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Officialized burn_drive_info_forget()

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This commit is contained in:
Thomas Schmitt 2006-09-11 17:49:42 +00:00
parent 569853d515
commit 89c2d7971d
2 changed files with 95 additions and 89 deletions
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26
trunk/libburn/libburn.h
View File

@ -488,13 +488,13 @@ void burn_message_free(struct burn_message *msg);
You are *strongly urged* to use this call whenever you know the drive
address in advance.
If not, then you have to use directly above calls. In that case, you are
*strongly urged* to end the libburn session as soon as possible,
including a call to burn_finish(). This is to close any unintended
drive which might get exclusively occupied and not closed by
burn_drive_scan().
You may start a new libburn session and should then use the function
described here with an address obtained after burn_drive_scan() via
a call of burn_drive_get_adr(&(drive_infos[driveno]), adr) .
*strongly urged* to drop any unintended drive which will be exclusively
occupied and not closed by burn_drive_scan().
This can be done by shutting down the library including a call to
burn_finish(). You may later start a new libburn session and should then
use the function described here with an address obtained after
burn_drive_scan() via burn_drive_get_adr(&(drive_infos[driveno]), adr) .
Another way is to drop the unwanted drives by burn_drive_info_forget().
@param drive_infos On success returns a one element array with the drive
(cdrom/burner). Thus use with driveno 0 only. On failure
the array has no valid elements at all.
@ -522,11 +522,12 @@ int burn_drive_scan_and_grab(struct burn_drive_info *drive_infos[],
@return 1 success, <=0 failure
*/
int burn_drive_add_whitelist(char *device_address);
/** Remove all drives from whitelist. This enables all possible drives. */
void burn_drive_clear_whitelist(void);
/** Scans for drives. This function MUST be called until it returns nonzero.
/** Scan for drives. This function MUST be called until it returns nonzero.
No drives can be in use when this is called or it will assert.
All drive pointers are invalidated by using this function. Do NOT store
drive pointers across calls to this function or death AND pain will ensue.
@ -546,9 +547,8 @@ int burn_drive_scan(struct burn_drive_info *drive_infos[],
unsigned int *n_drives);
/* ts A60904 : ticket 62, contribution by elmom */
/** EXPERIMENTAL: DO NOT USE IN PRODUCTION YET. DO NOT RELY ON PERSISTENCE YET.
Release memory about and any exclusive locks on a single drive
and become unable to inquire or grab it.
/** Release memory about a single drive and any exclusive lock on it.
Become unable to inquire or grab it. Expect FATAL consequences if you try.
@param drive_info pointer to a single element out of the array
obtained from burn_drive_scan() : &(drive_infos[driveno])
@param force controls degree of permissible drive usage at the moment this
@ -563,7 +563,7 @@ int burn_drive_scan(struct burn_drive_info *drive_infos[],
int burn_drive_info_forget(struct burn_drive_info *drive_info, int force);
/** Frees a burn_drive_info array returned by burn_drive_scan
/** Free a burn_drive_info array returned by burn_drive_scan
*/
void burn_drive_info_free(struct burn_drive_info drive_infos[]);
@ -577,7 +577,7 @@ void burn_drive_info_free(struct burn_drive_info drive_infos[]);
@param adr An application provided array of at least BURN_DRIVE_ADR_LEN
characters size. The persistent address gets copied to it.
*/
int burn_drive_get_adr(struct burn_drive_info *drive, char adr[]);
int burn_drive_get_adr(struct burn_drive_info *drive_info, char adr[]);
/** Grab a drive. This must be done before the drive can be used (for reading,

158
trunk/test/libburner.c
View File

@ -4,14 +4,6 @@
/* Provided under GPL, see also "License and copyright aspects" at file end */
/** IMPORTANT: By default this program tries to make a simulated burn
on the CD recorder. Some obey, some do not.
If you want to burn really readable CD for sure by default,
then set this macro to 0 .
