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/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* util/support/k5buf.c - string buffer functions */
/*
* Copyright 2008 Massachusetts Institute of Technology.
* All Rights Reserved.
*
* Export of this software from the United States of America may
* require a specific license from the United States Government.
* It is the responsibility of any person or organization contemplating
* export to obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
* distribute this software and its documentation for any purpose and
* without fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of M.I.T. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. Furthermore if you modify this software you must label
* your software as modified software and not distribute it in such a
* fashion that it might be confused with the original M.I.T. software.
* M.I.T. makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*/
/*
* Can't include krb5.h here, or k5-int.h which includes it, because krb5.h
* needs to be generated with error tables, after util/et, which builds after
* this directory.
*/
#include "k5buf-int.h"
#include <assert.h>
/*
* Structure invariants:
*
* buftype is BUFTYPE_FIXED, BUFTYPE_DYNAMIC, or BUFTYPE_ERROR
* if buftype is not BUFTYPE_ERROR:
* space > 0
* space <= floor(SIZE_MAX / 2) (to fit within ssize_t)
* len < space
* data[len] = '\0'
*/
/*
* Make sure there is room for LEN more characters in BUF, in addition to the
* null terminator and what's already in there. Return true on success. On
* failure, set the error flag and return false.
*/
static int
ensure_space(struct k5buf *buf, size_t len)
{
size_t new_space;
char *new_data;
if (buf->buftype == BUFTYPE_ERROR)
return 0;
if (buf->space - 1 - buf->len >= len) /* Enough room already. */
return 1;
if (buf->buftype == BUFTYPE_FIXED) /* Can't resize a fixed buffer. */
goto error_exit;
assert(buf->buftype == BUFTYPE_DYNAMIC);
new_space = buf->space * 2;
while (new_space <= SPACE_MAX && new_space - buf->len - 1 < len)
new_space *= 2;
if (new_space > SPACE_MAX)
goto error_exit;
new_data = realloc(buf->data, new_space);
if (new_data == NULL)
goto error_exit;
buf->data = new_data;
buf->space = new_space;
return 1;
error_exit:
if (buf->buftype == BUFTYPE_DYNAMIC) {
free(buf->data);
buf->data = NULL;
}
buf->buftype = BUFTYPE_ERROR;
return 0;
}
void
k5_buf_init_fixed(struct k5buf *buf, char *data, size_t space)
{
assert(space > 0);
buf->buftype = BUFTYPE_FIXED;
buf->data = data;
buf->space = space;
buf->len = 0;
buf->data[0] = '\0';
}
void
k5_buf_init_dynamic(struct k5buf *buf)
{
buf->buftype = BUFTYPE_DYNAMIC;
buf->space = DYNAMIC_INITIAL_SIZE;
buf->data = malloc(buf->space);
if (buf->data == NULL) {
buf->buftype = BUFTYPE_ERROR;
return;
}
buf->len = 0;
buf->data[0] = '\0';
}
void
k5_buf_add(struct k5buf *buf, const char *data)
{
k5_buf_add_len(buf, data, strlen(data));
}
void
k5_buf_add_len(struct k5buf *buf, const char *data, size_t len)
{
if (!ensure_space(buf, len))
return;
if (len > 0)
memcpy(buf->data + buf->len, data, len);
buf->len += len;
buf->data[buf->len] = '\0';
}
void
k5_buf_add_fmt(struct k5buf *buf, const char *fmt, ...)
{
va_list ap;
int r;
size_t remaining;
char *tmp;
if (buf->buftype == BUFTYPE_ERROR)
return;
remaining = buf->space - buf->len;
if (buf->buftype == BUFTYPE_FIXED) {
/* Format the data directly into the fixed buffer. */
va_start(ap, fmt);
r = vsnprintf(buf->data + buf->len, remaining, fmt, ap);
va_end(ap);
if (SNPRINTF_OVERFLOW(r, remaining))
buf->buftype = BUFTYPE_ERROR;
else
buf->len += (unsigned int) r;
return;
}
/* Optimistically format the data directly into the dynamic buffer. */
assert(buf->buftype == BUFTYPE_DYNAMIC);
va_start(ap, fmt);
r = vsnprintf(buf->data + buf->len, remaining, fmt, ap);
va_end(ap);
if (!SNPRINTF_OVERFLOW(r, remaining)) {
buf->len += (unsigned int) r;
return;
}
if (r >= 0) {
/* snprintf correctly told us how much space is required. */
if (!ensure_space(buf, r))
return;
remaining = buf->space - buf->len;
va_start(ap, fmt);
r = vsnprintf(buf->data + buf->len, remaining, fmt, ap);
va_end(ap);
if (SNPRINTF_OVERFLOW(r, remaining)) /* Shouldn't ever happen. */
buf->buftype = BUFTYPE_ERROR;
else
buf->len += (unsigned int) r;
return;
}
/* It's a pre-C99 snprintf implementation, or something else went wrong.
* Fall back to asprintf. */
va_start(ap, fmt);
r = vasprintf(&tmp, fmt, ap);
va_end(ap);
if (r < 0) {
buf->buftype = BUFTYPE_ERROR;
return;
}
if (ensure_space(buf, r)) {
/* Copy the temporary string into buf, including terminator. */
memcpy(buf->data + buf->len, tmp, r + 1);
buf->len += r;
}
free(tmp);
}
void
k5_buf_truncate(struct k5buf *buf, size_t len)
{
if (buf->buftype == BUFTYPE_ERROR)
return;
assert(len <= buf->len);
buf->len = len;
buf->data[buf->len] = '\0';
}
char *
k5_buf_data(struct k5buf *buf)
{
return (buf->buftype == BUFTYPE_ERROR) ? NULL : buf->data;
}
ssize_t
k5_buf_len(struct k5buf *buf)
{
return (buf->buftype == BUFTYPE_ERROR) ? -1 : (ssize_t) buf->len;
}
void
k5_free_buf(struct k5buf *buf)
{
if (buf->buftype == BUFTYPE_ERROR)
return;
assert(buf->buftype == BUFTYPE_DYNAMIC);
free(buf->data);
buf->data = NULL;
buf->buftype = BUFTYPE_ERROR;
}
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