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jbowensjbowens
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binfmt: add HexDump
Add a function that formats a []byte slice as a hex-encoded, wrapped string and displays the contained ASCII characters (like hexdump).
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‎internal/binfmt/hexdump.go‎

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package binfmt
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import (
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"bytes"
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"fmt"
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"io"
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"strconv"
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)
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// HexDump returns a string representation of the data in a hex dump format.
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// The width is the number of bytes per line.
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func HexDump(data []byte, width int, includeOffsets bool) string {
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var buf bytes.Buffer
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FHexDump(&buf, data, width, includeOffsets)
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return buf.String()
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}
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// FHexDump writes a hex dump of the data to w.
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func FHexDump(w io.Writer, data []byte, width int, includeOffsets bool) {
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offsetFormatWidth := len(fmt.Sprintf("%x", max(1, len(data)-1)))
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offsetFormatStr := "%0" + strconv.Itoa(offsetFormatWidth) + "x"
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for i := 0; i < len(data); i += width {
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if includeOffsets {
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fmt.Fprintf(w, offsetFormatStr+": ", i)
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}
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for j := 0; j < width; j++ {
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if j%4 == 0 {
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fmt.Fprint(w, " ")
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}
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if i+j >= len(data) {
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fmt.Fprintf(w, " ")
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} else {
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fmt.Fprintf(w, "%02x", data[i+j])
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}
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}
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fmt.Fprint(w, " | ")
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for j := 0; j < width; j++ {
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if i+j >= len(data) {
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break
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}
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if j%4 == 0 {
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fmt.Fprint(w, " ")
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}
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if data[i+j] < 32 || data[i+j] > 126 {
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fmt.Fprint(w, ".")
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} else {
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fmt.Fprintf(w, "%c", data[i+j])
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}
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}
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fmt.Fprintln(w)
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}
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}

‎internal/binfmt/hexdump_test.go‎

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package binfmt
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import (
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"fmt"
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"os"
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"testing"
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"github.com/cockroachdb/datadriven"
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"github.com/stretchr/testify/require"
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)
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func TestHexFmt(t *testing.T) {
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var width, offset, length int
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datadriven.RunTest(t, "testdata/hexdump", func(t *testing.T, d *datadriven.TestData) string {
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width = 16
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d.ScanArgs(t, "pos", &offset, &length)
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d.MaybeScanArgs(t, "width", &width)
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switch d.Cmd {
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case "read-file":
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path := d.CmdArgs[0].String()
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data, err := os.ReadFile(path)
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require.NoError(t, err)
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return HexDump(data[offset:offset+length], width, d.HasArg("include-offsets"))
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case "sequential":
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var size int
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d.ScanArgs(t, "size", &size)
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data := make([]byte, size)
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for i := 0; i < size; i++ {
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data[i] = byte(i)
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}
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return HexDump(data, width, d.HasArg("include-offsets"))
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default:
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return fmt.Sprintf("unknown command: %s", d.Cmd)
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}
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})
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}

