burl: prevent binary output in terminal

Author: ashtum

example/client/burl/any_iostream.cpp

@@ -9,6 +9,31 @@
 
 #include "any_iostream.hpp"
 
+#ifdef _MSC_VER
+#include <io.h>
+#else
+#include <unistd.h>
+#endif
+
+namespace
+{
+bool
+is_stdout_tty()
+{
+#ifdef _MSC_VER
+    return _isatty(_fileno(stdout));
+#else
+    return isatty(fileno(stdout));
+#endif
+}
+} // namespace
+
+any_ostream::any_ostream()
+    : stream_{ &std::cout }
+    , is_tty_{ ::is_stdout_tty() }
+{
+}
+
 any_ostream::any_ostream(core::string_view path)
 {
     if(path == "-")
@@ -29,6 +54,12 @@ any_ostream::any_ostream(core::string_view path)
     }
 }
 
+bool
+any_ostream::is_tty() const noexcept
+{
+    return is_tty_;
+}
+
 any_ostream::
 operator std::ostream&()
 {

example/client/burl/any_iostream.hpp

@@ -21,10 +21,16 @@ namespace core = boost::core;
 class any_ostream
 {
     std::variant<std::ofstream, std::ostream*> stream_;
+    bool is_tty_ = false;
 
 public:
+    any_ostream();
+
     any_ostream(core::string_view path);
 
+    bool
+    is_tty() const noexcept;
+
     operator std::ostream&();
 
     template<typename T>

example/client/burl/main.cpp

@@ -504,8 +504,20 @@ request(
         {
             for(auto cb : parser.pull_body())
             {
-                body_output << core::string_view{
+                auto chunk = core::string_view{
                     static_cast<const char*>(cb.data()), cb.size() };
+
+                if(body_output.is_tty() &&
+                    chunk.find(char{0}) != core::string_view::npos)
+                {
+                    std::cerr <<
+                        "Warning: Binary output can mess up your terminal.\n"
+                        "Warning: Use \"--output -\" to tell burl to output it to your terminal anyway, or\n"
+                        "Warning: consider \"--output <FILE>\" to save to a file.\n";
+                    co_return;
+                }
+
+                body_output << chunk;
                 parser.consume_body(cb.size());
             }
 
@@ -750,7 +762,7 @@ main(int argc, char* argv[])
         {
             if(vm.count("output"))
                 return any_ostream{ vm.at("output").as<std::string>() };
-            return any_ostream{ "-" };
+            return any_ostream{};
         }();
 
         auto header_output = [&]() -> std::optional<any_ostream>