17840: Deduplicate flag-parsing code.

[arvados.git] / lib / deduplicationreport / report.go

diff --git a/lib/deduplicationreport/report.go b/lib/deduplicationreport/report.go
index bb3405a493e987b31e53aa0168e112d68b2694e2..2f9521c65dc225a071b4479cdef104bc3e4c4074 100644 (file)
--- a/lib/deduplicationreport/report.go
+++ b/lib/deduplicationreport/report.go
@@ -10,6 +10,7 @@ import (
        "io"
        "strings"
 
+       "git.arvados.org/arvados.git/lib/cmd"
        "git.arvados.org/arvados.git/sdk/go/arvados"
        "git.arvados.org/arvados.git/sdk/go/arvadosclient"
        "git.arvados.org/arvados.git/sdk/go/manifest"
@@ -29,16 +30,17 @@ func deDuplicate(inputs []string) (trimmed []string) {
        return
 }
 
-func parseFlags(prog string, args []string, logger *logrus.Logger, stderr io.Writer) ([]string, error) {
-       flags := flag.NewFlagSet("", flag.ContinueOnError)
-       flags.SetOutput(stderr)
+// parseFlags returns either some inputs to process, or (if there are
+// no inputs to process) a nil slice and a suitable exit code.
+func parseFlags(prog string, args []string, logger *logrus.Logger, stderr io.Writer) (inputs []string, exitcode int) {
+       flags := flag.NewFlagSet(prog, flag.ContinueOnError)
        flags.Usage = func() {
                fmt.Fprintf(flags.Output(), `
 Usage:
   %s [options ...] <collection-uuid> <collection-uuid> ...
 
-  %s [options ...] <collection-pdh>,<collection_uuid> \
-     <collection-pdh>,<collection_uuid> ...
+  %s [options ...] <collection-pdh>,<collection-uuid> \
+     <collection-pdh>,<collection-uuid> ...
 
   This program analyzes the overlap in blocks used by 2 or more collections. It
   prints a deduplication report that shows the nominal space used by the
@@ -67,28 +69,24 @@ Options:
                flags.PrintDefaults()
        }
        loglevel := flags.String("log-level", "info", "logging level (debug, info, ...)")
-       err := flags.Parse(args)
-       if err == flag.ErrHelp {
-               return nil, err
-       } else if err != nil {
-               return nil, err
+       if ok, code := cmd.ParseFlags(flags, prog, args, "collection-uuid [...]", stderr); !ok {
+               return nil, code
        }
 
-       inputs := flags.Args()
-
-       inputs = deDuplicate(inputs)
+       inputs = deDuplicate(flags.Args())
 
        if len(inputs) < 1 {
-               err = fmt.Errorf("Error: no collections provided")
-               return inputs, err
+               fmt.Fprintf(stderr, "Error: no collections provided\n")
+               return nil, 2
        }
 
        lvl, err := logrus.ParseLevel(*loglevel)
        if err != nil {
-               return inputs, err
+               fmt.Fprintf(stderr, "Error: cannot parse log level: %s\n", err)
+               return nil, 2
        }
        logger.SetLevel(lvl)
-       return inputs, err
+       return inputs, 0
 }
 
 func blockList(collection arvados.Collection) (blocks map[string]int) {
@@ -103,14 +101,10 @@ func blockList(collection arvados.Collection) (blocks map[string]int) {
 
 func report(prog string, args []string, logger *logrus.Logger, stdout, stderr io.Writer) (exitcode int) {
        var inputs []string
-       var err error
-
-       inputs, err = parseFlags(prog, args, logger, stderr)
-       if err == flag.ErrHelp {
-               return 0
-       } else if err != nil {
-               logger.Error(err.Error())
-               return 2
+
+       inputs, exitcode = parseFlags(prog, args, logger, stderr)
+       if inputs == nil {
+               return
        }
 
        // Arvados Client setup