Hi! > >> In the svn tree there is a change that breaks my code: The ISO > >> driver automatically sends read binary APDUs until the number of > >> requested bytes is reached (iso7816.c:136). > > You mean r5237 [1] ?
Yes! > >> Previously only one APDU was sent. The change surely intendeds to > >> read as much as possible (and requested). The problem is that 6282 > >> is only recognized when the card returns 0 bytes of data > >> (iso7816.c:132). > > SW 6282 as in "End of file or record reached before reading Le > > bytes" Yes! > >> There are three alternatives for a fix, I think: > >> 1. Offer a flag to disable the new behaviour as it is done for get > >> response with SC_APDU_FLAGS_NO_GET_RESP. > > Flag for sc_read_binary I assume? Yes! > >> 2. Offer a possibilities to read a file to EOF. > >> 3. Correctly recognize 6282 even when data is present. > > How would the two approaches differ? 2) would return as much as > > possible, ignoring such (meaningless in some context?) errors and 3) > > would correctly raise the error, even if data is received? The second solution would require a mechanism to return a buffer of data with enough bytes allocated (so the library allocates the memory). But all other functions of libopensc require the caller to allocate enough space. In the third solution the caller still allocates memory. He then sequentially calls sc_read_binary with more and more space allocated. He stops when the first error is thrown. The problem I have is to read a file with an unknown length. I used the third solution which worked before r5237. > > I think that a flag could be invented for switching between these > > two modes of operation (the otherwise unused "flags" parameter to > > sc_read_binary). The default could be the mode that honors passed > > in parameters. > > Actually the 0x6282 is mapped to the general SC_ERROR_CARD_CMD_FAILED > error. > http://www.opensc-project.org/opensc/browser/trunk/src/libopensc/iso7816.c?rev=5237#L35 > > Possible resolution could be: > > A new code error is introduced for the SW 0x6282 . > The 6282 error is ignored if it's returned by the 'embedded' > iso7816_read_binary . > http://www.opensc-project.org/opensc/browser/trunk/src/libopensc/iso7816.c?rev=5237#L137 Line 138 very well tests the return code. BUT sc_check_sw is not called unless the number of bytes to be read is 0 (line 132, 133). So the iso7816_read_binary almost never recognizes errors which are communicated via the status bytes. So an other solution could be to always check the status bytes (not only for apdu.resplen == 0). But adding an error code for these status bytes could be useful anyway. > > [1]http://www.opensc-project.org/opensc/changeset/5237 Cheers, Frank.
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