From: Michael Jeanson <mjeanson@efficios.com>
Date: Tue, 13 Sep 2016 21:34:57 +0000 (+0000)
Subject: Port: Add posix_fallocate compat for mingw
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=26fdbcef74212634bb50e8e8c6b58ce0752dfb8f;p=deliverable%2Fbabeltrace.git

Port: Add posix_fallocate compat for mingw

Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/include/babeltrace/compat/fcntl-internal.h b/include/babeltrace/compat/fcntl-internal.h
index 47e5effc0..33c2a09f7 100644
--- a/include/babeltrace/compat/fcntl-internal.h
+++ b/include/babeltrace/compat/fcntl-internal.h
@@ -37,7 +37,101 @@ int bt_posix_fallocate(int fd, off_t offset, off_t len)
 	return posix_fallocate(fd, offset, len);
 }
 
-#else /* #ifdef BABELTRACE_HAVE_POSIX_FALLOCATE */
+#elif defined(__MINGW32__) /* #ifdef BABELTRACE_HAVE_POSIX_FALLOCATE */
+
+#include <assert.h>
+#include <windows.h>
+#include <fcntl.h>
+
+static inline
+int bt_posix_fallocate(int fd, off_t offset, off_t len)
+{
+	HANDLE handle;
+	LARGE_INTEGER pos, file_pos, orig_end_offset, range_end;
+	int ret = 0;
+	char zero = 0;
+	DWORD byteswritten;
+
+	if (offset < 0 || len <= 0) {
+		ret = EINVAL;
+		goto end;
+	}
+
+	range_end.QuadPart = (__int64) offset + (__int64) len;
+
+	/* Get a handle from the fd */
+	handle = (HANDLE) _get_osfhandle(fd);
+	if (handle == INVALID_HANDLE_VALUE) {
+		ret = EBADF;
+		goto end;
+	}
+
+	/* Get the file original end offset */
+	ret = GetFileSizeEx(handle, &orig_end_offset);
+	if (ret == 0) {
+		ret = EBADF;
+		goto end;
+	}
+
+	/* Make sure we don't truncate the file */
+	if (orig_end_offset.QuadPart >= range_end.QuadPart) {
+		ret = 0;
+		goto end;
+	}
+
+	/* Get the current file pointer position */
+	pos.QuadPart = 0;
+	ret = SetFilePointerEx(handle, pos, &file_pos, FILE_CURRENT);
+	if (ret == 0) {
+		ret = EBADF;
+		goto end;
+	}
+
+	/* Move the file pointer to the new end offset */
+	ret = SetFilePointerEx(handle, range_end, NULL, FILE_BEGIN);
+	if (ret == 0) {
+		ret = EBADF;
+		goto end;
+	}
+
+	/* Sets the physical file size to the current position */
+	ret = SetEndOfFile(handle);
+	if (ret == 0) {
+		ret = EINVAL;
+		goto restore;
+	}
+
+	/*
+	 * Move the file pointer back 1 byte, and write a single 0 at the
+	 * last byte of the new end offset, the operating system will zero
+	 * fill the file.
+	 */
+	pos.QuadPart = -1;
+	ret = SetFilePointerEx(handle, pos, NULL, FILE_END);
+	if (ret == 0) {
+		ret = EBADF;
+		goto end;
+	}
+
+	ret = WriteFile(handle, &zero, 1, &byteswritten, NULL);
+	if (ret == 0 || byteswritten != 1) {
+		ret = ENOSPC;
+	} else {
+		ret = 0;
+	}
+
+restore:
+	/* Restore the original file pointer position */
+	if (!SetFilePointerEx(handle, file_pos, NULL, FILE_BEGIN)) {
+		/* We moved the file pointer but failed to restore it. */
+		assert(0);
+	}
+
+end:
+	return ret;
+}
+
+#else
 
 #include <sys/types.h>
 #include <unistd.h>