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

runtime: linux iscgo support for not blocking nptl signals

2020-12-23T02:10:51+00:00

Under linux+cgo, OS threads are launched via pthread_create().
This abstraction, under linux, requires we avoid blocking
signals 32,33 and 34 indefinitely because they are needed to
reliably execute POSIX-semantics threading in glibc and/or musl.

When blocking signals the go runtime generally re-enables them
quickly. However, when a thread exits (under cgo, this is
via a return from mstart()), we avoid a deadlock in C-code by
not blocking these three signals.

Fixes #42494

Change-Id: I02dfb2480a1f97d11679e0c4b132b51bddbe4c14
Reviewed-on: https://go-review.googlesource.com/c/go/+/269799
Reviewed-by: Ian Lance Taylor 
Reviewed-by: Austin Clements 
Trust: Tobias Klauser

all: update to use os.ReadFile, os.WriteFile, os.CreateTemp, os.MkdirTemp

2020-12-09T19:12:23+00:00

As part of #42026, these helpers from io/ioutil were moved to os.
(ioutil.TempFile and TempDir became os.CreateTemp and MkdirTemp.)

Update the Go tree to use the preferred names.

As usual, code compiled with the Go 1.4 bootstrap toolchain
and code vendored from other sources is excluded.

ReadDir changes are in a separate CL, because they are not a
simple search and replace.

For #42026.

Change-Id: If318df0216d57e95ea0c4093b89f65e5b0ababb3
Reviewed-on: https://go-review.googlesource.com/c/go/+/266365
Trust: Russ Cox 
Run-TryBot: Russ Cox 
TryBot-Result: Go Bot 
Reviewed-by: Ian Lance Taylor

syscall: improve TestSetuidEtc() /proc/ parsing against races

2020-11-11T20:49:53+00:00

TestSetuidEtc() was failing sporadically on linux-ppc64. From the
three https://build.golang.org/ logs, it looked like the logged
errors could be associated with threads dying, but proc reads
were, in some way, racing with their demise.

Exploring ways to increase thread demise, revealed that races
of this type can happen on non-ppc64 systems, and that
os.IsNotExist(err) was not a sufficient error condition test
for a thread's status file disappearing. This change includes a
fix for that to.

The actual issue on linux-ppc64 appears to be tied to PID reaping
and reuse latency on whatever the build test environment is for
linux-ppc64-buildlet. I suspect this can happen on any linux
system, however, especially where the container has a limited PID
range.

The fix for this, limited to the test (the runtime syscall support
is unchanged), is to confirm that the Pid for the interrogated
thread's /proc//status file confirms that it is still
associated with the test-process' PID.

linux-ppc64-buildlet:
  go/bin/go test syscall -run=TestSetuidEtc -count=10000
  ok      syscall 104.285s

Fixes #42462

Change-Id: I55c84ab8361003570a405fa52ffec4949bf91113
Reviewed-on: https://go-review.googlesource.com/c/go/+/268717
Reviewed-by: Ian Lance Taylor 
Run-TryBot: Ian Lance Taylor 
TryBot-Result: Go Bot 
Trust: Tobias Klauser

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: disable TestAllThreadsSyscall on linux-ppc64

2020-10-24T03:06:05+00:00

For some reason, currently unknown, this test case fails exclusively
on the linux-ppc64 platform. Until such time as it can be made to
work, we'll disable this test case on that platform.

The same issue causes TestSetuidEtc to fail too, so disable that
on this platform.

Updates #42178

Change-Id: Idd3f6c2ee9f2fba2eb8ce4de69de7f316858bb15
Reviewed-on: https://go-review.googlesource.com/c/go/+/264719
Trust: Emmanuel Odeke 
Run-TryBot: Emmanuel Odeke 
TryBot-Result: Go Bot 
Reviewed-by: Ian Lance Taylor

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

all: update references to symbols moved from os to io/fs

2020-10-20T02:32:42+00:00

The old os references are still valid, but update our code
to reflect best practices and get used to the new locations.

Code compiled with the bootstrap toolchain
(cmd/asm, cmd/dist, cmd/compile, debug/elf)
must remain Go 1.4-compatible and is excluded.

For #41190.

Change-Id: I8f9526977867c10a221e2f392f78d7dec073f1bd
Reviewed-on: https://go-review.googlesource.com/c/go/+/243907
Trust: Russ Cox 
Run-TryBot: Russ Cox 
TryBot-Result: Go Bot 
Reviewed-by: Rob Pike

syscall: append to environment in tests, don't clobber it

2020-05-11T22:26:51+00:00

Fixes https://gcc.gnu.org/PR95061

Change-Id: I3cddfe5920b6da572ddeafa201617003c25175e6
Reviewed-on: https://go-review.googlesource.com/c/go/+/233318
Run-TryBot: Ian Lance Taylor 
TryBot-Result: Gobot Gobot 
Reviewed-by: Brad Fitzpatrick

syscall: skip TestSyscallNoError on mips{,le}

2019-11-09T19:25:46+00:00

On MIPS, Linux returns whether the syscall had an error in a separate
register (R7), not using a negative return value as on other
architectures. Thus, skip TestSyscallNoError as there is no error case
for syscall.RawSyscall which it could test against.

Also reformat the error output so the expected and gotten values are
aligned so they're easier to compare.

Fixes #35422

Change-Id: Ibc88f7c5382bb7ee8faf15ad4589ca1f9f017a06
Reviewed-on: https://go-review.googlesource.com/c/go/+/205898
Run-TryBot: Tobias Klauser 
Reviewed-by: Ian Lance Taylor 
Reviewed-by: Cherry Zhang

syscall: skip TestSyscallNoError when temp dir is mounted nosuid

2019-02-15T19:24:37+00:00

Fixes #30258

Change-Id: I73b63eb9d3aca00f562fdc3af010e96269bb6b9c
Reviewed-on: https://go-review.googlesource.com/c/162891
Run-TryBot: Brad Fitzpatrick 
TryBot-Result: Gobot Gobot 
Reviewed-by: Katie Hockman