pkg/report: remove unnecessary NewScan() calls

These are susceptible to potentially very long lines in the input.
Direct splitting by \n is more reliable.

4 files changed, 45 insertions, 37 deletions

diff --git a/pkg/report/bsd.go b/pkg/report/bsd.go
index b627ed4f4..75cfa3426 100644
--- a/pkg/report/bsd.go
+++ b/pkg/report/bsd.go
@@ -4,7 +4,6 @@
 package report
 
 import (
-	"bufio"
 	"bytes"
 	"fmt"
 	"path/filepath"
@@ -57,11 +56,9 @@ func (ctx *bsd) Symbolize(rep *Report) error {
 	symb := symbolizer.NewSymbolizer(ctx.config.target)
 	defer symb.Close()
 	var symbolized []byte
-	s := bufio.NewScanner(bytes.NewReader(rep.Report))
 	prefix := rep.reportPrefixLen
-	for s.Scan() {
-		line := append([]byte{}, s.Bytes()...)
-		line = append(line, '\n')
+	for _, line := range bytes.SplitAfter(rep.Report, []byte("\n")) {
+		line := bytes.Clone(line)
 		newLine := ctx.symbolizeLine(symb.Symbolize, line)
 		if prefix > len(symbolized) {
 			prefix += len(newLine) - len(line)
diff --git a/pkg/report/fuchsia.go b/pkg/report/fuchsia.go
index 7f3461061..c4cd602e9 100644
--- a/pkg/report/fuchsia.go
+++ b/pkg/report/fuchsia.go
@@ -4,7 +4,6 @@
 package report
 
 import (
-	"bufio"
 	"bytes"
 	"fmt"
 	"path/filepath"
@@ -97,8 +96,7 @@ func (ctx *fuchsia) shortenStarnixPanicReport(report []byte, maxUnrelatedLines,
 	out := new(bytes.Buffer)
 	unrelatedLines := 0
 	unmatchedLines := 0
-	for s := bufio.NewScanner(bytes.NewReader(report)); s.Scan(); {
-		line := s.Bytes()
+	for _, line := range lines(report) {
 		if matchesAny(line, starnixFramePatterns) {
 			unrelatedLines = 0
 			unmatchedLines = 0
@@ -113,16 +111,16 @@ func (ctx *fuchsia) shortenStarnixPanicReport(report []byte, maxUnrelatedLines,
 		out.Write(line)
 		out.WriteByte('\n')
 		if unmatchedLines == maxUnmatchedLines {
-			return out.Bytes()
+			break
 		}
 	}
-	return out.Bytes()
+	return append(bytes.TrimRight(out.Bytes(), "\n"), '\n')
 }
 
 func (ctx *fuchsia) shortenReport(report []byte) []byte {
 	out := new(bytes.Buffer)
-	for s := bufio.NewScanner(bytes.NewReader(report)); s.Scan(); {
-		line := zirconLinePrefix.ReplaceAll(s.Bytes(), nil)
+	for _, rawLine := range lines(report) {
+		line := zirconLinePrefix.ReplaceAll(rawLine, nil)
 		if matchesAny(line, zirconUnrelated) {
 			continue
 		}
@@ -139,14 +137,17 @@ func (ctx *fuchsia) symbolize(output []byte) []byte {
 	symb := symbolizer.NewSymbolizer(ctx.config.target)
 	defer symb.Close()
 	out := new(bytes.Buffer)
-	for s := bufio.NewScanner(bytes.NewReader(output)); s.Scan(); {
-		line := s.Bytes()
+
+	lines := lines(output)
+	for i := 0; i < len(lines); i++ {
+		line := lines[i]
 		if bytes.Contains(line, zirconAssertFailed) && len(line) == 127 {
 			// This is super hacky: but zircon splits the most important information in long assert lines
 			// (and they are always long) into several lines in irreversible way. Try to restore full line.
 			line = append([]byte{}, line...)
-			if s.Scan() {
-				line = append(line, s.Bytes()...)
+			if i+1 < len(lines) {
+				line = append(bytes.Clone(line), lines[i+1]...)
+				i++
 			}
 		}
 		if ctx.obj != "" {
diff --git a/pkg/report/linux.go b/pkg/report/linux.go
index 0fdcee54c..05f41676b 100644
--- a/pkg/report/linux.go
+++ b/pkg/report/linux.go
@@ -4,7 +4,6 @@
 package report
 
