You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
342 lines
13 KiB
342 lines
13 KiB
From 6c0be74305745c8f78bcfb69442c8c379459d99b Mon Sep 17 00:00:00 2001
|
|
From: DJ Delorie <dj@redhat.com>
|
|
Date: Mon, 8 Jul 2024 17:52:15 -0400
|
|
Subject: manual: add syscalls
|
|
|
|
The purpose of this patch is to add some system calls that (1) aren't
|
|
otherwise documented, and (2) are merely redirected to the kernel, so
|
|
can refer to their documentation; and define a standard way of doing
|
|
so in the future. A more detailed explaination of how system calls
|
|
are wrapped is added along with reference to the Linux Man-Pages
|
|
project.
|
|
|
|
Default version of man-pages is in configure.ac but can be overridden
|
|
by --with-man-pages=X.Y
|
|
|
|
Reviewed-by: Alejandro Colomar <alx@kernel.org>
|
|
|
|
diff --git a/config.make.in b/config.make.in
|
|
index 55e8b7563b..36096881b7 100644
|
|
--- a/config.make.in
|
|
+++ b/config.make.in
|
|
@@ -101,6 +101,7 @@ build-hardcoded-path-in-tests= @hardcode
|
|
build-pt-chown = @build_pt_chown@
|
|
have-tunables = @have_tunables@
|
|
pthread-in-libc = @pthread_in_libc@
|
|
+man-pages-version = @man_pages_version@
|
|
|
|
# Build tools.
|
|
CC = @CC@
|
|
diff --git a/configure b/configure
|
|
index 55e8b7563b..36096881b7 100644
|
|
--- a/configure 2024-07-17 15:45:55.033649362 -0400
|
|
+++ b/configure 2024-07-17 15:47:44.281886629 -0400
|
|
@@ -681,6 +681,7 @@ force_install
|
|
bindnow
|
|
hardcoded_path_in_tests
|
|
enable_timezone_tools
|
|
+man_pages_version
|
|
rtld_early_cflags
|
|
extra_nonshared_cflags
|
|
use_default_link
|
|
@@ -763,6 +764,7 @@ with_headers
|
|
with_default_link
|
|
with_nonshared_cflags
|
|
with_rtld_early_cflags
|
|
+with_man_pages
|
|
enable_sanity_checks
|
|
enable_shared
|
|
enable_profile
|
|
@@ -1483,6 +1485,8 @@ Optional Packages:
|
|
build nonshared libraries with additional CFLAGS
|
|
--with-rtld-early-cflags=CFLAGS
|
|
build early initialization with additional CFLAGS
|
|
+ --with-man-pages=VERSION
|
|
+ tie manual to a specific man-pages version
|
|
--with-cpu=CPU select code for CPU variant
|
|
|
|
Some influential environment variables:
|
|
@@ -3396,6 +3400,15 @@ fi
|
|
|
|
|
|
|
|
+man_pages_version=6.9.1
|
|
+
|
|
+
|
|
+# Check whether --with-man-pages was given.
|
|
+if test "${with_man_pages+set}" = set; then :
