1 files changed, 49 insertions, 0 deletions
diff --git a/libc/unistd/pwrite.c b/libc/unistd/pwrite.c
new file mode 100644
index 0000000..7f5e071
--- /dev/null
+++ b/libc/unistd/pwrite.c
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ * 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.
+ *
+ * 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 <sys/types.h>
+#include <unistd.h>
+#include <errno.h>
+
+/*
+ * Non-atomic emulation of the pwrite system call.
+ */
+ssize_t pwrite(int fd, void *buf, size_t count, off_t offset)
+{
+    int save_errno;
+    ssize_t nwrite;
+    off_t save_offset = lseek(fd, offset, SEEK_SET);
+    if (save_offset < 0) {
+        return -1;
+    }
+    nwrite = write(fd, buf, count);
+    save_errno = errno;
+    /* Even if the write failed, try to restore the seek pointer */
+    lseek(fd, save_offset, SEEK_SET);
+    errno = save_errno;
+    return nwrite;
+}