Replace SysV semaphore lock with file lock

Some systems, such as Android, do not support SysV semaphore locks.
This implements an alternative file lock mechanism using flock().

flock() was chosen because it's pretty straight forward. It's known to
be broken when using NFS, but I doubt we'll ever store our lock on an
NFS volume.

CQ-DEPEND=CL:327407,CL:325609
BUG=chrome-os-partner:49527
BRANCH=none
TEST=tested on Smaug by running mosys and ectool while reading
firmware ROM with flashrom, all three utilities eventually
ran successfully.

Change-Id: Ic73fe0281fbc1dfaae1bb03e5683774a0c04ae5b
Signed-off-by: David Hendricks <dhendrix@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/329430
Reviewed-by: Shawn N <shawnn@chromium.org>

1 files changed, 0 insertions, 105 deletions

diff --git a/util/lock/ipc_lock.c b/util/lock/ipc_lock.c
deleted file mode 100644
index 790014e67b..0000000000
--- a/util/lock/ipc_lock.c
+++ /dev/null
@@ -1,105 +0,0 @@
-/* Copyright 2012, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *    * Redistributions of source code must retain the above copyright
- *      notice, this list of conditions and the following disclaimer.
- *    * Redistributions in binary form must reproduce the above
- *      copyright notice, this list of conditions and the following
- *      disclaimer in the documentation and/or other materials provided
- *      with the distribution.
- *    * Neither the name of Google Inc. nor the names of its
- *      contributors may be used to endorse or promote products derived
- *      from this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <inttypes.h>
-#include <stdio.h>
-#include <time.h>
-
-#include "csem.h"
-#include "ipc_lock.h"
-
-static int lock_init(struct ipc_lock *lock)
-{
-	if (lock->sem < 0) {
-		/* get or create the semaphore, init to 1 if needed */
-		int sem = csem_get_or_create(lock->key, 1);
-		if (sem < 0)
-			return -1;
-
-		lock->sem = sem;
-	}
-	return 0;
-}
-
-static void msecs_to_timespec(int msecs, struct timespec *tmspec)
-{
-	tmspec->tv_sec = msecs / 1000;
-	tmspec->tv_nsec = (msecs % 1000) * 1000 * 1000;
-}
-
-int acquire_lock(struct ipc_lock *lock, int timeout_msecs)
-{
-	int ret;
-	struct timespec timeout;
-	struct timespec *timeout_ptr;
-
-	/* initialize the lock */
-	if (lock_init(lock) < 0) {
-		fprintf(stderr, "%s(): failed to init lock 0x%08x\n",
-			__func__, (uint32_t)lock->key);
-		return -1;
-	}
-
-	/* check if it is already held */
-	if (lock->is_held)
-		return 1;
-
-	/* calculate the timeout */
-	if (timeout_msecs >= 0) {
-		timeout_ptr = &timeout;
-		msecs_to_timespec(timeout_msecs, timeout_ptr);
-	} else {
-		timeout_ptr = NULL;
-	}
-
-	/* try to get the lock */
-	ret = csem_down_timeout_undo(lock->sem, timeout_ptr);
-	if (ret < 0) {
-		fprintf(stderr, "%s(): failed to acquire lock 0x%08x\n",
-			__func__, (uint32_t)lock->key);
-		return -1;
-	}
-
-	/* success */
-	lock->is_held = 1;
-	return 0;
-}
-
-int release_lock(struct ipc_lock *lock)
-{
-	if (lock->is_held) {
-		lock->is_held = 0;
-		csem_up_undo(lock->sem);
-		/* NOTE: do not destroy the semaphore, we want it to persist */
-		return 0;
-	}
-	/* did not hold the lock */
-	return -1;
-}