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strbuf.c
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strbuf.c
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/* strbuf - String buffer routines
*
* Copyright (c) 2010-2012 Mark Pulford <mark@kyne.com.au>
*
* 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 <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include "strbuf.h"
static void die(const char *fmt, ...)
{
va_list arg;
va_start(arg, fmt);
vfprintf(stderr, fmt, arg);
va_end(arg);
fprintf(stderr, "\n");
exit(-1);
}
void strbuf_init(strbuf_t *s, int len)
{
int size;
if (len <= 0)
size = STRBUF_DEFAULT_SIZE;
else
size = len + 1; /* \0 terminator */
s->buf = NULL;
s->size = size;
s->length = 0;
s->increment = STRBUF_DEFAULT_INCREMENT;
s->dynamic = 0;
s->reallocs = 0;
s->debug = 0;
s->buf = malloc(size);
if (!s->buf)
die("Out of memory");
strbuf_ensure_null(s);
}
strbuf_t *strbuf_new(int len)
{
strbuf_t *s;
s = malloc(sizeof(strbuf_t));
if (!s)
die("Out of memory");
strbuf_init(s, len);
/* Dynamic strbuf allocation / deallocation */
s->dynamic = 1;
return s;
}
void strbuf_set_increment(strbuf_t *s, int increment)
{
/* Increment > 0: Linear buffer growth rate
* Increment < -1: Exponential buffer growth rate */
if (increment == 0 || increment == -1)
die("BUG: Invalid string increment");
s->increment = increment;
}
static inline void debug_stats(strbuf_t *s)
{
if (s->debug) {
fprintf(stderr, "strbuf(%lx) reallocs: %d, length: %d, size: %d\n",
(long)s, s->reallocs, s->length, s->size);
}
}
/* If strbuf_t has not been dynamically allocated, strbuf_free() can
* be called any number of times strbuf_init() */
void strbuf_free(strbuf_t *s)
{
debug_stats(s);
if (s->buf) {
free(s->buf);
s->buf = NULL;
}
if (s->dynamic)
free(s);
}
char *strbuf_free_to_string(strbuf_t *s, int *len)
{
char *buf;
debug_stats(s);
strbuf_ensure_null(s);
buf = s->buf;
if (len)
*len = s->length;
if (s->dynamic)
free(s);
return buf;
}
static int calculate_new_size(strbuf_t *s, int len)
{
int reqsize, newsize;
if (len <= 0)
die("BUG: Invalid strbuf length requested");
/* Ensure there is room for optional NULL termination */
reqsize = len + 1;
/* If the user has requested to shrink the buffer, do it exactly */
if (s->size > reqsize)
return reqsize;
newsize = s->size;
if (s->increment < 0) {
/* Exponential sizing */
while (newsize < reqsize)
newsize *= -s->increment;
} else if (s->increment != 0) {
/* Linear sizing */
newsize = ((newsize + s->increment - 1) / s->increment) * s->increment;
}
return newsize;
}
/* Ensure strbuf can handle a string length bytes long (ignoring NULL
* optional termination). */
void strbuf_resize(strbuf_t *s, int len)
{
int newsize;
newsize = calculate_new_size(s, len);
if (s->debug > 1) {
fprintf(stderr, "strbuf(%lx) resize: %d => %d\n",
(long)s, s->size, newsize);
}
s->size = newsize;
s->buf = realloc(s->buf, s->size);
if (!s->buf)
die("Out of memory");
s->reallocs++;
}
void strbuf_append_string(strbuf_t *s, const char *str)
{
int space, i;
space = strbuf_empty_length(s);
for (i = 0; str[i]; i++) {
if (space < 1) {
strbuf_resize(s, s->length + 1);
space = strbuf_empty_length(s);
}
s->buf[s->length] = str[i];
s->length++;
space--;
}
}
/* strbuf_append_fmt() should only be used when an upper bound
* is known for the output string. */
void strbuf_append_fmt(strbuf_t *s, int len, const char *fmt, ...)
{
va_list arg;
int fmt_len;
strbuf_ensure_empty_length(s, len);
va_start(arg, fmt);
fmt_len = vsnprintf(s->buf + s->length, len, fmt, arg);
va_end(arg);
if (fmt_len < 0)
die("BUG: Unable to convert number"); /* This should never happen.. */
s->length += fmt_len;
}
/* strbuf_append_fmt_retry() can be used when the there is no known
* upper bound for the output string. */
void strbuf_append_fmt_retry(strbuf_t *s, const char *fmt, ...)
{
va_list arg;
int fmt_len, try;
int empty_len;
/* If the first attempt to append fails, resize the buffer appropriately
* and try again */
for (try = 0; ; try++) {
va_start(arg, fmt);
/* Append the new formatted string */
/* fmt_len is the length of the string required, excluding the
* trailing NULL */
empty_len = strbuf_empty_length(s);
/* Add 1 since there is also space to store the terminating NULL. */
fmt_len = vsnprintf(s->buf + s->length, empty_len + 1, fmt, arg);
va_end(arg);
if (fmt_len <= empty_len)
break; /* SUCCESS */
if (try > 0)
die("BUG: length of formatted string changed");
strbuf_resize(s, s->length + fmt_len);
}
s->length += fmt_len;
}
/* vi:ai et sw=4 ts=4:
*/