File: bitdump.go 1 /* 2 The MIT License (MIT) 3 4 Copyright © 2020-2025 pacman64 5 6 Permission is hereby granted, free of charge, to any person obtaining a copy of 7 this software and associated documentation files (the “Software”), to deal 8 in the Software without restriction, including without limitation the rights to 9 use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies 10 of the Software, and to permit persons to whom the Software is furnished to do 11 so, subject to the following conditions: 12 13 The above copyright notice and this permission notice shall be included in all 14 copies or substantial portions of the Software. 15 16 THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 19 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 20 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 21 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 22 SOFTWARE. 23 */ 24 25 /* 26 Single-file source-code for bitdump. 27 28 To compile a smaller-sized command-line app, you can use the `go` command as 29 follows: 30 31 go build -ldflags "-s -w" -trimpath bitdump.go 32 */ 33 34 package main 35 36 import ( 37 "bufio" 38 "errors" 39 "io" 40 "os" 41 "strconv" 42 ) 43 44 // Note: the code is avoiding using the fmt package to save hundreds of 45 // kilobytes on the resulting executable, which is a noticeable difference. 46 47 const info = ` 48 bitdump [options...] [filenames...] 49 50 51 Show all bits for all input bytes, starting each output line with the 52 leading byte's offset. 53 54 All (optional) leading options start with either single or double-dash: 55 56 -h show this help message 57 -help show this help message 58 ` 59 60 const itemsPerLine = 8 61 62 const errorStyle = "\x1b[31m" 63 64 // errNoMoreOutput is a dummy error, whose message is ignored, and which 65 // causes the app to quit immediately and successfully 66 var errNoMoreOutput = errors.New(`no more output`) 67 68 func main() { 69 if len(os.Args) > 1 { 70 switch os.Args[1] { 71 case `-h`, `--h`, `-help`, `--help`: 72 os.Stderr.WriteString(info[1:]) 73 return 74 } 75 } 76 77 if err := run(os.Stdout, os.Args[1:]); isActualError(err) { 78 os.Stderr.WriteString(errorStyle) 79 os.Stderr.WriteString(err.Error()) 80 os.Stderr.WriteString("\x1b[0m\n") 81 os.Exit(1) 82 } 83 } 84 85 func run(w io.Writer, args []string) error { 86 offset := 0 87 bw := bufio.NewWriter(w) 88 defer func() { 89 if offset%itemsPerLine == 0 && offset > 0 { 90 bw.WriteByte('\n') 91 } 92 bw.Flush() 93 }() 94 95 if len(args) == 0 { 96 return bitdump(bw, os.Stdin, &offset) 97 } 98 99 for _, name := range args { 100 if err := handleFile(bw, name, &offset); err != nil { 101 return err 102 } 103 } 104 return nil 105 } 106 107 func handleFile(w *bufio.Writer, name string, offset *int) error { 108 if name == `` || name == `-` { 109 return bitdump(w, os.Stdin, offset) 110 } 111 112 f, err := os.Open(name) 113 if err != nil { 114 return errors.New(`can't read from file named "` + name + `"`) 115 } 116 defer f.Close() 117 118 return bitdump(w, f, offset) 119 } 120 121 // isActualError is to figure out whether not to ignore an error, and thus 122 // show it as an error message 123 func isActualError(err error) bool { 124 return err != nil && err != io.EOF && err != errNoMoreOutput 125 } 126 127 func bitdump(w *bufio.Writer, r io.Reader, offset *int) error { 128 var buf [16 * 1024]byte 129 defer w.Flush() 130 131 for { 132 n, err := r.Read(buf[:]) 133 if n < 1 && err == io.EOF { 134 return nil 135 } 136 137 if err != nil && err != io.EOF { 138 return err 139 } 140 141 chunk := buf[:n] 142 143 for len(chunk) >= itemsPerLine { 144 if err := emitChunk(w, chunk[:itemsPerLine], offset); err != nil { 145 return err 146 } 147 148 chunk = chunk[itemsPerLine:] 149 *offset += itemsPerLine 150 } 151 152 if len(chunk) > 0 { 153 if err := emitChunk(w, chunk, offset); err != nil { 154 return err 155 } 156 157 *offset += len(chunk) 158 } 159 } 160 } 161 162 func emitChunk(w *bufio.Writer, chunk []byte, offset *int) error { 163 const pad = `00000000` 164 var str [24]byte 165 166 if *offset%itemsPerLine == 0 { 167 if *offset > 0 { 168 if err := w.WriteByte('\n'); err != nil { 169 // assume a write error is the consequence of stdout 170 // being closed, perhaps by another app along a pipe 171 return errNoMoreOutput 172 } 173 } 174 175 s := strconv.AppendInt(str[:0], int64(*offset), 10) 176 // pad small offsets with leading zeros 177 if len(s) < len(pad) { 178 w.WriteString(pad[len(s):]) 179 } 180 w.Write(s) 181 } 182 183 for _, b := range chunk { 184 w.WriteByte(' ') 185 w.WriteString(bits[b]) 186 } 187 return nil 188 } 189 190 /* 191 tlp = '(f"{bin(v)[2:]:>08}" for v in range(256))' | lineup 6 | 192 gsub '\t' '`, `' | tlp 'f"\t`{l}`,"' 193 */ 194 var bits = [256]string{ 195 `00000000`, `00000001`, `00000010`, `00000011`, `00000100`, `00000101`, 196 `00000110`, `00000111`, `00001000`, `00001001`, `00001010`, `00001011`, 197 `00001100`, `00001101`, `00001110`, `00001111`, `00010000`, `00010001`, 198 `00010010`, `00010011`, `00010100`, `00010101`, `00010110`, `00010111`, 199 `00011000`, `00011001`, `00011010`, `00011011`, `00011100`, `00011101`, 200 `00011110`, `00011111`, `00100000`, `00100001`, `00100010`, `00100011`, 201 `00100100`, `00100101`, `00100110`, `00100111`, `00101000`, `00101001`, 202 `00101010`, `00101011`, `00101100`, `00101101`, `00101110`, `00101111`, 203 `00110000`, `00110001`, `00110010`, `00110011`, `00110100`, `00110101`, 204 `00110110`, `00110111`, `00111000`, `00111001`, `00111010`, `00111011`, 205 `00111100`, `00111101`, `00111110`, `00111111`, `01000000`, `01000001`, 206 `01000010`, `01000011`, `01000100`, `01000101`, `01000110`, `01000111`, 207 `01001000`, `01001001`, `01001010`, `01001011`, `01001100`, `01001101`, 208 `01001110`, `01001111`, `01010000`, `01010001`, `01010010`, `01010011`, 209 `01010100`, `01010101`, `01010110`, `01010111`, `01011000`, `01011001`, 210 `01011010`, `01011011`, `01011100`, `01011101`, `01011110`, `01011111`, 211 `01100000`, `01100001`, `01100010`, `01100011`, `01100100`, `01100101`, 212 `01100110`, `01100111`, `01101000`, `01101001`, `01101010`, `01101011`, 213 `01101100`, `01101101`, `01101110`, `01101111`, `01110000`, `01110001`, 214 `01110010`, `01110011`, `01110100`, `01110101`, `01110110`, `01110111`, 215 `01111000`, `01111001`, `01111010`, `01111011`, `01111100`, `01111101`, 216 `01111110`, `01111111`, `10000000`, `10000001`, `10000010`, `10000011`, 217 `10000100`, `10000101`, `10000110`, `10000111`, `10001000`, `10001001`, 218 `10001010`, `10001011`, `10001100`, `10001101`, `10001110`, `10001111`, 219 `10010000`, `10010001`, `10010010`, `10010011`, `10010100`, `10010101`, 220 `10010110`, `10010111`, `10011000`, `10011001`, `10011010`, `10011011`, 221 `10011100`, `10011101`, `10011110`, `10011111`, `10100000`, `10100001`, 222 `10100010`, `10100011`, `10100100`, `10100101`, `10100110`, `10100111`, 223 `10101000`, `10101001`, `10101010`, `10101011`, `10101100`, `10101101`, 224 `10101110`, `10101111`, `10110000`, `10110001`, `10110010`, `10110011`, 225 `10110100`, `10110101`, `10110110`, `10110111`, `10111000`, `10111001`, 226 `10111010`, `10111011`, `10111100`, `10111101`, `10111110`, `10111111`, 227 `11000000`, `11000001`, `11000010`, `11000011`, `11000100`, `11000101`, 228 `11000110`, `11000111`, `11001000`, `11001001`, `11001010`, `11001011`, 229 `11001100`, `11001101`, `11001110`, `11001111`, `11010000`, `11010001`, 230 `11010010`, `11010011`, `11010100`, `11010101`, `11010110`, `11010111`, 231 `11011000`, `11011001`, `11011010`, `11011011`, `11011100`, `11011101`, 232 `11011110`, `11011111`, `11100000`, `11100001`, `11100010`, `11100011`, 233 `11100100`, `11100101`, `11100110`, `11100111`, `11101000`, `11101001`, 234 `11101010`, `11101011`, `11101100`, `11101101`, `11101110`, `11101111`, 235 `11110000`, `11110001`, `11110010`, `11110011`, `11110100`, `11110101`, 236 `11110110`, `11110111`, `11111000`, `11111001`, `11111010`, `11111011`, 237 `11111100`, `11111101`, `11111110`, `11111111`, 238 }