Support align and min_width module options

This patch enables users to define "align" and "min_width" options
right in the i3status module config sections.

Specifically this patch:
 * Adds macros for the two new options that are used in the option
   definitions. As the min_width option can take either a string or a
   number, a custom type has been added along with a corresponding callback
   function that parses the provided value (and provides input validation).
   The align option also uses a callback for input validation
 * Expands all module config option definitions to include the new
   options
 * Extends the SEC_CLOSE_MAP() macro to generate the JSON for the new
   options as necessary
 * Updates the manpage to explain the new options

3 files changed, 136 insertions, 0 deletions

diff --git a/i3status.c b/i3status.c
index 8d8536c..3733cf0 100644
--- a/i3status.c
+++ b/i3status.c
@@ -11,6 +11,7 @@
  * See file LICENSE for license information.
  *
  */
+#include <limits.h>
 #include <string.h>
 #include <stdio.h>
 #include <stdbool.h>
@@ -35,6 +36,9 @@
 
 #define exit_if_null(pointer, ...) { if (pointer == NULL) die(__VA_ARGS__); }
 
+#define CFG_CUSTOM_ALIGN_OPT \
+    CFG_STR_CB("align", NULL, CFGF_NONE, parse_align)
+
 #define CFG_COLOR_OPTS(good, degraded, bad) \
     CFG_STR("color_good", good, CFGF_NONE), \
     CFG_STR("color_degraded", degraded, CFGF_NONE), \
@@ -42,6 +46,9 @@
 
 #define CFG_CUSTOM_COLOR_OPTS CFG_COLOR_OPTS(NULL, NULL, NULL)
 
+#define CFG_CUSTOM_MIN_WIDTH_OPT \
+    CFG_PTR_CB("min_width", NULL, CFGF_NONE, parse_min_width, free)
+
 /* socket file descriptor for general purposes */
 int general_socket;
 
@@ -89,6 +96,54 @@ static char *sstrdup(const char *str) {
         return result;
 }
 
+/*
+ * Parses the "align" module option (to validate input).
+ */
+static int parse_align(cfg_t *context, cfg_opt_t *option, const char *value, void *result) {
+        if (strcasecmp(value, "left") != 0 && strcasecmp(value,"right") != 0 && strcasecmp(value, "center") != 0)
+                die("Invalid alignment attribute found in section %s, line %d: \"%s\"\n"
+                    "Valid attributes are: left, center, right\n", context->name, context->line, value);
+
+        char **cresult = result;
+        *cresult = sstrdup(value);
+
+        return 0;
+}
+
+/*
+ * Parses the "min_width" module option whose value can either be a string or an integer.
+ */
+static int parse_min_width(cfg_t *context, cfg_opt_t *option, const char *value, void *result) {
+        char *end;
+        long num = strtol(value, &end, 10);
+
+        if (num < 0)
+                die("Invalid min_width attribute found in section %s, line %d: %d\n"
+                    "Expected positive integer or string\n", context->name, context->line, num);
+        else if (num == LONG_MIN || num == LONG_MAX || (end && *end != '\0'))
+                num = 0;
+
+        if (strlen(value) == 0)
+                die("Empty min_width attribute found in section %s, line %d\n"
+                    "Expected positive integer or non-empty string\n", context->name, context->line);
+
+        if (strcmp(value, "0") == 0)
+                die("Invalid min_width attribute found in section %s, line %d: \"%s\"\n"
+                    "Expected positive integer or string\n", context->name, context->line, value);
+
+        struct min_width *parsed = scalloc(sizeof(struct min_width));
+        parsed->num = num;
+
+        /* num is preferred, but if it’s 0 (i.e. not valid), store and use
+         * the raw string value */
+        if (num == 0)
+                parsed->str = sstrdup(value);
+
+        struct min_width **cresult = result;
+        *cresult = parsed;
+
+        return 0;
+}
 
