[alsa-devel] [PATCH v2] alsactl: Store lockfile in /tmp

[Takashi Iwai]

At Wed, 07 May 2014 10:49:59 +0200,
Julian Scheel wrote:
> 
> Am 07.05.2014 09:19, schrieb Takashi Iwai:
> > At Tue,  6 May 2014 21:32:19 +0200,
> > Julian Scheel wrote:
> >>
> >> It can not be generally assumed that the directories in which asound.state
> >> resides are writable. Instead using /tmp as location for lock files seems more
> >> reliable.
> >
> > The subject and changelog don't match with the actual change.
> > Now it's /var/log instead of /tmp, right?
> 
> Sorry for that. Must have been too late.

Seems so...

> > Besides that, it'd be better to allow a full path name for a lock file
> > instead of a directory name.  If you give a different file name via -f
> > option, you have a high chance to conflict with the existing file in
> > /var/lock.
> 
> So, you'd prefer a --lock-file/-L option which can be used to set an 
> explicit lock file?

Yes.

> > Furthermore, for solving *your* problem (restoring from read-only
> > rootfs), an easier option would be allowing to restore the system
> > default without locking.
> 
> While this is true I think making the locking mechanism more robust is a 
> good thing anyway.

Of course, it's good to improve the lock mechanism.
OTOH, adding an option like --no-lock would be good, too.
This is a different solution, and the idea doesn't conflict.


Takashi

> Julian
> 
> >
> > Takashi
> >
> >>
> >> Signed-off-by: Julian Scheel <julian at jusst.de>
> >> ---
> >>   alsactl/alsactl.c |  7 +++++++
> >>   alsactl/alsactl.h |  1 +
> >>   alsactl/lock.c    | 13 ++++++++++---
> >>   3 files changed, 18 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/alsactl/alsactl.c b/alsactl/alsactl.c
> >> index 6bc013f..415dfb8 100644
> >> --- a/alsactl/alsactl.c
> >> +++ b/alsactl/alsactl.c
> >> @@ -38,6 +38,9 @@
> >>   #ifndef SYS_PIDFILE
> >>   #define SYS_PIDFILE "/var/run/alsactl.pid"
> >>   #endif
> >> +#ifndef SYS_LOCKPATH
> >> +#define SYS_LOCKPATH "/var/lock"
> >> +#endif
> >>
> >>   int debugflag = 0;
> >>   int force_restore = 1;
> >> @@ -46,6 +49,7 @@ int do_lock = 0;
> >>   int use_syslog = 0;
> >>   char *command;
> >>   char *statefile = NULL;
> >> +char *lockpath = SYS_LOCKPATH;
> >>
> >>   #define TITLE	0x0100
> >>   #define HEADER	0x0200
> >> @@ -71,6 +75,7 @@ static struct arg args[] = {
> >>   { HEADER, NULL, "Available state options:" },
> >>   { FILEARG | 'f', "file", "configuration file (default " SYS_ASOUNDRC ")" },
> >>   { 'l', "lock", "use file locking to serialize concurrent access" },
> >> +{ FILEARG | 'D', "lock-dir", "directory to use for lock files (default " SYS_LOCKPATH ")" },
> >>   { 'F', "force", "try to restore the matching controls as much as possible" },
> >>   { 0, NULL, "  (default mode)" },
> >>   { 'g', "ignore", "ignore 'No soundcards found' error" },
> >> @@ -232,6 +237,8 @@ int main(int argc, char *argv[])
> >>   		case 'l':
> >>   			do_lock = 1;
> >>   			break;
> >> +		case 'D':
> >> +			lockpath = optarg;
> >>   		case 'F':
> >>   			force_restore = 1;
> >>   			break;
> >> diff --git a/alsactl/alsactl.h b/alsactl/alsactl.h
> >> index 9109a70..6c6bee5 100644
> >> --- a/alsactl/alsactl.h
> >> +++ b/alsactl/alsactl.h
> >> @@ -5,6 +5,7 @@ extern int do_lock;
> >>   extern int use_syslog;
> >>   extern char *command;
> >>   extern char *statefile;
> >> +extern char *lockpath;
> >>
> >>   void info_(const char *fcn, long line, const char *fmt, ...);
> >>   void error_(const char *fcn, long line, const char *fmt, ...);
> >> diff --git a/alsactl/lock.c b/alsactl/lock.c
> >> index 587a109..c69e285 100644
> >> --- a/alsactl/lock.c
> >> +++ b/alsactl/lock.c
> >> @@ -36,17 +36,24 @@ static int state_lock_(const char *file, int lock, int timeout)
> >>   	struct flock lck;
> >>   	struct stat st;
> >>   	char lcktxt[12];
> >> +	char *filename;
> >>   	char *nfile;
> >>
> >>   	if (!do_lock)
> >>   		return 0;
> >> -	nfile = malloc(strlen(file) + 6);
> >> +
> >> +	/* only use the actual filename, not the path */
> >> +	filename = strrchr(file, '/');
> >> +	if (!filename)
> >> +		filename = file;
> >> +
> >> +	nfile = malloc(strlen(lockpath) + strlen(filename) + 7);
> >>   	if (nfile == NULL) {
> >>   		error("No enough memory...");
> >>   		return -ENOMEM;
> >>   	}
> >> -	strcpy(nfile, file);
> >> -	strcat(nfile, ".lock");
> >> +
> >> +	sprintf(nfile, "%s/%s.lock", lockpath, filename);
> >>   	lck.l_type = lock ? F_WRLCK : F_UNLCK;
> >>   	lck.l_whence = SEEK_SET;
> >>   	lck.l_start = 0;
> >> --
> >> 1.9.2
> >>
> >> _______________________________________________
> >> Alsa-devel mailing list
> >> Alsa-devel at alsa-project.org
> >> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
> >>
>