disk: Colorize output when below given threshold

New disk module options:
* threshold_type: ^(percentage|[kmgt]?bytes)_(free|avail)$
* low_threshold: <double>

fixes #912

4 files changed, 78 insertions, 3 deletions

diff --git a/i3status.c b/i3status.c
index 3733cf0..1811884 100644
--- a/i3status.c
+++ b/i3status.c
@@ -382,7 +382,10 @@ int main(int argc, char *argv[]) {
         cfg_opt_t disk_opts[] = {
                 CFG_STR("format", "%free", CFGF_NONE),
                 CFG_STR("prefix_type", "binary", CFGF_NONE),
+                CFG_STR("threshold_type", "percentage_avail", CFGF_NONE),
+                CFG_FLOAT("low_threshold", 0, CFGF_NONE),
                 CFG_CUSTOM_ALIGN_OPT,
+                CFG_CUSTOM_COLOR_OPTS,
                 CFG_CUSTOM_MIN_WIDTH_OPT,
                 CFG_END()
         };
@@ -601,7 +604,7 @@ int main(int argc, char *argv[]) {
 
                         CASE_SEC_TITLE("disk") {
                                 SEC_OPEN_MAP("disk_info");
-                                print_disk_info(json_gen, buffer, title, cfg_getstr(sec, "format"), cfg_getstr(sec, "prefix_type"));
+                                print_disk_info(json_gen, buffer, title, cfg_getstr(sec, "format"), cfg_getstr(sec, "prefix_type"), cfg_getstr(sec, "threshold_type"), cfg_getfloat(sec, "low_threshold"));
                                 SEC_CLOSE_MAP;
                         }
 
diff --git a/include/i3status.h b/include/i3status.h
index 8c64586..829fc4e 100644
--- a/include/i3status.h
+++ b/include/i3status.h
@@ -174,7 +174,7 @@ char *auto_detect_format();
 void set_timezone(const char *tz);
 
 void print_ipv6_info(yajl_gen json_gen, char *buffer, const char *format_up, const char *format_down);
-void print_disk_info(yajl_gen json_gen, char *buffer, const char *path, const char *format, const char *prefix_type);
+void print_disk_info(yajl_gen json_gen, char *buffer, const char *path, const char *format, const char *prefix_type, const char *threshold_type, const double low_threshold);
 void print_battery_info(yajl_gen json_gen, char *buffer, int number, const char *path, const char *format, const char *format_down, int low_threshold, char *threshold_type, bool last_full_capacity, bool integer_battery_capacity, bool hide_seconds);
 void print_time(yajl_gen json_gen, char *buffer, const char *format, const char *tz, time_t t);
 void print_ddate(yajl_gen json_gen, char *buffer, const char *format, time_t t);
diff --git a/man/i3status.man b/man/i3status.man
index 656a8bf..1182e54 100644
--- a/man/i3status.man
+++ b/man/i3status.man
@@ -223,6 +223,16 @@ SI prefixes (k, M, G, T) represent multiples of powers of 1000.
 custom::
 The custom prefixes (K, M, G, T) represent multiples of powers of 1024.
 
+It is possible to define a low_threshold that causes the disk text to be
+displayed using color_bad. The low_threshold type can be of threshold_type
+"bytes_free", "bytes_avail", "percentage_free", or "percentage_avail", where
+the former two can be prepended by a generic prefix (k, m, g, t) having
+prefix_type. So, if you configure low_threshold to 2, threshold_type to
+"gbytes_avail", and prefix_type to "binary", and the remaining available disk
+space is below 2 GiB, it will be colored bad. If not specified, threshold_type
+is assumed to be "percentage_avail" and low_threshold to be set to 0, which
+implies no coloring at all.
+
 *Example order*: +disk /mnt/usbstick+
 
 *Example format*: +%free (%avail)/ %total+
@@ -231,6 +241,10 @@ The custom prefixes (K, M, G, T) represent multiples of powers of 1024.
 
