`cat`/Makefile: add `cat`.

i thought this would be alot harder to implement, lol.
supports reading from stdin (including pipes) and files.
big dab moment.

Makefile

@@ -10,7 +10,7 @@ CC_FLAGS :=
 endif
 CC_FLAGS := -Ilib ${CC_FLAGS} 
 ifndef PROGS
-PROGS := arch basename ls pwd uname whoami yes
+PROGS := arch basename cat ls pwd uname whoami yes
 endif
 ifndef DESTDIR
 DESTDIR := /

src/cat.c

@@ -0,0 +1,56 @@
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+int main(int argc, char **argv) {
+  if (argc == 1) {
+    char ch;
+    while (read(STDIN_FILENO, &ch, 1) > 0) {
+      printf("%c", ch);
+    }
+    return 0;
+  } else {
+    char *file = NULL;
+    for (int i = 1; i < argc; i++) {
+      char *arg = argv[i];
+      if (!strcmp(arg, "--help")) {
+        char *help =
+            "Drake's Epic Coreutils (working title) " DRAKECU_VERSION "\n"
+            "cat - concatenate file to stdout.\n"
+            "Usage:\n"
+            "	cat [options] [FILE]\n"
+            "Available arguments:\n"
+            "	--help: show this help message\n"
+            "	--version: show the version of the program\n"
+            "Notes:\n"
+            "	If no file is specified, FILE will be stdin.";
+        printf("%s\n", help);
+        return 0;
+      } else if (!strcmp(arg, "--version")) {
+        printf("%s\n", DRAKECU_VERSION);
+        return 0;
+      } else {
+        file = arg;
+        break;
+      }
+    }
+    if (file == NULL) {
+      printf(
+          "somehow, you got past the argv check without a file. congrats?\n");
+      return 1;
+    }
+    FILE *fp;
+    fp = fopen(file, "r");
+    if (fp == NULL) {
+      printf("failed to open '%s'. perhaps the path doesn't exist?\n", file);
+      return 1;
+    }
+    char *contents = malloc(LINE_MAX + 1);
+    while (fgets(contents, LINE_MAX + 1, fp) != NULL) {
+      printf("%s", contents);
+    }
+    free(contents);
+  }
+}