delta/go-git.git/src/syscall/syscall_linux.go, branch dev.go2go

syscall: handle undefined r2 value on linux-ppc64x

2020-10-29T17:53:57+00:00

This change fixes two failng tests on linux-ppc64x:

- TestAllThreadsSyscall() exposed a real bug in the ppc64x support:
  - It turns out that the r2 syscall return value is not defined
    on all architectures. Notably linux-ppc64x so address that by
    introducing a private architectural constant in the syscall
    package, archHonorsR2: true if r2 has a determanistic value.

- TestSetuidEtc() was sensitive to /proc//status content:
  - The amount of padding space has changed with kernel vintage.
  - Stress testing revealed a race with /proc files disappearing.

Fixes #42178

Change-Id: Ie6fc0b8f2f94a409ac0e5756e73bfce113274709
Reviewed-on: https://go-review.googlesource.com/c/go/+/266202
Run-TryBot: Ian Lance Taylor 
Reviewed-by: Emmanuel Odeke 
Reviewed-by: Ian Lance Taylor 
TryBot-Result: Go Bot

syscall: support POSIX semantics for Linux syscalls

2020-10-23T20:53:14+00:00

This change adds two new methods for invoking system calls
under Linux: syscall.AllThreadsSyscall() and
syscall.AllThreadsSyscall6().

These system call wrappers ensure that all OSThreads mirror
a common system call. The wrappers serialize execution of the
runtime to ensure no race conditions where any Go code observes
a non-atomic OS state change. As such, the syscalls have
higher runtime overhead than regular system calls, and only
need to be used where such thread (or 'm' in the parlance
of the runtime sources) consistency is required.

The new support is used to enable these functions under Linux:

  syscall.Setegid(), syscall.Seteuid(), syscall.Setgroups(),
  syscall.Setgid(), syscall.Setregid(), syscall.Setreuid(),
  syscall.Setresgid(), syscall.Setresuid() and syscall.Setuid().

They work identically to their glibc counterparts.

Extensive discussion of the background issue addressed in this
patch can be found here:

   https://github.com/golang/go/issues/1435

In the case where cgo is used, the C runtime can launch pthreads that
are not managed by the Go runtime. As such, the added
syscall.AllThreadsSyscall*() return ENOTSUP when cgo is enabled.
However, for the 9 syscall.Set*() functions listed above, when cgo is
active, these functions redirect to invoke their C.set*() equivalents
in glibc, which wraps the raw system calls with a nptl:setxid fixup
mechanism. This achieves POSIX semantics for these functions in the
combined Go and C runtime.

As a side note, the glibc/nptl:setxid support (2019-11-30) does not
extend to all security related system calls under Linux so using
native Go (CGO_ENABLED=0) and these AllThreadsSyscall*()s, where
needed, will yield more well defined/consistent behavior over all
threads of a Go program. That is, using the
syscall.AllThreadsSyscall*() wrappers for things like setting state
through SYS_PRCTL and SYS_CAPSET etc.

Fixes #1435

Change-Id: Ib1a3e16b9180f64223196a32fc0f9dce14d9105c
Reviewed-on: https://go-review.googlesource.com/c/go/+/210639
Trust: Emmanuel Odeke 
Trust: Ian Lance Taylor 
Trust: Michael Pratt 
Run-TryBot: Emmanuel Odeke 
Reviewed-by: Michael Pratt 
Reviewed-by: Austin Clements

syscall: check secondary group membership for Faccessat(..., AT_EACCESS) on Linux

2020-06-20T08:40:13+00:00

Follow glibc's implementation and check secondary group memberships
using Getgroups.

No test since we cannot easily change file permissions when not running
as root and the test is meaningless if running as root.

Same as CL 238722 did for x/sys/unix

Updates #39660

Change-Id: I6af50e27b255e33405558947a0ab3dfbc33b2d50
Reviewed-on: https://go-review.googlesource.com/c/go/+/238937
Run-TryBot: Tobias Klauser 
TryBot-Result: Gobot Gobot 
Reviewed-by: Ian Lance Taylor

syscall: fix wrong unsafe.Pointer alignment in syscall

2019-10-18T19:06:39+00:00

Caught with:

	go test -a -short -gcflags=all=-d=checkptr log/syslog

and:

	grep -rE '\*\[([^2]|.{2,})\].*\)\(unsafe.Pointer' syscall

Updates #34972

Change-Id: Iafd199b3a34beb7cc3e88484bf2fbae45183f951
Reviewed-on: https://go-review.googlesource.com/c/go/+/201877
Run-TryBot: Cuong Manh Le 
TryBot-Result: Gobot Gobot 
Reviewed-by: Matthew Dempsky

syscall: don't use deprecated syscalls on linux/arm64

2019-10-08T10:45:48+00:00

Reimplement syscall wrappers for linux/arm64 in terms of supported
syscalls (or in case of Ustat make it return ENOSYS) and remove the
manually added SYS_* consts for the deprecated syscalls. Adapted from
golang.org/x/sys/unix where this is already done since CL 119655.

