Use authopen to acquire permissions to write to drives on macOS.

1 files changed, 53 insertions, 6 deletions

diff --git a/blockdev/linux/file_dev.c b/blockdev/linux/file_dev.c
index ef44028..2797248 100644
--- a/blockdev/linux/file_dev.c
+++ b/blockdev/linux/file_dev.c
@@ -39,6 +39,8 @@
 #include <fcntl.h>
 #include <sys/disk.h>
 #include <unistd.h>
+#include <stdlib.h>
+#include <sys/socket.h>
 #endif
 
 /**@brief   Default filename.*/
@@ -68,14 +70,58 @@ EXT4_BLOCKDEV_STATIC_INSTANCE(file_dev, EXT4_FILEDEV_BSIZE, 0, file_dev_open,
 static int file_dev_open(struct ext4_blockdev *bdev)
 {
 #ifdef __APPLE__
-	/* The fseek/ftell approach to finding the device's size does not seem
-	 * to work on macOS so do it this way instead.
+	/* We need to use authopen to open the device.  It asks the user for permission
+	 * then give us an open fd over a socket.
 	 */
-	int dev = open(fname, O_RDONLY);
-	if (dev == -1) {
+
+	int pipe[2];
+	if (socketpair(AF_UNIX, SOCK_STREAM, 0, pipe) < 0) {
+		return EFAULT;
+	}
+
+	pid_t pid = fork();
+	if (pid < 0) {
+		return EFAULT;
+	}
+
+	if (pid == 0) {
+		close(pipe[0]);
+		dup2(pipe[1], STDOUT_FILENO);
+		execl("/usr/libexec/authopen", "/usr/libexec/authopen", "-stdoutpipe", "-w", "-a", fname, (char *) 0);
+		exit(-1);
+	}
+
+	close(pipe[1]);
+
+	int dev = -1;
+
+	size_t const data_buffer_size = sizeof(struct cmsghdr) + sizeof(int);
+	char data_buffer[data_buffer_size];
+
+	struct iovec io_vec[1];
+	io_vec[0].iov_base = data_buffer;
+	io_vec[0].iov_len = data_buffer_size;
+
+	socklen_t const cmsg_socket_size = CMSG_SPACE(sizeof(int));
+	char cmsg_socket[cmsg_socket_size];
+	struct msghdr message = { 0 };
+	message.msg_iov = io_vec;
+	message.msg_iovlen = 1;
+	message.msg_control = cmsg_socket;
+	message.msg_controllen = cmsg_socket_size;
+
+	if (recvmsg(pipe[0], &message, 0) <= 0) {
 		return EIO;
 	}
 
+	struct cmsghdr* cmsg_socket_header = CMSG_FIRSTHDR(&message);
+	if (cmsg_socket_header && cmsg_socket_header->cmsg_level == SOL_SOCKET && cmsg_socket_header->cmsg_type == SCM_RIGHTS) {
+		dev = *((int *) CMSG_DATA(cmsg_socket_header));
+	}
+
+	/* The fseek/ftell approach to finding the device's size does not seem
+	 * to work on macOS so do it this way instead.
+	 */
 	uint64_t sectors = 0;
 	if (ioctl(dev, DKIOCGETBLOCKCOUNT, &sectors) < 0) {
 		close(dev);
@@ -88,10 +134,11 @@ static int file_dev_open(struct ext4_blockdev *bdev)
 	}
 
 	off_t size = sectors * sector_size;
-	close(dev);
-#endif
 
+	dev_file = fdopen(dev, "r+b");
+#else
 	dev_file = fopen(fname, "r+b");
+#endif
 
 	if (!dev_file)
 		return EIO;