quickjs-tart

bufq.h (9943B)

---

 #ifndef HEADER_CURL_BUFQ_H
 #define HEADER_CURL_BUFQ_H
 /***************************************************************************
  *                                  _   _ ____  _
  *  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 <curl/curl.h>
 
 /**
  * A chunk of bytes for reading and writing.
  * The size is fixed a creation with read and write offset
  * for where unread content is.
  */
 struct buf_chunk {
   struct buf_chunk *next;  /* to keep it in a list */
   size_t dlen;             /* the amount of allocated x.data[] */
   size_t r_offset;         /* first unread bytes */
   size_t w_offset;         /* one after last written byte */
   union {
     unsigned char data[1]; /* the buffer for `dlen` bytes */
     void *dummy;           /* alignment */
   } x;
 };
 
 /**
  * A pool for providing/keeping a number of chunks of the same size
  *
  * The same pool can be shared by many `bufq` instances. However, a pool
  * is not thread safe. All bufqs using it are supposed to operate in the
  * same thread.
  */
 struct bufc_pool {
   struct buf_chunk *spare;  /* list of available spare chunks */
   size_t chunk_size;        /* the size of chunks in this pool */
   size_t spare_count;       /* current number of spare chunks in list */
   size_t spare_max;         /* max number of spares to keep */
 };
 
 void Curl_bufcp_init(struct bufc_pool *pool,
                      size_t chunk_size, size_t spare_max);
 
 void Curl_bufcp_free(struct bufc_pool *pool);
 
 /**
  * A queue of byte chunks for reading and writing.
  * Reading is done from `head`, writing is done to `tail`.
  *
  * `bufq`s can be empty or full or neither. Its `len` is the number
  * of bytes that can be read. For an empty bufq, `len` will be 0.
  *
  * By default, a bufq can hold up to `max_chunks * chunk_size` number
  * of bytes. When `max_chunks` are used (in the `head` list) and the
  * `tail` chunk is full, the bufq will report that it is full.
  *
  * On a full bufq, `len` may be less than the maximum number of bytes,
  * e.g. when the head chunk is partially read. `len` may also become
  * larger than the max when option `BUFQ_OPT_SOFT_LIMIT` is used.
  *
  * By default, writing to a full bufq will return (-1, CURLE_AGAIN). Same
  * as reading from an empty bufq.
  * With `BUFQ_OPT_SOFT_LIMIT` set, a bufq will allow writing becond this
  * limit and use more than `max_chunks`. However it will report that it
  * is full nevertheless. This is provided for situation where writes
  * preferably never fail (except for memory exhaustion).
  *
  * By default and without a pool, a bufq will keep chunks that read
  * empty in its `spare` list. Option `BUFQ_OPT_NO_SPARES` will
  * disable that and free chunks once they become empty.
  *
  * When providing a pool to a bufq, all chunk creation and spare handling
  * will be delegated to that pool.
  */
 struct bufq {
   struct buf_chunk *head;       /* chunk with bytes to read from */
   struct buf_chunk *tail;       /* chunk to write to */
   struct buf_chunk *spare;      /* list of free chunks, unless `pool` */
   struct bufc_pool *pool;       /* optional pool for free chunks */
   size_t chunk_count;           /* current number of chunks in `head+spare` */
   size_t max_chunks;            /* max `head` chunks to use */
   size_t chunk_size;            /* size of chunks to manage */
   int opts;                     /* options for handling queue, see below */
 };
 
 /**
  * Default behaviour: chunk limit is "hard", meaning attempts to write
  * more bytes than can be hold in `max_chunks` is refused and will return
  * -1, CURLE_AGAIN. */
 #define BUFQ_OPT_NONE        (0)
 /**
  * Make `max_chunks` a "soft" limit. A bufq will report that it is "full"
  * when `max_chunks` are used, but allows writing beyond this limit.
  */
 #define BUFQ_OPT_SOFT_LIMIT  (1 << 0)
 /**
  * Do not keep spare chunks.
  */
 #define BUFQ_OPT_NO_SPARES   (1 << 1)
 
 /**
  * Initialize a buffer queue that can hold up to `max_chunks` buffers
  * each of size `chunk_size`. The bufq will not allow writing of
  * more bytes than can be held in `max_chunks`.
  */
 void Curl_bufq_init(struct bufq *q, size_t chunk_size, size_t max_chunks);
 
 /**
  * Initialize a buffer queue that can hold up to `max_chunks` buffers
  * each of size `chunk_size` with the given options. See `BUFQ_OPT_*`.
  */
 void Curl_bufq_init2(struct bufq *q, size_t chunk_size,
                      size_t max_chunks, int opts);
 
 void Curl_bufq_initp(struct bufq *q, struct bufc_pool *pool,
                      size_t max_chunks, int opts);
 
