1 files changed, 46 insertions, 0 deletions
diff --git a/src/cat.c b/src/cat.c
new file mode 100644
index 0000000..bf618cc
--- /dev/null
+++ b/src/cat.c
@@ -0,0 +1,46 @@
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#define error(...) ({ \
+    printf(__VA_ARGS__); \
+    exit(EXIT_FAILURE); \
+    })
+
+static void cat(char *s) {
+  int fd = STDIN_FILENO;
+  ssize_t in, out;
+  char buf[1024];
+
+  if(strcmp(s, "-")) {
+    fd = open(s, O_RDONLY);
+    if(fd < 0)
+      error("Error opening %s: %s\n", s, strerror(errno));
+  }
+
+  for(;;) {
+    in = read(fd, buf, sizeof(buf));
+    if(in < 0)
+      error("Error reading %s: %s\n", s, strerror(errno));
+    out = write(STDOUT_FILENO, buf, in);
+    if(out < in)
+      error("Error writiing output: %s\n", strerror(errno));
+    if(!in)
+      return;
+  }
+}
+
+int main(int argc, char **argv) {
+  if(argc == 1) {
+    cat("-");
+    return 0;
+  }
+
+  while(argc-- > 1)
+    cat(*(++argv));
+
+  return 0;
+}