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// Copyright 2016 CoreOS, Inc.
//
// 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.
package code
import (
"fmt"
"io"
"strings"
)
type Failpoint struct {
name string
varType string
code []string
// whitespace for padding
ws string
}
// newFailpoint makes a new failpoint based on the a line containing a
// failpoint comment header.
func newFailpoint(l string) (*Failpoint, error) {
lt := strings.TrimSpace(l)
isGoFail := strings.HasPrefix(lt, pfxGofail)
if !isGoFail {
// not a failpoint
return nil, nil
}
pfx := pfxGofail
cmd := strings.SplitAfter(l, pfx)[1]
fields := strings.Fields(cmd)
if len(fields) != 3 || fields[0] != "var" {
return nil, fmt.Errorf("failpoint: malformed comment header %q", l)
}
return &Failpoint{name: fields[1], varType: fields[2], ws: strings.Split(l, "//")[0]}, nil
}
// flush writes the failpoint code to a buffer
func (fp *Failpoint) flush(dst io.Writer) error {
if len(fp.code) == 0 {
return fp.flushSingle(dst)
}
return fp.flushMulti(dst)
}
func (fp *Failpoint) hdr(varname string) string {
ev := errVarGoFail
hdr := fp.ws + "if v" + fp.name + fmt.Sprintf(", %s := ", ev) + fp.Runtime() + ".Acquire();" + fmt.Sprintf(" %s == nil { ", ev)
if fp.varType == "struct{}" {
// unused
varname = "_"
}
return hdr + varname + ", __fpTypeOK := v" + fp.name +
".(" + fp.varType + "); if !__fpTypeOK { goto __badType" + fp.name + "} "
}
func (fp *Failpoint) footer() string {
return "; __badType" + fp.name + ": " +
fp.Runtime() + ".BadType(v" + fp.name + ", \"" + fp.varType + "\"); };"
}
func (fp *Failpoint) flushSingle(dst io.Writer) error {
if _, err := io.WriteString(dst, fp.hdr("_")); err != nil {
return err
}
_, err := io.WriteString(dst, fp.footer()+"\n")
return err
}
func (fp *Failpoint) flushMulti(dst io.Writer) error {
hdr := fp.hdr(fp.name) + "\n"
if _, err := io.WriteString(dst, hdr); err != nil {
return err
}
for _, code := range fp.code[:len(fp.code)-1] {
if _, err := io.WriteString(dst, code+"\n"); err != nil {
return err
}
}
code := fp.code[len(fp.code)-1]
_, err := io.WriteString(dst, code+fp.footer()+"\n")
return err
}
func (fp *Failpoint) Name() string { return fp.name }
func (fp *Failpoint) Runtime() string { return "__fp_" + fp.name }
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