conv.c

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/*-------------------------------------------------------------------------
 *
 *    Utility functions for conversion procs.
 *
 * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *    src/backend/utils/mb/conv.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"
#include "mb/pg_wchar.h"
 
 
/*
 * local2local: a generic single byte charset encoding
 * conversion between two ASCII-superset encodings.
 *
 * l points to the source string of length len
 * p is the output area (must be large enough!)
 * src_encoding is the PG identifier for the source encoding
 * dest_encoding is the PG identifier for the target encoding
 * tab holds conversion entries for the source charset
 * starting from 128 (0x80). each entry in the table holds the corresponding
 * code point for the target charset, or 0 if there is no equivalent code.
 *
 * Returns the number of input bytes consumed.  If noError is true, this can
 * be less than 'len'.
 */
int
local2local(const unsigned char *l,
            unsigned char *p,
            int len,
            int src_encoding,
            int dest_encoding,
            const unsigned char *tab,
            bool noError)
{
    const unsigned char *start = l;
    unsigned char c1,
                c2;
 
    while (len > 0)
    {
        c1 = *l;
        if (c1 == 0)
        {
            if (noError)
                break;
            report_invalid_encoding(src_encoding, (const char *) l, len);
        }
        if (!IS_HIGHBIT_SET(c1))
            *p++ = c1;
        else
        {
            c2 = tab[c1 - HIGHBIT];
            if (c2)
                *p++ = c2;
            else
            {
                if (noError)
                    break;
                report_untranslatable_char(src_encoding, dest_encoding,
                                           (const char *) l, len);
            }
        }
        l++;
        len--;
    }
    *p = '\0';
 
    return l - start;
}
 
/*
 * comparison routine for bsearch()
 * this routine is intended for combined UTF8 -> local code
 */
static int
compare3(const void *p1, const void *p2)
{
    uint32      s1,
                s2,
                d1,
                d2;
 
    s1 = *(const uint32 *) p1;
    s2 = *((const uint32 *) p1 + 1);
    d1 = ((const pg_utf_to_local_combined *) p2)->utf1;
    d2 = ((const pg_utf_to_local_combined *) p2)->utf2;
    return (s1 > d1 || (s1 == d1 && s2 > d2)) ? 1 : ((s1 == d1 && s2 == d2) ? 0 : -1);
}
 
/*
 * comparison routine for bsearch()
 * this routine is intended for local code -> combined UTF8
 */
static int
compare4(const void *p1, const void *p2)
{
    uint32      v1,
                v2;
 
    v1 = *(const uint32 *) p1;
    v2 = ((const pg_local_to_utf_combined *) p2)->code;
    return (v1 > v2) ? 1 : ((v1 == v2) ? 0 : -1);
}
 
/*
 * store 32bit character representation into multibyte stream
 */
static inline unsigned char *
store_coded_char(unsigned char *dest, uint32 code)
{
    if (code & 0xff000000)
        *dest++ = code >> 24;
    if (code & 0x00ff0000)
        *dest++ = code >> 16;
    if (code & 0x0000ff00)
        *dest++ = code >> 8;
    if (code & 0x000000ff)
        *dest++ = code;
    return dest;
}
 
/*
 * Convert a character using a conversion radix tree.
 *
 * 'l' is the length of the input character in bytes, and b1-b4 are
 * the input character's bytes.
 */
static inline uint32
pg_mb_radix_conv(const pg_mb_radix_tree *rt,
                 int l,
                 unsigned char b1,
                 unsigned char b2,
                 unsigned char b3,
                 unsigned char b4)
{
    if (l == 4)
    {
        /* 4-byte code */
 
        /* check code validity */
        if (b1 < rt->b4_1_lower || b1 > rt->b4_1_upper ||
            b2 < rt->b4_2_lower || b2 > rt->b4_2_upper ||
            b3 < rt->b4_3_lower || b3 > rt->b4_3_upper ||
            b4 < rt->b4_4_lower || b4 > rt->b4_4_upper)
            return 0;
 
