Added program options to control file/directory placement

Running ipp-usb in a container—such as a Snap or OCI container—may result
in a non-standard filesystem layout (see #108 for details).

To simplify using ipp-usb in such environments, the following command-line
options have been added:

   -path-conf-files-srch dir1[:dir2...]
       List of directories where configuration files (ipp-usb.conf)
       are searched (/etc/ipp-usb)

   -path-log-dir dir
       Path to the directory where log files (main.log and per-device
       <DEVICE>.log) are written (/var/log/ipp-usb)

   -path-lock-file file
       Path to the program's lock file (/var/ipp-usb/lock/ipp-usb.lock)

   -path-dev-state-dir dir
       Path to the directory where per-device state files are written
       (/var/ipp-usb/dev)

   -path-ctrl-sock file
       Path to the program's control socket
       (/var/ipp-usb/ctrl)

   -path-quirks-files-srch dir1[:dir2...]
       List of directories where quirks files (*.conf) is searched
       (/etc/ipp-usb/quirks:/usr/share/ipp-usb/quirks)

The manual page was updated appropriately.

Author: alexpevzner

conf.go

@@ -60,9 +60,9 @@ var Conf = Configuration{
 // ConfLoad loads the program configuration
 func ConfLoad() error {
 	// Build list of configuration files
-	files := []string{
-		filepath.Join(PathConfDir, ConfFileName),
-		filepath.Join(PathExecutableDir, ConfFileName),
+	files := filepath.SplitList(PathConfDirList)
+	for i := range files {
+		files[i] = filepath.Join(files[i], ConfFileName)
 	}
 
 	// Load file by file
@@ -74,11 +74,7 @@ func ConfLoad() error {
 	}
 
 	// Load quirks
-	quirksDirs := []string{
-		PathLocalQuirksDir,
-		PathGlobalQuirksDir,
-		filepath.Join(PathExecutableDir, "ipp-usb-quirks"),
-	}
+	quirksDirs := filepath.SplitList(PathQuirksDirList)
 
 	var err error
 	Conf.Quirks, err = LoadQuirksSet(quirksDirs...)

ipp-usb.8

@@ -29,9 +29,35 @@ check configuration and exit\. It also prints a list of all connected devices
 \fBstatus\fR
 print status of the running \fBipp\-usb\fR daemon, including information of all connected devices
 .SS "Options are"
-.TP
+.IP "\(bu" 4
 \fB\-bg\fR
+.br
 run in background (ignored in debug mode)
+.IP "\(bu" 4
+\fB\-path\-conf\-files\-srch dir1[:dir2\|\.\|\.\|\.]\fR
+.br
+List of directories where configuration files (ipp\-usb\.conf) are searched (/etc/ipp\-usb)
+.IP "\(bu" 4
+\fB\-path\-log\-dir dir\fR
+.br
+Path to the directory where log files (main\.log and per\-device \fIDEVICE\fR\.log) are written (/var/log/ipp\-usb)
+.IP "\(bu" 4
+\fB\-path\-lock\-file file\fR
+.br
+Path to the program's lock file (/var/ipp\-usb/lock/ipp\-usb\.lock)
+.IP "\(bu" 4
+\fB\-path\-dev\-state\-dir dir\fR
+.br
+Path to the directory where per\-device state files are written (/var/ipp\-usb/dev)
+.IP "\(bu" 4
+\fB\-path\-ctrl\-sock file\fR
+.br
+Path to the program's control socket (/var/ipp\-usb/ctrl)
+.IP "\(bu" 4
+\fB\-path\-quirks\-files\-srch dir1[:dir2\|\.\|\.\|\.]\fR
+.br
+List of directories where quirks files (*\.conf) is searched (/etc/ipp\-usb/quirks:/usr/share/ipp\-usb/quirks)
+.IP "" 0
 .SH "NETWORKING"
 Essentially, \fBipp\-usb\fR makes printer or scanner accessible from the network, converting network\-side HTTP operations to the USB operations\.
 .P

ipp-usb.8.md

@@ -41,9 +41,32 @@ IPP printing, eSCL scanning and web console are fully supported.
 
 ### Options are
 
-   * `-bg`:
+   * `-bg`<br>
      run in background (ignored in debug mode)
 
+   * `-path-conf-files-srch dir1[:dir2...]`<br>
+     List of directories where configuration files (ipp-usb.conf)
+     are searched (/etc/ipp-usb)
+
+   * `-path-log-dir dir`<br>
+      Path to the directory where log files (main.log and per-device
+      <DEVICE>.log) are written (/var/log/ipp-usb)
+
+   * `-path-lock-file file`<br>
+     Path to the program's lock file (/var/ipp-usb/lock/ipp-usb.lock)
+
+   * `-path-dev-state-dir dir`<br>
+     Path to the directory where per-device state files are written
+     (/var/ipp-usb/dev)
+
+   * `-path-ctrl-sock file`<br>
+     Path to the program's control socket
+     (/var/ipp-usb/ctrl)
+
+   * `-path-quirks-files-srch dir1[:dir2...]`<br>
+     List of directories where quirks files (\*.conf) is searched
+     (/etc/ipp-usb/quirks:/usr/share/ipp-usb/quirks)
+
 ## NETWORKING
 
 Essentially, `ipp-usb` makes printer or scanner accessible from the

logger.go

@@ -171,12 +171,12 @@ func (l *Logger) ToFile(path string) *Logger {
 
 // ToMainFile redirects log to the main log file
 func (l *Logger) ToMainFile() *Logger {
-	return l.ToFile(PathMainLogFile)
+	return l.ToFile(filepath.Join(PathLogDir, "main.log"))
 }
 
