Added wc command

commands/wc.go

@@ -0,0 +1,172 @@
+package commands
+
+import (
+	"fmt"
+	"io"
+	"unicode"
+
+	"github.com/josephlewis42/honeyssh/core/vos"
+)
+
+type wcCount struct {
+	bytes int
+	lines int
+	chars int
+	words int
+	name  string
+
+	inSpace bool
+}
+
+func (w *wcCount) Write(data []byte) (int, error) {
+	for _, c := range data {
+		w.bytes++
+
+		// Assume UTF-8 characters. Bytes following the leading byte always
+		// have MSB of 0b10 indicating they're part of a previous character.
+		if c < 0b10000000 || c > 0b10111111 {
+			w.chars++
+		}
+
+		if c == '\n' {
+			w.lines++
+		}
+
+		if unicode.IsSpace(rune(c)) {
+			if !w.inSpace {
+				w.words++
+			}
+
+			w.inSpace = true
+		} else {
+			w.inSpace = false
+		}
+	}
+
+	return len(data), nil
+}
+
+func NewWcCount(name string, fd io.Reader) (*wcCount, error) {
+	var out wcCount
+	out.name = name
+
+	if _, err := io.Copy(&out, fd); err != nil {
+		return nil, err
+	}
+
+	return &out, nil
+}
+
+func (w *wcCount) Increment(other *wcCount) {
+	w.bytes += other.bytes
+	w.chars += other.chars
+	w.lines += other.lines
+	w.words += other.words
+}
+
+// Wc implements the POSIX command by the same name.
+// https://pubs.opengroup.org/onlinepubs/009695399/utilities/wc.html
+func Wc(virtOS vos.VOS) int {
+	cmd := &SimpleCommand{
+		Use:   "wc [-c|-m] [-lw] [FILE...]",
+		Short: "Write the number of newlines, words, and bytes contained in each input file to the standard output.",
+	}
+
+	opts := cmd.Flags()
+	writeLines := opts.BoolLong("l", 'l', "write the number of newlines in each file")
+	writeWords := opts.BoolLong("w", 'w', "write the number of words in each file")
+	writeBytes := opts.BoolLong("c", 'c', "write the number of bytes in each file")
+	writeChars := opts.BoolLong("m", 'm', "write the number of characters in each file")
+
+	return cmd.RunE(virtOS, func() error {
+		args := opts.Args()
+
+		anyPicked := *writeLines || *writeWords || *writeBytes || *writeChars
+		nonePicked := !anyPicked
+
+		var cols []func(*wcCount) string
+
+		if *writeLines || nonePicked {
+			cols = append(cols, func(w *wcCount) string {
+				return fmt.Sprint(w.lines)
+			})
+		}
+		if *writeWords || nonePicked {
+			cols = append(cols, func(w *wcCount) string {
+				return fmt.Sprint(w.words)
+			})
+		}
+		if *writeBytes || nonePicked {
+			cols = append(cols, func(w *wcCount) string {
+				return fmt.Sprint(w.bytes)
+			})
+		}
+		if *writeChars {
+			cols = append(cols, func(w *wcCount) string {
+				return fmt.Sprint(w.chars)
+			})
+		}
+
+		displayCount := func(count *wcCount) {
+			for i, col := range cols {
+				if i != 0 {
+					fmt.Fprint(virtOS.Stdout(), " ")
+				}
+				fmt.Fprint(virtOS.Stdout(), col(count))
+			}
+			fmt.Fprintln(virtOS.Stdout())
+		}
+
+		writeCounts := func(countsList ...*wcCount) {
+			total := &wcCount{name: "total"}
+
+			for _, count := range countsList {
+				total.Increment(count)
+				displayCount(count)
+			}
+
+			if len(countsList) > 1 {
+				displayCount(total)
+			}
+		}
+
+		if len(args) == 0 {
+			count, err := NewWcCount("", virtOS.Stdin())
+			if err != nil {
+				return err
+			}
+			writeCounts(count)
+			return nil
+		}
+
+		cols = append(cols, func(w *wcCount) string {
+			return w.name
+		})
+
+		var counts []*wcCount
+		for _, path := range args {
+			fd, err := virtOS.Open(path)
+			if err != nil {
+				return err
+			}
+			defer fd.Close()
+
+			count, err := NewWcCount(path, fd)
+			if err != nil {
+				return err
+			}
+
+			counts = append(counts, count)
+		}
+
+		writeCounts(counts...)
+
+		return nil
+	})
+}
+
+var _ vos.ProcessFunc = Wc
+
+func init() {
+	addBinCmd("wc", Wc)
+}