CURLOPT_CONV_FROM_UTF8_FUNCTION man page
CURLOPT_CONV_FROM_UTF8_FUNCTION — convert data from UTF8 to host encoding
#include <curl/curl.h> CURLcode conv_callback(char *ptr, size_t length); CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CONV_FROM_UTF8_FUNCTION, conv_callback);
Pass a pointer to your callback function, which should match the prototype shown above.
Applies to non-ASCII platforms. curl_version_info(3) will return the CURL_VERSION_CONV feature bit set if this option is provided.
The data to be converted is in a buffer pointed to by the ptr parameter. The amount of data to convert is indicated by the length parameter. The converted data overlays the input data in the buffer pointed to by the ptr parameter. CURLE_OK must be returned upon successful conversion. A CURLcode return value defined by curl.h, such as CURLE_CONV_FAILED, should be returned if an error was encountered.
CURLOPT_CONV_FROM_UTF8_FUNCTION converts to host encoding from UTF8 encoding. It is required only for SSL processing.
If you set a callback pointer to NULL, or don't set it at all, the built-in libcurl iconv functions will be used. If HAVE_ICONV was not defined when libcurl was built, and no callback has been established, conversion will return the CURLE_CONV_REQD error code.
If HAVE_ICONV is defined, CURL_ICONV_CODESET_OF_HOST must also be defined. For example:
#define CURL_ICONV_CODESET_OF_HOST "IBM-1047"
The iconv code in libcurl will default the network and UTF8 codeset names as follows:
#define CURL_ICONV_CODESET_OF_NETWORK "ISO8859-1"
#define CURL_ICONV_CODESET_FOR_UTF8 "UTF-8"
You will need to override these definitions if they are different on your system.
Available only if CURL_DOES_CONVERSIONS was defined when libcurl was built.
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
curl_easy_setopt(3), CURLOPT_CONV_FROM_NETWORK_FUNCTION(3), CURLOPT_CONV_TO_NETWORK_FUNCTION(3).