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Polished txt and finally threw out getter functions

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This commit is contained in:
Thomas Schmitt 2007-04-16 21:20:39 +00:00
parent acaba76cda
commit 13b9f910e1
3 changed files with 23 additions and 99 deletions
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6
doc/ddlp.txt
View File

@ -12,7 +12,7 @@ has to take some extra precautions to participate.
If a program does not feel vulnerable to disturbance, then the precautions
impose much less effort than if the program feels the need for protection.
Two levels are specified:
Two locking strategies are specified:
DDLP-A operates on device files only. It is very Linux specific.
DDLP-B adds proxy lock files, inspired by FHS /var/lock standard.
@ -30,9 +30,9 @@ So this is advisory and exclusive locking.
With kernel 2.6 it seems to work on all device drivers which might get used
to access a CD/DVD drive.
The vulnerable programs do not start their operation before they occupied a
The vulnerable programs shall not start their operation before they occupied a
wide collection of drive representations.
Non-vulnerable programs take care to detect the occupation of _one_ such
Non-vulnerable programs shall take care to detect the occupation of _one_ such
representation.
So for Friendly Programs

51
libburn/ddlpa.c
View File

@ -16,8 +16,6 @@
#include <sys/ioctl.h>
#include <scsi/scsi.h>
/* No getter functions. This makes the compiled code leaner. */
#define DDLPA_H_NOT_ENCAPSULATED 1
/* All callers of ddlpa must do this */
#include "ddlpa.h"
@ -322,6 +320,9 @@ static int ddlpa_std_by_btl(struct ddlpa_lock *o)
return 0;
}
/* >>> add more info about busy and forbidden paths */
return ENOENT;
}
@ -344,7 +345,8 @@ static int ddlpa_open_all(struct ddlpa_lock *o)
/* There may be the same rdev but different inode. */
no_o_excl = (o->sibling_rdevs[i] == o->rdev);
/* Look for multiply registered device drivers */
/* Look for multiply registered device drivers with
distinct inodes. */
for (j = 0; j < i; j++) {
if (o->sibling_devs[j] == o->sibling_devs[i] &&
o->sibling_inodes[j] == o->sibling_inodes[i])
@ -467,40 +469,10 @@ int ddlpa_lock_btl(int bus, int target, int lun,
}
#ifndef DDLPA_H_NOT_ENCAPSULATED
int ddlpa_get_fd(struct ddlpa_lock *lockbundle)
{
/* >>> */
return -1;
}
char *ddlpa_get_fd_path(struct ddlpa_lock *lockbundle)
{
/* >>> */
return "none";
}
int ddlpa_get_siblings(struct ddlpa_lock *lockbundle,
char **std_path, int *num_siblings,
char ***sibling_paths, int **sibling_fds)
{
*num_siblings = 0;
/* >>> */
return 1;
}
#endif /* ! DDLPA_H_NOT_ENCAPSULATED */
#ifdef DDLPA_C_STANDALONE
/* ----------------------------- Test / Demo -------------------------- */
#ifdef DDLPA_C_STANDALONE
int main(int argc, char **argv)
{
@ -520,14 +492,19 @@ usage:;
if (my_path[0] != '/' && my_path[0] != '.' &&
strchr(my_path, ',') != NULL) {
/* cdrecord style dev=Bus,Target,Lun */
/*
cdrecord style dev=Bus,Target,Lun
*/
sscanf(my_path, "%d,%d,%d", &bus, &target, &lun);
ret = ddlpa_lock_btl(bus, target, lun, O_RDWR, 0, &lck,
&errmsg);
} else {
/* This substitutes for:
/*
This substitutes for:
fd = open(my_path, O_RDWR | O_EXCL);
*/
ret = ddlpa_lock_path(my_path, O_RDWR, 0, &lck, &errmsg);
}
if (ret) {
@ -537,7 +514,7 @@ usage:;
errmsg);
free(errmsg);
fprintf(stderr, "Error condition : %d '%s'\n",
errno, strerror(errno));
ret, strerror(ret));
exit(2);
}
fd = lck->fd;

