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0510e8b58c
curl/lib/bufq.c
Daniel Stenberg 5595e33617
bufq: remove Curl_bufq_skip_and_shift (unused) 
Closes #11915
2023-09-23 10:50:10 +02:00

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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at https://curl.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
* SPDX-License-Identifier: curl
*
***************************************************************************/
#include "curl_setup.h"
#include "bufq.h"
/* The last 3 #include files should be in this order */
#include "curl_printf.h"
#include "curl_memory.h"
#include "memdebug.h"
static bool chunk_is_empty(const struct buf_chunk *chunk)
{
return chunk->r_offset >= chunk->w_offset;
}
static bool chunk_is_full(const struct buf_chunk *chunk)
{
return chunk->w_offset >= chunk->dlen;
}
static size_t chunk_len(const struct buf_chunk *chunk)
{
return chunk->w_offset - chunk->r_offset;
}
static size_t chunk_space(const struct buf_chunk *chunk)
{
return chunk->dlen - chunk->w_offset;
}
static void chunk_reset(struct buf_chunk *chunk)
{
chunk->next = NULL;
chunk->r_offset = chunk->w_offset = 0;
}
static size_t chunk_append(struct buf_chunk *chunk,
const unsigned char *buf, size_t len)
{
unsigned char *p = &chunk->x.data[chunk->w_offset];
size_t n = chunk->dlen - chunk->w_offset;
DEBUGASSERT(chunk->dlen >= chunk->w_offset);
if(n) {
n = CURLMIN(n, len);
memcpy(p, buf, n);
chunk->w_offset += n;
}
return n;
}
static size_t chunk_read(struct buf_chunk *chunk,
unsigned char *buf, size_t len)
{
unsigned char *p = &chunk->x.data[chunk->r_offset];
size_t n = chunk->w_offset - chunk->r_offset;
DEBUGASSERT(chunk->w_offset >= chunk->r_offset);
if(!n) {
return 0;
}
else if(n <= len) {
memcpy(buf, p, n);
chunk->r_offset = chunk->w_offset = 0;
return n;
}
else {
memcpy(buf, p, len);
chunk->r_offset += len;
return len;
}
}
static ssize_t chunk_slurpn(struct buf_chunk *chunk, size_t max_len,
Curl_bufq_reader *reader,
void *reader_ctx, CURLcode *err)
{
unsigned char *p = &chunk->x.data[chunk->w_offset];
size_t n = chunk->dlen - chunk->w_offset; /* free amount */
ssize_t nread;
DEBUGASSERT(chunk->dlen >= chunk->w_offset);
if(!n) {
*err = CURLE_AGAIN;
return -1;
}
if(max_len && n > max_len)
n = max_len;
nread = reader(reader_ctx, p, n, err);
if(nread > 0) {
DEBUGASSERT((size_t)nread <= n);
chunk->w_offset += nread;
}
return nread;
}
static void chunk_peek(const struct buf_chunk *chunk,
const unsigned char **pbuf, size_t *plen)
{
DEBUGASSERT(chunk->w_offset >= chunk->r_offset);
*pbuf = &chunk->x.data[chunk->r_offset];
*plen = chunk->w_offset - chunk->r_offset;
}
static void chunk_peek_at(const struct buf_chunk *chunk, size_t offset,
const unsigned char **pbuf, size_t *plen)
{
offset += chunk->r_offset;
DEBUGASSERT(chunk->w_offset >= offset);
*pbuf = &chunk->x.data[offset];
*plen = chunk->w_offset - offset;
}
static size_t chunk_skip(struct buf_chunk *chunk, size_t amount)
{
size_t n = chunk->w_offset - chunk->r_offset;
DEBUGASSERT(chunk->w_offset >= chunk->r_offset);
if(n) {
n = CURLMIN(n, amount);
chunk->r_offset += n;
if(chunk->r_offset == chunk->w_offset)
