1 files changed, 83 insertions, 0 deletions
diff --git a/command/tee.c b/command/tee.c
new file mode 100644
index 0000000..0462517
--- /dev/null
+++ b/command/tee.c
@@ -0,0 +1,83 @@
+#include "command.h"
+#include "lslib.h"
+
+#include <signal.h>
+#include <stdlib.h>
+
+static struct {
+    bool append;
+    bool handle_sigint;
+} flags;
+
+static void help(void) {
+    printf("Usage: tee [-ai] [FILE]...\n\n");
+    printf("Copy stdin to each FILE, and also to stdout\n\n");
+	printf("\t-a	Append to the given FILEs, don't overwrite\n");
+	printf("\t-i	Ignore interrupt signals (SIGINT)\n");
+    exit(EXIT_SUCCESS);
+}
+
+static void handle(int dummy){UNUSED(dummy);}
+
+static void run_tee(int file_count, FILE** files) {
+    char c;
+    int i;
+
+    while((c = getchar()) != EOF) {
+        int i;
+        for (i = 0; i < file_count; i++) {
+            fwrite(&c, 1, 1, files[i]);
+            fflush(files[i]);
+        }
+        putchar(c);
+    }
+
+    for (i = 0; i < file_count; i++) {
+        fclose(files[i]);
+    }
+}
+
+static int short_arg(char c, char* next) {
+    UNUSED(next);
+    switch (c) {
+        case 'a':
+            flags.append = true;
+            break;
+        case 'i':
+            flags.handle_sigint = true;
+            break;
+        default:
+            return ARG_INVALID;
+    }
+    return ARG_UNUSED;
+}
+
+COMMAND(tee) {
+
+    int start, i;
+    FILE** files;
+
+    flags.append = false;
+    flags.handle_sigint = false;
+
+    start = parse_args(argc, argv, help, short_arg, NULL);
+
+    if (flags.handle_sigint) {
+        signal(SIGINT, handle);
+    }
+
+    if (argc - start < 1) {
+        run_tee(0, NULL);
+        return EXIT_SUCCESS;
+    }
+
+    files = malloc(sizeof(FILE*) * (argc - start));
+
+    for (i = start; i < argc; i++) {
+        FILE* file = get_file(argv[i], flags.append ? "a" : "w");
+        files[i - start] = file;
+    }
+
+    run_tee(argc - start, files);
+    return EXIT_SUCCESS;
+}