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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
#include "config.h"
#include <stddef.h>
#include <string.h>
* Returns the space remaining in a buffer assuming that the given number of
* bytes have already been written. If the number of bytes exceeds the size
* of the buffer, zero is returned.
* @param n
* The size of the buffer in bytes.
* @param length
* The number of bytes which have been written to the buffer so far. If
* the routine writing the bytes will automatically truncate its writes,
* this value may exceed the size of the buffer.
* @return
* The number of bytes remaining in the buffer. This value will always
* be non-negative. If the number of bytes written already exceeds the
* size of the buffer, zero will be returned.
#define REMAINING(n, length) (((n) < (length)) ? 0 : ((n) - (length)))
size_t guac_strlcpy(char* restrict dest, const char* restrict src, size_t n) {
return strlcpy(dest, src, n);
/* Calculate actual length of desired string */
size_t length = strlen(src);
/* Copy nothing if there is no space */
if (n == 0)
return length;
/* Calculate length of the string which will be copied */
size_t copy_length = length;
if (copy_length >= n)
copy_length = n - 1;
/* Copy only as much of string as possible, manually adding a null
* terminator */
memcpy(dest, src, copy_length);
dest[copy_length] = '\0';
/* Return the overall length of the desired string */
return length;
size_t guac_strlcat(char* restrict dest, const char* restrict src, size_t n) {
return strlcat(dest, src, n);
size_t length = strnlen(dest, n);
return length + guac_strlcpy(dest + length, src, REMAINING(n, length));
size_t guac_strljoin(char* restrict dest, const char* restrict const* elements,
int nmemb, const char* restrict delim, size_t n) {
size_t length = 0;
const char* restrict const* current = elements;
/* If no elements are provided, nothing to do but ensure the destination
* buffer is null terminated */
if (nmemb <= 0)
return guac_strlcpy(dest, "", n);
/* Initialize destination buffer with first element */
length += guac_strlcpy(dest, *current, n);
/* Copy all remaining elements, separated by delimiter */
for (current++; nmemb > 1; current++, nmemb--) {
length += guac_strlcat(dest + length, delim, REMAINING(n, length));
length += guac_strlcat(dest + length, *current, REMAINING(n, length));
return length;