u-boot/lib/membuff.c

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/*
* Copyright (c) 2015 Google, Inc
* Written by Simon Glass <sjg@chromium.org>
*
* Copyright (c) 1992 Simon Glass
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
#include <errno.h>
#include <malloc.h>
#include "membuff.h"
void membuff_purge(struct membuff *mb)
{
/* set mb->head and mb->tail so the buffers look empty */
mb->head = mb->start;
mb->tail = mb->start;
}
static int membuff_putrawflex(struct membuff *mb, int maxlen, bool update,
char ***data, int *offsetp)
{
int len;
/* always write to 'mb->head' */
assert(data && offsetp);
*data = &mb->start;
*offsetp = mb->head - mb->start;
/* if there is no buffer, we can do nothing */
if (!mb->start)
return 0;
/*
* if head is ahead of tail, we can write from head until the end of
* the buffer
*/
if (mb->head >= mb->tail) {
/* work out how many bytes can fit here */
len = mb->end - mb->head - 1;
if (maxlen >= 0 && len > maxlen)
len = maxlen;
/* update the head pointer to mark these bytes as written */
if (update)
mb->head += len;
/*
* if the tail isn't at start of the buffer, then we can
* write one more byte right at the end
*/
if ((maxlen < 0 || len < maxlen) && mb->tail != mb->start) {
len++;
if (update)
mb->head = mb->start;
}
/* otherwise now we can write until head almost reaches tail */
} else {
/* work out how many bytes can fit here */
len = mb->tail - mb->head - 1;
if (maxlen >= 0 && len > maxlen)
len = maxlen;
/* update the head pointer to mark these bytes as written */
if (update)
mb->head += len;
}
/* return the number of bytes which can be/must be written */
return len;
}
int membuff_putraw(struct membuff *mb, int maxlen, bool update, char **data)
{
char **datap;
int offset;
int size;
size = membuff_putrawflex(mb, maxlen, update, &datap, &offset);
*data = *datap + offset;
return size;
}
bool membuff_putbyte(struct membuff *mb, int ch)
{
char *data;
if (membuff_putraw(mb, 1, true, &data) != 1)
return false;
*data = ch;
return true;
}
int membuff_getraw(struct membuff *mb, int maxlen, bool update, char **data)
{
int len;
/* assume for now there is no data to get */
len = 0;
/*
* in this case head is ahead of tail, so we must return data between
*'tail' and 'head'
*/
if (mb->head > mb->tail) {
/* work out the amount of data */
*data = mb->tail;
len = mb->head - mb->tail;
/* check it isn't too much */
if (maxlen >= 0 && len > maxlen)
len = maxlen;
/* & mark it as read from the buffer */
if (update)
mb->tail += len;
}
/*
* if head is before tail, then we have data between 'tail' and 'end'
* and some more data between 'start' and 'head'(which we can't
* return this time
*/
else if (mb->head < mb->tail) {
/* work out the amount of data */
*data = mb->tail;
len = mb->end - mb->tail;
if (maxlen >= 0 && len > maxlen)
len = maxlen;
if (update) {
mb->tail += len;
if (mb->tail == mb->end)
mb->tail = mb->start;
}
}
debug("getraw: maxlen=%d, update=%d, head=%d, tail=%d, data=%d, len=%d",
maxlen, update, (int)(mb->head - mb->start),
(int)(mb->tail - mb->start), (int)(*data - mb->start), len);
/* return the number of bytes we found */
return len;
}
int membuff_getbyte(struct membuff *mb)
{
char *data = 0;
return membuff_getraw(mb, 1, true, &data) != 1 ? -1 : *(uint8_t *)data;
}
int membuff_peekbyte(struct membuff *mb)
{
char *data = 0;
return membuff_getraw(mb, 1, false, &data) != 1 ? -1 : *(uint8_t *)data;
}
int membuff_get(struct membuff *mb, char *buff, int maxlen)
{
char *data = 0, *buffptr = buff;
int len = 1, i;
/*
* do this in up to two lots(see GetRaw for why) stopping when there
* is no more data
*/
for (i = 0; len && i < 2; i++) {
/* get a pointer to the data available */
len = membuff_getraw(mb, maxlen, true, &data);
/* copy it into the buffer */
memcpy(buffptr, data, len);
buffptr += len;
maxlen -= len;
}
/* return the number of bytes read */
return buffptr - buff;
}
int membuff_put(struct membuff *mb, const char *buff, int length)
{
char *data;
int towrite, i, written;
for (i = written = 0; i < 2; i++) {
