47 lines
1.8 KiB
Groff
47 lines
1.8 KiB
Groff
.TH sc_lock 3 "April 2003" "OpenSC Programmer's Manual
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.SH NAME
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sc_lock, sc_unlock \- lock or unlock smart card
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.SH SYNOPSIS
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.nf
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.B #include <opensc.h>
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.sp
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.BI "int sc_lock(sc_card_t *" card ");
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.BI "int sc_unlock(sc_card_t *" card ");
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.fi
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.SH DESCRIPTION
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These functions handle locking of smart cards, in order to prevent
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concurrent access to the same card by different users.
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.PP
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Locking is important to prevent unauthorized access to the card
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after presenting the PIN, for instance.
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.PP
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After a call to \fBsc_lock\fP, concurrent access by other application
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to the same smart card reader is disallowed, provided the reader
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middleware supports this (see below). A lock must later be released
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by calling \fBsc_unlock\fP. When disconnecting from the card using
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\fBsc_disconnect_card\fP, there must not be anymore locks on the
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card.
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.PP
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Calls to \fBsc_lock\fP may be nested, i.e. if \fBsc_lock\fP is called
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five times in a row, the lock will not be released until the fifth
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call to \fBsc_unlock\fP.
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.PP
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Note that these functions do not offer mutual exclusion for different
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threads within the same application process. Multithread locking is
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the application's job (Note that the OpenSC PKCS11 module provides
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MT locking facilities, as that's part of the standard).
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.SH NOTES
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Whether locking is effective depends a lot on the middleware
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used to talk to the card reader. CT\-API based drivers for instance
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perform no interprocess locking at all.
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.PP
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The only middleware implementations currently supported by OpenSC that
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do perform this type of locking are PC/SC and OpenCT.
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.SH RETURN VALUE
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If an error occurred, a negative error code is returned, as described
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in \fbsc_error\fP(3). Otherwise, the function will return 0.
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.SH SEE ALSO
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.BR sc_connect_card (3).
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.SH AUTHOR
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This manual page was written by Olaf Kirch <okir@suse.de>
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