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Re: [Qemu-devel] [PATCH v2] block/raw-posix.c: Fixes raw_getlength() on
From: |
Programmingkid |
Subject: |
Re: [Qemu-devel] [PATCH v2] block/raw-posix.c: Fixes raw_getlength() on Mac OS X so that it reports the correct length of a real CD |
Date: |
Sat, 27 Dec 2014 22:00:47 -0500 |
On Dec 27, 2014, at 8:19 PM, Peter Maydell wrote:
> On 28 December 2014 at 00:36, Programmingkid <address@hidden> wrote:
>> The raw_getlength() function under Mac OS X incorrectly returned a constant
>> value instead of calculating the size of a real CD-ROM disc. This patch
>> fixes this problem and makes booting from a real CD-ROM disc possible again
>> under Mac OS X.
>>
>> signed-off-by: John Arbuckle <address@hidden>
>
> Thanks. (My Mac doesn't have a cdrom...)
>
>> ---
>> block/raw-posix.c | 11 ++++++++++-
>> 1 files changed, 10 insertions(+), 1 deletions(-)
>>
>> diff --git a/block/raw-posix.c b/block/raw-posix.c
>> index e51293a..d723133 100644
>> --- a/block/raw-posix.c
>> +++ b/block/raw-posix.c
>> @@ -1312,7 +1312,16 @@ again:
>> if (size == 0)
>> #endif
>> #if defined(__APPLE__) && defined(__MACH__)
>> - size = LLONG_MAX;
>> + // Query the number of sectors on the disk
>
> I note in passing that this whole function is a total mess
> -- look at that "if (size == 0)" in the previous #ifdef...
> However since I think it's impossible to both have the
> previous #ifdef and this one enabled it won't cause an issue.
I agree. This file needs a lot of work.
>
>> + uint64_t sectors = 0;
>> + ioctl(fd, DKIOCGETBLOCKCOUNT, §ors);
>
> You need to check the error return from these ioctl calls.
>
>> +
>> + // Query the size of each sector
>> + uint32_t sectorSize = 0;
>> + ioctl(fd, DKIOCGETBLOCKSIZE, §orSize);
>> +
>> + size = sectors * sectorSize;
>> + //printf("size of disc = %d MB\n", size/(1024*1024));
>> #else
>> size = lseek(fd, 0LL, SEEK_END);
>> if (size < 0) {
>
> Minor style issues you might want to fix for v2:
> * use /* */ comments, not //
> * declare variables only at the top of {} code blocks
> * don't leave commented out debug printfs in code
>
> thanks
> -- PMM
Here is version 2 of the patch. All the suggestions have been implemented.
signed-off-by: John Arbuckle <address@hidden>
---
block/raw-posix.c | 20 +++++++++++++++++++-
1 files changed, 19 insertions(+), 1 deletions(-)
diff --git a/block/raw-posix.c b/block/raw-posix.c
index e51293a..0148161 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -1312,7 +1312,25 @@ again:
if (size == 0)
#endif
#if defined(__APPLE__) && defined(__MACH__)
- size = LLONG_MAX;
+ #define IOCTL_ERROR_VALUE -1
+ uint64_t sectors = 0;
+ uint32_t sectorSize = 0;
+ int ret;
+
+ /* Query the number of sectors on the disk */
+ ret = ioctl(fd, DKIOCGETBLOCKCOUNT, §ors);
+ if(ret == IOCTL_ERROR_VALUE) {
+ printf("\n\nWarning: problem detected retrieving sector
count!\n\n");
+ return -errno;
+ }
+
+ /* Query the size of each sector */
+ ret = ioctl(fd, DKIOCGETBLOCKSIZE, §orSize);
+ if(ret == IOCTL_ERROR_VALUE) {
+ printf("\n\nWarning: problem detected retrieving sector size!\n\n");
+ return -errno;
+ }
+ size = sectors * sectorSize;
#else
size = lseek(fd, 0LL, SEEK_END);
if (size < 0) {
--
1.7.5.4