114 lines
2.2 KiB
Go
114 lines
2.2 KiB
Go
package tee
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import (
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"fmt"
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"os"
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)
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type WriteStringCloser interface {
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Write([]byte) (int, error)
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WriteString(string) (int, error)
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Close() error
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}
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// Tee emulates the Unix tee(1) command.
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type Tee struct {
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f WriteStringCloser
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Verbose bool
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}
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// NewOut writes to standard output only. The file is created, not
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// appended to.
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func NewOut(logFile string) (*Tee, error) {
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if logFile == "" {
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return &Tee{}, nil
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}
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f, err := os.Create(logFile)
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if err != nil {
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return nil, err
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}
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return &Tee{f: f}, nil
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}
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func (t *Tee) Write(p []byte) (int, error) {
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n, err := os.Stdout.Write(p)
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if err != nil {
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return n, err
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}
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if t.f != nil {
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return t.f.Write(p)
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}
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return n, nil
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}
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// Close calls Close on the underlying file if present.
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// It is safe to call Close on a Tee with no file; in that case, it returns nil.
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func (t *Tee) Close() error {
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if t == nil || t.f == nil {
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return nil
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}
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err := t.f.Close()
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t.f = nil
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return err
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}
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// Printf formats according to a format specifier and writes to the
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// tee instance.
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func (t *Tee) Printf(format string, args ...any) (int, error) {
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s := fmt.Sprintf(format, args...)
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n, err := os.Stdout.WriteString(s)
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if err != nil {
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return n, err
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}
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if t.f == nil {
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return n, err
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}
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return t.f.WriteString(s)
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}
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// VPrintf is a variant of Printf that only prints if the Tee's
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// Verbose flag is set.
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func (t *Tee) VPrintf(format string, args ...any) (int, error) {
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if t.Verbose {
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return t.Printf(format, args...)
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}
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return 0, nil
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}
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var globalTee = &Tee{}
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// Open will attempt to open the logFile for the global tee instance.
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func Open(logFile string) error {
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f, err := os.Create(logFile)
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if err != nil {
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return err
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}
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globalTee.f = f
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return nil
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}
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// Printf formats according to a format specifier and writes to the
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// global tee.
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func Printf(format string, args ...any) (int, error) {
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return globalTee.Printf(format, args...)
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}
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// VPrintf calls VPrintf on the global tee instance.
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func VPrintf(format string, args ...any) (int, error) {
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return globalTee.VPrintf(format, args...)
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}
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// Close calls close on the global tee instance.
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func Close() error {
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return globalTee.Close()
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}
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// SetVerbose controls the verbosity of the global tee.
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func SetVerbose(verbose bool) {
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globalTee.Verbose = verbose
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}
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