        /* perform lookup */
        if (rt->chars32)
        {
            uint32      idx = rt->b4root;
 
            idx = rt->chars32[b1 + idx - rt->b4_1_lower];
            idx = rt->chars32[b2 + idx - rt->b4_2_lower];
            idx = rt->chars32[b3 + idx - rt->b4_3_lower];
            return rt->chars32[b4 + idx - rt->b4_4_lower];
        }
        else
        {
            uint16      idx = rt->b4root;
 
            idx = rt->chars16[b1 + idx - rt->b4_1_lower];
            idx = rt->chars16[b2 + idx - rt->b4_2_lower];
            idx = rt->chars16[b3 + idx - rt->b4_3_lower];
            return rt->chars16[b4 + idx - rt->b4_4_lower];
        }
    }
    else if (l == 3)
    {
        /* 3-byte code */
 
        /* check code validity */
        if (b2 < rt->b3_1_lower || b2 > rt->b3_1_upper ||
            b3 < rt->b3_2_lower || b3 > rt->b3_2_upper ||
            b4 < rt->b3_3_lower || b4 > rt->b3_3_upper)
            return 0;
 
        /* perform lookup */
        if (rt->chars32)
        {
            uint32      idx = rt->b3root;
 
            idx = rt->chars32[b2 + idx - rt->b3_1_lower];
            idx = rt->chars32[b3 + idx - rt->b3_2_lower];
            return rt->chars32[b4 + idx - rt->b3_3_lower];
        }
        else
        {
            uint16      idx = rt->b3root;
 
            idx = rt->chars16[b2 + idx - rt->b3_1_lower];
            idx = rt->chars16[b3 + idx - rt->b3_2_lower];
            return rt->chars16[b4 + idx - rt->b3_3_lower];
        }
    }
    else if (l == 2)
    {
        /* 2-byte code */
 
        /* check code validity - first byte */
        if (b3 < rt->b2_1_lower || b3 > rt->b2_1_upper ||
            b4 < rt->b2_2_lower || b4 > rt->b2_2_upper)
            return 0;
 
        /* perform lookup */
        if (rt->chars32)
        {
            uint32      idx = rt->b2root;
 
            idx = rt->chars32[b3 + idx - rt->b2_1_lower];
            return rt->chars32[b4 + idx - rt->b2_2_lower];
        }
        else
        {
            uint16      idx = rt->b2root;
 
            idx = rt->chars16[b3 + idx - rt->b2_1_lower];
            return rt->chars16[b4 + idx - rt->b2_2_lower];
        }
    }
    else if (l == 1)
    {
        /* 1-byte code */
 
        /* check code validity - first byte */
        if (b4 < rt->b1_lower || b4 > rt->b1_upper)
            return 0;
 
        /* perform lookup */
        if (rt->chars32)
            return rt->chars32[b4 + rt->b1root - rt->b1_lower];
        else
            return rt->chars16[b4 + rt->b1root - rt->b1_lower];
    }
    return 0;                   /* shouldn't happen */
}
 
/*
 * UTF8 ---> local code
 *
 * utf: input string in UTF8 encoding (need not be null-terminated)
 * len: length of input string (in bytes)
 * iso: pointer to the output area (must be large enough!)
 *        (output string will be null-terminated)
 * map: conversion map for single characters
 * cmap: conversion map for combined characters
 *        (optional, pass NULL if none)
 * cmapsize: number of entries in the conversion map for combined characters
 *        (optional, pass 0 if none)
 * conv_func: algorithmic encoding conversion function
 *        (optional, pass NULL if none)
 * encoding: PG identifier for the local encoding
 *
 * For each character, the cmap (if provided) is consulted first; if no match,
 * the map is consulted next; if still no match, the conv_func (if provided)
 * is applied.  An error is raised if no match is found.
 *
 * See pg_wchar.h for more details about the data structures used here.
 *
 * Returns the number of input bytes consumed.  If noError is true, this can
 * be less than 'len'.
 */
int
UtfToLocal(const unsigned char *utf, int len,
           unsigned char *iso,
           const pg_mb_radix_tree *map,
           const pg_utf_to_local_combined *cmap, int cmapsize,
           utf_local_conversion_func conv_func,
           int encoding, bool noError)
{
    uint32      iutf;
    int         l;
    const pg_utf_to_local_combined *cp;
    const unsigned char *start = utf;
 
    if (!PG_VALID_ENCODING(encoding))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("invalid encoding number: %d", encoding)));
 
    for (; len > 0; len -= l)
    {
        unsigned char b1 = 0;
        unsigned char b2 = 0;
        unsigned char b3 = 0;
        unsigned char b4 = 0;
 
