OptionalfreeOptional cleanup callback called when the part is freed.
Read callback to provide data chunks.
Maximum number of bytes to read
Buffer, string, null for EOF, or CurlReadFunc value (Pause/Abort)
OptionalseekOptional seek callback for repositioning the data stream.
The offset to seek to
Seek origin: 0=SEEK_SET, 1=SEEK_CUR, 2=SEEK_END
true if seek succeeded, false otherwise
Type definition for MIME data callback functions.