Userland: Less: emulate cat when stdout is not a tty

This is the most logical behavior when less is used in a pipe.

1 files changed, 23 insertions, 2 deletions

diff --git a/Userland/Utilities/less.cpp b/Userland/Utilities/less.cpp
index 3662ba59a2..f89be6c5f4 100644
--- a/Userland/Utilities/less.cpp
+++ b/Userland/Utilities/less.cpp
@@ -286,10 +286,26 @@ static String get_key_sequence()
     return String(buff, n);
 }
 
-int main(int argc, char** argv)
+static void cat_file(FILE* file)
 {
-    VERIFY(isatty(STDOUT_FILENO));
+    ByteBuffer buffer = ByteBuffer::create_uninitialized(4096);
+    while (!feof(file)) {
+        size_t n = fread(buffer.data(), 1, buffer.size(), file);
+        if (n == 0 && ferror(file)) {
+            perror("fread");
+            exit(1);
+        }
+
+        n = fwrite(buffer.data(), 1, n, stdout);
+        if (n == 0 && ferror(stdout)) {
+            perror("fwrite");
+            exit(1);
+        }
+    }
+}
 
+int main(int argc, char** argv)
+{
     char const* filename = "-";
     char const* prompt = "?f%f :.(line %l)?e (END):.";
     bool dont_switch_buffer = false;
@@ -321,6 +337,11 @@ int main(int argc, char** argv)
         prompt = "--More--";
     }
 
+    if (!isatty(STDOUT_FILENO)) {
+        cat_file(file);
+        return 0;
+    }
+
     setup_tty(!dont_switch_buffer);
 
     Pager pager(file, stdout, g_wsize.ws_col, g_wsize.ws_row);