[Libmtp-discuss] Implementing Object Copy with Pipe

[James J. <me...@do...>]

Hello,

I am trying to implement object copy into this library using Linux pipes.

Since objects cannot be copied to except downloaded to a file and read 
back into an MTP file, which will take a lot of time. I played around 
pipes instead by concurrently writing to pipe and reading from pipe back 
to another MTP file. But I read that MTP is not multiplexed, so 
operations cannot be performed concurrently.

I have tried to implement this but I am getting some weird error. 
Because I assumed each transaction waits for the current to finish. This 
is what I have:

 > int LIBMTP__Copy_Object(LIBMTP_mtpdevice_t *src_device, > uint32_t 
const src_id, > LIBMTP_mtpdevice_t *dest_device, > LIBMTP_file_t 
*dest_file, > LIBMTP_progressfunc_t const callback, > void const * const 
data) > { > int fildes[2]; > > if (pipe(fildes) == -1) { > 
add_error_to_errorstack(src_device, LIBMTP_ERROR_GENERAL, 
"_LIBMTP_Copy_Object(): Could not create pipe."); > return -1; > } > > 
if (fork() == 0) { > uint16_t ret = 
LIBMTP_Send_File_From_File_Descriptor(dest_device, fildes[0], dest_file, 
callback, data); > close(fildes[0]); > if (ret == -1) { > 
add_ptp_error_to_errorstack(dest_device, ret, "_LIBMTP_Copy_Object(): 
could not write to destination object."); > return -1; > } > } else { > 
uint16_t ret = LIBMTP_Get_File_To_File_Descriptor(src_device, src_id, 
fildes[1], callback, data); > close(fildes[1]); > if (ret == -1) { > 
add_ptp_error_to_errorstack(src_device, ret, "_LIBMTP_Copy_Object(): 
could not copy object."); > return -1; > } > } > > return 0; > }


I need a help in finding why it LIBMTP_Send_File_From_File_Descriptoris 
not working. Or it can't work because it is not multiplexed?

A bit of a newbie here, still getting familiar with this library and the 
whole low-level thing. It's for the passion :)


Thank you

James