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Progress due to tests with test/open-cd-excl

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This commit is contained in:
Thomas Schmitt 2007-04-18 10:35:38 +00:00
parent 2ec2a34f51
commit 2a38890c5f
2 changed files with 56 additions and 14 deletions
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64
libburn/ddlpa.c
View File

@ -3,6 +3,23 @@
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.
Compile as test program:
cc -g -Wall \
-D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE=1 -D_LARGEFILE64_SOURCE \
-DDDLPA_C_STANDALONE -o ddlpa ddlpa.c
The system macros are needed for 8-bit off_t and for open flag O_LARGEFILE
which are not absolutely necessary but explicitely take into respect that
our devices can offer more than 2 GB of addressable data.
Run test program:
./ddlpa /dev/sr0 15
./ddlpa 0,0,0 15
*/
#include <stdio.h>
@ -91,7 +108,7 @@ static int ddlpa_std_by_rdev(struct ddlpa_lock *o)
if (ddlpa_debug_mode)
fprintf(stderr,
"DDLPA_DEBUG: ddlpa_std_by_rdev(\"%s\") = \"%s\"\n",
"DDLPA_DEBUG: ddlpa_std_by_rdev(\"%s\") = \"%s\"\n",
o->path, o->std_path);
return 0;
@ -143,20 +160,32 @@ static int ddlpa_fcntl_lock(struct ddlpa_lock *o, int fd, int l_type)
static int ddlpa_occupy(struct ddlpa_lock *o, char *path, int *fd,
int no_o_excl)
{
int ret, o_flags = O_RDWR | O_NDELAY;
int ret, o_flags, o_rw, l_type;
char *o_rwtext;
o_flags = o->o_flags | O_NDELAY;
if(!no_o_excl)
o_flags |= O_EXCL;
o_rw = (o_flags) & (O_RDONLY | O_WRONLY | O_RDWR);
o_rwtext = (o_rw == O_RDONLY ? "O_RDONLY" :
(o_rw == O_WRONLY ? "O_WRONLY" :
(o_rw == O_RDWR ? "O_RDWR " : "O_?rw-mode?")));
*fd = open(path, o_flags);
if (*fd == -1) {
o->errmsg = malloc(strlen(path)+160);
if (o->errmsg)
sprintf(o->errmsg,
"Failed to open O_RDWR | O_NDELAY %s: '%s'",
(no_o_excl ? "" : "| O_EXCL "), path);
"Failed to open %s | O_NDELAY %s: '%s'",
o_rwtext,
(o_flags & O_EXCL ? "| O_EXCL " : ""), path);
return (errno ? errno : EBUSY);
}
ret = ddlpa_fcntl_lock(o, *fd, F_WRLCK);
if (o_rw == O_RDWR || o_rw == O_WRONLY)
l_type = F_WRLCK;
else
l_type = F_RDLCK;
ret = ddlpa_fcntl_lock(o, *fd, l_type);
if (ret) {
o->errmsg = malloc(strlen(path)+160);
if (o->errmsg)
@ -167,7 +196,8 @@ static int ddlpa_occupy(struct ddlpa_lock *o, char *path, int *fd,
return ret;
}
if (ddlpa_debug_mode)
fprintf(stderr, "DDLPA_DEBUG: ddlpa_occupy() %s: '%s'\n",
fprintf(stderr, "DDLPA_DEBUG: ddlpa_occupy() %s %s: '%s'\n",
o_rwtext,
(no_o_excl ? " " : "O_EXCL "), path);
return 0;
}
@ -270,7 +300,7 @@ static int ddlpa_collect_siblings(struct ddlpa_lock *o)
if (ddlpa_debug_mode)
fprintf(stderr,
"DDLPA_DEBUG: ddlpa_collect_siblings() found \"%s\"\n",
"DDLPA_DEBUG: ddlpa_collect_siblings() found \"%s\"\n",
try_path);
(o->num_siblings)++;
@ -315,7 +345,7 @@ static int ddlpa_std_by_btl(struct ddlpa_lock *o)
if (ddlpa_debug_mode)
fprintf(stderr,
"DDLPA_DEBUG: ddlpa_std_by_rdev(%d,%d,%d) = \"%s\"\n",
"DDLPA_DEBUG: ddlpa_std_by_btl(%d,%d,%d) = \"%s\"\n",
t_bus, t_id, t_lun, o->std_path);
return 0;
@ -490,6 +520,14 @@ usage:;
if (duration < 0)
goto usage;
/* For our purpose, only O_RDWR is a suitable access mode.
But in order to allow experiments, o_flags are freely adjustable.
Warning: Do _not_ set an own O_EXCL flag with the following calls !
(This freedom to fail may get removed in a final version.)
*/
if (my_path[0] != '/' && my_path[0] != '.' &&
strchr(my_path, ',') != NULL) {
/*
@ -497,15 +535,17 @@ usage:;
*/
sscanf(my_path, "%d,%d,%d", &bus, &target, &lun);
ret = ddlpa_lock_btl(bus, target, lun, O_RDWR, 0, &lck,
&errmsg);
ret = ddlpa_lock_btl(bus, target, lun, O_RDWR | O_LARGEFILE,
0, &lck, &errmsg);
} else {
/*
This substitutes for:
fd = open(my_path, O_RDWR | O_EXCL);
fd = open(my_path, O_RDWR | O_EXCL | O_LARGEFILE);
*/
ret = ddlpa_lock_path(my_path, O_RDWR, 0, &lck, &errmsg);
ret = ddlpa_lock_path(my_path, O_RDWR | O_LARGEFILE,
0, &lck, &errmsg);
}
if (ret) {
fprintf(stderr, "Cannot exclusively open '%s'\n", my_path);

6
libburn/ddlpa.h
View File

@ -51,7 +51,9 @@ struct ddlpa_lock {
/** Lock a recorder by naming a device file path. Allocate a new container.
@param path Gives the file system path of the recorder
as known to the calling program.
@param o_flags flags for open(2)
@param o_flags flags for open(2). Do not use O_EXCL here because this
is done automatically whenever appropriate.
Advised is O_RDWR | O_LARGEFILE, eventually | O_NDELAY.
@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"
@ -75,7 +77,7 @@ int ddlpa_lock_path(char *path, int o_flags, int ddlpa_flags,
@param bus parameter to match ioctl(SCSI_IOCTL_GET_BUS_NUMBER)
@param target parameter to match ioctl(SCSI_IOCTL_GET_IDLUN) &0xff
@param lun parameter to match ioctl(SCSI_IOCTL_GET_IDLUN) &0xff00
@param o_flags flags for open(2)
@param o_flags see ddlpa_lock_path().
@param ddlpa_flags see ddlpa_lock_path(). Flag DDLPA_OPEN_GIVEN_PATH
will be ignored.
@param lockbundle see ddlpa_lock_path().