‎internal/binfmt/testdata/hexdump‎

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sequential size=512 include-offsets width=16 pos=(0,512)
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----
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000: 00010203 04050607 08090a0b 0c0d0e0f | .... .... .... ....
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010: 10111213 14151617 18191a1b 1c1d1e1f | .... .... .... ....
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020: 20212223 24252627 28292a2b 2c2d2e2f | !"# $%&' ()*+ ,-./
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030: 30313233 34353637 38393a3b 3c3d3e3f | 0123 4567 89:; <=>?
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040: 40414243 44454647 48494a4b 4c4d4e4f | @ABC DEFG HIJK LMNO
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050: 50515253 54555657 58595a5b 5c5d5e5f | PQRS TUVW XYZ[ \]^_
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060: 60616263 64656667 68696a6b 6c6d6e6f | `abc defg hijk lmno
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070: 70717273 74757677 78797a7b 7c7d7e7f | pqrs tuvw xyz{ |}~.
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080: 80818283 84858687 88898a8b 8c8d8e8f | .... .... .... ....
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090: 90919293 94959697 98999a9b 9c9d9e9f | .... .... .... ....
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0a0: a0a1a2a3 a4a5a6a7 a8a9aaab acadaeaf | .... .... .... ....
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0b0: b0b1b2b3 b4b5b6b7 b8b9babb bcbdbebf | .... .... .... ....
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0c0: c0c1c2c3 c4c5c6c7 c8c9cacb cccdcecf | .... .... .... ....
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0d0: d0d1d2d3 d4d5d6d7 d8d9dadb dcdddedf | .... .... .... ....
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0e0: e0e1e2e3 e4e5e6e7 e8e9eaeb ecedeeef | .... .... .... ....
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0f0: f0f1f2f3 f4f5f6f7 f8f9fafb fcfdfeff | .... .... .... ....
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100: 00010203 04050607 08090a0b 0c0d0e0f | .... .... .... ....
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110: 10111213 14151617 18191a1b 1c1d1e1f | .... .... .... ....
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120: 20212223 24252627 28292a2b 2c2d2e2f | !"# $%&' ()*+ ,-./
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130: 30313233 34353637 38393a3b 3c3d3e3f | 0123 4567 89:; <=>?
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140: 40414243 44454647 48494a4b 4c4d4e4f | @ABC DEFG HIJK LMNO
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150: 50515253 54555657 58595a5b 5c5d5e5f | PQRS TUVW XYZ[ \]^_
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160: 60616263 64656667 68696a6b 6c6d6e6f | `abc defg hijk lmno
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170: 70717273 74757677 78797a7b 7c7d7e7f | pqrs tuvw xyz{ |}~.
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180: 80818283 84858687 88898a8b 8c8d8e8f | .... .... .... ....
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190: 90919293 94959697 98999a9b 9c9d9e9f | .... .... .... ....
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1a0: a0a1a2a3 a4a5a6a7 a8a9aaab acadaeaf | .... .... .... ....
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1b0: b0b1b2b3 b4b5b6b7 b8b9babb bcbdbebf | .... .... .... ....
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1c0: c0c1c2c3 c4c5c6c7 c8c9cacb cccdcecf | .... .... .... ....
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1d0: d0d1d2d3 d4d5d6d7 d8d9dadb dcdddedf | .... .... .... ....
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1e0: e0e1e2e3 e4e5e6e7 e8e9eaeb ecedeeef | .... .... .... ....
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1f0: f0f1f2f3 f4f5f6f7 f8f9fafb fcfdfeff | .... .... .... ....
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read-file ../../testdata/db-stage-4/000004.sst pos=(10,200) include-offsets
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----
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00: 00000000 0209057a 010c0000 00000000 | .... ...z .... ....
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10: 74687265 65000b04 666f6f01 0d000000 | thre e... foo. ....
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20: 00000066 6f757200 00000001 00000000 | ...f our. .... ....
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30: 49ac4e14 00090267 11ffffff ffffffff | I.N. ...g .... ....
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40: 00390000 00000100 00000074 8d30d700 | .9.. .... ...t .0..
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50: 23017065 62626c65 2e726177 2e706f69 | #.pe bble .raw .poi
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60: 6e742d74 6f6d6273 746f6e65 2e6b6579 | nt-t ombs tone .key
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70: 2e73697a 65030024 04726f63 6b736462 | .siz e..$ .roc ksdb
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80: 2e626c6f 636b2e62 61736564 2e746162 | .blo ck.b ased .tab
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90: 6c652e69 6e646578 2e747970 65000000 | le.i ndex .typ e...
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a0: 001a1001 70726566 69782e66 696c7465 | .... pref ix.f ilte
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b0: 72696e67 301a1301 77686f6c 652e6b65 | ring 0... whol e.ke
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c0: 792e6669 6c746572 | y.fi lter
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read-file ../../testdata/db-stage-4/MANIFEST-000006 pos=(0,256) include-offsets width=32
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----
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00: 9ef1d093 22000101 1a6c6576 656c6462 2e427974 65776973 65436f6d 70617261 | .... "... .lev eldb .Byt ewis eCom para
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20: 746f7202 02030704 001cf77b d52d0001 02050306 040e6700 04c5050b 62617200 | tor. .... ...{ .-.. .... ..g. .... bar.
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40: 0e000000 0000000b 666f6f01 0d000000 0000000c 0e060585 a6b8ab06 01000000 | .... .... foo. .... .... .... .... ....
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60: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 | .... .... .... .... .... .... .... ....
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80: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 | .... .... .... .... .... .... .... ....
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a0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 | .... .... .... .... .... .... .... ....
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c0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 | .... .... .... .... .... .... .... ....
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e0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 | .... .... .... .... .... .... .... ....

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