Add front page of Fuzzer

fuzzer/go/fuzz/stacktrace.go

+package fuzz
+
+import (
+        "bufio"
+        "bytes"
+        "fmt"
+        "regexp"
+        "strconv"
+        "strings"
+
+        "github.com/skia-dev/glog"
+)
+
+type StackTrace struct {
+        Frames []StackTraceFrame `json:"frames"`
+}
+
+type StackTraceFrame struct {
+        PackageName  string `json:"packageName"`
+        FileName     string `json:"fileName"`
+        LineNumber   int    `json:"lineNumber"`
+        FunctionName string `json:"functionName"`
+}
+
+// The `?:` at the beginning of the groups prevent them from being captured
+var stackTraceLine = regexp.MustCompile(`(?:\.\./)+((?:\w+/)+)(.+):(\d+)\(`)
+
+// Given the files of a dump file (created through get_stack_trace [which uses catchsegv], return the stack trace)
+func ParseStackTrace(contents string) StackTrace {
+        r := bytes.NewReader([]byte(contents))
+        scan := bufio.NewScanner(r)
+
+        hasBegun := false
+
+        frames := make([]StackTraceFrame, 0, 5)
+
+        for scan.Scan() {
+                line := scan.Text()
+                if strings.Contains(line, "Backtrace") {
+                        hasBegun = true
+                }
+                if strings.Contains(line, "Memory map") {
+                        break
+                }
+                if !hasBegun {
+                        continue
+                }
+
+                if match := stackTraceLine.FindStringSubmatch(line); match != nil {
+                        // match[0] is the entire matched portion, [1] is the "package", [2] is the file name, [3] is the line number
+
+                        lineNumber, err := strconv.Atoi(match[3])
+                        if err != nil {
+                                glog.Errorf("Could not parse line number from stacktrace line %q: %s", match[0], err)
+                                continue
+                        }
+                        newFrame := BasicStackFrame(match[1], match[2], lineNumber)
+                        frames = append(frames, newFrame)
+                }
+        }
+
+        return StackTrace{frames}
+}
+
+func BasicStackFrame(packageName, fileName string, lineNumber int) StackTraceFrame {
+        return StackTraceFrame{packageName, fileName, lineNumber, ""}
+}
+
+type FindFunctionName func(packageName string, fileName string, lineNumber int) string
+
+// LookUpFunctions will go through all the stacktraces and call the passed in function to find the approximate function name the stacktrace is referring to
+func (st *StackTrace) LookUpFunctions(findFunctionName FindFunctionName) {
+        for i, f := range st.Frames {
+                // this awkward syntax is required to write to the actual StackTraceFrame, not the copy generated by range
+                st.Frames[i].FunctionName = findFunctionName(f.PackageName, f.FileName, f.LineNumber)
+        }
+}
+
+func (f *StackTraceFrame) String() string {
+        return fmt.Sprintf("%s%s:%d %s", f.PackageName, f.FileName, f.LineNumber, f.FunctionName)
+}
+
+func (st *StackTrace) String() string {
+        s := fmt.Sprintf("StackTrace with %d frames:\n", len(st.Frames))
+        for _, f := range st.Frames {
+                s += fmt.Sprintf("\t%s\n", f.String())
+        }
+        return s
+}
+
+func (st *StackTrace) IsEmpty() bool {
+        return len(st.Frames) == 0
+}