cutils.c

/*
 * C utilities
 * 
 * Copyright (c) 2017 Fabrice Bellard
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include <string.h>
#include "cutils.h"

void pstrcpy(char *buf, int buf_size, const char *str)
{
    int c;
    char *q = buf;

    if (buf_size <= 0)
        return;

    for(;;) {
        c = *str++;
        if (c == 0 || q >= buf + buf_size - 1)
            break;
        *q++ = c;
    }
    *q = '\0';
}

/* strcat and truncate. */
char *pstrcat(char *buf, int buf_size, const char *s)
{
    int len;
    len = strlen(buf);
    if (len < buf_size)
        pstrcpy(buf + len, buf_size - len, s);
    return buf;
}

int strstart(const char *str, const char *val, const char **ptr)
{
    const char *p, *q;
    p = str;
    q = val;
    while (*q != '\0') {
        if (*p != *q)
            return 0;
        p++;
        q++;
    }
    if (ptr)
        *ptr = p;
    return 1;
}

/* Note: at most 21 bits are encoded. At most UTF8_CHAR_LEN_MAX bytes
   are output. */
int unicode_to_utf8(uint8_t *buf, unsigned int c)
{
    uint8_t *q = buf;

    if (c < 0x80) {
        *q++ = c;
    } else {
        if (c < 0x800) {
            *q++ = (c >> 6) | 0xc0;
        } else {
            if (c < 0x10000) {
                *q++ = (c >> 12) | 0xe0;
            } else {
                if (c < 0x00200000) {
                    *q++ = (c >> 18) | 0xf0;
                } else {
                    return 0;
                }
                *q++ = ((c >> 12) & 0x3f) | 0x80;
            }
            *q++ = ((c >> 6) & 0x3f) | 0x80;
        }
        *q++ = (c & 0x3f) | 0x80;
    }
    return q - buf;
}

/* return -1 if error. *pp is not updated in this case. max_len must
   be >= 1. */
int unicode_from_utf8(const uint8_t *p, int max_len, const uint8_t **pp)
{
    int l, c, b, i, min_code;

    c = *p++;
    if (c < 0x80) {
        *pp = p;
        return c;
    } else if (c < 0xc0) {
        return -1;
    } else if (c < 0xe0) {
        l = 1;
    } else if (c < 0xf0) {
        l = 2;
    } else if (c < 0xf8) {
        l = 3;
    } else {
        return -1;
    }
    /* check that we have enough characters */
    if ((l + 1) > max_len)
        return -1;
    c &= 0x3f >> l;
    for(i = 0; i < l; i++) {
        b = *p++;
        if (b < 0x80 || b >= 0xc0)
            return -1;
        c = (c << 6) | (b & 0x3f);
    }
    if (l == 1)
        min_code = 0x80;
    else
        min_code = 1 << (5 * l + 1);
    if (c < min_code || c > 0x10ffff)
        return -1;
    *pp = p;
    return c;
}

void dbuf_init2(DynBuf *s, void *opaque, DynBufReallocFunc *realloc_func)
{
    memset(s, 0, sizeof(*s));
    s->opaque = opaque;
    s->realloc_func = realloc_func;
}

static void *dbuf_default_realloc(void *opaque, void *ptr, size_t size)
{
    return realloc(ptr, size);
}

void dbuf_init(DynBuf *s)
{
    dbuf_init2(s, NULL, dbuf_default_realloc);
}

/* return < 0 if error */
int dbuf_realloc(DynBuf *s, size_t new_size)
{
    size_t size;
    uint8_t *new_buf;
    if (new_size > s->allocated_size) {
        if (s->error)
            return -1;
        size = s->allocated_size * 3 / 2;
        if (size > new_size)
            new_size = size;
        new_buf = s->realloc_func(s->opaque, s->buf, new_size);
        if (!new_buf) {
            s->error = TRUE;
            return -1;
        }
        s->buf = new_buf;
        s->allocated_size = new_size;
    }
    return 0;
}

int dbuf_write(DynBuf *s, size_t offset, const uint8_t *data, size_t len)
{
    size_t end;
    end = offset + len;
    if (dbuf_realloc(s, end))
        return -1;
    memcpy(s->buf + offset, data, len);
    if (end > s->size)
        s->size = end;
    return 0;
}

int dbuf_put(DynBuf *s, const uint8_t *data, size_t len)
{
    if (unlikely((s->size + len) > s->allocated_size)) {
        if (dbuf_realloc(s, s->size + len))
            return -1;
    }
    memcpy(s->buf + s->size, data, len);
    s->size += len;
    return 0;
}

int dbuf_putc(DynBuf *s, uint8_t c)
{
    return dbuf_put(s, &c, 1);
}

int dbuf_putstr(DynBuf *s, const char *str)
{
    return dbuf_put(s, (const uint8_t *)str, strlen(str));
}

int __attribute__((format(printf, 2, 3))) dbuf_printf(DynBuf *s,
                                                      const char *fmt, ...)
{
    va_list ap;
    char buf[128];
    int len;
    
    va_start(ap, fmt);
    len = vsnprintf(buf, sizeof(buf), fmt, ap);
    va_end(ap);
    if (len < sizeof(buf)) {
        /* fast case */
        return dbuf_put(s, (uint8_t *)buf, len);
    } else {
        if (dbuf_realloc(s, s->size + len + 1))
            return -1;
        va_start(ap, fmt);
        vsnprintf((char *)(s->buf + s->size), s->allocated_size - s->size,
                  fmt, ap);
        va_end(ap);
        s->size += len;
    }
    return 0;
}

void dbuf_free(DynBuf *s)
{
    /* we test s->buf as a fail safe to avoid crashing if dbuf_free()
       is called twice */
    if (s->buf) {
        s->realloc_func(s->opaque, s->buf, 0);
    }
    memset(s, 0, sizeof(*s));
}