[patch] Supporting SCSI in eject

[Bernhard Fischer]

On Thu, Feb 07, 2008 at 03:56:35PM +0100, Nico Erfurth wrote:
>Hi,
>
>for our project we need the ability to cleanly eject an usb-storage
>device(better don't ask why ;)). If added support for this in the eject
>applet. Patch is attached. The code is taken from the original eject,
>but I refactored it a bit.
>
>The feature can be enabled via the config (FEATURE_EJECT_SCSI).
>
>Nico

>--- busybox-1.9.0.ORG/miscutils/eject.c	2007-12-21 23:00:31.000000000 +0100
>+++ busybox-1.9.0/miscutils/eject.c	2008-02-07 15:47:07.000000000 +0100
>@@ -25,15 +25,69 @@
> #define FLAG_CLOSE  1
> #define FLAG_SMART  2
> 
>+#if ENABLE_FEATURE_EJECT_SCSI
>+/* Code taken from the original eject (http://eject.sourceforge.net/),
>+ * refactored it a bit for busybox (ne-bb at nicoerfurth.de) */
>+#define FLAG_SCSI   4
>+
>+#include <scsi/sg.h>
>+#include <scsi/scsi.h>
>+static void eject_scsi(int fd) {
>+  int i;
>+  unsigned char sense_buffer[32];
>+  unsigned char inqBuff[2];
>+  sg_io_hdr_t io_hdr;
>+  char sg_commands[3][6] = {
>+    {ALLOW_MEDIUM_REMOVAL, 0, 0, 0, 0, 0},
>+    {START_STOP, 0, 0, 0, 1, 0},
>+    {START_STOP, 0, 0, 0, 2, 0}
>+  };
>+
>+  if ((ioctl(fd, SG_GET_VERSION_NUM, &i) < 0) || (i < 30000))
>+    bb_error_msg_and_die("not an sg device, or old sg driver\n");
>+  
>+  memset(&io_hdr, 0, sizeof(sg_io_hdr_t));
>+  io_hdr.interface_id = 'S';
>+  io_hdr.cmd_len = 6;
>+  io_hdr.mx_sb_len = sizeof(sense_buffer);
>+  io_hdr.dxfer_direction = SG_DXFER_NONE;
>+  io_hdr.dxfer_len = 0;
>+  io_hdr.dxferp = inqBuff;
>+  io_hdr.sbp = sense_buffer;
>+  io_hdr.timeout = 2000;
>+
>+  for(i=0; i < 3; i++) {
>+    io_hdr.cmdp = sg_commands[i];
>+    ioctl_or_perror_and_die(fd, SG_IO, (void *)&io_hdr, "ioctl (%i) failed", i);
>+  }
>+
>+  /* force kernel to reread partition table when new disc inserted */
>+  ioctl(fd, BLKRRPART);
>+}
>+#endif
>+
>+static void eject_cdrom(const int fd, const unsigned long flags, const char *device) {
>+  int cmd = CDROMEJECT;
>+	if (flags & FLAG_CLOSE
>+	 || (flags & FLAG_SMART && ioctl(fd, CDROM_DRIVE_STATUS) == CDS_TRAY_OPEN))
>+		cmd = CDROMCLOSETRAY;
>+
>+	return ioctl_or_perror_and_die(fd, cmd, NULL, "%s", device);
>+}
>+
> int eject_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
> int eject_main(int argc, char **argv)
> {
> 	unsigned long flags;
> 	const char *device;
>-	int dev, cmd;
>+	int dev;
> 
> 	opt_complementary = "?1:t--T:T--t";
>-	flags = getopt32(argv, "tT");
>+	flags = getopt32(argv, "tT"
>+#if ENABLE_FEATURE_EJECT_SCSI
>+      "s"
>+#endif

Better say USE_FEATURE_EJECT_SCSI("s")
>+  );
> 	device = argv[optind] ? : "/dev/cdrom";
> 
> 	// We used to do "umount <device>" here, but it was buggy
>@@ -46,12 +100,12 @@
> 	// eject
> 
> 	dev = xopen(device, O_RDONLY|O_NONBLOCK);

device_open()

>-	cmd = CDROMEJECT;
>-	if (flags & FLAG_CLOSE
>-	 || (flags & FLAG_SMART && ioctl(dev, CDROM_DRIVE_STATUS) == CDS_TRAY_OPEN))
>-		cmd = CDROMCLOSETRAY;
>-
>-	ioctl_or_perror_and_die(dev, cmd, NULL, "%s", device);
>+#if ENABLE_FEATURE_EJECT_SCSI
>+  if (flags & FLAG_SCSI) 
>+    eject_scsi(dev);
>+  else
>+#endif
>+    eject_cdrom(dev, flags, device);

Is it smaller if you use a functor here?
	void (*do_eject_fn)(const int fd, const unsigned long flags,
				const char *dev);
	do_eject_fn = eject_cdrom;
	if (ENABLE_FEATURE_EJECT_SCSI && flags & FLAG_SCSI)
		do_eject_fn = eject_scsi;
	/* Just Do It (tm) */
	do_eject_fn(fd, flags, dev);
> 
> 	if (ENABLE_FEATURE_CLEAN_UP)
> 		close(dev);

What's the size(1) with and without scsi support?