Notes: I copied .nf and .fi from futex.2, but they made no visual difference.
What do they actually do?
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
For consistency.
Most man pages use 'long' instead of 'long int'.
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
It is the DT_RUNPATH/DT_RPATH of the calling object (not the
executable) that is relevant for the library search. Verified
by experiment.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
When calling msgrcv() with the MSG_COPY flag, it will report
EINVAL error even we if have disabled CONFIG_CHECKPOINT_RESTORE.
ENOSYS will be reported only if we also specify the IPC_NOWAIT
flag.
[mtk: edited commit message]
Notes from mtk:
The relevant kernel code is this:
[[
#ifdef CONFIG_CHECKPOINT_RESTORE
...
#else
static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
{
return ERR_PTR(-ENOSYS);
}
...
static long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long
msgtyp, int msgflg,
long (*msg_handler)(void __user *, struct msg_msg *, size_t))
{
...
if (msgflg & MSG_COPY) {
if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT))
return -EINVAL;
copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax));
...
}
]]
We'll only hit the ENOSYS error if:
(1) MSG_COPY was specified;
(2) IPC_NOWAIT was not specified; and
(3) CONFIG_CHECKPOINT_RESTORE was not enabled.
Signed-off-by: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
fread(3), unlike read(2) which returns a ssize_t, returns a
size_t. It doesn't distinguish between error and enf-of-file.
Instead, either ferror(3) or feof(3) need to be checked if fread()
returned 0.
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
`p1` (and `p2` too) is `const void *` and it comes from a
`const char **` (for legacy reasons, argv is not `const` but should be
treated as if it were). That means, the ultimate `char` is `const`:
"a pointer to a pointer to a const char".
Let's see what is going on before the fix first, and then the fix.
Before the fix:
`(char *const *)` (I removed the space on purpose) casts `p1` to be
"a pointer to a const pointer to a non-const char". That's clearly
not what it originally was.
Then we dereference, ending with a `char *const`, which is
"a const pointer to a non-const char". But given that the pointer value
is passed to a function, `const` doesn't make sense there, because the
function will already take a copy of it, so it is impossible to modify
the pointer itself.
The fix:
`(const char **)` The only thing that is const is the ultimate `char`,
which is the only thing that matters, because it is the only thing
strcmp(3) has access to (everything else, i.e. the pointers, are
copies).
Then, after the dereference we end up with `const char *`, the type of
argv (more or less, as previously noted), which is also the type of the
arguments to strcmp(3).
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Casting `const void *` to `struct mi *` should result in a warning if
done implicitly. The explicit cast was probably silencing that warning.
`const` can and should be kept.
Now, casting `const void *` to `const struct mi *` is done implicitly.
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Casting `void *` to `struct child_args *` is already done implicitly.
Explicitly casting can silence warnings when mistakes are made, so it's
better to remove those casts when possible.
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The type `struct msgbuf *` is implicitly casted to `const void *`.
Not only that, but the explicit cast to `void *` was slightly
misleading.
Explicitly casting can silence warnings when mistakes are made, so it's
better to remove those casts when possible.
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Alejandro Colomar