        /* "break" cases all represent errors */
        if (*utf == '\0')
            break;
 
        l = pg_utf_mblen(utf);
        if (len < l)
            break;
 
        if (!pg_utf8_islegal(utf, l))
            break;
 
        if (l == 1)
        {
            /* ASCII case is easy, assume it's one-to-one conversion */
            *iso++ = *utf++;
            continue;
        }
 
        /* collect coded char of length l */
        if (l == 2)
        {
            b3 = *utf++;
            b4 = *utf++;
        }
        else if (l == 3)
        {
            b2 = *utf++;
            b3 = *utf++;
            b4 = *utf++;
        }
        else if (l == 4)
        {
            b1 = *utf++;
            b2 = *utf++;
            b3 = *utf++;
            b4 = *utf++;
        }
        else
        {
            elog(ERROR, "unsupported character length %d", l);
            iutf = 0;           /* keep compiler quiet */
        }
        iutf = (b1 << 24 | b2 << 16 | b3 << 8 | b4);
 
        /* First, try with combined map if possible */
        if (cmap && len > l)
        {
            const unsigned char *utf_save = utf;
            int         len_save = len;
            int         l_save = l;
 
            /* collect next character, same as above */
            len -= l;
 
            l = pg_utf_mblen(utf);
            if (len < l)
            {
                /* need more data to decide if this is a combined char */
                utf -= l_save;
                break;
            }
 
            if (!pg_utf8_islegal(utf, l))
            {
                if (!noError)
                    report_invalid_encoding(PG_UTF8, (const char *) utf, len);
                utf -= l_save;
                break;
            }
 
            /* We assume ASCII character cannot be in combined map */
            if (l > 1)
            {
                uint32      iutf2;
                uint32      cutf[2];
 
                if (l == 2)
                {
                    iutf2 = *utf++ << 8;
                    iutf2 |= *utf++;
                }
                else if (l == 3)
                {
                    iutf2 = *utf++ << 16;
                    iutf2 |= *utf++ << 8;
                    iutf2 |= *utf++;
                }
                else if (l == 4)
                {
                    iutf2 = *utf++ << 24;
                    iutf2 |= *utf++ << 16;
                    iutf2 |= *utf++ << 8;
                    iutf2 |= *utf++;
                }
                else
                {
                    elog(ERROR, "unsupported character length %d", l);
                    iutf2 = 0;  /* keep compiler quiet */
                }
 
                cutf[0] = iutf;
                cutf[1] = iutf2;
 
                cp = bsearch(cutf, cmap, cmapsize,
                             sizeof(pg_utf_to_local_combined), compare3);
 
                if (cp)
                {
                    iso = store_coded_char(iso, cp->code);
                    continue;
                }
            }
 
            /* fail, so back up to reprocess second character next time */
            utf = utf_save;
            len = len_save;
            l = l_save;
        }
 
        /* Now check ordinary map */
        if (map)
        {
            uint32      converted = pg_mb_radix_conv(map, l, b1, b2, b3, b4);
 
            if (converted)
            {
                iso = store_coded_char(iso, converted);
                continue;
            }
        }
 
        /* if there's a conversion function, try that */
        if (conv_func)
        {
            uint32      converted = (*conv_func) (iutf);
 
            if (converted)
            {
                iso = store_coded_char(iso, converted);
                continue;
            }
        }
 
        /* failed to translate this character */
        utf -= l;
        if (noError)
            break;
        report_untranslatable_char(PG_UTF8, encoding,
                                   (const char *) utf, len);
    }
 
    /* if we broke out of loop early, must be invalid input */
    if (len > 0 && !noError)
        report_invalid_encoding(PG_UTF8, (const char *) utf, len);
 
