From: Xi Ruoyao <xry111@xry111.site>
To: abushwang <abushwangs@gmail.com>,
libc-alpha@sourceware.org, carlos@redhat.com
Subject: Re: [PATCH] rt: fix shm_open not set ENAMETOOLONG when name exceeds {_POSIX_PATH_MAX}
Date: Tue, 07 Mar 2023 16:54:20 +0800 [thread overview]
Message-ID: <2ff8bc971b5244496b02ebc99ef623532a1a787b.camel@xry111.site> (raw)
In-Reply-To: <20230307083229.629411-1-abushwangs@gmail.com>
On Tue, 2023-03-07 at 16:32 +0800, abushwang via Libc-alpha wrote:
> according to man-pages-posix-2017, shm_open() function may fail if the length
> of the name argument exceeds {_POSIX_PATH_MAX} and set ENAMETOOLONG
It's "may" fail, not "shall" fail. POSIX 2017 says "may" means:
may
Describes a feature or behavior that is optional for an implementation
that conforms to POSIX.1-2017. An application should not rely on the
existence of the feature or behavior. An application that relies on such
a feature or behavior cannot be assured to be portable across conforming
implementations.
We should not break existing programs just for a "may" clause.
/* snip */
> int
> __shm_get_name (struct shmdir_name *result, const char *name, bool
> sem_prefix)
> @@ -50,13 +51,15 @@ __shm_get_name (struct shmdir_name *result, const
> char *name, bool sem_prefix)
> while (name[0] == '/')
> ++name;
> namelen = strlen (name);
> + if (namelen > NAME_MAX)
> + return ENAMETOOLONG;
>
> if (sem_prefix)
> alloc_buffer_copy_bytes (&buffer, "sem.", strlen ("sem."));
> alloc_buffer_copy_bytes (&buffer, name, namelen + 1);
> if (namelen == 0 || memchr (name, '/', namelen) != NULL
> || alloc_buffer_has_failed (&buffer))
If you really want ENAMETOOLONG I guess you can check if namelen >
NAME_MAX here (as a very long namelen would have caused an allocation
failure).
By the way if namelen <= NAME_MAX but alloc_buffer_has_failed (due to a
high memory usage) should we say ENOSPC instead of EINVAL? POSIX 2017
says:
[ENOSPC]
There is insufficient space for the creation of the new shared memory object.
> - return -1;
> + return EINVAL;
> return 0;
> }
--
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University
next prev parent reply other threads:[~2023-03-07 8:54 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-07 8:32 abushwang
2023-03-07 8:54 ` Xi Ruoyao [this message]
2023-03-07 9:46 ` abush wang
2023-03-07 9:46 ` abush wang
2023-03-07 9:45 abushwang
2023-03-07 10:02 ` Xi Ruoyao
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