mu: support MUHOME environment variable

NEWS.org

@@ -53,6 +53,9 @@
      much of this is not immediately visible but is an enabler for some new
      features.
 
+   - instead of passing ~--muhome~, you can now also set an environment variable
+ ~MUHOME~.
+
    - the ~info~ command now includes information about the last indexing operation
      and the last database change that took place; note that the information may
      be slightly delayed due to database caching.

man/mu-init.1

@@ -1,4 +1,4 @@
-.TH MU-INIT 1 "January 2022" "User Manuals"
+.TH MU-INIT 1 "May 2022" "User Manuals"
 
 .SH NAME
 
@@ -23,8 +23,12 @@ man-page and not here, as they apply to multiple mu commands.
 \fB\-\-muhome\fR
 use an alternative directory to store and read the database, write the logs,
 etc. By default, \fBmu\fR uses XDG Base Directory Specification (e.g. on Linux
-this defaults to \fI~/.cache/mu\fR, \fI~/.config/mu\fR). Earlier versions of
+this defaults to \fI~/.cache/mu\fR, \fI~/.config/mu\fR).
-\fBmu\fR defaulted to \fI~/.mu\fR, which now requires \fI\-\-muhome=~/.mu\fR.
+
+Earlier versions of \fBmu\fR defaulted to \fI~/.mu\fR, which now requires
+\fI\-\-muhome=~/.mu\fR.
+
+Alternatively, use can use the \fBMUHOME\fR environment variable (the command-line takes precedence).
 
 .TP
 \fB\-m\fR, \fB\-\-maildir\fR=\fI<maildir>\fR
@@ -52,6 +56,8 @@ shell program, the argument may need to b quoted.
 specified explicitly with \fB\-\-maildir\fR=\fI<maildir>\fR. If \fBMAILDIR\fR is
 not set, \fBmu init\fR uses \fI~/Maildir\fR.
 
+\fBMUHOME\fR can be used as an alternative to \fB\-\-muhome\fR.
+
 .SH RETURN VALUE
 
 \fBmu init\fR returns 0 upon successful completion, or a non-zero exit code if

man/mu.1

@@ -1,4 +1,4 @@
-.TH MU 1 "February 2021" "User Manuals"
+.TH MU 1 "May 2022" "User Manuals"
 
 .SH NAME
 
@@ -162,6 +162,12 @@ prints \fBmu\fR version and copyright information.
 \fB\-h\fR, \fB\-\-help\fR
 lists the various command line options.
 
+.SH ENVIRONMENT
+
+\fBMUHOME\fR can be used as an alternative to \fB\-\-muhome\fR. The latter has precedence.
+
+\fBNO_COLOR\fR can be used as an alternative to \fB\-\-nocolor\fR.
+
 .SH ERROR CODES
 
 The various mu subcommands typically exit with 0 (zero) upon success, and

mu/mu-config.cc

@@ -75,8 +75,17 @@ get_output_format(const char* formatstr)
 static void
 set_group_mu_defaults()
 {
-	/* If muhome is not set, we use the XDG Base Directory Specification
+	/* try to determine muhome from command-line or environment;
-	 * locations. */
+	 * note: if not specified, we use XDG defaults */
+
+	if (!MU_CONFIG.muhome) {
+		/* if not set explicity, try the environment */
+		const char* muhome;
+		muhome = g_getenv("MUHOME");
+		if (muhome)
+			MU_CONFIG.muhome = g_strdup(muhome);
+	}
+
 	if (MU_CONFIG.muhome)
 		expand_dir(MU_CONFIG.muhome);
 

mu/tests/test-mu-query.cc

@@ -45,14 +45,16 @@ static std::string
 make_database(const std::string& testdir)
 {
 	char*      tmpdir{test_mu_common_get_random_tmpdir()};
+
+	/* use the env var rather than `--muhome` */
+
+	g_setenv("MUHOME", tmpdir, 1);
 	const auto cmdline{format("/bin/sh -c '"
-				  "%s init  --muhome=%s --maildir=%s --quiet ; "
+				  "%s init --maildir=%s --quiet ; "
-				  "%s index --muhome=%s  --quiet'",
+				  "%s index --quiet'",
 				  MU_PROGRAM,
-				  tmpdir,
 				  testdir.c_str(),
-				  MU_PROGRAM,
+				  MU_PROGRAM)};
-				  tmpdir)};
 
 	if (g_test_verbose())
 		g_printerr("\n%s\n", cmdline.c_str());
@@ -61,6 +63,9 @@ make_database(const std::string& testdir)
 	auto xpath = g_strdup_printf("%s%c%s", tmpdir, G_DIR_SEPARATOR, "xapian");
 	g_free(tmpdir);
 
+	/* ensure MUHOME worked */
+	g_assert_cmpuint(::access(xpath, F_OK), ==, 0);
+
 	std::string dbpath{xpath};
 	g_free(xpath);
 

mu4e/mu4e.texi

@@ -401,9 +401,10 @@ different file-systems; and symbolic links are supported.
 @section Initializing the message store
 
 The first time you run @t{mu}, you need to initialize its store
-(database). The default location for that is @t{~/.cache/mu/xapian},
+(database). The default location for that is @t{~/.cache/mu/xapian}, but
-but you can change this using the @t{--muhome} option, and remember to
+you can change this using the @t{--muhome} option, and remember to pass
-pass that to the other commands as well.
+that to the other commands as well. Alternatively, you can use an
+environment variable @t{MUHOME}.
 
 Assuming that your maildir is at @file{~/Maildir}, we issue the
 following command:
@@ -428,7 +429,8 @@ slashes, for example:
   $ mu init --maildir=~/Maildir '--my-address=/foo-.*@@example\.com/'
 @end example
 
-If you want to see the current values, you can use @command{mu info}.
+If you want to see the values for your message-store, you can use
+@command{mu info}.
 
 @node Indexing your messages
 @section Indexing your messages