github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/tools/checklocks/test/branches.go (about)

     1  // Copyright 2020 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package test
    16  
    17  import (
    18  	"math/rand"
    19  )
    20  
    21  func testInconsistentReturn(tc *oneGuardStruct) { // +checklocksfail
    22  	if x := rand.Intn(10); x%2 == 1 {
    23  		tc.mu.Lock()
    24  	}
    25  }
    26  
    27  func testConsistentBranching(tc *oneGuardStruct) {
    28  	x := rand.Intn(10)
    29  	if x%2 == 1 {
    30  		tc.mu.Lock()
    31  	} else {
    32  		tc.mu.Lock()
    33  	}
    34  	tc.guardedField = 1
    35  	if x%2 == 1 {
    36  		tc.mu.Unlock()
    37  	} else {
    38  		tc.mu.Unlock()
    39  	}
    40  }
    41  
    42  func testInconsistentBranching(tc *oneGuardStruct) { // +checklocksfail:2
    43  	// We traverse the control flow graph in all consistent ways. We cannot
    44  	// determine however, that the first if block and second if block will
    45  	// evaluate to the same condition. Therefore, there are two consistent
    46  	// paths through this code, and two inconsistent paths. Either way, the
    47  	// guardedField should be also marked as an invalid access.
    48  	x := rand.Intn(10)
    49  	if x%2 == 1 {
    50  		tc.mu.Lock()
    51  	}
    52  	tc.guardedField = 1 // +checklocksfail
    53  	if x%2 == 1 {
    54  		tc.mu.Unlock() // +checklocksforce
    55  	}
    56  }