65
libburn/ddlpa.h
View File

@ -3,28 +3,14 @@
Implementation of Delicate Device Locking Protocol level A.
Copyright (C) 2007 Thomas Schmitt <scdbackup@gmx.net>
Provided under any of the following licenses: GPL, LGPL, BSD. Choose one.
See ../doc/ddlp.txt for a description of the protocol.
*/
#ifndef DDLPA_H_INCLUDED
#define DDLPA_H_INCLUDED 1
/* >>> For now : do not encapsulate the details of struct ddlpa_lock */
#ifndef DDLPA_H_NOT_ENCAPSULATED
#define DDLPA_H_NOT_ENCAPSULATED 1
#endif
#ifndef DDLPA_H_NOT_ENCAPSULATED
/** Container for locking state and parameters.
*/
struct ddlpa_lock;
#else /* ! DDLPA_H_NOT_ENCAPSULATED */
/* An upper limit for the length of standard paths and sibling paths */
#define DDLPA_MAX_STD_LEN 15
@ -60,8 +46,6 @@ struct ddlpa_lock {
char *errmsg;
};
#endif /* DDLPA_H_NOT_ENCAPSULATED */
/** Lock a recorder by naming a device file path. Allocate a new container.
@ -71,12 +55,11 @@ struct ddlpa_lock {
@param ddlpa_flags 0 = default behavior: the standard path will be opened
and treated by fcntl(F_SETLK)
DDLPA_OPEN_GIVEN_PATH causes the input parameter "path"
to be used with open(2) and fcntl(2). Caution: This
weakens the fcntl part of DDLP-A.
to be used with open(2) and fcntl(2).
DDLPA_ALLOW_MISSING_SGRCD allows to grant a lock
although not both, a sg and a sr|scd device, have been
found during sibling search. Normally this is counted
as failure due to EBUSY.
although not all three, a sg, a sr and a scd device
file have been found during sibling search. Normally
this is counted as failure due to EBUSY.
@param lockbundle gets allocated and then represents the locking state
@param errmsg if *errmsg is not NULL after the call, it contains an
error message. Then to be released by free(3).
@ -113,42 +96,6 @@ int ddlpa_destroy(struct ddlpa_lock **lockbundle);
#ifndef DDLPA_H_NOT_ENCAPSULATED
/** Obtain the file descriptor for doing serious work on the recorder.
@param lockbundle the lock which has been activated either by
ddlpa_lock_path() or ddlpa_lock_btl()
@return the file descriptor
*/
int ddlpa_get_fd(struct ddlpa_lock *lockbundle);
/** Obtain the path which was used to open the file descriptor.
@param lockbundle the lock
@return a pointer to the path string.
Do not alter that string ! Do not free(3) it !
*/
char *ddlpa_get_fd_path(struct ddlpa_lock *lockbundle);
/* Obtain info about the standard path and eventual locked siblings.
@param lockbundle the lock to inquire
@param std_path a pointer to the string with the standard path.
Do not alter that string ! Do not free(3) it !
@param num_siblings Tells the number of elements in sibling_*[].
0 and 1 will be the most frequent values.
@param sibling_paths Tells the device file paths of the opened sibling
device representations
Do not alter those strings ! Do not free(3) them !
@param sibling_fds Contains the opened file descriptors on sibling_paths
@return 0=success , 1=failure (will hardly happen)
*/
int ddlpa_get_siblings(struct ddlpa_lock *lockbundle,
char **std_path, int *num_siblings,
char ***sibling_paths, int **sibling_fds);
#endif /* ! DDLPA_H_NOT_ENCAPSULATED */
/** Definitions of macros used in above functions */
#define DDLPA_OPEN_GIVEN_PATH 1