 /**
  * Reset the buffer queue to be empty. Will keep any allocated buffer
  * chunks around.
  */
 void Curl_bufq_reset(struct bufq *q);
 
 /**
  * Free all resources held by the buffer queue.
  */
 void Curl_bufq_free(struct bufq *q);
 
 /**
  * Return the total amount of data in the queue.
  */
 size_t Curl_bufq_len(const struct bufq *q);
 
 /**
  * Returns TRUE iff there is no data in the buffer queue.
  */
 bool Curl_bufq_is_empty(const struct bufq *q);
 
 /**
  * Returns TRUE iff there is no space left in the buffer queue.
  */
 bool Curl_bufq_is_full(const struct bufq *q);
 
 /**
  * Write buf to the end of the buffer queue. The buf is copied
  * and the amount of copied bytes is returned.
  * CURLE_AGAIN is returned if the buffer queue is full.
  */
 CURLcode Curl_bufq_write(struct bufq *q,
                          const unsigned char *buf, size_t len,
                          size_t *pnwritten);
 
 CURLcode Curl_bufq_cwrite(struct bufq *q,
                           const char *buf, size_t len,
                           size_t *pnwritten);
 
 /**
  * Read buf from the start of the buffer queue. The buf is copied
  * and the amount of copied bytes is returned.
  */
 CURLcode Curl_bufq_read(struct bufq *q, unsigned char *buf, size_t len,
                         size_t *pnread);
 
 CURLcode Curl_bufq_cread(struct bufq *q, char *buf, size_t len,
                          size_t *pnread);
 
 /**
  * Peek at the head chunk in the buffer queue. Returns a pointer to
  * the chunk buf (at the current offset) and its length. Does not
  * modify the buffer queue.
  * Returns TRUE iff bytes are available. Sets `pbuf` to NULL and `plen`
  * to 0 when no bytes are available.
  * Repeated calls return the same information until the buffer queue
  * is modified, see `Curl_bufq_skip()``
  */
 bool Curl_bufq_peek(struct bufq *q,
                     const unsigned char **pbuf, size_t *plen);
 
 bool Curl_bufq_peek_at(struct bufq *q, size_t offset,
                        const unsigned char **pbuf, size_t *plen);
 
 /**
  * Tell the buffer queue to discard `amount` buf bytes at the head
  * of the queue. Skipping more buf than is currently buffered will
  * just empty the queue.
  */
 void Curl_bufq_skip(struct bufq *q, size_t amount);
 
 typedef CURLcode Curl_bufq_writer(void *writer_ctx,
                                   const unsigned char *buf, size_t len,
                                   size_t *pwritten);
 /**
  * Passes the chunks in the buffer queue to the writer and returns
  * the amount of buf written. A writer may return -1 and CURLE_AGAIN
  * to indicate blocking at which point the queue will stop and return
  * the amount of buf passed so far.
  * -1 is returned on any other errors reported by the writer.
  * Note that in case of a -1 chunks may have been written and
  * the buffer queue will have different length than before.
  */
 CURLcode Curl_bufq_pass(struct bufq *q, Curl_bufq_writer *writer,
                         void *writer_ctx, size_t *pwritten);
 
 typedef CURLcode Curl_bufq_reader(void *reader_ctx,
                                   unsigned char *buf, size_t len,
                                   size_t *pnread);
 
 /**
  * Read date and append it to the end of the buffer queue until the
  * reader returns blocking or the queue is full. A reader returns
  * CURLE_AGAIN to indicate blocking.
  * Returns the total amount of buf read (may be 0) in `pnread` on success.
  * Note that in case of an error chunks may have been read and
  * the buffer queue will have different length than before.
  */
 CURLcode Curl_bufq_slurp(struct bufq *q, Curl_bufq_reader *reader,
                          void *reader_ctx, size_t *pnread);
 
 /**
  * Read *once* up to `max_len` bytes and append it to the buffer.
  * if `max_len` is 0, no limit is imposed besides the chunk space.
  * Returns the total amount of buf read (may be 0) or -1 on other
  * reader errors.
  */
 CURLcode Curl_bufq_sipn(struct bufq *q, size_t max_len,
                         Curl_bufq_reader *reader, void *reader_ctx,
                         size_t *pnread);
 
 /**
  * Write buf to the end of the buffer queue.
  * Will write bufq content or passed `buf` directly using the `writer`
  * callback when it sees fit. 'buf' might get passed directly
  * on or is placed into the buffer, depending on `len` and current
  * amount buffered, chunk size, etc.
  */
 CURLcode Curl_bufq_write_pass(struct bufq *q,
                               const unsigned char *buf, size_t len,
                               Curl_bufq_writer *writer, void *writer_ctx,
                               size_t *pwritten);
 
 #endif /* HEADER_CURL_BUFQ_H */