main: add flags to override config files

Add --aerc-conf, --binds-conf and --accounts-conf CLI flags, which
respectively override the default aerc.conf, binds.conf and
accounts.conf configuration files. If the specified files do not exist
or cannot be read, exit with an error.

Implements: https://todo.sr.ht/~rjarry/aerc/209
Changelog-added: CLI flags to override paths to config files.
Signed-off-by: Bence Ferdinandy <bence@ferdinandy.com>
Acked-by: Robin Jarry <robin@jarry.cc>

8 files changed, 62 insertions, 32 deletions

diff --git a/config/accounts.go b/config/accounts.go
index dbc0cdb4..413b77b1 100644
--- a/config/accounts.go
+++ b/config/accounts.go
@@ -119,14 +119,16 @@ const (
 
 var Accounts []*AccountConfig
 
-func parseAccounts(root string, accts []string) error {
-	filename := path.Join(root, "accounts.conf")
-	err := checkConfigPerms(filename)
-	if errors.Is(err, os.ErrNotExist) {
-		// No config triggers account configuration wizard
-		return nil
-	} else if err != nil {
-		return err
+func parseAccounts(root string, accts []string, filename string) error {
+	if filename == "" {
+		filename = path.Join(root, "accounts.conf")
+		err := checkConfigPerms(filename)
+		if errors.Is(err, os.ErrNotExist) {
+			// No config triggers account configuration wizard
+			return nil
+		} else if err != nil {
+			return err
+		}
 	}
 
 	log.Debugf("Parsing accounts configuration from %s", filename)
diff --git a/config/binds.go b/config/binds.go
index 8eda890d..bedc6d9a 100644
--- a/config/binds.go
+++ b/config/binds.go
@@ -101,12 +101,14 @@ func defaultBindsConfig() *BindingConfig {
 
 var Binds = defaultBindsConfig()
 
-func parseBinds(root string) error {
-	filename := path.Join(root, "binds.conf")
-	if _, err := os.Stat(filename); errors.Is(err, os.ErrNotExist) {
-		fmt.Printf("%s not found, installing the system default\n", filename)
-		if err := installTemplate(root, "binds.conf"); err != nil {
-			return err
+func parseBinds(root string, filename string) error {
+	if filename == "" {
+		filename = path.Join(root, "binds.conf")
+		if _, err := os.Stat(filename); errors.Is(err, os.ErrNotExist) {
+			fmt.Printf("%s not found, installing the system default\n", filename)
+			if err := installTemplate(root, "binds.conf"); err != nil {
+				return err
+			}
 		}
 	}
 	log.Debugf("Parsing key bindings configuration from %s", filename)
diff --git a/config/config.go b/config/config.go
index 092b73a6..1efbf896 100644
--- a/config/config.go
+++ b/config/config.go
@@ -77,18 +77,21 @@ func installTemplate(root, name string) error {
 	return nil
 }
 
-func LoadConfigFromFile(root *string, accts []string) error {
+func LoadConfigFromFile(
+	root *string, accts []string, filename, bindPath, acctPath string,
+) error {
 	if root == nil {
 		_root := xdg.ConfigPath("aerc")
 		root = &_root
 	}
-	filename := path.Join(*root, "aerc.conf")
-
-	// if it doesn't exist copy over the template, then load
-	if _, err := os.Stat(filename); errors.Is(err, os.ErrNotExist) {
-		fmt.Printf("%s not found, installing the system default\n", filename)
-		if err := installTemplate(*root, "aerc.conf"); err != nil {
-			return err
+	if filename == "" {
+		filename = path.Join(*root, "aerc.conf")
+		// if it doesn't exist copy over the template, then load
+		if _, err := os.Stat(filename); errors.Is(err, os.ErrNotExist) {
+			fmt.Printf("%s not found, installing the system default\n", filename)
+			if err := installTemplate(*root, "aerc.conf"); err != nil {
+				return err
+			}
 		}
 	}
 
@@ -129,10 +132,10 @@ func LoadConfigFromFile(root *string, accts []string) error {
 	if err := parseTemplates(file); err != nil {
 		return err
 	}
-	if err := parseAccounts(*root, accts); err != nil {
+	if err := parseAccounts(*root, accts, acctPath); err != nil {
 		return err
 	}
-	if err := parseBinds(*root); err != nil {
+	if err := parseBinds(*root, bindPath); err != nil {
 		return err
 	}
 
diff --git a/doc/aerc-accounts.5.scd b/doc/aerc-accounts.5.scd
index 9d95af32..5f89033a 100644
--- a/doc/aerc-accounts.5.scd
+++ b/doc/aerc-accounts.5.scd
@@ -9,7 +9,8 @@ aerc-accounts - account configuration file format for *aerc*(1)
 The _accounts.conf_ file is  used for configuring each mail account used for
 aerc. It is expected to be in your XDG config home plus _aerc_, which defaults
 to _~/.config/aerc/accounts.conf_. This file must be kept secret, as it may
-include your account credentials.
+include your account credentials. An alternate file can be specified via the
+_--accounts-conf_ command line argument, see *aerc*(1).
 
