(dst_char, &target[j]);
                        }
                        continue;

unknown:
                        dst_char = cpu_to_le16(0x003f);
                        charlen = 1;
                }

ctoUTF16:
                /*
                 * character may take more than one byte in the source string,
                 * but will take exactly two bytes in the target string
                 */
                i += charlen;
                put_unaligned(dst_char, &target[j]);
        }

ctoUTF16_out:
        put_unaligned(0, &target[j]); /* Null terminate target unicode string */
        kfree(wchar_to);
        return j;
}

/*
 * cifs_local_to_utf16_bytes - how long will a string be after conversion?
 * @from - pointer to input string
 * @maxbytes - don't go past this many bytes of input string
 * @codepage - source codepage
 *
 * Walk a string and return the number of bytes that the string will
 * be after being converted to the given charset, not including any null
 * termination required. Don't walk past maxbytes in the source buffer.
 */

static int
cifs_local_to_utf16_bytes(const char *from, int len,
                          const struct nls_table *codepage)
{
        int charlen;
        int i;
        wchar_t wchar_to;

        for (i = 0; len && *from; i++, from += charlen, len -= charlen) {
                charlen = codepage->char2uni(from, len, &wchar_to);
                /* Failed conversion defaults to a question mark */
                if (charlen < 1)
                        charlen = 1;
        }
        return 2 * i; /* UTF16 characters are two bytes */
}

/*
 * cifs_strndup_to_utf16 - copy a string to wire format from the local codepage
 * @src - source string
 * @maxlen - don't walk past this many bytes in the source string
 * @utf16_len - the length of the allocated string in bytes (including null)
 * @cp - source codepage
 * @remap - map special chars
 *
 * Take a string convert it from the local codepage to UTF16 and
 * put it in a new buffer. Returns a pointer to the new string or NULL on
 * error.
 */
__le16 *
cifs_strndup_to_utf16(const char *src, const int maxlen, int *utf16_len,
                      const struct nls_table *cp, int remap)
{
        int len;
        __le16 *dst;

        if (!src)
                return NULL;

        len = cifs_local_to_utf16_bytes(src, maxlen, cp);
        len += 2; /* NULL */
        dst = kmalloc(len, GFP_KERNEL);
        if (!dst) {
                *utf16_len = 0;
                return NULL;
        }
        cifsConvertToUTF16(dst, src, strlen(src), cp, remap);
        *utf16_len = len;
        return dst;
}