Ticket History #2763: file ccache should be held open while scanning for credentials

I ran "kvno" under strace, and found it opened my credential cache
file for reading (and acquired and released an advisory lock, and
closed the file) 22 times.

I think it made two passes over the credentials, once looking for the
requested service and once looking for the TGT, and opening the file
anew for each credential object read. It also made at least a couple
passes reading out header info. So it looks like searching for
credentials that are at the end of the file or not present, in a
ccache of n entries, is O(n) file opens and O(n^2) reads.

Looks like krb5_get_credentials or whatever should temporarily set the
ccache flag that causes the file to be kept open.

(And, of course, it's reading each sub-object with a separate read()
call, but we knew that sucked already.)

Ken

Create a ccache get-flags operation.
The MSLSA and CCAPI versions are untested!

* cc_file.c (krb5_fcc_get_flags): New function.
(krb5_fcc_ops, krb5_cc_file_ops): Add it.
* cc_memory.c (krb5_mcc_get_flags): New function.
(krb5_mcc_ops): Add it.
* cc_mslsa.c (krb5_lcc_get_flags): New function.
(krb5_lcc_ops): Add it.
* ccfns.c (krb5_cc_get_flags): New function.
* ccapi/stdcc.c (krb5_stdcc_get_flags): New function.
(krb5_cc_stdcc_ops): Add it.
* ccapi/stdcc.h (krb5_stdcc_get_flags): Declare.


To generate a diff of this commit:



cvs diff -r5.147 -r5.148 krb5/src/lib/krb5/ccache/ChangeLog
cvs diff -r5.41 -r5.42 krb5/src/lib/krb5/ccache/cc_file.c
cvs diff -r5.16 -r5.17 krb5/src/lib/krb5/ccache/cc_memory.c
cvs diff -r5.33 -r5.34 krb5/src/lib/krb5/ccache/cc_mslsa.c
cvs diff -r5.4 -r5.5 krb5/src/lib/krb5/ccache/ccfns.c
cvs diff -r1.38 -r1.39 krb5/src/lib/krb5/ccache/ccapi/ChangeLog
cvs diff -r1.24 -r1.25 krb5/src/lib/krb5/ccache/ccapi/stdcc.c
cvs diff -r1.14 -r1.15 krb5/src/lib/krb5/ccache/ccapi/stdcc.h

Now a kvno invocation will only open the ccache file a small number of
times, but there's still excessive seeking and re-reading of data
happening.

* cc_retr.c (krb5_cc_retrieve_cred_seq): Temporarily clear the
KRB5_TC_OPENCLOSE flag on the credentials cache while reading multiple entries
from it.


To generate a diff of this commit:



cvs diff -r5.148 -r5.149 krb5/src/lib/krb5/ccache/ChangeLog
cvs diff -r5.6 -r5.7 krb5/src/lib/krb5/ccache/cc_retr.c