|
|
+ withval=$with_man_pages; man_pages_version=$withval
|
|
+fi
|
|
+
|
|
+
|
|
|
|
# Check whether --enable-sanity-checks was given.
|
|
if test "${enable_sanity_checks+set}" = set; then :
|
|
diff --git a/configure.ac b/configure.ac
|
|
index e48957f318..9cbc0bf68f 100644
|
|
--- a/configure.ac 2024-07-17 15:45:52.181538742 -0400
|
|
+++ b/configure.ac 2024-07-17 15:46:29.885001095 -0400
|
|
@@ -169,6 +169,15 @@ AC_ARG_WITH([rtld-early-cflags],
|
|
[rtld_early_cflags=])
|
|
AC_SUBST(rtld_early_cflags)
|
|
|
|
+man_pages_version=6.9.1
|
|
+
|
|
+AC_ARG_WITH([man-pages],
|
|
+ AS_HELP_STRING([--with-man-pages=VERSION],
|
|
+ [tie manual to a specific man-pages version]),
|
|
+ [man_pages_version=$withval],
|
|
+ [])
|
|
+AC_SUBST(man_pages_version)
|
|
+
|
|
AC_ARG_ENABLE([sanity-checks],
|
|
AS_HELP_STRING([--disable-sanity-checks],
|
|
[really do not use threads (should not be used except in special situations) @<:@default=yes@:>@]),
|
|
diff --git a/manual/Makefile b/manual/Makefile
|
|
index b5fda4a7ae..a6c05db540 100644
|
|
--- a/manual/Makefile
|
|
+++ b/manual/Makefile
|
|
@@ -117,6 +117,7 @@ $(objpfx)stamp-pkgvers: $(common-objpfx)config.make
|
|
echo "@set PKGVERSION_DEFAULT" >> $(objpfx)pkgvers-tmp; \
|
|
fi
|
|
echo "@set REPORT_BUGS_TO $(REPORT_BUGS_TEXI)" >> $(objpfx)pkgvers-tmp
|
|
+ echo "@set man_pages_version $(man-pages-version)" >> $(objpfx)pkgvers-tmp; \
|
|
echo "@end ifclear" >> $(objpfx)pkgvers-tmp
|
|
$(move-if-change) $(objpfx)pkgvers-tmp $(objpfx)pkgvers.texi
|
|
touch $@
|
|
diff --git a/manual/intro.texi b/manual/intro.texi
|
|
index ff43c5a7fb..879c1b38d9 100644
|
|
--- a/manual/intro.texi
|
|
+++ b/manual/intro.texi
|
|
@@ -85,6 +85,7 @@ standards each function or symbol comes from.
|
|
* Berkeley Unix:: BSD and SunOS.
|
|
* SVID:: The System V Interface Description.
|
|
* XPG:: The X/Open Portability Guide.
|
|
+* Linux Kernel:: The Linux kernel.
|
|
@end menu
|
|
|
|
@node ISO C, POSIX, , Standards and Portability
|
|
@@ -941,7 +942,7 @@ inter-process communication and shared memory, the @code{hsearch} and
|
|
@code{drand48} families of functions, @code{fmtmsg} and several of the
|
|
mathematical functions.
|
|
|
|
-@node XPG, , SVID, Standards and Portability
|
|
+@node XPG, Linux Kernel, SVID, Standards and Portability
|
|
@subsection XPG (The X/Open Portability Guide)
|
|
|
|
The X/Open Portability Guide, published by the X/Open Company, Ltd., is
|
|
@@ -960,6 +961,20 @@ fulfilling the XPG standard with the Unix extensions is a
|
|
precondition for getting the Unix brand chances are good that the
|
|
functionality is available on commercial systems.
|
|
|
|
+@node Linux Kernel, , XPG, Standards and Portability
|
|
+@subsection Linux (The Linux Kernel)
|
|
+
|
|
+@Theglibc{} includes by reference the Linux man-pages
|
|
+@value{man_pages_version} documentation to document the listed
|
|
+syscalls for the Linux kernel. For reference purposes only the latest
|
|
+@uref{https://www.kernel.org/doc/man-pages/,Linux man-pages Project}
|
|
+documentation can be accessed from the
|
|
+@uref{https://www.kernel.org,Linux kernel} website. Where the syscall
|
|
+has more specific documentation in this manual that more specific
|
|
+documentation is considered authoritative.
|
|
+
|
|
+Additional details on the Linux system call interface can be found in
|
|
+@xref{System Calls}.
|
|
|
|
@node Using the Library, Roadmap to the Manual, Standards and Portability, Introduction
|
|
@section Using the Library
|
|
diff --git a/manual/llio.texi b/manual/llio.texi
|
|
index 78c7c79913..6f0a48609b 100644
|
|
--- a/manual/llio.texi
|
|
+++ b/manual/llio.texi
|
|
@@ -65,6 +65,7 @@ directly.)
|
|
* Interrupt Input:: Getting an asynchronous signal when
|
|
input arrives.
|
|
* IOCTLs:: Generic I/O Control operations.
|
|
+* Other Low-Level I/O APIs:: Other low-level-I/O-related functions.
|
|
@end menu
|
|
|
|
|
|
@@ -2324,6 +2325,8 @@ file descriptor, or until the timeout period expires.
|
|
There is another example showing the use of @code{select} to multiplex
|
|
input from multiple sockets in @ref{Server Example}.
|
|
|
|
+For an alternate interface to this functionality, see @code{poll}
|
|
+(@pxref{Other Low-Level I/O APIs}).
