src/lib/str.c

/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "buffer.h"
#include "printf-format-fix.h"
#include "str.h"

#include <stdio.h>

string_t *str_new(pool_t pool, size_t initial_size)
{
    /* never allocate a 0 byte size buffer. this is especially important
       when str_c() is called on an empty string from a different stack
       frame (see the comment in buffer.c about this). */
    return buffer_create_dynamic(pool, I_MAX(initial_size, 1));
}

string_t *str_new_const(pool_t pool, const char *str, size_t len)
{
    string_t *ret;

    i_assert(str[len] == '\0');

    ret = p_new(pool, buffer_t, 1);
    buffer_create_from_const_data(ret, str, len + 1);
    str_truncate(ret, len);
    return ret;
}

string_t *t_str_new(size_t initial_size)
{
    return str_new(pool_datastack_create(), initial_size);
}

string_t *t_str_new_const(const char *str, size_t len)
{
    return str_new_const(pool_datastack_create(), str, len);
}

void str_free(string_t **str)
{
    if (str == NULL || *str == NULL)
        return;

    buffer_free(str);
}

static void str_add_nul(string_t *str)
{
    const unsigned char *data = str_data(str);
    size_t len = str_len(str);
    size_t alloc = buffer_get_size(str);

    if (len == alloc || data[len] != '\0') {
        buffer_write(str, len, "", 1);
        /* remove the \0 - we don't want to keep it */
        buffer_set_used_size(str, len);
    }
}

char *str_free_without_data(string_t **str)
{
    str_add_nul(*str);
    return buffer_free_without_data(str);
}

const char *str_c(string_t *str)
{
    str_add_nul(str);
    return str->data;
}

char *str_c_modifiable(string_t *str)
{
    str_add_nul(str);
    return buffer_get_modifiable_data(str, NULL);
}

bool str_equals(const string_t *str1, const string_t *str2)
{
    if (str1->used != str2->used)
        return FALSE;

    return memcmp(str1->data, str2->data, str1->used) == 0;
}

void str_append_n(string_t *str, const void *cstr, size_t max_len)
{
    const char *p;
    size_t len;

    p = memchr(cstr, '\0', max_len);
    if (p == NULL)
        len = max_len;
    else
        len = p - (const char *)cstr;
    buffer_append(str, cstr, len);
}

void str_printfa(string_t *str, const char *fmt, ...)
{
    va_list args;

    va_start(args, fmt);
    str_vprintfa(str, fmt, args);
    va_end(args);
}

void str_vprintfa(string_t *str, const char *fmt, va_list args)
{
#define SNPRINTF_INITIAL_EXTRA_SIZE 128
    va_list args2;
    char *tmp;
    size_t init_size;
    size_t pos = str->used;
    int ret, ret2;

    VA_COPY(args2, args);

    /* the format string is modified only if %m exists in it. it happens
       only in error conditions, so don't try to t_push() here since it'll
       just slow down the normal code path. */
    fmt = printf_format_fix_get_len(fmt, &init_size);
    init_size += SNPRINTF_INITIAL_EXTRA_SIZE;

    /* @UNSAFE */
    if (pos+init_size > buffer_get_writable_size(str) &&
        pos < buffer_get_writable_size(str)) {
        /* avoid growing buffer larger if possible. this is also
           required if buffer isn't dynamically growing. */
        init_size = buffer_get_writable_size(str)-pos;
    }
    tmp = buffer_get_space_unsafe(str, pos, init_size);
    ret = vsnprintf(tmp, init_size, fmt, args);
    i_assert(ret >= 0);

    if ((unsigned int)ret >= init_size) {
        /* didn't fit with the first guess. now we know the size,
           so try again. */
        tmp = buffer_get_space_unsafe(str, pos, ret + 1);
        ret2 = vsnprintf(tmp, ret + 1, fmt, args2);
        i_assert(ret2 == ret);
    }
    va_end(args2);

    /* drop the unused data, including terminating NUL */
    buffer_set_used_size(str, pos + ret);
}