chunk->r_offset = chunk->w_offset = 0;
}
return n;
}
static void chunk_list_free(struct buf_chunk **anchor)
{
struct buf_chunk *chunk;
while(*anchor) {
chunk = *anchor;
*anchor = chunk->next;
free(chunk);
}
}
void Curl_bufcp_init(struct bufc_pool *pool,
size_t chunk_size, size_t spare_max)
{
DEBUGASSERT(chunk_size > 0);
DEBUGASSERT(spare_max > 0);
memset(pool, 0, sizeof(*pool));
pool->chunk_size = chunk_size;
pool->spare_max = spare_max;
}
static CURLcode bufcp_take(struct bufc_pool *pool,
struct buf_chunk **pchunk)
{
struct buf_chunk *chunk = NULL;
if(pool->spare) {
chunk = pool->spare;
pool->spare = chunk->next;
--pool->spare_count;
chunk_reset(chunk);
*pchunk = chunk;
return CURLE_OK;
}
chunk = calloc(1, sizeof(*chunk) + pool->chunk_size);
if(!chunk) {
*pchunk = NULL;
return CURLE_OUT_OF_MEMORY;
}
chunk->dlen = pool->chunk_size;
*pchunk = chunk;
return CURLE_OK;
}
static void bufcp_put(struct bufc_pool *pool,
struct buf_chunk *chunk)
{
if(pool->spare_count >= pool->spare_max) {
free(chunk);
}
else {
chunk_reset(chunk);
chunk->next = pool->spare;
pool->spare = chunk;
++pool->spare_count;
}
}
void Curl_bufcp_free(struct bufc_pool *pool)
{
chunk_list_free(&pool->spare);
pool->spare_count = 0;
}
static void bufq_init(struct bufq *q, struct bufc_pool *pool,
size_t chunk_size, size_t max_chunks, int opts)
{
DEBUGASSERT(chunk_size > 0);
DEBUGASSERT(max_chunks > 0);
memset(q, 0, sizeof(*q));
q->chunk_size = chunk_size;
q->max_chunks = max_chunks;
q->pool = pool;
q->opts = opts;
}
void Curl_bufq_init2(struct bufq *q, size_t chunk_size, size_t max_chunks,
int opts)
{
bufq_init(q, NULL, chunk_size, max_chunks, opts);
}
void Curl_bufq_init(struct bufq *q, size_t chunk_size, size_t max_chunks)
{
bufq_init(q, NULL, chunk_size, max_chunks, BUFQ_OPT_NONE);
}
void Curl_bufq_initp(struct bufq *q, struct bufc_pool *pool,
size_t max_chunks, int opts)
{
bufq_init(q, pool, pool->chunk_size, max_chunks, opts);
}
void Curl_bufq_free(struct bufq *q)
{
chunk_list_free(&q->head);
chunk_list_free(&q->spare);
q->tail = NULL;
q->chunk_count = 0;
}
void Curl_bufq_reset(struct bufq *q)
{
struct buf_chunk *chunk;
while(q->head) {
chunk = q->head;
q->head = chunk->next;
chunk->next = q->spare;
q->spare = chunk;
}
q->tail = NULL;
}
size_t Curl_bufq_len(const struct bufq *q)
{
const struct buf_chunk *chunk = q->head;
size_t len = 0;
while(chunk) {
len += chunk_len(chunk);
chunk = chunk->next;
}
return len;
}
size_t Curl_bufq_space(const struct bufq *q)
{
size_t space = 0;
if(q->tail)
space += chunk_space(q->tail);
if(q->spare) {
struct buf_chunk *chunk = q->spare;
while(chunk) {
space += chunk->dlen;
chunk = chunk->next;
}
}
if(q->chunk_count < q->max_chunks) {
space += (q->max_chunks - q->chunk_count) * q->chunk_size;
}
return space;
}
bool Curl_bufq_is_empty(const struct bufq *q)
{
return !q->head || chunk_is_empty(q->head);
}
bool Curl_bufq_is_full(const struct bufq *q)
{
if(!q->tail || q->spare)
return FALSE;
if(q->chunk_count < q->max_chunks)
return FALSE;
if(q->chunk_count > q->max_chunks)
return TRUE;
/* we have no spares and cannot make more, is the tail full? */
return chunk_is_full(q->tail);
}
static struct buf_chunk *get_spare(struct bufq *q)
