crashpad/test/multiprocess_posix_test.cc
Mark Mentovai 00b6442752 Make file_io reads more rational and predictable
ReadFile() attempted to continue reading after a short read. In most
cases, this is fine. However, ReadFile() would keep trying to fill a
partially-filled buffer until experiencing a 0-length read(), signaling
end-of-file. For certain weird file descriptors like terminal input, EOF
is an ephemeral condition, and attempting to read beyond EOF doesn’t
actually return 0 (EOF) provided that they remain open, it will block
waiting for more input. Consequently, ReadFile() and anything based on
ReadFile() had an undocumented and quirky interface, which was that any
short read that it returned (not an underlying short read) actually
indicated EOF.

This facet of ReadFile() was unexpected, so it’s being removed. The new
behavior is that ReadFile() will return an underlying short read. The
behavior of FileReaderInterface::Read() is updated in accordance with
this change.

Upon experiencing a short read, the caller can determine the best
action. Most callers were already prepared for this behavior. Outside of
util/file, only crashpad_database_util properly implemented EOF
detection according to previous semantics, and adapting it to new
semantics is trivial.

Callers who require an exact-length read can use the new
ReadFileExactly(), or the newly renamed LoggingReadFileExactly() or
CheckedReadFileExactly(). These functions will retry following a short
read. The renamed functions were previously called LoggingReadFile() and
CheckedReadFile(), but those names implied that they were simply
wrapping ReadFile(), which is not the case. They wrapped ReadFile() and
further, insisted on a full read. Since ReadFile()’s semantics are now
changing but these functions’ are not, they’re now even more distinct
from ReadFile(), and must be renamed to avoid confusion.

Test: *
Change-Id: I06b77e0d6ad8719bd2eb67dab93a8740542dd908
Reviewed-on: https://chromium-review.googlesource.com/456676
Reviewed-by: Robert Sesek <rsesek@chromium.org>
2017-03-16 20:07:43 +00:00