 /*
  * Validates a color in "#RRGGBB" format
@@ -219,35 +274,45 @@ int main(int argc, char *argv[]) {
         cfg_opt_t run_watch_opts[] = {
                 CFG_STR("pidfile", NULL, CFGF_NONE),
                 CFG_STR("format", "%title: %status", CFGF_NONE),
+                CFG_CUSTOM_ALIGN_OPT,
                 CFG_CUSTOM_COLOR_OPTS,
+                CFG_CUSTOM_MIN_WIDTH_OPT,
                 CFG_END()
         };
 
         cfg_opt_t path_exists_opts[] = {
                 CFG_STR("path", NULL, CFGF_NONE),
                 CFG_STR("format", "%title: %status", CFGF_NONE),
+                CFG_CUSTOM_ALIGN_OPT,
                 CFG_CUSTOM_COLOR_OPTS,
+                CFG_CUSTOM_MIN_WIDTH_OPT,
                 CFG_END()
         };
 
         cfg_opt_t wireless_opts[] = {
                 CFG_STR("format_up", "W: (%quality at %essid, %bitrate) %ip", CFGF_NONE),
                 CFG_STR("format_down", "W: down", CFGF_NONE),
+                CFG_CUSTOM_ALIGN_OPT,
                 CFG_CUSTOM_COLOR_OPTS,
+                CFG_CUSTOM_MIN_WIDTH_OPT,
                 CFG_END()
         };
 
         cfg_opt_t ethernet_opts[] = {
                 CFG_STR("format_up", "E: %ip (%speed)", CFGF_NONE),
                 CFG_STR("format_down", "E: down", CFGF_NONE),
+                CFG_CUSTOM_ALIGN_OPT,
                 CFG_CUSTOM_COLOR_OPTS,
+                CFG_CUSTOM_MIN_WIDTH_OPT,
                 CFG_END()
         };
 
         cfg_opt_t ipv6_opts[] = {
                 CFG_STR("format_up", "%ip", CFGF_NONE),
                 CFG_STR("format_down", "no IPv6", CFGF_NONE),
+                CFG_CUSTOM_ALIGN_OPT,
                 CFG_CUSTOM_COLOR_OPTS,
+                CFG_CUSTOM_MIN_WIDTH_OPT,
                 CFG_END()
         };
 
@@ -260,35 +325,47 @@ int main(int argc, char *argv[]) {
                 CFG_BOOL("last_full_capacity", false, CFGF_NONE),
                 CFG_BOOL("integer_battery_capacity", false, CFGF_NONE),
                 CFG_BOOL("hide_seconds", false, CFGF_NONE),
+                CFG_CUSTOM_ALIGN_OPT,
                 CFG_CUSTOM_COLOR_OPTS,
+                CFG_CUSTOM_MIN_WIDTH_OPT,
                 CFG_END()
         };
 
         cfg_opt_t time_opts[] = {
                 CFG_STR("format", "%Y-%m-%d %H:%M:%S", CFGF_NONE),
+                CFG_CUSTOM_ALIGN_OPT,
+                CFG_CUSTOM_MIN_WIDTH_OPT,
                 CFG_END()
         };
 
         cfg_opt_t tztime_opts[] = {
                 CFG_STR("format", "%Y-%m-%d %H:%M:%S %Z", CFGF_NONE),
                 CFG_STR("timezone", "", CFGF_NONE),
+                CFG_CUSTOM_ALIGN_OPT,
+                CFG_CUSTOM_MIN_WIDTH_OPT,
                 CFG_END()
         };
 
         cfg_opt_t ddate_opts[] = {
                 CFG_STR("format", "%{%a, %b %d%}, %Y%N - %H", CFGF_NONE),
+                CFG_CUSTOM_ALIGN_OPT,
+                CFG_CUSTOM_MIN_WIDTH_OPT,
                 CFG_END()
         };
 
         cfg_opt_t load_opts[] = {
                 CFG_STR("format", "%1min %5min %15min", CFGF_NONE),
                 CFG_FLOAT("max_threshold", 5, CFGF_NONE),
+                CFG_CUSTOM_ALIGN_OPT,
                 CFG_CUSTOM_COLOR_OPTS,
+                CFG_CUSTOM_MIN_WIDTH_OPT,
                 CFG_END()
         };
 
         cfg_opt_t usage_opts[] = {
                 CFG_STR("format", "%usage", CFGF_NONE),
+                CFG_CUSTOM_ALIGN_OPT,
+                CFG_CUSTOM_MIN_WIDTH_OPT,
                 CFG_END()
         };
 