{
struct buf_chunk *chunk = NULL;
if(q->spare) {
chunk = q->spare;
q->spare = chunk->next;
chunk_reset(chunk);
return chunk;
}
if(q->chunk_count >= q->max_chunks && (!(q->opts & BUFQ_OPT_SOFT_LIMIT)))
return NULL;
if(q->pool) {
if(bufcp_take(q->pool, &chunk))
return NULL;
++q->chunk_count;
return chunk;
}
else {
chunk = calloc(1, sizeof(*chunk) + q->chunk_size);
if(!chunk)
return NULL;
chunk->dlen = q->chunk_size;
++q->chunk_count;
return chunk;
}
}
static void prune_head(struct bufq *q)
{
struct buf_chunk *chunk;
while(q->head && chunk_is_empty(q->head)) {
chunk = q->head;
q->head = chunk->next;
if(q->tail == chunk)
q->tail = q->head;
if(q->pool) {
bufcp_put(q->pool, chunk);
--q->chunk_count;
}
else if((q->chunk_count > q->max_chunks) ||
(q->opts & BUFQ_OPT_NO_SPARES)) {
/* SOFT_LIMIT allowed us more than max. free spares until
* we are at max again. Or free them if we are configured
* to not use spares. */
free(chunk);
--q->chunk_count;
}
else {
chunk->next = q->spare;
q->spare = chunk;
}
}
}
static struct buf_chunk *get_non_full_tail(struct bufq *q)
{
struct buf_chunk *chunk;
if(q->tail && !chunk_is_full(q->tail))
return q->tail;
chunk = get_spare(q);
if(chunk) {
/* new tail, and possibly new head */
if(q->tail) {
q->tail->next = chunk;
q->tail = chunk;
}
else {
DEBUGASSERT(!q->head);
q->head = q->tail = chunk;
}
}
return chunk;
}
ssize_t Curl_bufq_write(struct bufq *q,
const unsigned char *buf, size_t len,
CURLcode *err)
{
struct buf_chunk *tail;
ssize_t nwritten = 0;
size_t n;
DEBUGASSERT(q->max_chunks > 0);
while(len) {
tail = get_non_full_tail(q);
if(!tail) {
if(q->chunk_count < q->max_chunks) {
*err = CURLE_OUT_OF_MEMORY;
return -1;
}
break;
}
n = chunk_append(tail, buf, len);
if(!n)
break;
nwritten += n;
buf += n;
len -= n;
}
if(nwritten == 0 && len) {
*err = CURLE_AGAIN;
return -1;
}
*err = CURLE_OK;
return nwritten;
}
ssize_t Curl_bufq_read(struct bufq *q, unsigned char *buf, size_t len,
CURLcode *err)
{
ssize_t nread = 0;
size_t n;
*err = CURLE_OK;
while(len && q->head) {
n = chunk_read(q->head, buf, len);
if(n) {
nread += n;
buf += n;
len -= n;
}
prune_head(q);
}
if(nread == 0) {
*err = CURLE_AGAIN;
return -1;
}
return nread;
}
bool Curl_bufq_peek(struct bufq *q,
const unsigned char **pbuf, size_t *plen)
{
if(q->head && chunk_is_empty(q->head)) {
prune_head(q);
}
if(q->head && !chunk_is_empty(q->head)) {
chunk_peek(q->head, pbuf, plen);
return TRUE;
}
*pbuf = NULL;
*plen = 0;
return FALSE;
}
bool Curl_bufq_peek_at(struct bufq *q, size_t offset,
const unsigned char **pbuf, size_t *plen)
{
struct buf_chunk *c = q->head;
size_t clen;
while(c) {
clen = chunk_len(c);
if(!clen)
break;
if(offset >= clen) {
offset -= clen;
c = c->next;
continue;
}
chunk_peek_at(c, offset, pbuf, plen);
return TRUE;
}
*pbuf = NULL;
*plen = 0;
return FALSE;
}
void Curl_bufq_skip(struct bufq *q, size_t amount)
{
size_t n;
while(amount && q->head) {
n = chunk_skip(q->head, amount);
amount -= n;
prune_head(q);
}
}
ssize_t Curl_bufq_pass(struct bufq *q, Curl_bufq_writer *writer,
void *writer_ctx, CURLcode *err)
{
const unsigned char *buf;
size_t blen;
ssize_t nwritten = 0;
while(Curl_bufq_peek(q, &buf, &blen)) {