Change-Id: I94ab48a4645924df3822497d0575f1a1573d509f
Reviewed-on: https://go-review.googlesource.com/c/go/+/199140
Run-TryBot: Tobias Klauser 
TryBot-Result: Gobot Gobot 
Reviewed-by: Ian Lance Taylor

syscall: move Renameat to syscall_linux_$GOARCH.go

2019-08-28T15:44:01+00:00

On linux/riscv64, the renameat syscall no longer exists and has been
superseded by renameat2. Thus we'll have to use Renameat2 to implement
Renameat on linux/riscv64 for #27532. Prepare for this by moving the
Renameat definition to the GOARCH specific files.

Follow CL 157899 which did the same for golang.org/x/sys/unix

Change-Id: I9670213cc3987df48fee962ddee36915a7785560
Reviewed-on: https://go-review.googlesource.com/c/go/+/192077
Run-TryBot: Tobias Klauser 
TryBot-Result: Gobot Gobot 
Reviewed-by: Brad Fitzpatrick

syscall: support Faccessat flags argument

2018-07-27T21:13:43+00:00

The Linux kernel faccessat system call does not take a flags parameter.
The flag parameter to the C library faccessat function is implemented in C.
The syscall.Faccessat function takes a flags parameter. In older releases
we have passed the flags parameter to the kernel, which ignored it.
In CL 120015 we started returning an error if any flags were set.
That seems clearly better than ignoring them, but it turns out that some
code was using the flags. The code was previously subtly broken.
Now it is obviously broken. That is better, but we can do better still:
we can implement the flags as the C library does. That is what this CL does.

Change-Id: I259bd6f240c3951e939b81c3032dead3d9c567b4
Reviewed-on: https://go-review.googlesource.com/126415
Run-TryBot: Ian Lance Taylor 
TryBot-Result: Gobot Gobot 
Reviewed-by: Brad Fitzpatrick

syscall: check faccessat flags parameter on Linux

2018-06-21T06:47:46+00:00

Port CL 119495 from golang.org/x/sys/unix to the syscall package.

Currently Linux faccessat(2) syscall implementation doesn't support the
flags parameter. As per the discussion in #25845, permit the same flags
as glibc [1].

[1] https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/faccessat.c;h=ea42b2303ff4b2d2d6548ea04376fb265f773436;hb=HEAD

Updates #25845

Change-Id: I132b33275a9cc72b3a97acea5482806c7f47d7f7
Reviewed-on: https://go-review.googlesource.com/120015
Run-TryBot: Tobias Klauser 
TryBot-Result: Gobot Gobot 
Reviewed-by: Ian Lance Taylor

syscall: check Fchmodat flags parameter on Linux

2018-06-13T20:32:08+00:00

As mentioned in #25845, port CL 46474 from golang.org/x/sys/unix to the
syscall package.

Currently Linux' fchmodat(2) syscall implementation doesn't support the
flags parameter (though it might in future versions [1]). Fchmodat in
the syscall package takes the parameter and (wrongly) passes it on to the
syscall which will ignore it.

According to the POSIX.1-2008 manual page [2], AT_SYMLINK_NOFOLLOW is
the only valid value for the flags parameter and EOPNOTSUPP should be
returned in case changing the mode of a symbolic link is not supported
by the underlying system. EINVAL should be returned for any other value
of the flags parameter.

  [1] https://patchwork.kernel.org/patch/9596301/
  [2] http://pubs.opengroup.org/onlinepubs/9699919799/functions/chmod.html

Updates #20130
Updates #25845

Change-Id: I1021dd0e6a4f4cb3557cb1c1b34dd618c378cda6
Reviewed-on: https://go-review.googlesource.com/118658
Reviewed-by: Ian Lance Taylor

syscall: fix EpollWait for arm64

2018-06-04T15:13:16+00:00

The SYS_EPOLL_WAIT syscall doesn't exist on arm64. This CL implements EpollWait
with SYS_EPOLL_PWAIT syscall.

Change-Id: Ica9107a58d7da45351fe2e900f59bec5b7b18f39
Reviewed-on: https://go-review.googlesource.com/115735
Run-TryBot: Tobias Klauser 
TryBot-Result: Gobot Gobot 
Reviewed-by: Tobias Klauser 
Reviewed-by: Brad Fitzpatrick