system: move system access packages

These packages loosely belong in the "system" package and "system" provides high level wrappers for all of them.

Signed-off-by: Ophestra <cat@gensokyo.uk>

system/dbus/config.go

@@ -0,0 +1,162 @@
+package dbus
+
+import (
+	"encoding/json"
+	"errors"
+	"io"
+	"os"
+	"strings"
+)
+
+// ProxyPair is an upstream dbus address and a downstream socket path.
+type ProxyPair [2]string
+
+type Config struct {
+	// See set 'see' policy for NAME (--see=NAME)
+	See []string `json:"see"`
+	// Talk set 'talk' policy for NAME (--talk=NAME)
+	Talk []string `json:"talk"`
+	// Own set 'own' policy for NAME (--own=NAME)
+	Own []string `json:"own"`
+
+	// Call set RULE for calls on NAME (--call=NAME=RULE)
+	Call map[string]string `json:"call"`
+	// Broadcast set RULE for broadcasts from NAME (--broadcast=NAME=RULE)
+	Broadcast map[string]string `json:"broadcast"`
+
+	Log    bool `json:"log,omitempty"`
+	Filter bool `json:"filter"`
+}
+
+func (c *Config) interfaces(yield func(string) bool) {
+	for _, iface := range c.See {
+		if !yield(iface) {
+			return
+		}
+	}
+	for _, iface := range c.Talk {
+		if !yield(iface) {
+			return
+		}
+	}
+	for _, iface := range c.Own {
+		if !yield(iface) {
+			return
+		}
+	}
+
+	for iface := range c.Call {
+		if !yield(iface) {
+			return
+		}
+	}
+	for iface := range c.Broadcast {
+		if !yield(iface) {
+			return
+		}
+	}
+}
+
+func (c *Config) checkInterfaces(segment string) error {
+	for iface := range c.interfaces {
+		/*
+			xdg-dbus-proxy fails without output when this condition is not met:
+				char *dot = strrchr (filter->interface, '.');
+				if (dot != NULL)
+				  {
+				    *dot = 0;
+				    if (strcmp (dot + 1, "*") != 0)
+				      filter->member = g_strdup (dot + 1);
+				  }
+
+			trim ".*" since they are removed before searching for '.':
+				if (g_str_has_suffix (name, ".*"))
+				  {
+				    name[strlen (name) - 2] = 0;
+				    wildcard = TRUE;
+				  }
+		*/
+		if strings.IndexByte(strings.TrimSuffix(iface, ".*"), '.') == -1 {
+			return &BadInterfaceError{iface, segment}
+		}
+	}
+	return nil
+}
+
+func (c *Config) Args(bus ProxyPair) (args []string) {
+	argc := 2 + len(c.See) + len(c.Talk) + len(c.Own) + len(c.Call) + len(c.Broadcast)
+	if c.Log {
+		argc++
+	}
+	if c.Filter {
+		argc++
+	}
+
+	args = make([]string, 0, argc)
+	args = append(args, bus[0], bus[1])
+	if c.Filter {
+		args = append(args, "--filter")
+	}
+	for _, name := range c.See {
+		args = append(args, "--see="+name)
+	}
+	for _, name := range c.Talk {
+		args = append(args, "--talk="+name)
+	}
+	for _, name := range c.Own {
+		args = append(args, "--own="+name)
+	}
+	for name, rule := range c.Call {
+		args = append(args, "--call="+name+"="+rule)
+	}
+	for name, rule := range c.Broadcast {
+		args = append(args, "--broadcast="+name+"="+rule)
+	}
+	if c.Log {
+		args = append(args, "--log")
+	}
+
+	return
+}
+
+func (c *Config) Load(r io.Reader) error { return json.NewDecoder(r).Decode(&c) }
+
+// NewConfigFromFile opens the target config file at path and parses its contents into *Config.
+func NewConfigFromFile(path string) (*Config, error) {
+	if f, err := os.Open(path); err != nil {
+		return nil, err
+	} else {
+		c := new(Config)
+		err1 := c.Load(f)
+		err = f.Close()
+
+		return c, errors.Join(err1, err)
+	}
+}
+
+// NewConfig returns a reference to a Config struct with optional defaults.
+// If id is an empty string own defaults are omitted.
+func NewConfig(id string, defaults, mpris bool) (c *Config) {
+	c = &Config{
+		Call:      make(map[string]string),
+		Broadcast: make(map[string]string),
+
+		Filter: true,
+	}
+
+	if defaults {
+		c.Talk = []string{"org.freedesktop.DBus", "org.freedesktop.Notifications"}
+
+		c.Call["org.freedesktop.portal.*"] = "*"
+		c.Broadcast["org.freedesktop.portal.*"] = "@/org/freedesktop/portal/*"
+
+		if id != "" {
+			c.Own = []string{id + ".*"}
+			if mpris {
+				c.Own = append(c.Own, "org.mpris.MediaPlayer2."+id+".*")
+			}
+		}
+	}
+
+	return
+}