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Re: [Qemu-devel] [PATCH v6] block/raw-posix.c: Fixes raw_getlength() on
From: |
Programmingkid |
Subject: |
Re: [Qemu-devel] [PATCH v6] block/raw-posix.c: Fixes raw_getlength() on Mac OS X so that it reports the correct length of a real CD |
Date: |
Wed, 14 Jan 2015 13:21:44 -0500 |
On Jan 14, 2015, at 12:02 PM, Peter Maydell wrote:
> On 13 January 2015 at 20:07, Programmingkid <address@hidden> wrote:
>> Allows QEMU on Mac OS X to use a real cdrom again.
>>
>> Signed-off-by: John Arbuckle <address@hidden>
>>
>> ---
>> Added fallback code - uses lseek() if ioctl() fails.
>>
>> block/raw-posix.c | 25 ++++++++++++++++++++++++-
>> 1 files changed, 24 insertions(+), 1 deletions(-)
>>
>> diff --git a/block/raw-posix.c b/block/raw-posix.c
>> index e51293a..5815707 100644
>> --- a/block/raw-posix.c
>> +++ b/block/raw-posix.c
>> @@ -1312,7 +1312,30 @@ again:
>> if (size == 0)
>> #endif
>> #if defined(__APPLE__) && defined(__MACH__)
>> - size = LLONG_MAX;
>> + {
>> + uint64_t sectors = 0;
>> + uint32_t sector_size = 0;
>> + bool ioctl_problem = false;
>> + ret = 0;
>> +
>> + /* Query the number of sectors on the disk */
>> + ret = ioctl(fd, DKIOCGETBLOCKCOUNT, §ors);
>> + if (ret != 0)
>> + ioctl_problem = true;
>> +
>> + /* Query the size of each sector */
>> + ret = ioctl(fd, DKIOCGETBLOCKSIZE, §or_size);
>> + if (ret != 0)
>> + ioctl_problem = true;
>> +
>> + /* If everything is ok */
>> + if (ioctl_problem == false)
>> + size = sectors * sector_size;
>> +
>> + /* If a problem occurred with ioctl(), fallback to lseek() */
>> + else
>> + size = lseek(fd, 0LL, SEEK_END);
>> + }
>> #else
>
> This fixes the "make check" problem, but you're not catching
> the possibility of lseek failing. (Also the if() statements
> are all missing braces our coding style requires.) You can
> avoid that bool flag like this:
>
> {
> uint64_t sectors = 0;
> uint32_t sector_size = 0;
>
> if (ioctl(fd, DKIOCGETBLOCKCOUNT, §ors) == 0
> && ioctl(fd, DKIOCGETBLOCKSIZE, §or_size) == 0) {
> size = sectors * sector_size;
> } else {
> size = lseek(fd, 0LL, SEEK_END);
> if (size < 0) {
> return -errno;
> }
> }
> }
Yeah, your code looks great. I will make a patch for it if you need me to.