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Allowed for Friendly Programs: O_EXCL | O_RDONLY

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Thomas Schmitt 2007-04-18 10:34:12 +00:00
parent 10e320911a
commit 2ec2a34f51
1 changed files with 5 additions and 5 deletions
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10
doc/ddlp.txt
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@ -2,6 +2,7 @@
Delicate Device Locking Protocol Delicate Device Locking Protocol
(a joint sub project of cdrkit and libburnia) (a joint sub project of cdrkit and libburnia)
(contact: scdbackup@gmx.net )
DDLP shall help to avoid collisions between programs in the process of DDLP shall help to avoid collisions between programs in the process of
@ -43,10 +44,9 @@ as long as it does not get closed. There are two alternative ways to achieve
this. this.
Very reliable is Very reliable is
open( some_path , O_EXCL | O_RDWR | ...) open( some_path , O_EXCL | ...)
Regrettably, O_EXCL | O_RDONLY did not always succeed with our tests on But: O_EXCL | O_RDONLY does not succeed with /dev/sg* on several systems.
kernel 2.6 systems.
So it may be necessary to use a cautious open() without O_EXCL and to aquire So it may be necessary to use a cautious open() without O_EXCL and to aquire
a POSIX lock via fcntl(). a POSIX lock via fcntl().
@ -115,8 +115,8 @@ Use it to occupy a drive's representations for a given number of seconds
It should do no harm to any of your running activities. It should do no harm to any of your running activities.
If it does: Please, please alert us. If it does: Please, please alert us.
Your own programs should not be able to circumvent the occupation if the Your own programs should not be able to circumvent the occupation if they
obey the rules for Friendly Programs. obey above rules for Friendly Programs.
Of course ./ddlpa should be unable to circumvent itself. Of course ./ddlpa should be unable to circumvent itself.
A successfull occupation looks like A successfull occupation looks like