 If _accounts.conf_ does not exist, the *:new-account* configuration wizard will
 be executed automatically on first startup.
diff --git a/doc/aerc-binds.5.scd b/doc/aerc-binds.5.scd
index f9cdd668..b00c12d8 100644
--- a/doc/aerc-binds.5.scd
+++ b/doc/aerc-binds.5.scd
@@ -9,7 +9,8 @@ aerc-binds - key bindings configuration file format for *aerc*(1)
 The _binds.conf_ file is used for configuring keybindings used in the aerc
 interactive client. It is expected to be in your XDG config home plus _aerc_,
 which defaults to _~/.config/aerc/binds.conf_. If the file does not exist, the
-built-in default will be installed.
+built-in default will be installed. An alternate file can be specified via the
+_--binds-conf_ command line argument, see *aerc*(1).
 
 This file is written in the ini format with key bindings defined as:
 
diff --git a/doc/aerc-config.5.scd b/doc/aerc-config.5.scd
index 5acb9427..f3d45085 100644
--- a/doc/aerc-config.5.scd
+++ b/doc/aerc-config.5.scd
@@ -9,7 +9,8 @@ aerc-config - configuration file format for *aerc*(1)
 There are three aerc config files: _aerc.conf_, _binds.conf_, and
 _accounts.conf_. The last one must be kept secret, as it may include your
 account credentials. We look for these files in your XDG config home plus
-_aerc_, which defaults to _~/.config/aerc_.
+_aerc_, which defaults to _~/.config/aerc_. Alternate files can be specified via
+command line arguments, see *aerc*(1).
 
 Examples of these config files are typically included with your installation of
 aerc and are usually installed in _/usr/share/aerc_.
diff --git a/doc/aerc.1.scd b/doc/aerc.1.scd
index ee5b27c5..5be01751 100644
--- a/doc/aerc.1.scd
+++ b/doc/aerc.1.scd
@@ -24,6 +24,18 @@ from your terminal.
 	can also be a comma separated list of names. This option may be
 	specified multiple times. The account order will be preserved.
 
+*--aerc-conf* _</path/to/aerc.conf>_
+	Instead of using _$XDG_CONFIG_HOME/aerc/aerc.conf_ use the file at the
+	specified path for configuring aerc.
+
+*--accounts-conf* _</path/to/accounts.conf>_
+	Instead of using _$XDG_CONFIG_HOME/aerc/accounts.conf_ use the file at the
+	specified path for configuring accounts.
+
+*--binds-conf* _</path/to/binds.conf>_
+	Instead of using _$XDG_CONFIG_HOME/aerc/binds.conf_ use the file at the
+	specified path for configuring binds.
+
 *mailto:*_address[,address][?query[&query]]_
 	Open the composer with the address(es) in the To field. These
 	addresses must not be percent encoded.
diff --git a/main.go b/main.go
index ad926a63..06178d2d 100644
--- a/main.go
+++ b/main.go
@@ -119,10 +119,13 @@ func setWindowTitle() {
 }
 
 type Opts struct {
-	Help     bool     `opt:"-h" action:"ShowHelp"`
-	Version  bool     `opt:"-v" action:"ShowVersion"`
-	Accounts []string `opt:"-a" action:"ParseAccounts" metavar:"<account>"`
-	Command  []string `opt:"..." required:"false" metavar:"mailto:<address> | mbox:<file> | :<command...>"`
+	Help         bool     `opt:"-h" action:"ShowHelp"`
+	Version      bool     `opt:"-v" action:"ShowVersion"`
+	Accounts     []string `opt:"-a" action:"ParseAccounts" metavar:"<account>"`
+	ConfAerc     string   `opt:"--aerc-conf"`
+	ConfAccounts string   `opt:"--accounts-conf"`
+	ConfBinds    string   `opt:"--binds-conf"`
+	Command      []string `opt:"..." required:"false" metavar:"mailto:<address> | mbox:<file> | :<command...>"`
 }
 
 func (o *Opts) ShowHelp(arg string) error {
@@ -138,6 +141,9 @@ Options:
                      accounts. It can also be a comma separated list of names.
                      This option may be specified multiple times. The account
                      order will be preserved.
+  --aerc-conf        Path to configuration file to be used instead of the default.
+  --accounts-conf    Path to configuration file to be used instead of the default.
+  --binds-conf       Path to configuration file to be used instead of the default.
   mailto:<address>   Open the composer with the address(es) in the To field.
                      If aerc is already running, the composer is started in
                      this instance, otherwise aerc will be started.
@@ -186,7 +192,9 @@ func main() {
 		retryExec = true
 	}
 
-	err = config.LoadConfigFromFile(nil, opts.Accounts)
+	err = config.LoadConfigFromFile(
+		nil, opts.Accounts, opts.ConfAerc, opts.ConfBinds, opts.ConfAccounts,
+	)
 	if err != nil {
 		die("failed to load config: %s", err)
 	}