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Implemented drive role 3, sequential write-only stdio drives (e.g. stdout)

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This commit is contained in:
Thomas Schmitt
2007-09-24 13:54:52 +00:00
parent 83fe9f3621
commit 5e995c9cd0
7 changed files with 149 additions and 54 deletions
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49
libburn/libburn.h
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@ -622,9 +622,11 @@ void burn_allow_untested_profiles(int yes);
/* ts A60823 */
/** Aquire a drive with known persistent address. This is the sysadmin friendly
way to open one drive and to leave all others untouched. It bundles
the following API calls to form a non-obtrusive way to use libburn:
/** Aquire a drive with known persistent address.
This is the sysadmin friendly way to open one drive and to leave all
others untouched. It bundles the following API calls to form a
non-obtrusive way to use libburn:
burn_drive_add_whitelist() , burn_drive_scan() , burn_drive_grab()
You are *strongly urged* to use this call whenever you know the drive
address in advance.
@ -639,28 +641,48 @@ void burn_allow_untested_profiles(int yes);
Another way is to drop the unwanted drives by burn_drive_info_forget().
Operating on multiple drives:
Different than with burn_drive_scan() it is allowed to call
burn_drive_scan_and_grab() without giving up any other scanned drives. So
this call can be used to get a collection of more than one aquired drives.
The attempt to aquire the same drive twice will fail, though.
Pseudo-drives:
burn_drive_scan_and_grab() is able to aquire virtual drives which will
accept options much like a MMC burner drive. Many of those options will not
cause any effect, though. The address of a pseudo-drive begins with
prefix "stdio:" optionally followed by the path to an existing regular
file, or to a not yet existing file, or to an existing block device.
Example: "stdio:/tmp/pseudo_drive"
If the path is empty then the resulting pseudo-drive is a null-drive.
A null-drive will pretend to have loaded no media and support no writing.
A pseudo-drive with a non-empty path is called a stdio-drive.
It will perform all its eventual data transfer activities on a file
prefix "stdio:" followed by a path.
Examples: "stdio:/tmp/pseudo_drive" , "stdio:/dev/null" , "stdio:-"
If the path is empty, the result is a null-drive = drive role 0.
It pretends to have loaded no media and supports no reading or writing.
If the path leads to an existing regular file, or to a not yet existing
file, or to an existing block device, then the result is a random access
stdio-drive capable of reading and writing = drive role 2.
If the path leads to an existing file of any type other than directory,
then the result is a sequential write-only stdio-drive = drive role 3.
The special address form "stdio:/dev/fd/<number>" is interpreted literally
as reference to open file descriptor <number>. This address form coincides
with real files on some systems, but it is in fact hardcoded in libburn.
Special address "stdio:-" means stdout = "stdio:/dev/fd/1".
The role of such a drive is determined by the file type obtained via
fstat(<number>).
Roles 2 and 3 perform all their eventual data transfer activities on a file
via standard i/o functions open(2), lseek(2), read(2), write(2), close(2).
Its capabilities resemble DVD-RAM but the media profile reported is 0xffff,
it can simulate writing and it issues no realistic write space information.
The media profile is reported as 0xffff. Write space information from those
media is not necessarily realistic.
The capabilities of role 2 resemble DVD-RAM but it can simulate writing.
If the path does not exist in the filesystem yet, it is attempted to create
it as a regular file as soon as write operations are started.
The capabilities of role 3 resemble a blank DVD-R.
One may distinguish pseudo-drives from MMC drives by call
burn_drive_get_drive_role().
@ -2004,7 +2026,8 @@ int burn_read_data(struct burn_drive *d, off_t byte_address,
@param d The drive to inquire
@return 0= null-drive
1= real MMC drive
2= stdio-drive
2= stdio-drive, random access, read-write
3= stdio-drive, sequential, write-only
*/
int burn_drive_get_drive_role(struct burn_drive *d);