Received Data Callback

Collaboration diagram for Received Data Callback:

Data Structures
struct	curl_write_data
	Context structure passed to ast_curl_write_default_cb. More...

Functions
size_t	curl_write_cb (char *data, size_t size, size_t nmemb, void *clientp)
	A default implementation of a write data callback. More...
void	curl_write_data_free (void *obj)

Detailed Description

If you need to do something with the data received other than save it in a memory buffer, you can define a callback that curl will call for each "chunk" of data it receives from the server.

Your callback must follow the specification defined for CURLOPT_WRITEFUNCTION and implement the 'curl_write_callback' prototype.

The following ast_curl_write objects compose a default implementation that will write the data to any FILE * descriptor you choose.

Function Documentation

curl_write_cb()

size_t curl_write_cb	(	char *	data,
		size_t	size,
		size_t	nmemb,
		void *	clientp
	)

A default implementation of a write data callback.

This is a default implementation of the function described by CURLOPT_WRITEFUNCTION that writes data received to a user-provided FILE *. This function is called by curl itself when it determines it has enough data to warrant a write. This may be influenced by the value of ast_curl_optional_data.per_write_buffer_size. See the CURLOPT_WRITEFUNCTION documentation for more info.

The curl prototype for this function is 'curl_write_callback'

Parameters

data	Data read by curl.
size	Always 1.
nitems	The number of bytes read.
client_data	A pointer to whatever structure you passed to ast_curler in the curl_write_data parameter.

Returns

Number of bytes handled. Must be (size * nitems) or an error is signalled.

Definition at line 150 of file curl_utils.c.

{
    struct curl_write_data *cb_data = client_data;
    size_t realsize = size * nmemb;
    size_t bytes_written = 0;
    char *debug_info = S_OR(cb_data->debug_info, "");
    SCOPE_ENTER(5, "'%s': Writing data chunk of %zu bytes\n",
        debug_info, realsize);
 
    if (!cb_data->output) {
        cb_data->output = open_memstream(
            &cb_data->stream_buffer,
            &cb_data->stream_bytes_downloaded);
        if (!cb_data->output) {
            SCOPE_EXIT_LOG_RTN_VALUE(CURL_WRITEFUNC_ERROR, LOG_WARNING,
                "'%s': Xfer failed. "
                "open_memstream failed: %s\n", debug_info, strerror(errno));
        }
        cb_data->_internal_memstream = 1;
    }
 
    if (cb_data->max_download_bytes > 0 &&
        cb_data->stream_bytes_downloaded + realsize >
        cb_data->max_download_bytes) {
        SCOPE_EXIT_LOG_RTN_VALUE(CURL_WRITEFUNC_ERROR, LOG_WARNING,
            "'%s': Xfer failed. "
            "Exceeded maximum %zu bytes transferred\n", debug_info,
            cb_data->max_download_bytes);
    }
 
    bytes_written = fwrite(data, 1, realsize, cb_data->output);
    cb_data->bytes_downloaded += bytes_written;
    if (bytes_written != realsize) {
        SCOPE_EXIT_LOG_RTN_VALUE(CURL_WRITEFUNC_ERROR, LOG_WARNING,
            "'%s': Xfer failed. "
            "Expected to write %zu bytes but wrote %zu\n",
            debug_info, realsize, bytes_written);
    }
 
    SCOPE_EXIT_RTN_VALUE(realsize, "Wrote %zu bytes\n", bytes_written);
}

References curl_write_data::_internal_memstream, curl_write_data::bytes_downloaded, CURL_WRITEFUNC_ERROR, curl_write_data::debug_info, errno, LOG_WARNING, curl_write_data::max_download_bytes, curl_write_data::output, S_OR, SCOPE_ENTER, SCOPE_EXIT_LOG_RTN_VALUE, SCOPE_EXIT_RTN_VALUE, curl_write_data::stream_buffer, and curl_write_data::stream_bytes_downloaded.

Referenced by curler().

curl_write_data_free()

void curl_write_data_free

(

void *

obj

)

Definition at line 134 of file curl_utils.c.

{
    struct curl_write_data *cb_data = obj;
    if (!cb_data) {
        return;
    }
    if (cb_data->output) {
        fclose(cb_data->output);
    }
    if (cb_data->debug_info) {
        ast_free(cb_data->debug_info);
    }
    ast_std_free(cb_data->stream_buffer);
    ast_free(cb_data);
}

References ast_free, ast_std_free(), curl_write_data::debug_info, curl_write_data::output, and curl_write_data::stream_buffer.

Referenced by retrieve_cert_from_url().