Explicit options: --burn_for_real and --try_to_simulate
*/
#define Libburner_try_to_simulatE 1
/** Overview
libburner is a minimal demo application for the library libburn as provided
@ -29,7 +21,7 @@
approaches are shown here in application functions:
libburner_aquire_by_adr() demonstrates usage as of cdrecord traditions
libburner_aquire_by_driveno() demonstrates a scan-and-choose approach
With that aquired drive you blank a CD-RW
With that aquired drive you can blank a CD-RW
libburner_blank_disc()
Between blanking and burning one eventually has to reload the drive status
libburner_regrab()
@ -81,8 +73,12 @@ static unsigned int drive_count;
finally released */
static int drive_is_grabbed = 0;
/** Wether to burn for real or to *try* to simulate a burn */
static int simulate_burn = Libburner_try_to_simulatE ;
/** Here you may enable simulated burn by default. This does not apply to
blanking. Anyway, some CD recorders obey the request to simulate, some do
not. Explicit options are: --burn_for_real and --try_to_simulate
*/
static int simulate_burn = 0;
/* Some in-advance definitions to allow a more comprehensive ordering
@ -98,15 +94,11 @@ int libburner_aquire_by_driveno(int *drive_no);
whitelisting, scanning for drives and finally grabbing one of them.
If you have a persistent address of the drive, then the compact call is
to prefer. It avoids a shutdown-init cycle of libburn and thus is more
safe against race conditions between competing users of that drive.
On modern Linux kernels, race conditions are supposed to end up by
having one single winner or by having all losers. On modern Linux
kernels, there should be no fatal disturbance of ongoing burns
of other libburn instances. We use open(O_EXCL) by default.
There are variants of cdrecord which participate in advisory O_EXCL
locking of block devices. Others possibly don't. Some kernels do
nevertheless impose locking on open drives anyway (e.g. SuSE 9.0, 2.4.21).
to prefer because it only touches one drive. On modern Linux kernels,
there should be no fatal disturbance of ongoing burns of other libburn
instances with any of our approaches. We use open(O_EXCL) by default.
On /dev/hdX it should cooperate with growisofs and some cdrecord variants.
On /dev/sgN versus /dev/scdM expect it not to respect other programs.
*/
int libburner_aquire_drive(char *drive_adr, int *driveno)
{
@ -137,7 +129,7 @@ int libburner_aquire_by_adr(char *drive_adr)
strncmp(drive_adr,"/dev/hd",7) != 0)
fprintf(stderr,"\nHINT: Consider addresses like '/dev/hdc' or '/dev/sg0'\n");
} else {
printf("done\n");
printf("Done\n");
drive_is_grabbed = 1;
}
return ret;
@ -145,12 +137,12 @@ int libburner_aquire_by_adr(char *drive_adr)
/** This method demonstrates how to use libburn without knowing a persistent
drive address in advance. It has to make sure that after assessing the
list of available drives, all drives get closed again. Only then it is
sysadmin-acceptable to aquire the desired drive for a prolonged time.
This drive closing is enforced here by shutting down libburn and
restarting it again with the much more un-obtrusive approach to use
a persistent address and thus to only touch the one desired drive.
drive address in advance. It has to make sure that after assessing the list
of available drives, all unwanted drives get closed again. As long as they
are open, no other libburn instance can see them. This is an intended
locking feature. The application is responsible for giving up the locks
by either burn_drive_release() (only after burn_drive_grab() !),
burn_drive_info_forget(), burn_drive_info_free(), or burn_finish().
@param driveno the index number in libburn's drive list. This will get
set to 0 on success and will then be the drive index to
use in the further dourse of processing.
@ -168,20 +160,21 @@ int libburner_aquire_by_driveno(int *driveno)
printf("FAILED (no drives found)\n");
return 0;
}
printf("done\n");
printf("Done\n");
/* Interactive programs may choose the drive number at this moment.
/*
Interactive programs may choose the drive number at this moment.
drive[0] to drive[drive_count-1] are struct burn_drive_info
as defined in libburn/libburn.h . This structure is part of API
and thus will strive for future compatibility on source level.
Have a look at the info offered.
Caution: do not take .location for drive address. Always use
burn_drive_get_adr() or you might become incompatible
in future.
Note: bugs with struct burn_drive_info - if any - will not be
easy to fix. Please report them but also strive for
workarounds on application level.
drive[0] to drive[drive_count-1] are struct burn_drive_info
as defined in libburn/libburn.h . This structure is part of API
and thus will strive for future compatibility on source level.
Have a look at the info offered.
Caution: do not take .location for drive address. Always use
burn_drive_get_adr() or you might become incompatible
in future.
