vo_gpu, options: don't return NaN through API

Internally, vo_gpu uses NaN for some options to indicate a default value
that is different depending on the context (e.g. different scalers).
There are 2 problems with this:

1. you couldn't reset the options to their defaults
2. NaN is a damn mess and shouldn't be part of the API

The option parser already rejected NaN explicitly, which is why 1.
didn't work. Regarding 2., JSON might be a good example, and actually
caused a bug report.

Fix this by mapping NaN to the special value "default". I think I'd
prefer other mechanisms (maybe just having every scaler expose separate
options?), but for now this will do. See you in a future commit, which
painfully deprecates this and replaces it with something else.

I refrained from using "no" (my favorite magic value for "unset" etc.)
because then I'd have e.g. make --no-scale-param1 work, which in
addition to a lot of effort looks dumb and nobody will use it.

Here's also an apology for the shitty added test script.

Fixes: #6691

1 files changed, 28 insertions, 9 deletions

diff --git a/options/m_option.c b/options/m_option.c
index 7bb43ad399..5df8b00291 100644
--- a/options/m_option.c
+++ b/options/m_option.c
@@ -918,6 +918,11 @@ static int parse_double(struct mp_log *log, const m_option_t *opt,
     if (bstr_eatstart0(&rest, ":") || bstr_eatstart0(&rest, "/"))
         tmp_float /= bstrtod(rest, &rest);
 
+    if ((opt->flags & M_OPT_DEFAULT_NAN) && bstr_equals0(param, "default")) {
+        tmp_float = NAN;
+        goto done;
+    }
+
     if (rest.len) {
         mp_err(log, "The %.*s option must be a floating point number or a "
                "ratio (numerator[:/]denominator): %.*s\n",
@@ -931,6 +936,7 @@ static int parse_double(struct mp_log *log, const m_option_t *opt,
         return M_OPT_OUT_OF_RANGE;
     }
 
+done:
     if (dst)
         VAL(dst) = tmp_float;
     return 1;
@@ -938,12 +944,18 @@ static int parse_double(struct mp_log *log, const m_option_t *opt,
 
 static char *print_double(const m_option_t *opt, const void *val)
 {
-    return talloc_asprintf(NULL, "%f", VAL(val));
+    double f = VAL(val);
+    if (isnan(f) && (opt->flags & M_OPT_DEFAULT_NAN))
+        return talloc_strdup(NULL, "default");
+    return talloc_asprintf(NULL, "%f", f);
 }
 
 static char *print_double_f3(const m_option_t *opt, const void *val)
 {
-    return talloc_asprintf(NULL, "%.3f", VAL(val));
+    double f = VAL(val);
+    if (isnan(f))
+        return print_double(opt, val);
+    return talloc_asprintf(NULL, "%.3f", f);
 }
 
 static void add_double(const m_option_t *opt, void *val, double add, bool wrap)
@@ -989,8 +1001,14 @@ static int double_set(const m_option_t *opt, void *dst, struct mpv_node *src)
 static int double_get(const m_option_t *opt, void *ta_parent,
                       struct mpv_node *dst, void *src)
 {
-    dst->format = MPV_FORMAT_DOUBLE;
-    dst->u.double_ = *(double *)src;
+    double f = *(double *)src;
+    if (isnan(f) && (opt->flags & M_OPT_DEFAULT_NAN)) {
+        dst->format = MPV_FORMAT_STRING;
+        dst->u.string = talloc_strdup(ta_parent, "default");
+    } else {
+        dst->format = MPV_FORMAT_DOUBLE;
+        dst->u.double_ = f;
+    }
     return 1;
 }
 
@@ -1023,12 +1041,14 @@ static int parse_float(struct mp_log *log, const m_option_t *opt,
 
 static char *print_float(const m_option_t *opt, const void *val)
 {
-    return talloc_asprintf(NULL, "%f", VAL(val));
+    double tmp = VAL(val);
+    return print_double(opt, &tmp);
 }
 
 static char *print_float_f3(const m_option_t *opt, const void *val)
 {
-    return talloc_asprintf(NULL, "%.3f", VAL(val));
+    double tmp = VAL(val);
+    return print_double_f3(opt, &tmp);
 }
 
 static void add_float(const m_option_t *opt, void *val, double add, bool wrap)
@@ -1057,9 +1077,8 @@ static int float_set(const m_option_t *opt, void *dst, struct mpv_node *src)
 static int float_get(const m_option_t *opt, void *ta_parent,
                      struct mpv_node *dst, void *src)
 {
-    dst->format = MPV_FORMAT_DOUBLE;
-    dst->u.double_ = VAL(src);
-    return 1;
+    double tmp = VAL(src);
+    return double_get(opt, ta_parent, dst, &tmp);
 }
 
 const m_option_type_t m_option_type_float = {