Add a linter to disable fmt.Printf in code (#4154)

Printf is often used while developping to inspect or debug code. It
happens that these statements are forgotten and commited. We can prevent
that by using a linter to disable them.

We have some cases where fmt.Printf was used to print useful stuff, like
in the CLI. They have been rewritten in fmt.Fprintf to avoid been
flagged by the linter.

.golangci.yaml

@@ -47,6 +47,7 @@ linters:
     - bidichk 
     - exportloopref 
     - errname
+    - forbidigo
     - gocritic
     - gofmt
     - govet
@@ -60,6 +61,11 @@ linters:
   # Default: false
   fast: false
 linters-settings:
+  forbidigo:
+    # Forbid fmt.Printf, as they are often used for debugging and they should
+    # not be commited. The good cases can be written fmt.Fprintf(os.Stdout, ).
+    forbid:
+      - fmt.Printf
   gocritic:
     disabled-checks:
       - appendAssign

client/instances.go

@@ -548,7 +548,7 @@ func (ac *AdminClient) Export(opts *ExportOptions) error {
 						filename = params["filename"]
 					}
 
-					fmt.Printf("Exporting archive %d/%d (%s)... ", i+1, partsCount, filename)
+					fmt.Fprintf(os.Stdout, "Exporting archive %d/%d (%s)... ", i+1, partsCount, filename)
 
 					filepath := path.Join(opts.LocalPath, filename)
 					f, err := os.OpenFile(filepath, os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0600)

cmd/apps.go

@@ -310,7 +310,7 @@ var activateMaintenanceKonnectorsCmd = &cobra.Command{
 				break
 			}
 			if len(locale) > 5 {
-				fmt.Printf("Invalid locale name: %q\n", locale)
+				fmt.Fprintf(os.Stdout, "Invalid locale name: %q\n", locale)
 				continue
 			}
 			shortMessage := prompt("Short message:")
@@ -366,7 +366,7 @@ func installApp(cmd *cobra.Command, args []string, appType string) error {
 				}
 				return err
 			}
-			fmt.Printf("Application installed successfully on %s\n", in.Attrs.Domain)
+			fmt.Fprintf(os.Stdout, "Application installed successfully on %s\n", in.Attrs.Domain)
 			return nil
 		})
 	}
@@ -393,7 +393,7 @@ func installApp(cmd *cobra.Command, args []string, appType string) error {
 	if err != nil {
 		return err
 	}
-	fmt.Printf("%s (%s) has been installed on %s\n", slug, manifest.Attrs.Version, flagDomain)
+	fmt.Fprintf(os.Stdout, "%s (%s) has been installed on %s\n", slug, manifest.Attrs.Version, flagDomain)
 
 	return nil
 }
@@ -420,7 +420,7 @@ func updateApp(cmd *cobra.Command, args []string, appType string) error {
 				}
 				return err
 			}
-			fmt.Printf("Application updated successfully on %s\n", in.Attrs.Domain)
+			fmt.Fprintf(os.Stdout, "Application updated successfully on %s\n", in.Attrs.Domain)
 			return nil
 		})
 	}
@@ -457,7 +457,7 @@ func updateApp(cmd *cobra.Command, args []string, appType string) error {
 	} else if app.IsMoreRecent(newManifest.Attrs.Version, manifest.Attrs.Version) {
 		msg = "%s has been downgraded to %s\n"
 	}
-	fmt.Printf(msg, args[0], newManifest.Attrs.Version)
+	fmt.Fprintf(os.Stdout, msg, args[0], newManifest.Attrs.Version)
 
 	return nil
 }
@@ -478,7 +478,7 @@ func uninstallApp(cmd *cobra.Command, args []string, appType string) error {
 	if err != nil {
 		return err
 	}
-	fmt.Printf("%s has been uninstalled\n", manifest.Attrs.Slug)
+	fmt.Fprintf(os.Stdout, "%s has been uninstalled\n", manifest.Attrs.Slug)
 	return nil
 }
 
@@ -525,7 +525,7 @@ func showWebAppTriggers(cmd *cobra.Command, args []string, appType string) error
 
 	var triggerIDs []string
 	if manifest.Attrs.Services == nil {
-		fmt.Printf("No triggers\n")
+		fmt.Fprintf(os.Stdout, "No triggers\n")
 		return nil
 	}
 	for _, service := range *manifest.Attrs.Services {

cmd/check.go

@@ -127,7 +127,7 @@ triggers of the same type, for the same worker, and with the same arguments.
 		if len(result) > 0 {
 			for _, r := range result {
 				j, _ := json.Marshal(r)
-				fmt.Printf("%s\n", j)
+				fmt.Fprintf(os.Stdout, "%s\n", j)
 			}
 			os.Exit(1)
 		}
@@ -167,7 +167,7 @@ generation smaller than their generation.
 		if len(result) > 0 {
 			for _, r := range result {
 				j, _ := json.Marshal(r)
-				fmt.Printf("%s\n", j)
+				fmt.Fprintf(os.Stdout, "%s\n", j)
 			}
 			os.Exit(1)
 		}
@@ -220,7 +220,7 @@ check via the flags.
 		if len(result) > 0 {
 			for _, r := range result {
 				j, _ := json.Marshal(r)
-				fmt.Printf("%s\n", j)
+				fmt.Fprintf(os.Stdout, "%s\n", j)
 			}
 			os.Exit(1)
 		}