291 lines
7.6 KiB
C++

// Copyright 2014 The Crashpad Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "test/multiprocess.h"
#include <signal.h>
#include <stdlib.h>
#include <unistd.h>
#include "base/macros.h"
#include "gtest/gtest.h"
#include "test/gtest_death_check.h"
#include "util/file/file_io.h"
namespace crashpad {
namespace test {
namespace {
class TestMultiprocess final : public Multiprocess {
public:
TestMultiprocess() : Multiprocess() {}
~TestMultiprocess() {}
private:
// Multiprocess:
void MultiprocessParent() override {
FileHandle read_handle = ReadPipeHandle();
char c;
CheckedReadFileExactly(read_handle, &c, 1);
EXPECT_EQ('M', c);
pid_t pid;
CheckedReadFileExactly(read_handle, &pid, sizeof(pid));
EXPECT_EQ(pid, ChildPID());
c = 'm';
CheckedWriteFile(WritePipeHandle(), &c, 1);
// The child will close its end of the pipe and exit. Make sure that the
// parent sees EOF.
CheckedReadFileAtEOF(read_handle);
}
void MultiprocessChild() override {
FileHandle write_handle = WritePipeHandle();
char c = 'M';
CheckedWriteFile(write_handle, &c, 1);
pid_t pid = getpid();
CheckedWriteFile(write_handle, &pid, sizeof(pid));
CheckedReadFileExactly(ReadPipeHandle(), &c, 1);
EXPECT_EQ('m', c);
}
DISALLOW_COPY_AND_ASSIGN(TestMultiprocess);
};
TEST(Multiprocess, Multiprocess) {
TestMultiprocess multiprocess;
multiprocess.Run();
}
class TestMultiprocessUnclean final : public Multiprocess {
public:
enum TerminationType {
kExitSuccess = 0,
kExitFailure,
kExit2,
kAbort,
};
explicit TestMultiprocessUnclean(TerminationType type)
: Multiprocess(),
type_(type) {
if (type_ == kAbort) {
SetExpectedChildTermination(kTerminationSignal, SIGABRT);
} else {
SetExpectedChildTermination(kTerminationNormal, ExitCode());
}
}
~TestMultiprocessUnclean() {}
private:
int ExitCode() const {
return type_;
}
// Multiprocess:
void MultiprocessParent() override {
}
void MultiprocessChild() override {
if (type_ == kAbort) {
abort();
} else {
_exit(ExitCode());
}
}
TerminationType type_;
DISALLOW_COPY_AND_ASSIGN(TestMultiprocessUnclean);
};
TEST(Multiprocess, SuccessfulExit) {
TestMultiprocessUnclean multiprocess(TestMultiprocessUnclean::kExitSuccess);
multiprocess.Run();
}
TEST(Multiprocess, UnsuccessfulExit) {
TestMultiprocessUnclean multiprocess(TestMultiprocessUnclean::kExitFailure);
multiprocess.Run();
}
TEST(Multiprocess, Exit2) {
TestMultiprocessUnclean multiprocess(TestMultiprocessUnclean::kExit2);
multiprocess.Run();
}
TEST(Multiprocess, AbortSignal) {
TestMultiprocessUnclean multiprocess(TestMultiprocessUnclean::kAbort);
multiprocess.Run();
}
class TestMultiprocessClosePipe final : public Multiprocess {
public:
enum WhoCloses {
kParentCloses = 0,
kChildCloses,
};
enum WhatCloses {
kReadCloses = 0,
kWriteCloses,
kReadAndWriteClose,
};
TestMultiprocessClosePipe(WhoCloses who_closes, WhatCloses what_closes)
: Multiprocess(),
who_closes_(who_closes),
what_closes_(what_closes) {
}
~TestMultiprocessClosePipe() {}
private:
void VerifyInitial() {
ASSERT_NE(-1, ReadPipeHandle());
ASSERT_NE(-1, WritePipeHandle());
}
// Verifies that the partner process did what it was supposed to do. This must
// only be called when who_closes_ names the partner process, not this
// process.
//
// If the partner was supposed to close its write pipe, the read pipe will be
// checked to ensure that it shows end-of-file.
//
// If the partner was supposed to close its read pipe, the write pipe will be
// checked to ensure that a checked write causes death. This can only be done
// if the partner also provides some type of signal when it has closed its
// read pipe, which is done in the form of it closing its write pipe, causing
// the read pipe in this process to show end-of-file.
void VerifyPartner() {
if (what_closes_ == kWriteCloses) {
CheckedReadFileAtEOF(ReadPipeHandle());
} else if (what_closes_ == kReadAndWriteClose) {
CheckedReadFileAtEOF(ReadPipeHandle());
char c = '\0';
// This will raise SIGPIPE. If fatal (the normal case), that will cause
// process termination. If SIGPIPE is being handled somewhere, the write
// will still fail and set errno to EPIPE, and CheckedWriteFile() will
// abort execution. Regardless of how SIGPIPE is handled, the process will
// be terminated. Because the actual termination mechanism is not known,
// no regex can be specified.
EXPECT_DEATH_CHECK(CheckedWriteFile(WritePipeHandle(), &c, 1), "");
}
}
void Close() {
switch (what_closes_) {
case kReadCloses:
CloseReadPipe();
EXPECT_NE(-1, WritePipeHandle());
EXPECT_DEATH_CHECK(ReadPipeHandle(), "fd");
break;
case kWriteCloses:
CloseWritePipe();
EXPECT_NE(-1, ReadPipeHandle());
EXPECT_DEATH_CHECK(WritePipeHandle(), "fd");
break;
case kReadAndWriteClose:
CloseReadPipe();
CloseWritePipe();
EXPECT_DEATH_CHECK(ReadPipeHandle(), "fd");
EXPECT_DEATH_CHECK(WritePipeHandle(), "fd");
break;
}
}
// Multiprocess:
void MultiprocessParent() override {
ASSERT_NO_FATAL_FAILURE(VerifyInitial());
if (who_closes_ == kParentCloses) {
Close();
} else {
VerifyPartner();
}
}
void MultiprocessChild() override {
ASSERT_NO_FATAL_FAILURE(VerifyInitial());
if (who_closes_ == kChildCloses) {
Close();
} else {
VerifyPartner();
}
}
WhoCloses who_closes_;
WhatCloses what_closes_;
DISALLOW_COPY_AND_ASSIGN(TestMultiprocessClosePipe);
};
TEST(MultiprocessDeathTest, ParentClosesReadPipe) {
TestMultiprocessClosePipe multiprocess(
TestMultiprocessClosePipe::kParentCloses,
TestMultiprocessClosePipe::kReadCloses);
multiprocess.Run();
}
TEST(MultiprocessDeathTest, ParentClosesWritePipe) {
TestMultiprocessClosePipe multiprocess(
TestMultiprocessClosePipe::kParentCloses,
TestMultiprocessClosePipe::kWriteCloses);
multiprocess.Run();
}
TEST(MultiprocessDeathTest, ParentClosesReadAndWritePipe) {
TestMultiprocessClosePipe multiprocess(
TestMultiprocessClosePipe::kParentCloses,
TestMultiprocessClosePipe::kReadAndWriteClose);
multiprocess.Run();
}
TEST(MultiprocessDeathTest, ChildClosesReadPipe) {
TestMultiprocessClosePipe multiprocess(
TestMultiprocessClosePipe::kChildCloses,
TestMultiprocessClosePipe::kReadCloses);
multiprocess.Run();
}
TEST(MultiprocessDeathTest, ChildClosesWritePipe) {
TestMultiprocessClosePipe multiprocess(
TestMultiprocessClosePipe::kChildCloses,
TestMultiprocessClosePipe::kWriteCloses);
multiprocess.Run();
}
TEST(MultiprocessDeathTest, ChildClosesReadAndWritePipe) {
TestMultiprocessClosePipe multiprocess(
TestMultiprocessClosePipe::kChildCloses,
TestMultiprocessClosePipe::kReadAndWriteClose);
multiprocess.Run();
}
} // namespace
} // namespace test
} // namespace crashpad