From 744778be30f2f78bea4af5523f00da98480cda4d Mon Sep 17 00:00:00 2001
From: Maxime Coste <mawww@kakoune.org>
Date: Sun, 7 Apr 2019 09:31:36 +1000
Subject: [PATCH] Add a -to-file <filename> switch to the echo command

As discussed in #2836
---
 doc/pages/commands.asciidoc   | 4 ++++
 src/commands.cc               | 7 ++++++-
 src/file.cc                   | 9 +++++++++
 src/file.hh                   | 1 +
 test/compose/echo-to-file/cmd | 1 +
 test/compose/echo-to-file/in  | 1 +
 test/compose/echo-to-file/out | 1 +
 7 files changed, 23 insertions(+), 1 deletion(-)
 create mode 100644 test/compose/echo-to-file/cmd
 create mode 100644 test/compose/echo-to-file/in
 create mode 100644 test/compose/echo-to-file/out

diff --git a/doc/pages/commands.asciidoc b/doc/pages/commands.asciidoc
index 8a215e3d..62b80818 100644
--- a/doc/pages/commands.asciidoc
+++ b/doc/pages/commands.asciidoc
@@ -206,6 +206,10 @@ of the file onto the filesystem
     *-debug*:::
         print the given text to the *\*debug** buffer
 
+    *-to-file* <filename>:::
+        write the given text to the given file on the host
+        filesystem.
+
 *set-face* <scope> <name> <facespec>::
     *alias* face +
     define a face in *scope*
diff --git a/src/commands.cc b/src/commands.cc
index 4176f673..f1e2b71a 100644
--- a/src/commands.cc
+++ b/src/commands.cc
@@ -1200,6 +1200,7 @@ const CommandDesc echo_cmd = {
     "echo <params>...: display given parameters in the status line",
     ParameterDesc{
         { { "markup", { false, "parse markup" } },
+          { "to-file", { true, "echo contents to given filename" } },
           { "debug", { false, "write to debug buffer instead of status line" } } },
         ParameterDesc::Flags::SwitchesOnlyAtStart
     },
@@ -1208,7 +1209,11 @@ const CommandDesc echo_cmd = {
     CommandCompleter{},
     [](const ParametersParser& parser, Context& context, const ShellContext&)
     {
-        String message = fix_atom_text(join(parser, ' ', false));
+        String message = join(parser, ' ', false);
+        if (auto filename = parser.get_switch("to-file"))
+            return write_to_file(*filename, message);
+
+        message = fix_atom_text(message);
         if (parser.get_switch("debug"))
             write_to_debug_buffer(message);
         else if (parser.get_switch("markup"))
diff --git a/src/file.cc b/src/file.cc
index 7b49595e..52a0f288 100644
--- a/src/file.cc
+++ b/src/file.cc
@@ -257,6 +257,15 @@ void write(int fd, StringView data)
     }
 }
 
+void write_to_file(StringView filename, StringView data)
+{
+    const int fd = open(filename.zstr(), O_CREAT | O_WRONLY | O_TRUNC, 0644);
+    if (fd == -1)
+        throw file_access_error(filename, strerror(errno));
+    auto close_fd = on_scope_end([fd]{ close(fd); });
+    write(fd, data);
+}
+
 struct BufferedWriter
 {
     BufferedWriter(int fd) : fd{fd} {}
diff --git a/src/file.hh b/src/file.hh
index 6871a1a3..5264616b 100644
--- a/src/file.hh
+++ b/src/file.hh
@@ -39,6 +39,7 @@ bool fd_writable(int fd);
 String read_fd(int fd, bool text = false);
 String read_file(StringView filename, bool text = false);
 void write(int fd, StringView data);
+void write_to_file(StringView filename, StringView data);
 
 struct MappedFile
 {
diff --git a/test/compose/echo-to-file/cmd b/test/compose/echo-to-file/cmd
new file mode 100644
index 00000000..f5e4924b
--- /dev/null
+++ b/test/compose/echo-to-file/cmd
@@ -0,0 +1 @@
+:echo -to-file data %{foo bar}<ret>!cat data<ret>
diff --git a/test/compose/echo-to-file/in b/test/compose/echo-to-file/in
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/test/compose/echo-to-file/in
@@ -0,0 +1 @@
+
diff --git a/test/compose/echo-to-file/out b/test/compose/echo-to-file/out
new file mode 100644
index 00000000..d675fa44
--- /dev/null
+++ b/test/compose/echo-to-file/out
@@ -0,0 +1 @@
+foo bar