Fix raw_fallocate for Android and deal with unsupported filesystems. #2363
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LGTM, thanks! It would be nice to hear from an Android user before merging this, so let's wait some time. |
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@SergioRAgostinho I think we should also merge this and hope for the best. |
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is it for sure the issue is fixed for android? |
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This PR does two things:
::fallocateinstead of::posix_fallocate(no member named 'posix_fallocate' in the global namespace #2358).lseek+write.It's quite important not to fall back to
lseek+writeon all allocation failures, since the whole reason for the allocation was to preventSIGBUSerrors when allocation fails after mmaping. Ignoring allocation failure for supported filesystems would defeat that purpose, but always failing on unsupported filesystems even if space is available does not seem acceptable.I skipped the fallback to
ftruncate, because I think it is equally likely to fail due to lack of filesystem support if(posix_)fallocatedid.I also didn't implement a fallback in the OS X version because I can't find any relevant documentation on the failure modes. It could be useful if someone on OS X tries to call
raw_fallocateon a file on FAT32 and NTFS filesystem to see if that fails, and with whaterrnovalue.