From 4211f24424a4b22b5941a52e8acd988a500488ee Mon Sep 17 00:00:00 2001
From: Nikias Bassen
Date: Mon, 16 Jul 2012 16:07:01 +0200
Subject: ipsw: implemented file locking for on-demand downloading

---
 src/locking.c | 116 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 116 insertions(+)
 create mode 100644 src/locking.c

(limited to 'src/locking.c')

diff --git a/src/locking.c b/src/locking.c
new file mode 100644
index 0000000..dbbbd7c
--- /dev/null
+++ b/src/locking.c
@@ -0,0 +1,116 @@
+/*
+ * locking.c
+ * locking extras
+ *
+ * Copyright (c) 2012 Nikias Bassen. All Rights Reserved.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+#ifdef WIN32
+#include <windows.h>
+#else
+#include <errno.h>
+#endif
+
+#include "locking.h"
+#include "common.h"
+
+int lock_file(const char* filename, lock_info_t* lockinfo)
+{
+	if (!lockinfo) {
+		return -1;
+	}
+#ifdef WIN32
+	lockinfo->fp = CreateFile(filename, GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
+	if (lockinfo->fp == INVALID_HANDLE_VALUE) {
+		debug("ERROR: could not open or create lockfile '%s'\n", filename);
+		return -1;
+	}
+
+	lockinfo->ldata.Offset = 0;
+	lockinfo->ldata.OffsetHigh = 0;
+
+	if (!LockFileEx(lockinfo->fp, LOCKFILE_EXCLUSIVE_LOCK, 0, 1, 0, &lockinfo->ldata)) {
+		debug("ERROR: can't lock file, error %d\n", GetLastError());
+		CloseHandle(lockinfo->fp);
+		lockinfo->fp = INVALID_HANDLE_VALUE;
+		return -1;
+	}
+#else
+	lockinfo->fp = fopen(filename, "a+");
+
+	if (!lockinfo->fp) {
+		debug("ERROR: could not open or create lockfile '%s'\n", filename);
+		return -1;
+	}
+
+	lockinfo->ldata.l_type = F_WRLCK;
+	lockinfo->ldata.l_whence = SEEK_SET;
+	lockinfo->ldata.l_start = 0;
+	lockinfo->ldata.l_len = 0;
+
+	if (fcntl(fileno(lockinfo->fp), F_SETLKW, &lockinfo->ldata) < 0) {
+		debug("ERROR: can't lock file, error %d\n", errno);
+		fclose(lockinfo->fp);
+		lockinfo->fp = NULL;
+		return -1;
+	}
+#endif
+	return 0;
+}
+
+int unlock_file(lock_info_t* lockinfo)
+{
+	if (!lockinfo) {
+		return -1;
+	}
+#ifdef WIN32
+	if (lockinfo->fp == INVALID_HANDLE_VALUE) {
+		return -1;
+	}
+
+	lockinfo->ldata.Offset = 0;
+	lockinfo->ldata.OffsetHigh = 0;
+
+	if (!UnlockFileEx(lockinfo->fp, 0, 1, 0, &lockinfo->ldata)) {
+		debug("ERROR: can't unlock file, error %d\n", GetLastError());
+		CloseHandle(lockinfo->fp);
+		lockinfo->fp = INVALID_HANDLE_VALUE;
+		return -1;
+	}
+	CloseHandle(lockinfo->fp);
+	lockinfo->fp = INVALID_HANDLE_VALUE;
+#else
+	if (!lockinfo->fp) {
+		return -1;
+	}
+
+	lockinfo->ldata.l_type = F_UNLCK;
+	lockinfo->ldata.l_whence = SEEK_SET;
+	lockinfo->ldata.l_start = 0;
+	lockinfo->ldata.l_len = 0;
+
+	if (fcntl(fileno(lockinfo->fp), F_SETLK, &lockinfo->ldata) < 0) {
+		debug("ERROR: can't unlock file, error %d\n", errno);
+		fclose(lockinfo->fp);
+		lockinfo->fp = NULL;
+		return -1;
+	}
+	fclose(lockinfo->fp);
+	lockinfo->fp = NULL;
+#endif
+	return 0;
+}
+
-- 
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