Hopefully fix TOCTOU by calling fopen() before stat()
At least this should prevent Coverity to complain about it:
CID 1090346 (#1 of 1): Time of check time of use (TOCTOU)
fs_check_call: Calling function "stat(char const *, struct stat *)" to perform check on "filename".
toctou: Calling function "fopen(char const * restrict, char const * restrict)" that uses "filename" after a check function. This can cause a time-of-check, time-of-use race condition.
Note that it seems pretty hard to avoid completely:
https://en.wikipedia.org/wiki/Time_of_check_to_time_of_use#Preventing_TOCTTOU
* in main():
** errx()/err()/return -> exit()
** return values -> EXIT_SUCCESS & EXIT_FAILURE
* out of main:
** err()/errx()/exit() -> return
** change retval from size_t to int to allow returning errors
** don't use EXIT_SUCCESS / EXIT_FAILURE as retvals
* add nfc_close() & nfc_exit() to exit() on errors
* add missing fclose() on errors
* add missing test if (pnd == NULL)
* unify style if (pnd == / != NULL)
* remove goto's
* few related fixes
* remove if(pnd!=NULL) test on nfc_close() calls
nfc-emulate-forum-tag4.c:117: warning: no previous prototype for ‘nfcforum_tag4_io’
nfc-emulate-forum-tag4.c:231: warning: no previous prototype for ‘stop_emulation’
nfc-emulate-forum-tag4.c:241: warning: no previous prototype for ‘ndef_message_load’
nfc-emulate-forum-tag4.c:269: warning: no previous prototype for ‘ndef_message_save’
nfc-emulate-forum-tag4.c:285: warning: no previous prototype for ‘usage’
- nfc_device is now an opaque type;
- PN53x specific errors are not public anymore;
- nfc_device_name() renamed to nfc_device_get_name() for the sake of consistency;
- examples/*, utils/* uses the new nfc_device_get_name() function instead of access directly to struct's content;
- new error defined: NFC_ERFTRANS for notifying about RF transmission error, its used by mifare.c to detect permissions error on mifare;
- drivers initiator_transceive_bytes() function now returns libnfc's error code on failure (<0), and received bytes count on success (>=0);
- remove some unused errors.