 // ToDevFile redirects log to per-device log file
 func (l *Logger) ToDevFile(info UsbDeviceInfo) *Logger {
-	return l.ToFile(filepath.Join(PathDevLogDir, info.Ident()+".log"))
+	return l.ToFile(filepath.Join(PathLogDir, info.Ident()+".log"))
 }
 
 // HasDestination reports if Logger destination is already

main.go

@@ -30,6 +30,29 @@ Modes are:
 
 Options are
     -bg         - run in background (ignored in debug mode)
+
+    -path-conf-files-srch dir1[:dir2...]
+        List of directories where configuration files (ipp-usb.conf)
+	are searched (%s)
+
+    -path-log-dir dir
+        Path to the directory where log files (main.log and per-device
+	<DEVICE>.log) are written (%s)
+
+    -path-lock-file file
+        Path to the program's lock file (%s)
+
+    -path-dev-state-dir dir
+        Path to the directory where per-device state files are written
+	(%s)
+
+    -path-ctrl-sock file
+        Path to the program's control socket
+	(%s)
+
+    -path-quirks-files-srch dir1[:dir2...]
+        List of directories where quirks files (*.conf) is searched
+	(%s)
 `
 
 // RunMode represents the program run mode
@@ -81,7 +104,15 @@ type RunParameters struct {
 
 // usage prints detailed usage and exits
 func usage() {
-	fmt.Printf(usageText, os.Args[0])
+	fmt.Printf(usageText,
+		os.Args[0],
+		PathConfDirList,
+		PathLogDir,
+		PathLockFile,
+		PathDevStateDir,
+		PathControlSocket,
+		PathQuirksDirList,
+	)
 	os.Exit(0)
 }
 
@@ -110,7 +141,10 @@ func parseArgv() (params RunParameters) {
 	params.Mode = RunDebug
 
 	modes := 0
-	for _, arg := range os.Args[1:] {
+	for i := 1; i < len(os.Args); i++ {
+		arg := os.Args[i]
+		var optarg *string
+
 		switch arg {
 		case "-h", "-help", "--help":
 			usage()
@@ -131,9 +165,38 @@ func parseArgv() (params RunParameters) {
 			modes++
 		case "-bg":
 			params.Background = true
+
+		case "-path-log-dir":
+			optarg = &PathLogDir
+
+		case "-path-lock-file":
+			optarg = &PathLockFile
+
+		case "-path-dev-state-dir":
+			optarg = &PathDevStateDir
+
+		case "-path-conf-files-srch":
+			optarg = &PathConfDirList
+
+		case "-path-ctrl-sock":
+			optarg = &PathControlSocket
+
+		case "-path-quirks-files-srch":
+			optarg = &PathQuirksDirList
+
 		default:
 			usageError("Invalid argument %s", arg)
 		}
+
+		if optarg != nil {
+			if i+1 == len(os.Args) {
+				usageError(
+					"Option requires an argument: %s", arg)
+			}
+
+			i++
+			*optarg = os.Args[i]
+		}
 	}
 
 	if modes > 1 {

paths.go

@@ -12,30 +12,19 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"strings"
 )
 
 // Effective paths, may be altered with the command-line options:
 var (
-	// Configuration directory
-	PathConfDir = DefaultPathConfDir
-
 	// Control socket
 	PathControlSocket = DefaultPathControlSocket
 
-	// Global (installed) quirks files
-	PathGlobalQuirksDir = DefaultPathGlobalQuirksDir
-
-	// Local (admin-defined) quirks files
-	PathLocalQuirksDir = DefaultPathLocalQuirksDir
-
 	// Lock file
 	PathLockFile = DefaultPathLockFile
 
 	// Directory for per-device logs
-	PathDevLogDir = DefaultPathLogDir
-
-	// Main log file
-	PathMainLogFile = DefaultPathMainLogFile
+	PathLogDir = DefaultPathLogDir
 
 	// Directory that contains per-device state files
 	PathDevStateDir = DefaultPathDevStateDir
@@ -47,6 +36,18 @@ var (
 	// Path to the directory that contains the executable file.
 	// Initialized by PathInit()
 	PathExecutableDir string
+
+	// List of configuration directories.
+	// Initialized by PathInit():
+	//   DefaultPathConfDir + ":" + PathExecutableDir
+	PathConfDirList string
+
+	// List of quirks directories.
+	// Initialized by PathInit():
+	//   DefaultPathLocalQuirksDir + ":" +
+	//   DefaultPathGlobalQuirksDir + ":" +
+	//   filepath.Join(PathExecutableDir, "ipp-usb-quirks")
+	PathQuirksDirList string
 )
 
 // Default paths:
@@ -81,9 +82,6 @@ const (
 
 	// DefaultPathLogDir defines path to log directory
 	DefaultPathLogDir = "/var/log/ipp-usb"
-
-	// DefaultPathMainLogFile defines path to the main log file
-	DefaultPathMainLogFile = DefaultPathLogDir + "/main.log"
 )
 
 // PathsInit initializes paths handling.
@@ -99,6 +97,27 @@ func PathsInit() error {
 
 	PathExecutableDir = filepath.Dir(PathExecutableFile)
 
+	// Initialize derived paths
+	PathConfDirList =
+		strings.Join(
+			[]string{
+				DefaultPathConfDir,
+				PathExecutableDir,
+			},
+			string(filepath.ListSeparator),
+		)
+
+	PathQuirksDirList =
+		strings.Join(
+			[]string{
+				DefaultPathLocalQuirksDir,
+				DefaultPathGlobalQuirksDir,
+				filepath.Join(PathExecutableDir,
+					"ipp-usb-quirks"),
+			},
+			string(filepath.ListSeparator),
+		)
+
 	return nil
 }