    *iso = '\0';
 
    return utf - start;
}
 
/*
 * local code ---> UTF8
 *
 * iso: input string in local encoding (need not be null-terminated)
 * len: length of input string (in bytes)
 * utf: pointer to the output area (must be large enough!)
 *        (output string will be null-terminated)
 * map: conversion map for single characters
 * cmap: conversion map for combined characters
 *        (optional, pass NULL if none)
 * cmapsize: number of entries in the conversion map for combined characters
 *        (optional, pass 0 if none)
 * conv_func: algorithmic encoding conversion function
 *        (optional, pass NULL if none)
 * encoding: PG identifier for the local encoding
 *
 * For each character, the map is consulted first; if no match, the cmap
 * (if provided) is consulted next; if still no match, the conv_func
 * (if provided) is applied.  An error is raised if no match is found.
 *
 * See pg_wchar.h for more details about the data structures used here.
 *
 * Returns the number of input bytes consumed.  If noError is true, this can
 * be less than 'len'.
 */
int
LocalToUtf(const unsigned char *iso, int len,
           unsigned char *utf,
           const pg_mb_radix_tree *map,
           const pg_local_to_utf_combined *cmap, int cmapsize,
           utf_local_conversion_func conv_func,
           int encoding,
           bool noError)
{
    uint32      iiso;
    int         l;
    const pg_local_to_utf_combined *cp;
    const unsigned char *start = iso;
 
    if (!PG_VALID_ENCODING(encoding))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("invalid encoding number: %d", encoding)));
 
    for (; len > 0; len -= l)
    {
        unsigned char b1 = 0;
        unsigned char b2 = 0;
        unsigned char b3 = 0;
        unsigned char b4 = 0;
 
        /* "break" cases all represent errors */
        if (*iso == '\0')
            break;
 
        if (!IS_HIGHBIT_SET(*iso))
        {
            /* ASCII case is easy, assume it's one-to-one conversion */
            *utf++ = *iso++;
            l = 1;
            continue;
        }
 
        l = pg_encoding_verifymbchar(encoding, (const char *) iso, len);
        if (l < 0)
            break;
 
        /* collect coded char of length l */
        if (l == 1)
            b4 = *iso++;
        else if (l == 2)
        {
            b3 = *iso++;
            b4 = *iso++;
        }
        else if (l == 3)
        {
            b2 = *iso++;
            b3 = *iso++;
            b4 = *iso++;
        }
        else if (l == 4)
        {
            b1 = *iso++;
            b2 = *iso++;
            b3 = *iso++;
            b4 = *iso++;
        }
        else
        {
            elog(ERROR, "unsupported character length %d", l);
            iiso = 0;           /* keep compiler quiet */
        }
        iiso = (b1 << 24 | b2 << 16 | b3 << 8 | b4);
 
        if (map)
        {
            uint32      converted = pg_mb_radix_conv(map, l, b1, b2, b3, b4);
 
            if (converted)
            {
                utf = store_coded_char(utf, converted);
                continue;
            }
 
            /* If there's a combined character map, try that */
            if (cmap)
            {
                cp = bsearch(&iiso, cmap, cmapsize,
                             sizeof(pg_local_to_utf_combined), compare4);
 
                if (cp)
                {
                    utf = store_coded_char(utf, cp->utf1);
                    utf = store_coded_char(utf, cp->utf2);
                    continue;
                }
            }
        }
 
        /* if there's a conversion function, try that */
        if (conv_func)
        {
            uint32      converted = (*conv_func) (iiso);
 
            if (converted)
            {
                utf = store_coded_char(utf, converted);
                continue;
            }
        }
 
        /* failed to translate this character */
        iso -= l;
        if (noError)
            break;
        report_untranslatable_char(encoding, PG_UTF8,
                                   (const char *) iso, len);
    }
 
    /* if we broke out of loop early, must be invalid input */
    if (len > 0 && !noError)
        report_invalid_encoding(encoding, (const char *) iso, len);
 
    *utf = '\0';
 
    return iso - start;
}