utf8_and_iso8859_1.c

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/*-------------------------------------------------------------------------
 *
 *    ISO8859_1 <--> UTF8
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *    src/backend/utils/mb/conversion_procs/utf8_and_iso8859_1/utf8_and_iso8859_1.c
 *
 *-------------------------------------------------------------------------
 */
 
#include "postgres.h"
#include "fmgr.h"
#include "mb/pg_wchar.h"
 
PG_MODULE_MAGIC_EXT(
                    .name = "utf8_and_iso8859_1",
                    .version = PG_VERSION
);
 
PG_FUNCTION_INFO_V1(iso8859_1_to_utf8);
PG_FUNCTION_INFO_V1(utf8_to_iso8859_1);
 
/* ----------
 * conv_proc(
 *      INTEGER,    -- source encoding id
 *      INTEGER,    -- destination encoding id
 *      CSTRING,    -- source string (null terminated C string)
 *      CSTRING,    -- destination string (null terminated C string)
 *      INTEGER,    -- source string length
 *      BOOL        -- if true, don't throw an error if conversion fails
 * ) returns INTEGER;
 *
 * Returns the number of bytes successfully converted.
 * ----------
 */
 
Datum
iso8859_1_to_utf8(PG_FUNCTION_ARGS)
{
    unsigned char *src = (unsigned char *) PG_GETARG_CSTRING(2);
    unsigned char *dest = (unsigned char *) PG_GETARG_CSTRING(3);
    int         len = PG_GETARG_INT32(4);
    bool        noError = PG_GETARG_BOOL(5);
    unsigned char *start = src;
    unsigned short c;
 
    CHECK_ENCODING_CONVERSION_ARGS(PG_LATIN1, PG_UTF8);
 
    while (len > 0)
    {
        c = *src;
        if (c == 0)
        {
            if (noError)
                break;
            report_invalid_encoding(PG_LATIN1, (const char *) src, len);
        }
        if (!IS_HIGHBIT_SET(c))
            *dest++ = c;
        else
        {
            *dest++ = (c >> 6) | 0xc0;
            *dest++ = (c & 0x003f) | HIGHBIT;
        }
        src++;
        len--;
    }
    *dest = '\0';
 
    PG_RETURN_INT32(src - start);
}
 
Datum
utf8_to_iso8859_1(PG_FUNCTION_ARGS)
{
    unsigned char *src = (unsigned char *) PG_GETARG_CSTRING(2);
    unsigned char *dest = (unsigned char *) PG_GETARG_CSTRING(3);
    int         len = PG_GETARG_INT32(4);
    bool        noError = PG_GETARG_BOOL(5);
    unsigned char *start = src;
    unsigned short c,
                c1;
 
    CHECK_ENCODING_CONVERSION_ARGS(PG_UTF8, PG_LATIN1);
 
    while (len > 0)
    {
        c = *src;
        if (c == 0)
        {
            if (noError)
                break;
            report_invalid_encoding(PG_UTF8, (const char *) src, len);
        }
        /* fast path for ASCII-subset characters */
        if (!IS_HIGHBIT_SET(c))
        {
            *dest++ = c;
            src++;
            len--;
        }
        else
        {
            int         l = pg_utf_mblen(src);
 
            if (l > len || !pg_utf8_islegal(src, l))
            {
                if (noError)
                    break;
                report_invalid_encoding(PG_UTF8, (const char *) src, len);
            }
            if (l != 2)
            {
                if (noError)
                    break;
                report_untranslatable_char(PG_UTF8, PG_LATIN1,
                                           (const char *) src, len);
            }
            c1 = src[1] & 0x3f;
            c = ((c & 0x1f) << 6) | c1;
            if (c >= 0x80 && c <= 0xff)
            {
                *dest++ = (unsigned char) c;
                src += 2;
                len -= 2;
            }
            else
            {
                if (noError)
                    break;
                report_untranslatable_char(PG_UTF8, PG_LATIN1,
                                           (const char *) src, len);
            }
        }
    }
    *dest = '\0';
 
    PG_RETURN_INT32(src - start);
}