site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com You have three problems. The first one is the most severe: 1) 2) 3) #define HFSIOC_RESIZE_VOLUME _IOW('h', 2, u_int64_t) #define HFS_RESIZE_VOLUME IOCBASECMD(HFSIOC_RESIZE_VOLUME) #define IOCBASEDCMD(x) ((x) & ~(IOCPARM_MASK << 16)) -- Cheers, -- Terry Thanks anyway so far! Michael Shantonu Sen <ssen@apple.com> 23.01.2009 15:52 To Michael Alfred Schmidt <michael.alfred.schmidt@utimaco.de> cc darwin-kernel@lists.apple.com Subject Re: problems with hfs_truncatefs() / HFS_RESIZE_VOLUME Please read my post again. Shantonu Sent from my MacBook On Jan 23, 2009, at 12:25 AM, Michael Alfred Schmidt wrote: Shantonu, Michael Shantonu Sen <ssen@apple.com> 22.01.2009 18:11 To Michael Alfred Schmidt <michael.alfred.schmidt@utimaco.de> cc mm w <openspecies@gmail.com>, darwin-kernel@lists.apple.com Subject Re: problems with hfs_truncatefs() / HFS_RESIZE_VOLUME Shantonu Sen ssen@apple.com Sent from my Mac Pro On Jan 22, 2009, at 9:06 AM, Michael Alfred Schmidt wrote: The volume has both sufficient site to expand and to shrink. Michael mm w <openspecies@gmail.com> 22.01.2009 17:50 To Michael Alfred Schmidt <michael.alfred.schmidt@utimaco.de> cc darwin-kernel@lists.apple.com Subject Re: problems with hfs_truncatefs() / HFS_RESIZE_VOLUME you certainly get a ENOSPC message somewhere, bad sample you are using - yoda Cheers! -- -mmw _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/ssen%40apple.com This email sent to ssen@apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/tlambert%40apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.a... You should really be solving this problem by using popen() on the diskutil command, rather than trying to replace/rewrite the diskutil command. If you had started out this way, no matter what changes we made in the future, so long as the input and output of that command didn't change, then your code would have been isolated and continued to run and be happy. You didn't do this. The second problem is that you didn't give us all the information up front. The most important piece you left out for this particular type of problem is that you failed to tell us your code was 64 bit. When passing size variant parameters to fsctl, ioctl, and fcntl, it's important to know this. Effectively, these end up with different definition values for their manifest constants, and when that happens, they do not match the case statement entries for the 32 bit values, so unless we've gone out of our way to deal with this issue, many of these controls will not work from 32 bit code (size variance can also be a function of structure packing, even if the parameter structure contains no sized types). Fortunately for you, the parameter in this case is 64 bit on both 32 and 64 bit platforms, but... Now the third problem: you are using the wrong command parameter to accomplish what you are attempting to accomplish. The command parameter you are using is HFS_RESIZE_VOLUME; the correct one is HFSIOC_RESIZE_VOLUME: What does IOCBASECMD() do? It strips the command size out of the manifest constant, like so: Why? Because when you are calling fsctl, fcntl, or ioctl with a size variant argument value, this will allow you to have a single case statement entry which is agnostic as to t whether or not the command is coming from 32 or 64 bit code. This is useful, in that it allows us to isolate the bit-ness dependence into the case statement entry. This is why when it's decoding these, it applies the IOCBASEDCMD() macro to the command argument, and uses the size-agnostic version of the call to do the switch statement case entries, and then these entries go on and cast the data portion of the command buffer to parameter value pointers of the appropriate type, and dereference them for input and output. This works this way because the fsctl, fcntl, and ioctl code in the kernel copies the parameter data into an internal kernel buffer (size constrained) and deal with the data as kernel data rather than user data (among other things, this prevents the race between validation and use of the data in some cases where it would otherwise have to be copied in twice). When the operation is done, it copies the data back out. Both of these copy operations are predicated on control bits in the command parameter (specifically, if IOC_IN is present, the data is copied in on the way in and if IOC_OUT is present, it's copied out on the way out). So given that you made the call and told it that your data length is 0, how much data was copied in? 0 bytes. So what's in the buffer 'data' that's getting dereferenced out? Stack garbage. This is why the value is the same each time you call it. Luckily, since these are data interfaces behind an authorization check, so you don't have to worry about this being a security issue; the data being dereferenced is already in a kernel buffer, so it's not gong to result in a fault on reference, and since it's no procedural, as long as we range check our arguments (we do), then you're not going to do anything much (except get yourself an error, which is what you saw was happening). My suggestion would be to not attempt to use non-public interfaces unless you understand precisely how they work; even the public interfaces, as problem #2 demonstrates, can be problematic. Your best bet would be to wrap system tools which do what you want, and are well enough documented and mature enough, that you aren't going to have to worry much about them changing on you. If you insist on going forward in writing your own low level code for this instead of writing intermediate code to wrap the utility, well, at least now you know why it was failing, why you were seeing the results you were seeing, and to be more careful about research in the future. On Jan 23, 2009, at 7:28 AM, Michael Alfred Schmidt wrote: Thanks, I understand. Anyway, my goal is to shrink the volume rather than to expand it. So the repartitioning problem shouldn't apply. As I eventually managed to set up the kernel debugger, I was able to verify the calling parameters of 'hfs_truncatefs()' (in the kernel - hfs_vfsops.c). What I figured there is that the 'newsize' paramter always had a constant value, regardless of the various valid input parameters that I passed into userland 'fsctl()' for 'uiNewSize' (see my code). So I assume that this value gets lost somewhwere between userland and kernel. This is why I assume that I might have some kind of thunking problem (maybe between 32-bit/64- bit code) with my input pointer. Unfortunately, my kernel debugging skills aren't good enough yet to trace the parameter passing to the kernel. diskutil is an integrated solution that does both repartitioning and filesystem resizing. The "limits" it prints out assume that it is also going to be doing repartitioning. The 128MB freespace is outside of the partition boundaries. If you want to use it (which I don't recommend), you need to repartition first to increase the size of your partition to use some of that freespace, and then increase the filesystem to match. I'm testing on a MacBook Pro with default factory partitioning, i.e. there are 128 MB left free on top of the OS partition (see http://developer.apple.com/technotes/tn2006/tn2166.html#SECPARTITIONINGPOLIC...) . I verify upfront with 'diskutil resizeVolume <resp. volume device> limits' what freedom to expand or shrink I have. Since my goal is to shrink the partition rather than to expand it anyway, I concentrate my tests on shrinking (by ~ 10%). How do you know it has space to expand? You know you have to repartition the disk first, right (so that the container block device is large enough). This fsctl is something that is straightforward to use the same way the Disk Utility/diskutil use it. How big is your filesystem? How many allocation blocks? What sizes are you requesting? I do get ENOSPC in case the code runs into 'hfs_extendfs(): not enough space on device', or EINVAL in case the code runs into 'hfs_truncatefs(): invalid size'. I get both erros with my test program when I only try often enough, i. e. I get both errors for the same value. The same behavior (both errors possible) applies to any other arbitrary value of uiNewSize. This is why I believe that the value is currently somehow lost. On Thu, Jan 22, 2009 at 8:16 AM, Michael Alfred Schmidt <michael.alfred.schmidt@utimaco.de> wrote:

