From 35f0578cea7c44efe0e643c611082b656a788fe2 Mon Sep 17 00:00:00 2001
From: g1n <g1n@ttm.sh>
Date: Fri, 12 Aug 2022 10:52:05 +0300
Subject: [PATCH] Add tee util

---
 src/tee.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 src/tee.c

diff --git a/src/tee.c b/src/tee.c
new file mode 100644
index 0000000..46f74c9
--- /dev/null
+++ b/src/tee.c
@@ -0,0 +1,50 @@
+#include <stdbool.h>
+#include <stdio.h>
+#include <signal.h>
+#include <unistd.h>
+
+int usage(char *argv0) {
+  printf("Usage: %s [-ai] [file ...]\n", argv0);
+  return 2;
+}
+
+int main(int argc, char *argv[]){
+  int opt;
+  bool append = false;
+  bool iflag = false;
+  while ((opt = getopt(argc, argv, ":ai")) != -1) {
+    switch (opt) {
+      case 'a':
+        append = true;
+        break;
+      case 'i':
+        iflag = true;
+        break;
+      case '?':
+        fprintf(stderr, "%s: invalid option -- '%c'\n", argv[0], optopt);
+        return usage(argv[0]);
+    }
+  }
+
+  if (iflag && signal(SIGINT, SIG_IGN) == SIG_ERR) {} // FIXME
+
+  int arg = optind;
+  void *buf[BUFSIZ];
+  FILE *file;
+  ssize_t n;
+
+  while ((n = read(0, buf, sizeof(buf))) > 0) {
+    optind = arg;
+    if (optind < argc) {
+      for (; optind < argc; optind++) {
+        file = fopen(argv[optind], append ? "w" : "a+");
+        fwrite(buf, BUFSIZ, 1, file);
+        fclose(file);
+        append = true;
+      }
+    } else {
+      fwrite(buf, BUFSIZ, 1, stdout);
+    }
+  }
+  return 0;
+}