From bc9d556f3a890cf5f99e9dced0117e2d8a91ff09 Mon Sep 17 00:00:00 2001
From: "Avi Halachmi (:avih)" <avihpit@yahoo.com>
Date: Thu, 10 Jun 2021 12:32:28 +0300
Subject: js: add mp.utils.append_file

Also, for consistency with other APIs, mp.utils.{write,append}_file
now return true on success (and still throw on any error).
---
 DOCS/man/javascript.rst       | 10 ++++++++--
 player/javascript.c           | 22 +++++++++++++---------
 player/javascript/defaults.js |  2 ++
 3 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/DOCS/man/javascript.rst b/DOCS/man/javascript.rst
index 1e5ce99cdc..0cd4fb806e 100644
--- a/DOCS/man/javascript.rst
+++ b/DOCS/man/javascript.rst
@@ -221,7 +221,8 @@ Additional utilities
 
 ``mp.utils.get_user_path(path)``
     Expands (mpv) meta paths like ``~/x``, ``~~/y``, ``~~desktop/z`` etc.
-    ``read_file``, ``write_file`` and ``require`` already use this internaly.
+    ``read_file``, ``write_file``, ``append_file`` and ``require`` already use
+    this internaly.
 
 ``mp.utils.read_file(fname [,max])``
     Returns the content of file ``fname`` as string. If ``max`` is provided and
@@ -232,7 +233,12 @@ Additional utilities
     prefixed with ``file://`` as simple protection against accidental arguments
     switch, e.g. ``mp.utils.write_file("file://~/abc.txt", "hello world")``.
 
-Note: ``read_file`` and ``write_file`` throw on errors, allow text content only.
+``mp.utils.append_file(fname, str)``
+    Same as ``mp.utils.write_file`` if the file ``fname`` does not exist. If it
+    does exist then append instead of overwrite.
+
+Note: ``read_file``, ``write_file`` and ``append_file`` throw on errors, allow
+text content only.
 
 ``mp.get_time_ms()``
     Same as ``mp.get_time()`` but in ms instead of seconds.
diff --git a/player/javascript.c b/player/javascript.c
index 406a469447..136a5965b9 100644
--- a/player/javascript.c
+++ b/player/javascript.c
@@ -924,27 +924,31 @@ static void script_get_user_path(js_State *J, void *af)
     js_pushstring(J, mp_get_user_path(af, jctx(J)->mpctx->global, path));
 }
 
-// args: prefixed file name, data (c-str)
-static void script_write_file(js_State *J, void *af)
+// args: is_append, prefixed file name, data (c-str)
+static void script__write_file(js_State *J, void *af)
 {
     static const char *prefix = "file://";
-    const char *fname = js_tostring(J, 1);
-    const char *data = js_tostring(J, 2);
+    bool append = js_toboolean(J, 1);
+    const char *fname = js_tostring(J, 2);
+    const char *data = js_tostring(J, 3);
+    const char *opstr = append ? "append" : "write";
+
     if (strstr(fname, prefix) != fname)  // simple protection for incorrect use
         js_error(J, "File name must be prefixed with '%s'", prefix);
     fname += strlen(prefix);
     fname = mp_get_user_path(af, jctx(J)->mpctx->global, fname);
-    MP_VERBOSE(jctx(J), "Writing file '%s'\n", fname);
+    MP_VERBOSE(jctx(J), "%s file '%s'\n", opstr, fname);
 
-    FILE *f = fopen(fname, "wb");
+    FILE *f = fopen(fname, append ? "ab" : "wb");
     if (!f)
-        js_error(J, "Cannot open file for writing: '%s'", fname);
+        js_error(J, "Cannot open (%s) file: '%s'", opstr, fname);
     add_af_file(af, f);
 
     int len = strlen(data);  // limited by terminating null
     int wrote = fwrite(data, 1, len, f);
     if (len != wrote)
-        js_error(J, "Cannot write to file: '%s'", fname);
+        js_error(J, "Cannot %s to file: '%s'", opstr, fname);
+    js_pushboolean(J, 1);  // success. doesn't touch last_error
 }
 
 // args: env var name
@@ -1179,7 +1183,7 @@ static const struct fn_entry utils_fns[] = {
     FN_ENTRY(get_env_list, 0),
 
     FN_ENTRY(read_file, 2),
-    AF_ENTRY(write_file, 2),
+    AF_ENTRY(_write_file, 3),
     FN_ENTRY(getenv, 1),
     FN_ENTRY(compile_js, 2),
     FN_ENTRY(_gc, 1),
diff --git a/player/javascript/defaults.js b/player/javascript/defaults.js
index c4482c88ce..037f931d94 100644
--- a/player/javascript/defaults.js
+++ b/player/javascript/defaults.js
@@ -665,6 +665,8 @@ mp.get_time = function() { return mp.get_time_ms() / 1000 };
 mp.utils.getcwd = function() { return mp.get_property("working-directory") };
 mp.utils.getpid = function() { return mp.get_property_number("pid") }
 mp.get_mouse_pos = function() { return mp.get_property_native("mouse-pos") };
+mp.utils.write_file = mp.utils._write_file.bind(null, false);
+mp.utils.append_file = mp.utils._write_file.bind(null, true);
 mp.dispatch_event = dispatch_event;
 mp.process_timers = process_timers;
 mp.notify_idle_observers = notify_idle_observers;
-- 
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