Hi,

I'm trying to shrink an HFS+ partition, just as 'diskutil resizeVolume...'

does. However, I'm facing problems implementing the HFS_RESIZE_VOLUME

command via fsctl(), as proposed by Amit Singh on p. 1572 of 'Mac OS X

Internals'.

My code looks as follows:

int iRet = 0;

u_int32_t uiBlockSize;

u_int64_t uiBlockCount, uiCurrentSize, uiNewSize;

struct statfs StatFS;

// only works if device mounted

iRet = statfs ("/etc/", &StatFS);

if (iRet < 0)

{

perror ("statfs failed with");

return;

}

uiBlockSize = StatFS.f_bsize;

uiBlockCount = StatFS.f_blocks;

printf ("block size:\t %u\n", uiBlockSize);

printf ("block count:\t %llu\n", uiBlockCount);

uiCurrentSize = uiBlockSize * uiBlockCount;

printf ("partition size:\t %llu\n\n", uiBlockSize * uiBlockCount);

uiNewSize = uiCurrentSize; // only test here!!!

printf ("new volume size: %llu, hex: %llX\n", uiNewSize, uiNewSize);

iRet = fsctl ("/", HFS_RESIZE_VOLUME, &uiNewSize, 0);

if (iRet < 0)

{

perror ("fsctl failed with");

return;

}

fsctl() fails with either 'hfs_extendfs(): not enough space on device' or

'hfs_truncatefs(): invalid size', even if the new size equals the old size

(as in the code sample above). It looks like the &uiNewSize input parameter

is fully ignored, as other "new sizes" show the same unpredictable results.

On the kernel side, the respective code resides in bsd/hfs/ hfs_readwrite.c.

...

From looking at that code, I cannot see any obvious mistake in my code. I'm

wondering whether there is any thunking (pointer conversion) problem with

the pointer to u_int64_t in the transition from userland to kernel.

My target system is Mac OS X 10.5.x (Intel), compiled with XCode 3.1 with

default build settings.

I'm grateful for any idea on what's wrong with my code!

Thanks in advance!

Michael

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