Note: bugs with struct burn_drive_info - if any - will not be
easy to fix. Please report them but also strive for
workarounds on application level.
*/
printf("\nOverview of accessible drives (%d found) :\n",
drive_count);
@ -194,50 +187,60 @@ int libburner_aquire_by_driveno(int *driveno)
}
printf("-----------------------------------------------------------------------------\n\n");
/*
On multi-drive systems save yourself from sysadmins' revenge.
Be aware that you hold reserved all available drives at this point.
So either make your choice quick enough not to annoy other system
users, or set free the drives for a while.
The tested way of setting free all drives is to shutdown the library
and to restart when the choice has been made. The list of selectable
drives should also hold persistent drive addresses as obtained
above by burn_drive_get_adr(). By such an address one may use
burn_drive_scan_and_grab() to finally aquire exactly one drive.
A not yet tested shortcut should be to call burn_drive_info_free()
and to call either burn_drive_scan() or burn_drive_scan_and_grab()
before accessing any drives again.
In both cases you have to be aware that the desired drive might get
aquired in the meantime by another user resp. libburn process.
*/
/* We already made our choice via command line. (default is 0)
So we just have to keep our desired drive and drop all others.
No other libburn instance will have a chance to steal our drive.
*/
if (*driveno < 0) {
printf("Pseudo-drive \"-\" given : bus scanning done.\n");
return 2; /* only return 1 will cause a burn */
return 2; /* the program will end after this */
}
/* We already made our choice via command line. (default is 0) */
if (drive_count <= *driveno || *driveno < 0) {
if (drive_count <= *driveno) {
fprintf(stderr,
"Found only %d drives. Number %d not available.\n",
drive_count, *driveno);
return 0;
return 0; /* the program will end after this */
}
/* Now save yourself from sysadmins' revenge */
/* If drive_count == 1 this would be not really necessary, though.
You could now call burn_drive_grab() and avoid libburn restart.
We don't try to be smart here and follow the API's strong urge. */
if (burn_drive_get_adr(&(drive_list[*driveno]), adr) <=0) {
fprintf(stderr,
"Cannot inquire persistent drive address of drive number %d\n",
*driveno);
return 0;
/* Drop all drives which we do not want to use */
for (i = 0; i < drive_count; i++) {
if (i == *driveno) /* the one drive we want to keep */
continue;
ret = burn_drive_info_forget(&(drive_list[i]),0);
if (ret != 1)
fprintf(stderr, "Cannot drop drive %d. Please report \"ret=%d\" to libburn-hackers@pykix.org\n",
i, ret);
else
printf("Dropped unwanted drive %d\n",i);
}
printf("Detected '%s' as persistent address of drive number %d\n",
adr,*driveno);
burn_drive_info_free(drive_list);
burn_finish();
printf(
"Re-Initializing library to release any unintended drives ...\n");
if (burn_initialize())
printf("done\n");
else {
printf("FAILED\n");
fprintf(stderr,"\nFailed to re-initialize libburn.\n");
/* Make the one we want ready for blanking or burning */
ret= burn_drive_grab(drive_list[*driveno].drive, 1);
if (ret != 1)
return 0;
}
ret = libburner_aquire_by_adr(adr);
if (ret > 0)
*driveno = 0;
return ret;
drive_is_grabbed = 1;
return 1;
}
@ -297,7 +300,10 @@ int libburner_blank_disc(struct burn_drive *drive, int blank_fast)
}
/** This gesture is necessary to get the drive info after blanking */
/** This gesture is necessary to get the drive info after blanking.
It opens a small gap for losing the drive to another libburn instance.
We will work on closing this gap.
*/
int libburner_regrab(struct burn_drive *drive) {
int ret;
@ -308,7 +314,7 @@ int libburner_regrab(struct burn_drive *drive) {
ret = burn_drive_grab(drive, 0);
if (ret != 0) {
drive_is_grabbed = 1;
printf("done\n");
printf("Done\n");
} else
printf("FAILED\n");
return !!ret;
@ -577,7 +583,7 @@ int main(int argc, char **argv)
printf("Initializing library ...\n");
if (burn_initialize())
printf("done\n");
printf("Done\n");
else {
printf("FAILED\n");
fprintf(stderr,"\nFATAL: Failed to initialize libburn.\n");