tar: remove strconv dependency for tar checksum octal numbers (#536)

goos: linux goarch: amd64 pkg: github.com/gabriel-vasile/mimetype cpu: Intel(R) Core(TM) i7-10510U CPU @ 1.80GHz │ common_master │ common_dev │ │ sec/op │ sec/op vs base │ Common/.xlsx-8 401.2n ± 3% 312.2n ± 5% -22.17% (p=0.000 n=10) Common/.pptx-8 1.708µ ± 4% 1.535µ ± 3% -10.10% (p=0.000 n=10) Common/.docx-8 1.260µ ± 7% 1.116µ ± 4% -11.43% (p=0.000 n=10) Common/.tar-8 1011.0n ± 7% 785.0n ± 4% -22.35% (p=0.000 n=10) Common/.zip-8 742.3n ± 11% 616.2n ± 16% -16.99% (p=0.003 n=10) Common/.pdf-8 291.6n ± 4% 191.9n ± 4% -34.20% (p=0.000 n=10) Common/.jpg-8 410.7n ± 9% 374.1n ± 17% -8.90% (p=0.019 n=10) Common/.png-8 425.1n ± 8% 327.8n ± 8% -22.89% (p=0.000 n=10) Common/.gif-8 480.4n ± 4% 396.9n ± 7% -17.38% (p=0.000 n=10) Common/.xls-8 427.2n ± 6% 324.7n ± 4% -24.00% (p=0.000 n=10) Common/.webm-8 1160.0n ± 5% 724.8n ± 5% -37.52% (p=0.000 n=10) Common/.csv-8 6.965µ ± 7% 5.671µ ± 6% -18.57% (p=0.000 n=10) geomean 784.9n 620.0n -21.01% │ common_master │ common_dev │ │ B/op │ B/op vs base │ Common/.xlsx-8 312.0 ± 0% 312.0 ± 0% ~ (p=1.000 n=10) ¹ Common/.pptx-8 592.0 ± 0% 592.0 ± 0% ~ (p=1.000 n=10) ¹ Common/.docx-8 504.0 ± 0% 504.0 ± 0% ~ (p=1.000 n=10) ¹ Common/.tar-8 200.0 ± 0% 192.0 ± 0% -4.00% (p=0.000 n=10) Common/.zip-8 224.0 ± 0% 224.0 ± 0% ~ (p=1.000 n=10) ¹ Common/.pdf-8 192.0 ± 0% 192.0 ± 0% ~ (p=1.000 n=10) ¹ Common/.jpg-8 192.0 ± 0% 192.0 ± 0% ~ (p=1.000 n=10) ¹ Common/.png-8 192.0 ± 0% 192.0 ± 0% ~ (p=1.000 n=10) ¹ Common/.gif-8 192.0 ± 0% 192.0 ± 0% ~ (p=1.000 n=10) ¹ Common/.xls-8 288.0 ± 0% 288.0 ± 0% ~ (p=1.000 n=10) ¹ Common/.webm-8 192.0 ± 0% 192.0 ± 0% ~ (p=1.000 n=10) ¹ Common/.csv-8 7.390Ki ± 0% 7.323Ki ± 0% -0.90% (p=0.000 n=10) geomean 339.8 338.4 -0.41% ¹ all samples are equal │ common_master │ common_dev │ │ allocs/op │ allocs/op vs base │ Common/.xlsx-8 4.000 ± 0% 4.000 ± 0% ~ (p=1.000 n=10) ¹ Common/.pptx-8 15.00 ± 0% 15.00 ± 0% ~ (p=1.000 n=10) ¹ Common/.docx-8 13.00 ± 0% 13.00 ± 0% ~ (p=1.000 n=10) ¹ Common/.tar-8 3.000 ± 0% 2.000 ± 0% -33.33% (p=0.000 n=10) Common/.zip-8 6.000 ± 0% 6.000 ± 0% ~ (p=1.000 n=10) ¹ Common/.pdf-8 2.000 ± 0% 2.000 ± 0% ~ (p=1.000 n=10) ¹ Common/.jpg-8 2.000 ± 0% 2.000 ± 0% ~ (p=1.000 n=10) ¹ Common/.png-8 2.000 ± 0% 2.000 ± 0% ~ (p=1.000 n=10) ¹ Common/.gif-8 2.000 ± 0% 2.000 ± 0% ~ (p=1.000 n=10) ¹ Common/.xls-8 3.000 ± 0% 3.000 ± 0% ~ (p=1.000 n=10) ¹ Common/.webm-8 2.000 ± 0% 2.000 ± 0% ~ (p=1.000 n=10) ¹ Common/.csv-8 34.00 ± 0% 31.00 ± 0% -8.82% (p=0.000 n=10) geomean 4.349 4.173 -4.06% ¹ all samples are equal │ rand_master │ rand_dev │ │ sec/op │ sec/op vs base │ SliceRand-8 457.4n ± 4% 398.1n ± 3% -12.96% (p=0.000 n=10) │ rand_master │ rand_dev │ │ B/op │ B/op vs base │ SliceRand-8 160.00 ± 0% 96.00 ± 0% -40.00% (p=0.000 n=10) │ rand_master │ rand_dev │ │ allocs/op │ allocs/op vs base │ SliceRand-8 4.000 ± 0% 1.000 ± 0% -75.00% (p=0.000 n=10)
gabriel-vasile · May 27, 2024 · 77e3848 · 77e3848
1 parent 09ff708
commit 77e3848
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Showing 2 changed files with 27 additions and 39 deletions.
diff --git a/internal/magic/archive.go b/internal/magic/archive.go
@@ -3,7 +3,6 @@ package magic
 import (
 	"bytes"
 	"encoding/binary"
-	"strconv"
 )
 
