Set rc_dir based on W3M_DIR environment variable.

By default, w3m puts all of its data in the `~/.w3m/` directory
(creating it as necessary). This was not configurable in any way.

This commit adds some quick reconfigurability -- when the "W3M_DIR"
environment variable is set, w3m will use that location instead. The
default location is unchanged.

Fixes #130.

doc/FAQ.html

@@ -725,7 +725,7 @@ from Tatsuya Kinoshita <tats@debian.org>
    </dt>
    <dd>
     <p>
-     It is ~/.w3m/config.
+     By default, it is ~/.w3m/config.
     </p>
 
     <p>
@@ -734,6 +734,12 @@ from Tatsuya Kinoshita <tats@debian.org>
      setting panel. Each line contains one option setting, consisting
      of an option name and its value with a space as a separator.
     </p>
+
+    <p>
+     If the W3M_DIR environment variable is set to the name of a
+     directory, w3m will store its files in that directory instead of
+     in ~/.w3m.
+    </p>
     
     <p>Without a user-specific configuration file, w3m honours
     the system wide configuration file /etc/w3m/config.

doc/MANUAL.html

@@ -91,6 +91,11 @@ insertions tagged with "mh 2016-03-29" and "mh 2016-06-11" come from the latest
    from standard input and display it. If it doesn't find a document
    there either then normally w3m will terminate.
   </p>
+  <p>
+   You can change how w3m behaves by providing it with options, either
+   via the command line or through the configuration file. The user
+   config file is located at $W3M_DIR/config (~/.w3m/config by default).
+  </p>
   <p>
    Options include:
   </p>

doc/w3m.1

@@ -266,9 +266,16 @@ $ w3m \-v
 .EE
 .\".SH Errors
 .SH ENVIRONMENT
-\fIw3m\fP recognises the environment variable WWW_HOME as defining a
+\fIw3m\fP recognises the environment variable \fBWWW_HOME\fP as
-fallback target for use if it is invoked without one.
+defining a fallback target for use if it is invoked without one.
+
+If the \fBW3M_DIR\fP environment variable is set to a directory
+name, \fIw3m\fP will store its user files there instead of
+under the ~/.w3m directory.
 .SH FILES
+The default locations of some files are listed below. These
+locations can be altered via the \fBW3M_DIR\fP environment
+variable.
 .TP
 \f(CW~/.w3m/bookmark.html\fP
 default bookmark file

rc.c

@@ -1238,6 +1238,58 @@ do_mkdir(const char *dir, long mode)
 #endif				/* not __MINW32_VERSION */
 #endif				/* not __EMX__ */
 
+static int
+do_recursive_mkdir(const char *dir)
+{
+    char *ch, *dircpy, tmp;
+    size_t n;
+    struct stat st;
+
+    n = strlen(dir);
+    if (n == 0)
+	 return -1;
+
+    if ((dircpy = malloc(n + 1)) == NULL)
+	 return -1;
+    strcpy(dircpy, dir);
+
+    ch = dircpy + 1;
+    do {
+	while (!(*ch == '/' || *ch == '\0')) {
+	    ch++;
+	}
+
+	tmp = *ch;
+	*ch = '\0';
+
+	if (stat(dircpy, &st) < 0) {
+	    if (errno != ENOENT) {	/* no directory */
+		goto err;
+	    }
+	    if (do_mkdir(dircpy, 0700) < 0) {
+		goto err;
+	    }
+	    stat(dircpy, &st);
+	}
+	if (!S_ISDIR(st.st_mode)) {
+	    /* not a directory */
+	    goto err;
+	}
+	if (!(st.st_mode & S_IWUSR)) {
+	    goto err;
+	}
+
+	*ch = tmp;
+
+    } while (*ch++ != '\0');
+
+    free(dircpy);
+    return 0;
+err:
+    free(dircpy);
+    return -1;
+}
+
 static void loadSiteconf(void);
 
 void
@@ -1298,13 +1350,16 @@ void
 init_rc(void)
 {
     int i;
-    struct stat st;
     FILE *f;
 
     if (rc_dir != NULL)
 	goto open_rc;
 
-    rc_dir = expandPath(RC_DIR);
+    if ((rc_dir = getenv("W3M_DIR")) == NULL || *rc_dir == '\0') {
+	rc_dir = RC_DIR;
+    }
+    rc_dir = expandPath(rc_dir);
+
     i = strlen(rc_dir);
     if (i > 1 && rc_dir[i - 1] == '/')
 	rc_dir[i - 1] = '\0';
@@ -1315,30 +1370,9 @@ init_rc(void)
     system_charset_str = display_charset_str;
 #endif
 
-    if (stat(rc_dir, &st) < 0) {
+    if (do_recursive_mkdir(rc_dir) == -1)
-	if (errno == ENOENT) {	/* no directory */
-	    if (do_mkdir(rc_dir, 0700) < 0) {
-		/* fprintf(stderr, "Can't create config directory (%s)!\n", rc_dir); */
-		goto rc_dir_err;
-	    }
-	    else {
-		stat(rc_dir, &st);
-	    }
-	}
-	else {
-	    /* fprintf(stderr, "Can't open config directory (%s)!\n", rc_dir); */
-	    goto rc_dir_err;
-	}
-    }
-    if (!S_ISDIR(st.st_mode)) {
-	/* not a directory */
-	/* fprintf(stderr, "%s is not a directory!\n", rc_dir); */
 	goto rc_dir_err;
-    }
+
-    if (!(st.st_mode & S_IWUSR)) {
-	/* fprintf(stderr, "%s is not writable!\n", rc_dir); */
-	goto rc_dir_err;
-    }
     no_rc_dir = FALSE;
     tmp_dir = rc_dir;