New component: cat

Generically reads an arbitrary file natively.

Saves a few layers of execution in comparison to using `run_command`
with an argument like `cat ./file`.

Makefile

@@ -7,6 +7,7 @@ include config.mk
 REQ = util
 COM =\
 	components/battery\
+	components/cat\
 	components/cpu\
 	components/datetime\
 	components/disk\

README

@@ -7,6 +7,7 @@ slstatus is a suckless status monitor for window managers that use WM_NAME
 Features
 --------
 - Battery percentage/state/time left
+- Cat (read file)
 - CPU usage
 - CPU frequency
 - Custom shell commands

components/cat.c

@@ -0,0 +1,32 @@
+/* See LICENSE file for copyright and license details. */
+#include <stdio.h>
+#include <string.h>
+
+#include "../slstatus.h"
+#include "../util.h"
+
+const char *
+cat(const char *path)
+{
+        char *f;
+        FILE *fp;
+
+        if (!(fp = fopen(path, "r"))) {
+                warn("fopen '%s':", path);
+                return NULL;
+        }
+
+        f = fgets(buf, sizeof(buf) - 1, fp);
+        if (fclose(fp) < 0) {
+                warn("fclose '%s':", path);
+                return NULL;
+        }
+        if (!f)
+                return NULL;
+
+        if ((f = strrchr(buf, '\n')))
+                f[0] = '\0';
+
+        return buf[0] ? buf : NULL;
+}
+

config.def.h

@@ -18,6 +18,7 @@ static const char unknown_str[] = "n/a";
  *                                                     NULL on OpenBSD/FreeBSD
  * battery_remaining   battery remaining HH:MM         battery name (BAT0)
  *                                                     NULL on OpenBSD/FreeBSD
+ * cat                 read arbitrary file             path
  * cpu_perc            cpu usage in percent            NULL
  * cpu_freq            cpu frequency in MHz            NULL
  * datetime            date and time                   format string (%F %T)

slstatus.h

@@ -5,6 +5,9 @@ const char *battery_perc(const char *);
 const char *battery_state(const char *);
 const char *battery_remaining(const char *);
 
+/* cat */
+const char *cat(const char *path);
+
 /* cpu */
 const char *cpu_freq(const char *unused);
 const char *cpu_perc(const char *unused);