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lib/43919: EFAULT is not documented in aio_read
>Synopsis: EFAULT is not documented in aio_read
>Arrival-Date: Tue Sep 28 11:50:00 +0000 2010
>Originator: Alexander Nasonov
I don't have an access to that machine at the moment.
If struct aiocb is read-only protected, aio_read returns error and sets errno
to EFAULT. The error is not documented.
Actually, neither POSIX nor man page are clear about read-only aiocb. They
allude to illegal addresses (invalid references) but a pointer to read-only
page is a legal address.
POSIX: "If the buffer pointed to by aiocbp->aio_buf or the control block
pointed to by aiocbp becomes an illegal address prior to asynchronous I/O
completion, then the behaviour is undefined."
"If the request is successfully enqueued, the value of aiocbp->aio_offset can
be modified during the request as context, so this value must not be referenced
after the request is enqueued."
"The Asynchronous I/O Control Block structure pointed to by aiocbp and the
buffer that the aiocbp->aio_buf member of that structure references must remain
valid until the operation has completed."
- Allocate space for struct aiocb using mmap
- Properly initialise members of aiocb
- Call mprotect with PROT_READ and pass a pointer to allocated space
- Call aio_read
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