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Add info and read sub commands to example program
To make room for a new convert sub command, using parallel convert. This
is also a better example, having only the relevant argument and separate
file for every example command.
Example usage:
% ./go-qcow2reader-example
Usage: ./go-qcow2reader-example COMMAND [OPTIONS...]
Available commands:
info show image information
read read image data and print to stdout
% ./go-qcow2reader-example info /tmp/images/test.zlib.qcow2
{
"type": "qcow2",
"size": 3758096384,
...
% time ./go-qcow2reader-example read /tmp/images/test.zlib.qcow2 >/dev/null
./go-qcow2reader-example read /tmp/images/test.zlib.qcow2 > /dev/null 10.05s user 0.35s system 101% cpu 10.279 total
Signed-off-by: Nir Soffer <[email protected]>- Loading branch information
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,67 @@ | ||
| package main | ||
|
|
||
| import ( | ||
| "encoding/json" | ||
| "errors" | ||
| "flag" | ||
| "fmt" | ||
| "os" | ||
|
|
||
| "github.com/lima-vm/go-qcow2reader" | ||
| "github.com/lima-vm/go-qcow2reader/image" | ||
| ) | ||
|
|
||
| func cmdInfo(args []string) error { | ||
| var ( | ||
| // Required | ||
| filename string | ||
|
|
||
| // Options | ||
| debug bool | ||
| ) | ||
|
|
||
| fs := flag.NewFlagSet("info", flag.ExitOnError) | ||
| fs.Usage = func() { | ||
| fmt.Fprintf(fs.Output(), "Usage: %s info [OPTIONS...] FILE\n", os.Args[0]) | ||
| fs.PrintDefaults() | ||
| } | ||
| fs.BoolVar(&debug, "debug", false, "enable printing debug messages") | ||
| if err := fs.Parse(args); err != nil { | ||
| return err | ||
| } | ||
|
|
||
| switch len(fs.Args()) { | ||
| case 0: | ||
| return errors.New("no file was specified") | ||
| case 1: | ||
| filename = fs.Arg(0) | ||
| default: | ||
| return errors.New("too many files specified") | ||
| } | ||
|
|
||
| f, err := os.Open(filename) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| defer f.Close() | ||
|
|
||
| img, err := qcow2reader.Open(f) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| defer img.Close() | ||
|
|
||
| imgInfo := image.NewImageInfo(img) | ||
| j, err := json.MarshalIndent(imgInfo, "", " ") | ||
| if err != nil { | ||
| return err | ||
| } | ||
| if _, err = fmt.Println(string(j)); err != nil { | ||
| return err | ||
| } | ||
| if err = img.Readable(); err != nil { | ||
| logWarn(err.Error()) | ||
| } | ||
|
|
||
| return nil | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,73 @@ | ||
| package main | ||
|
|
||
| import ( | ||
| "errors" | ||
| "flag" | ||
| "fmt" | ||
| "io" | ||
| "os" | ||
|
|
||
| "github.com/lima-vm/go-qcow2reader" | ||
| "github.com/lima-vm/go-qcow2reader/log" | ||
| ) | ||
|
|
||
| func cmdRead(args []string) error { | ||
| var ( | ||
| // Required | ||
| filename string | ||
|
|
||
| // Options | ||
| debug bool | ||
| bufferSize int | ||
| offset int64 | ||
| length int64 | ||
| ) | ||
|
|
||
| fs := flag.NewFlagSet("read", flag.ExitOnError) | ||
| fs.Usage = func() { | ||
| fmt.Fprintf(fs.Output(), "Usage: %s read [OPTIONS...] FILE\n", os.Args[0]) | ||
| flag.PrintDefaults() | ||
| } | ||
| fs.BoolVar(&debug, "debug", false, "enable printing debug messages") | ||
| fs.IntVar(&bufferSize, "buffer-size", 65536, "buffer size") | ||
| fs.Int64Var(&offset, "offset", 0, "offset to read") | ||
| fs.Int64Var(&length, "length", -1, "length to read") | ||
| if err := fs.Parse(args); err != nil { | ||
| return err | ||
| } | ||
|
|
||
| if debug { | ||
| log.SetDebugFunc(logDebug) | ||
| } | ||
|
|
||
| switch len(fs.Args()) { | ||
| case 0: | ||
| return errors.New("no file was specified") | ||
| case 1: | ||
| filename = fs.Arg(0) | ||
| default: | ||
| return errors.New("too many files were specified") | ||
| } | ||
|
|
||
| f, err := os.Open(filename) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| defer f.Close() | ||
|
|
||
| img, err := qcow2reader.Open(f) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| defer img.Close() | ||
|
|
||
| if length < 0 { | ||
| length = img.Size() | ||
| } | ||
|
|
||
| buf := make([]byte, bufferSize) | ||
| sr := io.NewSectionReader(img, offset, length) | ||
| _, err = io.CopyBuffer(os.Stdout, sr, buf) | ||
|
|
||
| return err | ||
| } |
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