 var (
@@ -110,37 +109,35 @@ func Tar(raw []byte, _ uint32) bool {
 	}
 
 	// Get the checksum recorded into the file.
-	recsum, err := tarParseOctal(raw[148:156])
-	if err != nil {
+	recsum := tarParseOctal(raw[148:156])
+	if recsum == -1 {
 		return false
 	}
 	sum1, sum2 := tarChksum(raw)
 	return recsum == sum1 || recsum == sum2
 }
 
 // tarParseOctal converts octal string to decimal int.
-func tarParseOctal(b []byte) (int64, error) {
+func tarParseOctal(b []byte) int64 {
 	// Because unused fields are filled with NULs, we need to skip leading NULs.
 	// Fields may also be padded with spaces or NULs.
 	// So we remove leading and trailing NULs and spaces to be sure.
 	b = bytes.Trim(b, " \x00")
 
 	if len(b) == 0 {
-		return 0, nil
+		return -1
 	}
-	x, err := strconv.ParseUint(tarParseString(b), 8, 64)
-	if err != nil {
-		return 0, err
-	}
-	return int64(x), nil
-}
-
-// tarParseString converts a NUL ended bytes slice to a string.
-func tarParseString(b []byte) string {
-	if i := bytes.IndexByte(b, 0); i >= 0 {
-		return string(b[:i])
+	ret := int64(0)
+	for _, b := range b {
+		if b == 0 {
+			break
+		}
+		if !(b >= '0' && b <= '7') {
+			return -1
+		}
+		ret = (ret << 3) | int64(b-'0')
 	}
-	return string(b)
+	return ret
 }
 
 // tarChksum computes the checksum for the header block b.

diff --git a/internal/magic/archive_test.go b/internal/magic/archive_test.go
@@ -6,32 +6,23 @@ func TestTarParseOctal(t *testing.T) {
 	tests := []struct {
 		in   string
 		want int64
-		ok   bool
 	}{
-		{"0000000\x00", 0, true},
-		{" \x0000000\x00", 0, true},
-		{" \x0000003\x00", 3, true},
-		{"00000000227\x00", 0227, true},
-		{"032033\x00 ", 032033, true},
-		{"320330\x00 ", 0320330, true},
-		{"0000660\x00 ", 0660, true},
-		{"\x00 0000660\x00 ", 0660, true},
-		{"0123456789abcdef", 0, false},
-		{"0123456789\x00abcdef", 0, false},
-		{"01234567\x0089abcdef", 342391, true},
-		{"0123\x7e\x5f\x264123", 0, false},
+		{"0000000\x00", 0},
+		{" \x0000000\x00", 0},
+		{" \x0000003\x00", 3},
+		{"00000000227\x00", 0227},
+		{"032033\x00 ", 032033},
+		{"320330\x00 ", 0320330},
+		{"0000660\x00 ", 0660},
+		{"\x00 0000660\x00 ", 0660},
+		{"0123456789abcdef", -1},
+		{"0123456789\x00abcdef", -1},
+		{"01234567\x0089abcdef", 01234567},
+		{"0123\x7e\x5f\x264123", -1},
 	}
 
 	for _, tt := range tests {
-		got, err := tarParseOctal([]byte(tt.in))
-		ok := err == nil
-		if ok != tt.ok {
-			if tt.ok {
-				t.Errorf("parseOctal(%q): got parsing failure, want success", tt.in)
-			} else {
-				t.Errorf("parseOctal(%q): got parsing success, want failure", tt.in)
-			}
-		}
+		got := tarParseOctal([]byte(tt.in))
 		if got != tt.want {
 			t.Errorf("parseOctal(%q): got %d, want %d", tt.in, got, tt.want)
 		}