str_iconv.c

str_iconv.c

/* str_iconv() function */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <iconv.h>

static char *
str_iconv(const char *fromcode, const char *tocode, const char *str, size_t len)
{
    iconv_t cd = (iconv_t)(-1);
    char buf[8192];
    char *outbuf = NULL;
    size_t outlen;
    char *newbuf;
    const char *from;
    size_t fromlen;
    char *to;
    size_t tolen;
    size_t r;

    cd = iconv_open(tocode, fromcode);
    if (cd == (iconv_t)(-1))
        return NULL;

    from = str;
    if (len == (size_t)(-1))
        fromlen = strlen(str);
    else
        fromlen = len;

    outlen = 1;
    outbuf = calloc(outlen, sizeof(char));
    if (outbuf == NULL)
        goto onerror;

    while (fromlen > 0) {
        to = buf;
        tolen = sizeof(buf);
        r = iconv(cd, (void *)&from, &fromlen, &to, &tolen);
        if (r == (size_t)(-1)) {
            if (errno == E2BIG) {
                /* There is not sufficient room at *outbuf. */
                /* Verbose check. */
                if (to == buf)
                    goto onerror;
            } else if (errno == EILSEQ) {
                /* An invalid multibyte sequence has been encountered in
                 * the input. */
                goto onerror;
            } else if (errno == EINVAL) {
                /* An incomplete multibyte sequence has been encountered
                 * in the input. */
                /* Read more bytes from input if possible. */
                goto onerror;
            } else {
                /* Unknown error.  Probarly never happen. */
                goto onerror;
            }
        }
        newbuf = realloc(outbuf, outlen + (to - buf));
        if (newbuf == NULL)
            goto onerror;
        outbuf = newbuf;
        memmove(outbuf + outlen - 1, buf, to - buf);
        outlen = outlen + (to - buf);
        outbuf[outlen - 1] = '\0';
    }

    /* flush */
    to = buf;
    tolen = sizeof(buf);
    r = iconv(cd, NULL, NULL, &to, &tolen);
    if (r == (size_t)(-1))
        goto onerror;
    if (to - buf > 0) {
        newbuf = realloc(outbuf, outlen + (to - buf));
        if (newbuf == NULL)
            goto onerror;
        outbuf = newbuf;
        memmove(outbuf + outlen - 1, buf, to - buf);
        outlen = outlen + (to - buf);
        outbuf[outlen - 1] = '\0';
    }

    iconv_close(cd);

    return outbuf;

onerror:
    if (outbuf != NULL)
        free(outbuf);
    if (cd != (iconv_t)(-1))
        iconv_close(cd);
    return NULL;
}

int
main(int argc, char **argv)
{
    char *buf;
    char *p;

    buf = str_iconv("utf-8", "cp932", "あいうえお", -1);
    printf("cp932: ");
    for (p = buf; *p != '\0'; ++p) {
        printf("%02x ", (unsigned char)*p);
    }
    printf("\n");
    free(buf);

    buf = str_iconv("utf-8", "euc-jp", "あいうえお", -1);
    printf("euc-jp: ");
    for (p = buf; *p != '\0'; ++p) {
        printf("%02x ", (unsigned char)*p);
    }
    printf("\n");
    free(buf);

    return 0;
}