|
|
|
|
@node Synchronizing I/O
|
|
@section Synchronizing I/O operations
|
|
@@ -3407,7 +3410,9 @@ require additional arguments to be supplied. These additional arguments
|
|
and the return value and error conditions are given in the detailed
|
|
descriptions of the individual commands.
|
|
|
|
-Briefly, here is a list of what the various commands are.
|
|
+Briefly, here is a list of what the various commands are. For an
|
|
+exhaustive list of kernel-specific options, please see @xref{System
|
|
+Calls}.
|
|
|
|
@vtable @code
|
|
@item F_DUPFD
|
|
@@ -4743,5 +4748,28 @@ Most IOCTLs are OS-specific and/or only used in special system utilities,
|
|
and are thus beyond the scope of this document. For an example of the use
|
|
of an IOCTL, see @ref{Out-of-Band Data}.
|
|
|
|
-@c FIXME this is undocumented:
|
|
-@c dup3
|
|
+@node Other Low-Level I/O APIs
|
|
+@section Other low-level-I/O-related functions
|
|
+
|
|
+@deftp {Data Type} {struct pollfd}
|
|
+@standards{POSIX.1,poll.h}
|
|
+@end deftp
|
|
+
|
|
+@deftp {Data Type} {struct epoll_event}
|
|
+@standards{Linux,sys/epoll.h}
|
|
+@end deftp
|
|
+
|
|
+@deftypefun int poll (struct pollfd *@var{fds}, nfds_t @var{nfds}, int @var{timeout})
|
|
+
|
|
+@manpagefunctionstub{poll,2}
|
|
+@end deftypefun
|
|
+
|
|
+@deftypefun int epoll_create(int @var{size})
|
|
+
|
|
+@manpagefunctionstub{epoll_create,2}
|
|
+@end deftypefun
|
|
+
|
|
+@deftypefun int epoll_wait(int @var{epfd}, struct epoll_event *@var{events}, int @var{maxevents}, int @var{timeout})
|
|
+
|
|
+@manpagefunctionstub{epoll_wait,2}
|
|
+@end deftypefun
|
|
diff --git a/manual/macros.texi b/manual/macros.texi
|
|
index 4a2e22f473..579da3fb81 100644
|
|
--- a/manual/macros.texi
|
|
+++ b/manual/macros.texi
|
|
@@ -282,4 +282,11 @@ cwd\comments\
|
|
@macro standardsx {element, standard, header}
|
|
@end macro
|
|
|
|
+@macro manpagefunctionstub {func,sec}
|
|
+This documentation is a stub. For additional information on this
|
|
+function, consult the manual page
|
|
+@url{https://man7.org/linux/man-pages/man\sec\/\func\.\sec\.html}.
|
|
+@xref{Linux Kernel}.
|
|
+@end macro
|
|
+
|
|
@end ifclear
|
|
diff --git a/manual/socket.texi b/manual/socket.texi
|
|
index f0e35d9e13..8708cbb07c 100644
|
|
--- a/manual/socket.texi
|
|
+++ b/manual/socket.texi
|
|
@@ -41,6 +41,7 @@ aren't documented either so far.
|
|
is to make it work with Inetd.
|
|
* Socket Options:: Miscellaneous low-level socket options.
|
|
* Networks Database:: Accessing the database of network names.
|
|
+* Other Socket APIs:: Other socket-related functions.
|
|
@end menu
|
|
|
|
@node Socket Concepts
|
|
@@ -3134,38 +3135,8 @@ You can use plain @code{recv} (@pxref{Receiving Data}) instead of
|
|
treat all possible senders alike). Even @code{read} can be used if
|
|
you don't want to specify @var{flags} (@pxref{I/O Primitives}).
|
|
|
|
-@ignore
|
|
-@c sendmsg and recvmsg are like readv and writev in that they
|
|
-@c use a series of buffers. It's not clear this is worth
|
|
-@c supporting or that we support them.
|
|
-@c !!! they can do more; it is hairy
|
|
-
|
|
-@deftp {Data Type} {struct msghdr}
|
|
-@standards{BSD, sys/socket.h}
|
|
-@end deftp
|
|
-
|
|
-@deftypefun ssize_t sendmsg (int @var{socket}, const struct msghdr *@var{message}, int @var{flags})
|
|
-@standards{BSD, sys/socket.h}
|
|
-@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
|
|
-
|
|
-This function is defined as a cancellation point in multi-threaded
|
|
-programs, so one has to be prepared for this and make sure that
|
|
-allocated resources (like memory, files descriptors, semaphores or
|
|
-whatever) are freed even if the thread is cancel.