cmd/config.go

@@ -170,7 +170,7 @@ $ bmFjbNFjY+XZkS26YtVPUIKKm/JdnAGwG30n6A4ypS1p1dHev8hOtaRbW+lGneoO7PS9JCW8U5GSXh
 			return err
 		}
 		data := base64.StdEncoding.EncodeToString(dataEncrypted)
-		fmt.Printf("%s\n", data)
+		fmt.Fprintf(os.Stdout, "%s\n", data)
 
 		return nil
 	},
@@ -198,7 +198,7 @@ var decryptCredentialsDataCmd = &cobra.Command{
 			return err
 		}
 
-		fmt.Printf("%s\n", decrypted)
+		fmt.Fprintf(os.Stdout, "%s\n", decrypted)
 
 		return nil
 	},
@@ -222,7 +222,7 @@ var encryptCredentialsCmd = &cobra.Command{
 		if err != nil {
 			return err
 		}
-		fmt.Printf("Encrypted credentials: %s\n", encryptedCreds)
+		fmt.Fprintf(os.Stdout, "Encrypted credentials: %s\n", encryptedCreds)
 		return nil
 	},
 }
@@ -251,10 +251,11 @@ var decryptCredentialsCmd = &cobra.Command{
 			return fmt.Errorf("Could not decrypt cipher text: %s", err)
 		}
 
-		fmt.Printf(`Decrypted credentials:
+		fmt.Fprintf(os.Stdout, `Decrypted credentials:
 login:    %q
 password: %q
 `, login, password)
+
 		return nil
 	},
 }

cmd/feature.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"net/url"
+	"os"
 	"strings"
 
 	"github.com/cozy/cozy-stack/client/request"
@@ -58,14 +59,14 @@ cozy-stack feature show displays the feature flags that are shown by apps.
 			return err
 		}
 		for k, v := range obj.Data.Attributes {
-			fmt.Printf("- %s: %s\n", k, string(v))
+			fmt.Fprintf(os.Stdout, "- %s: %s\n", k, string(v))
 		}
 		if len(obj.Included) > 0 {
-			fmt.Printf("\nSources:\n")
+			fmt.Fprintf(os.Stdout, "\nSources:\n")
 			for _, source := range obj.Included {
-				fmt.Printf("- %s\n", source.ID)
+				fmt.Fprintf(os.Stdout, "- %s\n", source.ID)
 				for k, v := range source.Attributes {
-					fmt.Printf("\t- %s: %s\n", k, string(v))
+					fmt.Fprintf(os.Stdout, "\t- %s: %s\n", k, string(v))
 				}
 			}
 		}
@@ -109,7 +110,7 @@ If you give a null value, the flag will be removed.
 			return err
 		}
 		for k, v := range obj {
-			fmt.Printf("- %s: %s\n", k, string(v))
+			fmt.Fprintf(os.Stdout, "- %s: %s\n", k, string(v))
 		}
 		return nil
 	},
@@ -159,7 +160,7 @@ All the sets can be removed by setting an empty list ('').
 			return err
 		}
 		for _, set := range sets {
-			fmt.Printf("- %v\n", set)
+			fmt.Fprintf(os.Stdout, "- %v\n", set)
 		}
 		return nil
 	},
@@ -200,7 +201,7 @@ To remove a flag, set it to an empty array (or null).
 			return err
 		}
 		for k, v := range obj {
-			fmt.Printf("- %s: %s\n", k, string(v))
+			fmt.Fprintf(os.Stdout, "- %s: %s\n", k, string(v))
 		}
 		return nil
 	},
@@ -234,7 +235,7 @@ These flags are read only and can only be updated by changing configuration and
 			return err
 		}
 		for k, v := range obj {
-			fmt.Printf("- %s: %s\n", k, string(v))
+			fmt.Fprintf(os.Stdout, "- %s: %s\n", k, string(v))
 		}
 		return nil
 	},
@@ -271,7 +272,7 @@ If you give a null value, the flag will be removed.
 			return err
 		}
 		for k, v := range obj {
-			fmt.Printf("- %s: %s\n", k, string(v))
+			fmt.Fprintf(os.Stdout, "- %s: %s\n", k, string(v))
 		}
 		return nil
 	},

cmd/files.go

@@ -121,29 +121,29 @@ var usageFilesCmd = &cobra.Command{
 		if err != nil {
 			return err
 		}
-		fmt.Printf("Usage: %v\n", info["used"])
+		fmt.Fprintf(os.Stdout, "Usage: %v\n", info["used"])
 
