* man2/sigaction.2 (.SS Undocumented): Provide information about
relation between the second argument of sa_handler and
uc_mcontext field of the struct ucontext structure.
Signed-off-by: Eugene Syromyatnikov <evgsyr@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Some architectures do provide an 'l_sysid' declaration in
struct flock; however, it is not used anyway.
* man2/fcntl.2 (.SH NOTES): Note that l_sysid field is not used on
Linux even if present on some architectures.
Signed-off-by: Eugene Syromyatnikov <evgsyr@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
I need to get the TTL of UDP datagrams from userspace, so I set
the IP_RECVTTL socket option. And as promised by ip.7, I then get
IP_TTL messages from recvfrom. However, unlike what the manpage
promises, the TTL field gets passed as a 32 bit integer.
The following userspace code works:
uint32_t ttl32;
for (cmsg = CMSG_FIRSTHDR(msgh); cmsg != NULL; cmsg = CMSG_NXTHDR(msgh,cmsg)) {
if ((cmsg->cmsg_level == IPPROTO_IP) && (cmsg->cmsg_type == IP_TTL) &&
CMSG_LEN(sizeof(ttl32)) == cmsg->cmsg_len) {
memcpy(&ttl32, CMSG_DATA(cmsg), sizeof(ttl32));
*ttl=ttl32;
return true;
}
else
cerr<<"Saw something else "<<(cmsg->cmsg_type == IP_TTL) <<
", "<<(int)cmsg->cmsg_level<<", "<<cmsg->cmsg_len<<", "<<
CMSG_LEN(1)<<endl;
}
The 'else' field was used to figure out I go the length wrong.
Note from mtk:
Reading the source code also seems to confirm this, from
net/ipv4/ip_sockglue.c:
[[
static void ip_cmsg_recv_ttl(struct msghdr *msg, struct sk_buff *skb)
{
int ttl = ip_hdr(skb)->ttl;
put_cmsg(msg, SOL_IP, IP_TTL, sizeof(int), &ttl);
}
]]
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This best belongs at the end of the page, after the subsections
that already make some mention of user namespaces.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The text stated that the execve() capability transitions are not
performed for the same reasons that setuid and setgid mode bits
may be ignored (as described in execve(2)). But, that's not quite
correct: rather, the file capability sets are treated as empty
for the purpose of the capability transition calculations.
Also merge the new 'no_file_caps' kernel option text into the
same paragraph.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Remove crufty sentence suggesting use of deprecated capsetp(3) and
capgetp(3); the manual page for those functions has long (at least
as far back as 2007) noted that they are deprecated.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Clarify the "Capabilities and execution of programs by root"
section, and correct a couple of details:
* If a process with rUID == 0 && eUID != 0 does an exec,
the process will nevertheless gain effective capabilities
if the file effective bit is set.
* Set-UID-root programs only confer a full set of capabilities
if the binary does not also have attached capabilities.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
fs/proc/uptime.c:uptime_proc_show() fetches time using
ktime_get_boottime which includes the time spent in suspend.
Signed-off-by: Stephan Knauss <linux@stephans-server.de>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Balbir pointed out that v1 delegation was not an accidental
feature.
Reported-by: Balbir Singh <bsingharora@gmail.com>
Reported-by: Marcus Gelderie <redmnic@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Update the bug reporting email address to that shown by
/bin/time --help
Signed-off-by: Jakub Wilk <jwilk@jwilk.net>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Use \(aq for ASCII apostrophes and \(ga for backtick,
as recommended by groff_man(7).
Signed-off-by: Jakub Wilk <jwilk@jwilk.net>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
I was reading the local-gen bash script, looking for why I'm
getting locale errors, when I noticed that localdef's -f and -c
options were named, in what I think, is a very confusing way.
-c is the same as --force, and
-f charmapfile is the same as --charmap=charmapfile.
Yes, it would have been better if they're names had been reversed,
like this:
-f is the same as --force, and
-c charmapfile is the same as --charmap=charmapfile.
But given what they are, I thought it would be helpful to give a
heads up to watch for their irregular naming. I hope I've worded
it appropriately.
I'm not ccing this to anyone else, (i.e. developers, etc), as
these features work as described in the man page. They're just
confusing.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
According to the latest glibc, the bsd_signal() function is just
declared when POSIX.1-2008 (or newer) instead of POSIX.1-2001 is
not set since glibc v2.26.
Please see the following code from signal/signal.h:
-----------------------------------------------------------------
/* The X/Open definition of `signal' conflicts with the BSD version.
So they defined another function `bsd_signal'. */
extern __sighandler_t bsd_signal (int __sig, __sighandler_t __handler)
__THROW;
-----------------------------------------------------------------
Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
O_RSYNC is defined in <asm/fcntl.h> on HP PA-RISC, but is not
used anyway.
Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Michael Kerrisk