@@ -296,13 +373,17 @@ int main(int argc, char *argv[]) {
                 CFG_STR("format", "%degrees C", CFGF_NONE),
                 CFG_STR("path", NULL, CFGF_NONE),
                 CFG_INT("max_threshold", 75, CFGF_NONE),
+                CFG_CUSTOM_ALIGN_OPT,
                 CFG_CUSTOM_COLOR_OPTS,
+                CFG_CUSTOM_MIN_WIDTH_OPT,
                 CFG_END()
         };
 
         cfg_opt_t disk_opts[] = {
                 CFG_STR("format", "%free", CFGF_NONE),
                 CFG_STR("prefix_type", "binary", CFGF_NONE),
+                CFG_CUSTOM_ALIGN_OPT,
+                CFG_CUSTOM_MIN_WIDTH_OPT,
                 CFG_END()
         };
 
@@ -312,7 +393,9 @@ int main(int argc, char *argv[]) {
                 CFG_STR("device", "default", CFGF_NONE),
                 CFG_STR("mixer", "Master", CFGF_NONE),
                 CFG_INT("mixer_idx", 0, CFGF_NONE),
+                CFG_CUSTOM_ALIGN_OPT,
                 CFG_CUSTOM_COLOR_OPTS,
+                CFG_CUSTOM_MIN_WIDTH_OPT,
                 CFG_END()
         };
 
diff --git a/include/i3status.h b/include/i3status.h
index 95da091..8c64586 100644
--- a/include/i3status.h
+++ b/include/i3status.h
@@ -88,6 +88,22 @@ enum { O_DZEN2, O_XMOBAR, O_I3BAR, O_TERM, O_NONE } output_format;
 #define SEC_CLOSE_MAP \
 	do { \
 		if (output_format == O_I3BAR) { \
+			char *_align = cfg_getstr(sec, "align"); \
+			if (_align) { \
+				yajl_gen_string(json_gen, (const unsigned char *)"align", strlen("align")); \
+				yajl_gen_string(json_gen, (const unsigned char *)_align, strlen(_align)); \
+			} \
+			struct min_width *_width = cfg_getptr(sec, "min_width"); \
+			if (_width) { \
+				/* if the value can be parsed as a number, we use the numerical value */ \
+				if (_width->num > 0) { \
+					yajl_gen_string(json_gen, (const unsigned char *)"min_width", strlen("min_width")); \
+					yajl_gen_integer(json_gen, _width->num); \
+				} else { \
+					yajl_gen_string(json_gen, (const unsigned char *)"min_width", strlen("min_width")); \
+					yajl_gen_string(json_gen, (const unsigned char *)_width->str, strlen(_width->str)); \
+				} \
+			} \
 			const char *_sep = cfg_getstr(cfg_general, "separator"); \
 			if (strlen(_sep) == 0) {\
 				yajl_gen_string(json_gen, (const unsigned char *)"separator", strlen("separator")); \
@@ -132,6 +148,14 @@ enum { O_DZEN2, O_XMOBAR, O_I3BAR, O_TERM, O_NONE } output_format;
 
 typedef enum { CS_DISCHARGING, CS_CHARGING, CS_FULL } charging_status_t;
 
+/*
+ * The "min_width" module option may either be defined as a string or a number.
+ */
+struct min_width {
+    long num;
+    const char *str;
+};
+
 /* src/general.c */
 char *skip_character(char *input, char character, int amount);
 void die(const char *fmt, ...);
diff --git a/man/i3status.man b/man/i3status.man
index 7ba4422..656a8bf 100644
--- a/man/i3status.man
+++ b/man/i3status.man
@@ -404,6 +404,35 @@ volume master {
 }
 -------------------------------------------------------------
 
+== Universal module options
+
+When using the i3bar output format, there are a few additional options that
+can be used with all modules to customize their appearance:
+
+align::
+	The alignment policy to use when the minimum width (see below) is not
+	reached. Either +center+ (default), +right+ or +left+.
+min_width::
+	The minimum width (in pixels) the module should occupy. If the module takes
+	less space than the specified size, the block will be padded to the left
+	and/or the right side, according to the defined alignment policy. This is
+	useful when you want to prevent the whole status line from shifting when
+	values take more or less space between each iteration.
+	The option can also be a string. In this case, the width of the given text
+	determines the minimum width of the block. This is useful when you want to
+	set a sensible minimum width regardless of which font you are using, and at
+	what particular size. Please note that a number enclosed with quotes will
+	still be treated as a number.
+
+*Example configuration*:
+-------------------------------------------------------------
+disk "/" {
+    format = "%avail"
+    align = "left"
+    min_width = 100
+}
+-------------------------------------------------------------
+
 == Using i3status with dzen2
 
 After installing dzen2, you can directly use it with i3status. Just ensure that