 import (
-	"bufio"
 	"bytes"
 	"encoding/binary"
 	"fmt"
@@ -404,8 +403,8 @@ func (ctx *linux) symbolize(rep *Report) error {
 	}
 	var symbolized []byte
 	prefix := rep.reportPrefixLen
-	for _, originalLine := range bytes.SplitAfter(rep.Report, []byte("\n")) {
-		line := append([]byte{}, originalLine...)
+	for _, line := range bytes.SplitAfter(rep.Report, []byte("\n")) {
+		line := bytes.Clone(line)
 		newLine := symbolizeLine(symbFunc, ctx.symbols, ctx.vmlinux, ctx.kernelBuildSrc, line)
 		if prefix > len(symbolized) {
 			prefix += len(newLine) - len(line)
@@ -658,8 +657,12 @@ func (ctx *linux) decompileOpcodes(text []byte, report *Report) []byte {
 	// Iterate over all "Code: " lines and pick the first that could be decompiled
 	// that might be of interest to the user.
 	var decompiled *decompiledOpcodes
-	var prevLine []byte
-	for s := bufio.NewScanner(bytes.NewReader(text)); s.Scan(); prevLine = append([]byte{}, s.Bytes()...) {
+	lines := lines(text)
+	for i, line := range lines {
+		var prevLine []byte
+		if i > 0 {
+			prevLine = lines[i-1]
+		}
 		// We want to avoid decompiling code from user-space as it is not of big interest during
 		// debugging kernel problems.
 		// For now this check only works for x86/amd64, but Linux on other architectures supported
@@ -667,7 +670,7 @@ func (ctx *linux) decompileOpcodes(text []byte, report *Report) []byte {
 		if linuxUserSegmentRe.Match(prevLine) {
 			continue
 		}
-		match := linuxCodeRe.FindSubmatch(s.Bytes())
+		match := linuxCodeRe.FindSubmatch(line)
 		if match == nil {
 			continue
 		}
@@ -731,12 +734,13 @@ func (ctx *linux) extractGuiltyFileRaw(title string, report []byte) string {
 }
 
 func (ctx *linux) extractGuiltyFileImpl(report []byte) string {
-	scanner := bufio.NewScanner(bytes.NewReader(report))
-
 	// Extract the first possible guilty file.
 	guilty := ""
-	for scanner.Scan() {
-		match := filenameRe.FindSubmatch(scanner.Bytes())
+	var line []byte
+	lines := lines(report)
+	for len(lines) > 0 {
+		line, lines = lines[0], lines[1:]
+		match := filenameRe.FindSubmatch(line)
 		if match == nil {
 			continue
 		}
@@ -748,7 +752,7 @@ func (ctx *linux) extractGuiltyFileImpl(report []byte) string {
 			guilty = string(file)
 		}
 
-		if matchesAny(file, ctx.guiltyFileIgnores) || ctx.guiltyLineIgnore.Match(scanner.Bytes()) {
+		if matchesAny(file, ctx.guiltyFileIgnores) || ctx.guiltyLineIgnore.Match(line) {
 			continue
 		}
 		guilty = filepath.Clean(string(file))
@@ -757,13 +761,14 @@ func (ctx *linux) extractGuiltyFileImpl(report []byte) string {
 
 	// Search for deeper filepaths in the stack trace below the first possible guilty file.
 	deepestPath := filepath.Dir(guilty)
-	for scanner.Scan() {
-		match := filenameRe.FindSubmatch(scanner.Bytes())
+	for len(lines) > 0 {
+		line, lines = lines[0], lines[1:]
+		match := filenameRe.FindSubmatch(line)
 		if match == nil {
 			continue
 		}
 		file := match[1]
-		if matchesAny(file, ctx.guiltyFileIgnores) || ctx.guiltyLineIgnore.Match(scanner.Bytes()) {
+		if matchesAny(file, ctx.guiltyFileIgnores) || ctx.guiltyLineIgnore.Match(line) {
 			continue
 		}
 		clean := filepath.Clean(string(file))
@@ -839,7 +844,7 @@ func (ctx *linux) isCorrupted(title string, report []byte, format oopsFormat) (b
 		if match == nil {
 			continue
 		}
-		frames := bytes.Split(report[match[0]:], []byte{'\n'})
+		frames := lines(report[match[0]:])
 		if len(frames) < 4 {
 			return true, "call trace is missed"
 		}
diff --git a/pkg/report/report.go b/pkg/report/report.go
index 38f2ec758..514a47734 100644
--- a/pkg/report/report.go
+++ b/pkg/report/report.go
@@ -6,7 +6,6 @@
 package report
 
 import (
-	"bufio"
 	"bytes"
 	"fmt"
 	"regexp"
@@ -585,9 +584,13 @@ func extractStackFrame(params *stackParams, stack *stackFmt, output []byte) ([]s
 	return extractStackFrameImpl(params, output, skipRe, stack.parts2, extractor)
 }
 
+func lines(text []byte) [][]byte {
+	return bytes.Split(text, []byte("\n"))
+}
+
 func extractStackFrameImpl(params *stackParams, output []byte, skipRe *regexp.Regexp,
 	parts []*regexp.Regexp, extractor frameExtractor) ([]string, bool) {
-	s := bufio.NewScanner(bytes.NewReader(output))
+	lines := lines(output)
 	var frames, results []string
 	ok := true
 	numStackTraces := 0
@@ -607,8 +610,9 @@ nextPart:
 		part := parts[partIdx]
 		if part == parseStackTrace {
 			numStackTraces++
-			for s.Scan() {
-				ln := s.Bytes()
+			var ln []byte
+			for len(lines) > 0 {
+				ln, lines = lines[0], lines[1:]
 				if matchesAny(ln, params.corruptedLines) {
 					ok = false
 					continue nextPart
@@ -635,8 +639,9 @@ nextPart:
 				frames = appendStackFrame(frames, match, params, skipRe)
 			}
 		} else {
-			for s.Scan() {
-				ln := s.Bytes()
+			var ln []byte
+			for len(lines) > 0 {
+				ln, lines = lines[0], lines[1:]
 				if matchesAny(ln, params.corruptedLines) {
 					ok = false
 					continue nextPart