 *Example prefix_type*: +custom+
 
+*Example low_threshold*: +5+
+
+*Example threshold_type*: +percentage_free+
+
 === Run-watch
 
 Expands the given path to a pidfile and checks if the process ID found inside
diff --git a/src/print_disk_info.c b/src/print_disk_info.c
index 2308305..d586839 100644
--- a/src/print_disk_info.c
+++ b/src/print_disk_info.c
@@ -53,13 +53,63 @@ static int print_bytes_human(char *outwalk, uint64_t bytes, const char *prefix_t
 }
 
 /*
+ * Determines whether remaining bytes are below given threshold.
+ *
+ */
+#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__OpenBSD__) || defined(__DragonFly__)
+static bool below_threshold(struct statfs buf, const char *prefix_type, const char *threshold_type, const double low_threshold) {
+#else
+static bool below_threshold(struct statvfs buf, const char *prefix_type, const char *threshold_type, const double low_threshold) {
+#endif
+        if (strcasecmp(threshold_type, "percentage_free") == 0) {
+                return 100.0 * (double)buf.f_bfree / (double)buf.f_blocks < low_threshold;
+        } else if (strcasecmp(threshold_type, "percentage_avail") == 0) {
+                return 100.0 * (double)buf.f_bavail / (double)buf.f_blocks < low_threshold;
+        } else if (strcasecmp(threshold_type, "bytes_free") == 0) {
+                return (double)buf.f_bsize * (double)buf.f_bfree < low_threshold;
+        } else if (strcasecmp(threshold_type, "bytes_avail") == 0) {
+                return (double)buf.f_bsize * (double)buf.f_bavail < low_threshold;
+        } else if (threshold_type[0] != '\0' && strncasecmp(threshold_type+1, "bytes_", strlen("bytes_")) == 0) {
+                uint64_t base = strcasecmp(prefix_type, "decimal") == 0 ? DECIMAL_BASE : BINARY_BASE;
+                double factor = 1;
+
+                switch (threshold_type[0]) {
+                case 'T':
+                case 't':
+                        factor *= base;
+                case 'G':
+                case 'g':
+                        factor *= base;
+                case 'M':
+                case 'm':
+                        factor *= base;
+                case 'K':
+                case 'k':
+                        factor *= base;
+                        break;
+                default:
+                        return false;
+                }
+
+                if (strcasecmp(threshold_type+1, "bytes_free") == 0) {
+                        return (double)buf.f_bsize * (double)buf.f_bfree < low_threshold * factor;
+                } else if (strcasecmp(threshold_type+1, "bytes_avail") == 0) {
+                        return (double)buf.f_bsize * (double)buf.f_bavail < low_threshold * factor;
+                }
+        }
+
+        return false;
+}
+
+/*
  * Does a statvfs and prints either free, used or total amounts of bytes in a
  * human readable manner.
  *
  */
-void print_disk_info(yajl_gen json_gen, char *buffer, const char *path, const char *format, const char *prefix_type) {
+void print_disk_info(yajl_gen json_gen, char *buffer, const char *path, const char *format, const char *prefix_type, const char *threshold_type, const double low_threshold) {
         const char *walk;
         char *outwalk = buffer;
+        bool colorful_output = false;
 
         INSTANCE(path);
 
@@ -75,6 +125,11 @@ void print_disk_info(yajl_gen json_gen, char *buffer, const char *path, const ch
                 return;
 #endif
 
+        if (low_threshold > 0 && below_threshold(buf, prefix_type, threshold_type, low_threshold)) {
+                START_COLOR("color_bad");
+                colorful_output = true;
+        }
+
         for (walk = format; *walk != '\0'; walk++) {
                 if (*walk != '%') {
                         *(outwalk++) = *walk;
@@ -122,6 +177,9 @@ void print_disk_info(yajl_gen json_gen, char *buffer, const char *path, const ch
                 }
         }
 
+        if (colorful_output)
+                END_COLOR;
+
         *outwalk = '\0';
         OUTPUT_FULL_TEXT(buffer);
 }