From 8bdedf9062074f03b13820487fccc892105eb472 Mon Sep 17 00:00:00 2001
From: wm4 <wm4@nowhere>
Date: Wed, 18 Dec 2019 06:00:37 +0100
Subject: options: make keys in key/value lists unique

I don't even know anymore whether this was intended or not. Certain use
cases for the "-o" options might require this. These options are for
passing general FFmpeg options. These are translated to av_opt_set()
calls, which may or may not accumulate the option values on multiple
calls with the same option name (how should I know?).

Anyway, it seems crazy to allow non-unique keys, so make them unique.

The ad-hoc nature of the option code makes this wonderfully complicated
(when I wrote that this code is cursed, I meant it). In combination with
lazy testing, it probably means there are lots of bugs here.
---
 DOCS/man/mpv.rst   |  3 +++
 options/m_option.c | 27 +++++++++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/DOCS/man/mpv.rst b/DOCS/man/mpv.rst
index eaced80082..9ff62ae4f0 100644
--- a/DOCS/man/mpv.rst
+++ b/DOCS/man/mpv.rst
@@ -520,6 +520,9 @@ Suffix        Meaning
 -add          Append 1 or more items (same syntax as -set)
 ============= ===============================================
 
+Keys are unique within the list. If an already present key is set, the existing
+key is removed before the new value is appended.
+
 Filter options
 ~~~~~~~~~~~~~~
 
diff --git a/options/m_option.c b/options/m_option.c
index 1ff3d26d22..2ebe79cff3 100644
--- a/options/m_option.c
+++ b/options/m_option.c
@@ -1621,6 +1621,28 @@ const m_option_type_t m_option_type_string_list = {
 static int read_subparam(struct mp_log *log, bstr optname, char *termset,
                          bstr *str, bstr *out_subparam);
 
+static int keyvalue_list_find_key(char **lst, bstr str)
+{
+    for (int n = 0; lst && lst[n] && lst[n + 1]; n += 2) {
+        if (bstr_equals0(str, lst[n]))
+            return n / 2;
+    }
+    return -1;
+}
+
+static void keyvalue_list_del_key(char **lst, int index)
+{
+    int count = 0;
+    for (int n = 0; lst && lst[n]; n++)
+        count++;
+    assert(index * 2 + 1 < count);
+    count += 1; // terminating item
+    talloc_free(lst[index * 2 + 0]);
+    talloc_free(lst[index * 2 + 1]);
+    MP_TARRAY_REMOVE_AT(lst, count, index * 2 + 1);
+    MP_TARRAY_REMOVE_AT(lst, count, index * 2 + 0);
+}
+
 static int parse_keyvalue_list(struct mp_log *log, const m_option_t *opt,
                                struct bstr name, struct bstr param, void *dst)
 {
@@ -1664,6 +1686,11 @@ static int parse_keyvalue_list(struct mp_log *log, const m_option_t *opt,
                 break;
         }
         if (dst) {
+            int index = keyvalue_list_find_key(lst, key);
+            if (index >= 0) {
+                keyvalue_list_del_key(lst, index);
+                num -= 2;
+            }
             MP_TARRAY_APPEND(NULL, lst, num, bstrto0(NULL, key));
             MP_TARRAY_APPEND(NULL, lst, num, bstrto0(NULL, val));
         }
-- 
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