ssize_t chunk_written;
chunk_written = writer(writer_ctx, buf, blen, err);
if(chunk_written < 0) {
if(!nwritten || *err != CURLE_AGAIN) {
/* blocked on first write or real error, fail */
nwritten = -1;
}
break;
}
if(!chunk_written) {
if(!nwritten) {
/* treat as blocked */
*err = CURLE_AGAIN;
nwritten = -1;
}
break;
}
Curl_bufq_skip(q, (size_t)chunk_written);
nwritten += chunk_written;
}
return nwritten;
}
ssize_t Curl_bufq_write_pass(struct bufq *q,
const unsigned char *buf, size_t len,
Curl_bufq_writer *writer, void *writer_ctx,
CURLcode *err)
{
ssize_t nwritten = 0, n;
*err = CURLE_OK;
while(len) {
if(Curl_bufq_is_full(q)) {
/* try to make room in case we are full */
n = Curl_bufq_pass(q, writer, writer_ctx, err);
if(n < 0) {
if(*err != CURLE_AGAIN) {
/* real error, fail */
return -1;
}
/* would block, bufq is full, give up */
break;
}
}
/* Add whatever is remaining now to bufq */
n = Curl_bufq_write(q, buf, len, err);
if(n < 0) {
if(*err != CURLE_AGAIN) {
/* real error, fail */
return -1;
}
/* no room in bufq */
break;
}
/* edge case of writer returning 0 (and len is >0)
* break or we might enter an infinite loop here */
if(n == 0)
break;
/* Maybe only part of `data` has been added, continue to loop */
buf += (size_t)n;
len -= (size_t)n;
nwritten += (size_t)n;
}
if(!nwritten && len) {
*err = CURLE_AGAIN;
return -1;
}
*err = CURLE_OK;
return nwritten;
}
ssize_t Curl_bufq_sipn(struct bufq *q, size_t max_len,
Curl_bufq_reader *reader, void *reader_ctx,
CURLcode *err)
{
struct buf_chunk *tail = NULL;
ssize_t nread;
*err = CURLE_AGAIN;
tail = get_non_full_tail(q);
if(!tail) {
if(q->chunk_count < q->max_chunks) {
*err = CURLE_OUT_OF_MEMORY;
return -1;
}
/* full, blocked */
*err = CURLE_AGAIN;
return -1;
}
nread = chunk_slurpn(tail, max_len, reader, reader_ctx, err);
if(nread < 0) {
return -1;
}
else if(nread == 0) {
/* eof */
*err = CURLE_OK;
}
return nread;
}
/**
* Read up to `max_len` bytes and append it to the end of the buffer queue.
* if `max_len` is 0, no limit is imposed and the call behaves exactly
* the same as `Curl_bufq_slurp()`.
* Returns the total amount of buf read (may be 0) or -1 on other
* reader errors.
* Note that even in case of a -1 chunks may have been read and
* the buffer queue will have different length than before.
*/
static ssize_t bufq_slurpn(struct bufq *q, size_t max_len,
Curl_bufq_reader *reader, void *reader_ctx,
CURLcode *err)
{
ssize_t nread = 0, n;
*err = CURLE_AGAIN;
while(1) {
n = Curl_bufq_sipn(q, max_len, reader, reader_ctx, err);
if(n < 0) {
if(!nread || *err != CURLE_AGAIN) {
/* blocked on first read or real error, fail */
nread = -1;
}
else
*err = CURLE_OK;
break;
}
else if(n == 0) {
/* eof */
*err = CURLE_OK;
break;
}
nread += (size_t)n;
if(max_len) {
DEBUGASSERT((size_t)n <= max_len);
max_len -= (size_t)n;
if(!max_len)
break;
}
/* give up slurping when we get less bytes than we asked for */
if(q->tail && !chunk_is_full(q->tail))
break;
}
return nread;
}
ssize_t Curl_bufq_slurp(struct bufq *q, Curl_bufq_reader *reader,
void *reader_ctx, CURLcode *err)
{
return bufq_slurpn(q, 0, reader, reader_ctx, err);
}
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