Do not gather full input data in a single string when piping

Refactor ShellManager and pipe to feed lines from the buffer directly,
this should reduce memory use when piping big chunks of buffers.

The pipe output is still provided as a single big buffer.

1 files changed, 11 insertions, 1 deletions

diff --git a/src/shell_manager.hh b/src/shell_manager.hh
index f6ef38a4..3dc62e0a 100644
--- a/src/shell_manager.hh
+++ b/src/shell_manager.hh
@@ -58,10 +58,20 @@ public:
     friend constexpr bool with_bit_ops(Meta::Type<Flags>) { return true; }
 
     std::pair<String, int> eval(StringView cmdline, const Context& context,
-                                StringView input = {},
+                                FunctionRef<StringView ()> stdin_generator,
                                 Flags flags = Flags::WaitForStdout,
                                 const ShellContext& shell_context = {});
 
+    std::pair<String, int> eval(StringView cmdline, const Context& context,
+                                StringView stdin,
+                                Flags flags = Flags::WaitForStdout,
+                                const ShellContext& shell_context = {})
+    {
+        return eval(cmdline, context,
+                    [stdin]() mutable { return std::exchange(stdin, StringView{}); },
+                    flags, shell_context);
+    }
+
     Shell spawn(StringView cmdline,
                 const Context& context,
                 bool open_stdin,