/* ask where some data can be written */
towrite = membuff_putraw(mb, length, true, &data);
/* and write it, updating the bytes length */
memcpy(data, buff, towrite);
written += towrite;
buff += towrite;
length -= towrite;
}
/* return the number of bytes written */
return written;
}
bool membuff_isempty(struct membuff *mb)
{
return mb->head == mb->tail;
}
int membuff_avail(struct membuff *mb)
{
struct membuff copy;
int i, avail;
char *data = 0;
/* make a copy of this buffer's control data */
copy = *mb;
/* now read everything out of the copied buffer */
for (i = avail = 0; i < 2; i++)
avail += membuff_getraw(&copy, -1, true, &data);
/* and return how much we read */
return avail;
}
int membuff_size(struct membuff *mb)
{
return mb->end - mb->start;
}
bool membuff_makecontig(struct membuff *mb)
{
int topsize, botsize;
debug("makecontig: head=%d, tail=%d, size=%d",
(int)(mb->head - mb->start), (int)(mb->tail - mb->start),
(int)(mb->end - mb->start));
/*
* first we move anything at the start of the buffer into the correct
* place some way along
*/
if (mb->tail > mb->head) {
/*
* the data is split into two parts, from 0 to ->head and
* from ->tail to ->end. We move the stuff from 0 to ->head
* up to make space for the other data before it
*/
topsize = mb->end - mb->tail;
botsize = mb->head - mb->start;
/*
* must move data at bottom up by 'topsize' bytes - check if
* there's room
*/
if (mb->head + topsize >= mb->tail)
return false;
memmove(mb->start + topsize, mb->start, botsize);
debug(" - memmove(%d, %d, %d)", topsize, 0, botsize);
/* nothing at the start, so skip that step */
} else {
topsize = mb->head - mb->tail;
botsize = 0;
}
/* now move data at top down to the bottom */
memcpy(mb->start, mb->tail, topsize);
debug(" - memcpy(%d, %d, %d)", 0, (int)(mb->tail - mb->start), topsize);
/* adjust pointers */
mb->tail = mb->start;
mb->head = mb->start + topsize + botsize;
debug(" - head=%d, tail=%d", (int)(mb->head - mb->start),
(int)(mb->tail - mb->start));
/* all ok */
return true;
}
int membuff_free(struct membuff *mb)
{
return mb->end == mb->start ? 0 :
(mb->end - mb->start) - 1 - membuff_avail(mb);
}
int membuff_readline(struct membuff *mb, char *str, int maxlen, int minch)
{
int len; /* number of bytes read (!= string length) */
char *s, *end;
bool ok = false;
char *orig = str;
end = mb->head >= mb->tail ? mb->head : mb->end;
for (len = 0, s = mb->tail; s < end && len < maxlen - 1; str++) {
*str = *s++;
len++;
if (*str == '\n' || *str < minch) {
ok = true;
break;
}
if (s == end && mb->tail > mb->head) {
s = mb->start;
end = mb->head;
}
}
/* couldn't get the whole string */
if (!ok) {
if (maxlen)
*orig = '\0';
return 0;
}
/* terminate the string, update the membuff and return success */
*str = '\0';
mb->tail = s == mb->end ? mb->start : s;
return len;
}
int membuff_extend_by(struct membuff *mb, int by, int max)
{
int oldhead, oldtail;
int size, orig;
char *ptr;
/* double the buffer size until it is big enough */
assert(by >= 0);
for (orig = mb->end - mb->start, size = orig; size < orig + by;)
size *= 2;
if (max != -1)
size = min(size, max);
by = size - orig;
/* if we're already at maximum, give up */
if (by <= 0)
return -E2BIG;
oldhead = mb->head - mb->start;
oldtail = mb->tail - mb->start;
ptr = realloc(mb->start, size);
if (!ptr)
return -ENOMEM;
mb->start = ptr;
mb->head = mb->start + oldhead;
mb->tail = mb->start + oldtail;
if (mb->head < mb->tail) {
memmove(mb->tail + by, mb->tail, orig - oldtail);
mb->tail += by;
}
mb->end = mb->start + size;
return 0;
}
void membuff_init(struct membuff *mb, char *buff, int size)
{
mb->start = buff;
mb->end = mb->start + size;
membuff_purge(mb);
}
int membuff_new(struct membuff *mb, int size)
{
mb->start = malloc(size);
if (!mb->start)
return -ENOMEM;
membuff_init(mb, mb->start, size);
return 0;
}
void membuff_uninit(struct membuff *mb)
{
mb->end = NULL;
mb->start = NULL;
membuff_purge(mb);
}
void membuff_dispose(struct membuff *mb)
{
free(&mb->start);
membuff_uninit(mb);
}