153 lines
3.4 KiB
Markdown
153 lines
3.4 KiB
Markdown
---
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c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
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SPDX-License-Identifier: curl
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Title: CURLOPT_CHUNK_BGN_FUNCTION
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Section: 3
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Source: libcurl
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See-also:
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- CURLOPT_CHUNK_END_FUNCTION (3)
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- CURLOPT_WILDCARDMATCH (3)
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---
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# NAME
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CURLOPT_CHUNK_BGN_FUNCTION - callback before a transfer with FTP wildcard match
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# SYNOPSIS
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~~~c
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#include <curl/curl.h>
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struct curl_fileinfo {
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char *filename;
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curlfiletype filetype;
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time_t time; /* always zero! */
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unsigned int perm;
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int uid;
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int gid;
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curl_off_t size;
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long int hardlinks;
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struct {
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/* If some of these fields is not NULL, it is a pointer to b_data. */
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char *time;
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char *perm;
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char *user;
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char *group;
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char *target; /* pointer to the target filename of a symlink */
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} strings;
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unsigned int flags;
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/* used internally */
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char *b_data;
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size_t b_size;
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size_t b_used;
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};
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long chunk_bgn_callback(const void *transfer_info, void *ptr,
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int remains);
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CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CHUNK_BGN_FUNCTION,
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chunk_bgn_callback);
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~~~
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# DESCRIPTION
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Pass a pointer to your callback function, which should match the prototype
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shown above.
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This callback function gets called by libcurl before a part of the stream is
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going to be transferred (if the transfer supports chunks).
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The *transfer_info* pointer points to a **curl_fileinfo** struct with
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details about the file that is about to get transferred.
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This callback makes sense only when using the CURLOPT_WILDCARDMATCH(3)
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option for now.
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The target of transfer_info parameter is a "feature depended" structure. For
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the FTP wildcard download, the target is **curl_fileinfo** structure (see
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*curl/curl.h*). The parameter *ptr* is a pointer given by
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CURLOPT_CHUNK_DATA(3). The parameter remains contains number of chunks
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remaining per the transfer. If the feature is not available, the parameter has
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zero value.
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Return *CURL_CHUNK_BGN_FUNC_OK* if everything is fine,
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*CURL_CHUNK_BGN_FUNC_SKIP* if you want to skip the concrete chunk or
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*CURL_CHUNK_BGN_FUNC_FAIL* to tell libcurl to stop if some error occurred.
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# DEFAULT
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NULL
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# PROTOCOLS
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FTP
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# EXAMPLE
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~~~c
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#include <stdio.h>
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struct callback_data {
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FILE *output;
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};
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static long file_is_coming(struct curl_fileinfo *finfo,
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void *ptr,
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int remains)
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{
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struct callback_data *data = ptr;
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printf("%3d %40s %10luB ", remains, finfo->filename,
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(unsigned long)finfo->size);
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switch(finfo->filetype) {
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case CURLFILETYPE_DIRECTORY:
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printf(" DIR\n");
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break;
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case CURLFILETYPE_FILE:
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printf("FILE ");
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break;
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default:
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printf("OTHER\n");
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break;
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}
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if(finfo->filetype == CURLFILETYPE_FILE) {
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/* do not transfer files >= 50B */
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if(finfo->size > 50) {
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printf("SKIPPED\n");
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return CURL_CHUNK_BGN_FUNC_SKIP;
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}
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data->output = fopen(finfo->filename, "wb");
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if(!data->output) {
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return CURL_CHUNK_BGN_FUNC_FAIL;
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}
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}
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return CURL_CHUNK_BGN_FUNC_OK;
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}
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int main()
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{
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/* data for callback */
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struct callback_data callback_info;
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CURL *curl = curl_easy_init();
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/* callback is called before download of concrete file started */
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curl_easy_setopt(curl, CURLOPT_CHUNK_BGN_FUNCTION, file_is_coming);
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curl_easy_setopt(curl, CURLOPT_CHUNK_DATA, &callback_info);
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}
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~~~
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# AVAILABILITY
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This was added in 7.21.0
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# RETURN VALUE
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Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
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