 		if files, ok := info["files"]; ok {
-			fmt.Printf("  Including latest version of files: %v\n", files)
+			fmt.Fprintf(os.Stdout, "  Including latest version of files: %v\n", files)
 		}
 		if versions, ok := info["versions"]; ok {
-			fmt.Printf("  Including older versions of files: %v\n", versions)
+			fmt.Fprintf(os.Stdout, "  Including older versions of files: %v\n", versions)
 		}
 
 		if flagIncludeTrash {
 			if trashed, ok := info["trashed"]; ok {
-				fmt.Printf("  Including trashed files: %v\n", trashed)
+				fmt.Fprintf(os.Stdout, "  Including trashed files: %v\n", trashed)
 			}
 		}
 
 		if quota, ok := info["quota"]; ok {
-			fmt.Printf("Quota: %v\n", quota)
+			fmt.Fprintf(os.Stdout, "Quota: %v\n", quota)
 		}
 		if count, ok := info["doc_count"]; ok {
-			fmt.Printf("Documents count: %v\n", count)
+			fmt.Fprintf(os.Stdout, "Documents count: %v\n", count)
 		}
 		if count, ok := info["versions_count"]; ok {
-			fmt.Printf("Versions Documents count: %v\n", count)
+			fmt.Fprintf(os.Stdout, "Versions Documents count: %v\n", count)
 		}
 		return nil
 	},
@@ -338,7 +338,7 @@ func treeCmd(c *client.Client, root string, w io.Writer, verbose bool) error {
 			return err
 		}
 		if verbose {
-			fmt.Printf("%s ", doc.ID)
+			fmt.Fprintf(os.Stdout, "%s ", doc.ID)
 		}
 
 		attrs := doc.Attrs
@@ -461,11 +461,11 @@ func importFiles(c *client.Client, from, to string, match *regexp.Regexp) error
 		return err
 	}
 	if !fromInfos.IsDir() {
-		fmt.Printf("Importing file %s to cozy://%s\n", from, to)
+		fmt.Fprintf(os.Stdout, "Importing file %s to cozy://%s\n", from, to)
 		return i.upload(from, to)
 	}
 
-	fmt.Printf("Importing from %s to cozy://%s\n", from, to)
+	fmt.Fprintf(os.Stdout, "Importing from %s to cozy://%s\n", from, to)
 
 	return filepath.Walk(from, func(localname string, f os.FileInfo, err error) error {
 		if err != nil {
@@ -485,14 +485,14 @@ func importFiles(c *client.Client, from, to string, match *regexp.Regexp) error
 
 		distname := path.Join(to, strings.TrimPrefix(localname, from))
 		if f.IsDir() {
-			fmt.Printf("create dir %s\n", distname)
+			fmt.Fprintf(os.Stdout, "create dir %s\n", distname)
 			if !flagImportDryRun {
 				if _, err = i.mkdir(distname); err != nil {
 					return err
 				}
 			}
 		} else {
-			fmt.Printf("copying file %s to %s\n", localname, distname)
+			fmt.Fprintf(os.Stdout, "copying file %s to %s\n", localname, distname)
 			if !flagImportDryRun {
 				return i.upload(localname, distname)
 			}

cmd/fix.go

@@ -55,7 +55,7 @@ var mimeFixerCmd = &cobra.Command{
 			if class == attrs.Class {
 				return nil
 			}
-			fmt.Printf("Fix %s: %s -> %s\n", attrs.Name, attrs.Class, class)
+			fmt.Fprintf(os.Stdout, "Fix %s: %s -> %s\n", attrs.Name, attrs.Class, class)
 			_, err = c.UpdateAttrsByID(doc.ID, &client.FilePatch{
 				Rev: doc.Rev,
 				Attrs: client.FilePatchAttrs{
@@ -91,7 +91,7 @@ var jobsFixer = &cobra.Command{
 			return err
 		}
 
-		fmt.Printf("Cleaned %d jobs on %s\n", result.Deleted, args[0])
+		fmt.Fprintf(os.Stdout, "Cleaned %d jobs on %s\n", result.Deleted, args[0])
 		return nil
 	},
 }
@@ -227,11 +227,11 @@ var contactEmailsFixer = &cobra.Command{
 						address = strings.TrimSpace(address)
 						_, err := mail.ParseAddress(address)
 						if err == nil {
-							fmt.Printf("    Email fixed: \"%s\" → \"%s\"\n", old, address)
+							fmt.Fprintf(os.Stdout, "    Email fixed: \"%s\" → \"%s\"\n", old, address)
 							changed = true
 							email["address"] = address
 						} else {
-							fmt.Printf("    Invalid email: \"%s\" → \"%s\"\n", old, address)
+							fmt.Fprintf(os.Stdout, "    Invalid email: \"%s\" → \"%s\"\n", old, address)
 						}
 					}
 				}