[OpenWrt-Devel] [PATCH] busybox: lock: implement -n "Fail rather than wait"

[Felix Fietkau]

On 2015-08-06 17:28, Alexander Couzens wrote:
> lock -n is similiar to flock -n. If the lock was already taken,
> fail with exit code = 1 and write error message to stderr.
> 
> example:
> if ! lock -n /tmp/foo ; then
> 	echo lock exits.
> else
> 	echo lock was free. But is locked now.
> fi
>> lock was free. But is locked now.
>> lock exists.
> 
> Signed-off-by: Alexander Couzens <lynxis at fe80.eu>
> ---
>  package/utils/busybox/patches/220-add_lock_util.patch | 18 +++++++++++++++---
>  1 file changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/package/utils/busybox/patches/220-add_lock_util.patch b/package/utils/busybox/patches/220-add_lock_util.patch
> index f42edcb..08f489a 100644
> --- a/package/utils/busybox/patches/220-add_lock_util.patch
> +++ b/package/utils/busybox/patches/220-add_lock_util.patch
> @@ -33,9 +33,11 @@
>   lib-$(CONFIG_MAKEDEVS)    += makedevs.o
>   lib-$(CONFIG_MAN)         += man.o
>   lib-$(CONFIG_MICROCOM)    += microcom.o
> +Index: busybox-1.23.2/miscutils/lock.c
> +===================================================================
>  --- /dev/null
> -+++ b/miscutils/lock.c
> -@@ -0,0 +1,135 @@
> ++++ busybox-1.23.2/miscutils/lock.c
> +@@ -0,0 +1,145 @@
Please use the right refresh method or run make package/busybox/refresh.

> @@ -65,6 +68,7 @@
>  +	                "	-s	Use shared locking\n"
>  +	                "	-u	Unlock\n"
>  +	                "	-w	Wait for the lock to become free, don't acquire lock\n"
> ++			"	-n	Fail rather than wait\n"
>  +					"\n", name);
>  +	exit(1);
>  +}
> @@ -104,7 +110,10 @@
>  +		}
>  +	}
>  +
> -+	if (flock(fd, (shared ? LOCK_SH : LOCK_EX)) < 0) {
> ++	flags = shared ? LOCK_SH : LOCK_EX;
> ++	flags |= failinsteadwait ? LOCK_NB : 0;
> ++
> ++	if ((ret = flock(fd, flags)) < 0) {
>  +		fprintf(stderr, "Can't lock %s\n", file);
>  +		return 1;
>  +	}
"failinsteadwait" sounds a bit quirky, how about something like
"try_lock" instead. Same applies for the description.

- Felix
_______________________________________________
openwrt-devel mailing list
openwrt-devel at lists.openwrt.org
https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel