libcmdutils/common/custr.c

/*
 * This file and its contents are supplied under the terms of the
 * Common Development and Distribution License ("CDDL"), version 1.0.
 * You may only use this file in accordance with the terms of version
 * 1.0 of the CDDL.
 *
 * A full copy of the text of the CDDL should have accompanied this
 * source.  A copy of the CDDL is also available via the Internet at
 * http://www.illumos.org/license/CDDL.
 */

/*
 * String utility functions with dynamic memory management.
 */

/*
 * Copyright 2016 Joyent, Inc.
 */

#include <stdlib.h>
#include <err.h>
#include <string.h>
#include <stdio.h>
#include <stdarg.h>
#include <sys/debug.h>

#include "libcmdutils.h"

typedef enum {
    CUSTR_FIXEDBUF  = 0x01
} custr_flags_t;

struct custr {
    size_t cus_strlen;
    size_t cus_datalen;
    char *cus_data;
    custr_flags_t cus_flags;
};

#define STRING_CHUNK_SIZE   64

void
custr_reset(custr_t *cus)
{
    if (cus->cus_data == NULL)
        return;

    cus->cus_strlen = 0;
    cus->cus_data[0] = '\0';
}

size_t
custr_len(custr_t *cus)
{
    return (cus->cus_strlen);
}

const char *
custr_cstr(custr_t *cus)
{
    if (cus->cus_data == NULL) {
        VERIFY(cus->cus_strlen == 0);
        VERIFY(cus->cus_datalen == 0);

        /*
         * This function should never return NULL.  If no buffer has
         * been allocated, return a pointer to a zero-length string.
         */
        return ("");
    }
    return (cus->cus_data);
}

int
custr_append_vprintf(custr_t *cus, const char *fmt, va_list ap)
{
    int len = vsnprintf(NULL, 0, fmt, ap);
    size_t chunksz = STRING_CHUNK_SIZE;

    if (len == -1)
        return (len);

    while (chunksz < len) {
        chunksz *= 2;
    }

    if (len + cus->cus_strlen + 1 >= cus->cus_datalen) {
        char *new_data;
        size_t new_datalen = cus->cus_datalen + chunksz;

        if (cus->cus_flags & CUSTR_FIXEDBUF) {
            errno = EOVERFLOW;
            return (-1);
        }

        /*
         * Allocate replacement memory:
         */
        if ((new_data = malloc(new_datalen)) == NULL) {
            return (-1);
        }

        /*
         * Copy existing data into replacement memory and free
         * the old memory.
         */
        if (cus->cus_data != NULL) {
            (void) memcpy(new_data, cus->cus_data,
                cus->cus_strlen + 1);
            free(cus->cus_data);
        }

        /*
         * Swap in the replacement buffer:
         */
        cus->cus_data = new_data;
        cus->cus_datalen = new_datalen;
    }
    /*
     * Append new string to existing string:
     */
    len = vsnprintf(cus->cus_data + cus->cus_strlen,
        (uintptr_t)cus->cus_data - (uintptr_t)cus->cus_strlen, fmt, ap);
    if (len == -1)
        return (len);
    cus->cus_strlen += len;

    return (0);
}

int
custr_appendc(custr_t *cus, char newc)
{
    return (custr_append_printf(cus, "%c", newc));
}

int
custr_append_printf(custr_t *cus, const char *fmt, ...)
{
    va_list ap;
    int ret;

    va_start(ap, fmt);
    ret = custr_append_vprintf(cus, fmt, ap);
    va_end(ap);

    return (ret);
}

int
custr_append(custr_t *cus, const char *name)
{
    return (custr_append_printf(cus, "%s", name));
}

int
custr_alloc(custr_t **cus)
{
    custr_t *t;

    if ((t = calloc(1, sizeof (*t))) == NULL) {
        *cus = NULL;
        return (-1);
    }

    *cus = t;
    return (0);
}

int
custr_alloc_buf(custr_t **cus, void *buf, size_t buflen)
{
    int ret;

    if (buflen == 0 || buf == NULL) {
        errno = EINVAL;
        return (-1);
    }

    if ((ret = custr_alloc(cus)) != 0)
        return (ret);

    (*cus)->cus_data = buf;
    (*cus)->cus_datalen = buflen;
    (*cus)->cus_strlen = 0;
    (*cus)->cus_flags = CUSTR_FIXEDBUF;
    (*cus)->cus_data[0] = '\0';

    return (0);
}

void
custr_free(custr_t *cus)
{
    if (cus == NULL)
        return;

    if ((cus->cus_flags & CUSTR_FIXEDBUF) == 0)
        free(cus->cus_data);
    free(cus);
}