|
|
-@c @xref{pthread_cleanup_push}, for a method how to do this.
|
|
-@end deftypefun
|
|
-
|
|
-@deftypefun ssize_t recvmsg (int @var{socket}, struct msghdr *@var{message}, int @var{flags})
|
|
-@standards{BSD, sys/socket.h}
|
|
-@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
|
|
-
|
|
-This function is defined as a cancellation point in multi-threaded
|
|
-programs, so one has to be prepared for this and make sure that
|
|
-allocated resources (like memory, files descriptors, semaphores or
|
|
-whatever) are freed even if the thread is canceled.
|
|
-@c @xref{pthread_cleanup_push}, for a method how to do this.
|
|
-@end deftypefun
|
|
-@end ignore
|
|
+If you need more flexibility and/or control over sending and receiving
|
|
+packets, see @code{sendmsg} and @code{recvmsg} (@pxref{Other Socket APIs}).
|
|
|
|
@node Datagram Example
|
|
@subsection Datagram Socket Example
|
|
@@ -3664,3 +3635,20 @@ returns a null pointer if there are no more entries.
|
|
@c libc_lock_unlock @aculock
|
|
This function closes the networks database.
|
|
@end deftypefun
|
|
+
|
|
+@node Other Socket APIs
|
|
+@section Other Socket APIs
|
|
+
|
|
+@deftp {Data Type} {struct msghdr}
|
|
+@standards{BSD, sys/socket.h}
|
|
+@end deftp
|
|
+
|
|
+@deftypefun ssize_t sendmsg (int @var{socket}, const struct msghdr *@var{message}, int @var{flags})
|
|
+
|
|
+@manpagefunctionstub{sendmsg,2}
|
|
+@end deftypefun
|
|
+
|
|
+@deftypefun ssize_t recvmsg (int @var{socket}, struct msghdr *@var{message}, int @var{flags})
|
|
+
|
|
+@manpagefunctionstub{recvmsg,2}
|
|
+@end deftypefun
|
|
diff --git a/manual/startup.texi b/manual/startup.texi
|
|
index 224dd98c1e..747beed4d9 100644
|
|
--- a/manual/startup.texi
|
|
+++ b/manual/startup.texi
|
|
@@ -689,7 +689,25 @@ you don't need to know about it because you can just use @theglibc{}'s
|
|
@code{chmod} function.
|
|
|
|
@cindex kernel call
|
|
-System calls are sometimes called kernel calls.
|
|
+System calls are sometimes called syscalls or kernel calls, and this
|
|
+interface is mostly a purely mechanical translation from the kernel's
|
|
+ABI to the C ABI. For the set of syscalls where we do not guarantee
|
|
+POSIX Thread cancellation the wrappers only organize the incoming
|
|
+arguments from the C calling convention to the calling convention of
|
|
+the target kernel. For the set of syscalls where we provided POSIX
|
|
+Thread cancellation the wrappers set some internal state in the
|
|
+library to support cancellation, but this does not impact the
|
|
+behaviour of the syscall provided by the kernel.
|
|
+
|
|
+In some cases, if @theglibc{} detects that a system call has been
|
|
+superseded by a more capable one, the wrapper may map the old call to
|
|
+the new one. For example, @code{dup2} is implemented via @code{dup3}
|
|
+by passing an additional empty flags argument, and @code{open} calls
|
|
+@code{openat} passing the additional @code{AT_FDCWD}. Sometimes even
|
|
+more is done, such as converting between 32-bit and 64-bit time
|
|
+values. In general, though, such processing is only to make the
|
|
+system call better match the C ABI, rather than change its
|
|
+functionality.
|
|
|
|
However, there are times when you want to make a system call explicitly,
|
|
and for that, @theglibc{} provides the @code{syscall} function.
|
|
@@ -711,6 +729,8 @@ we won't describe it here either because anyone who is coding
|
|
library source code as a specification of the interface between them
|
|
anyway.
|
|
|
|
+@code{syscall} does not provide cancellation logic, even if the system
|
|
+call you're calling is listed as cancellable above.
|
|
|
|
@code{syscall} is declared in @file{unistd.h}.
|
|
|