options: add some way to more or less "unapply" profiles

Make it possible to restore from profiles by backing up the option
values before profile application. This is sort of like unapplying a
profile. Since there might be multiple ways to do this, a profile needs
to explicitly provide the "profile-restore" option, which specifies how
exactly this should be done.

This is a big mess. There is not natural way to do this. Profile
application is "destructive" and simply changes the values of the
options. Maybe one could argue that the option system should have
hierarchical "overlays" of profiles instead, where unset options will
use the value of the lower profiles. Options set interactively by the
user would be the top profile. Default values would be in the lowest
profile. You could unapply a profile by simply removing it from this
overlay stack.

But uh, let's not, so here's something stupid. It reuses some code used
for file local options to reduce code size. At least the overlay idea
would still be possible in theory, and could be added as another
profile-restore mode.

This is used by the following commit.

3 files changed, 124 insertions, 55 deletions

diff --git a/options/m_config_frontend.c b/options/m_config_frontend.c
index 94cc9c015a..a3356c4111 100644
--- a/options/m_config_frontend.c
+++ b/options/m_config_frontend.c
@@ -51,17 +51,28 @@ struct m_profile {
     char *name;
     char *desc;
     char *cond;
+    int restore_mode;
     int num_opts;
     // Option/value pair array.
     // name,value = opts[n*2+0],opts[n*2+1]
     char **opts;
+    // For profile restoring.
+    struct m_opt_backup *backups;
 };
 
 // In the file local case, this contains the old global value.
+// It's also used for profile restoring.
 struct m_opt_backup {
     struct m_opt_backup *next;
     struct m_config_option *co;
-    void *backup;
+    int flags;
+    void *backup, *nval;
+};
+
+static const struct m_option profile_restore_mode_opt = {
+    .name = "profile-restore",
+    .type = &m_option_type_choice,
+    M_CHOICES({"default", 0}, {"copy", 1}, {"copy-equal", 2}),
 };
 
 static void list_profiles(struct m_config *config)
@@ -178,44 +189,66 @@ error:
     return NULL;
 }
 
-static void ensure_backup(struct m_config *config, struct m_config_option *co)
+static void backup_dtor(void *p)
+{
+    struct m_opt_backup *bc = p;
+    m_option_free(bc->co->opt, bc->backup);
+    if (bc->nval)
+        m_option_free(bc->co->opt, bc->nval);
+}
+
+#define BACKUP_LOCAL 1
+#define BACKUP_NVAL 2
+static void ensure_backup(struct m_opt_backup **list, int flags,
+                          struct m_config_option *co)
 {
     if (!co->data)
         return;
-    for (struct m_opt_backup *cur = config->backup_opts; cur; cur = cur->next) {
+    for (struct m_opt_backup *cur = *list; cur; cur = cur->next) {
         if (cur->co->data == co->data) // comparing data ptr catches aliases
             return;
     }
     struct m_opt_backup *bc = talloc_ptrtype(NULL, bc);
+    talloc_set_destructor(bc, backup_dtor);
     *bc = (struct m_opt_backup) {
         .co = co,
         .backup = talloc_zero_size(bc, co->opt->type->size),
+        .nval = flags & BACKUP_NVAL
+            ? talloc_zero_size(bc, co->opt->type->size) : NULL,
+        .flags = flags,
     };
     m_option_copy(co->opt, bc->backup, co->data);
-    bc->next = config->backup_opts;
-    config->backup_opts = bc;
-    co->is_set_locally = true;
+    bc->next = *list;
+    *list = bc;
+    if (bc->flags & BACKUP_LOCAL)
+        co->is_set_locally = true;
 }
 
-void m_config_restore_backups(struct m_config *config)
+static void restore_backups(struct m_opt_backup **list, struct m_config *config)
 {
-    while (config->backup_opts) {
-        struct m_opt_backup *bc = config->backup_opts;
-        config->backup_opts = bc->next;
+    while (*list) {
+        struct m_opt_backup *bc = *list;
+        *list = bc->next;
 
-        m_config_set_option_raw(config, bc->co, bc->backup, 0);
+        if (!bc->nval || m_option_equal(bc->co->opt, bc->co->data, bc->nval))
+            m_config_set_option_raw(config, bc->co, bc->backup, 0);
 
-        m_option_free(bc->co->opt, bc->backup);
-        bc->co->is_set_locally = false;
+        if (bc->flags & BACKUP_LOCAL)
+            bc->co->is_set_locally = false;
         talloc_free(bc);
     }
 }
 
+void m_config_restore_backups(struct m_config *config)
+{
+    restore_backups(&config->backup_opts, config);
+}
+
 void m_config_backup_opt(struct m_config *config, const char *opt)
 {
     struct m_config_option *co = m_config_get_co(config, bstr0(opt));
     if (co) {
-        ensure_backup(config, co);
+        ensure_backup(&config->backup_opts, BACKUP_LOCAL, co);
     } else {
         MP_ERR(config, "Option %s not found.\n", opt);
     }
@@ -224,7 +257,7 @@ void m_config_backup_opt(struct m_config *config, const char *opt)
 void m_config_backup_all_opts(struct m_config *config)
 {
     for (int n = 0; n < config->num_opts; n++)
-        ensure_backup(config, &config->opts[n]);
+        ensure_backup(&config->backup_opts, BACKUP_LOCAL, &config->opts[n]);
 }
 
 
@@ -360,7 +393,7 @@ static int handle_set_opt_flags(struct m_config *config,
         return M_OPT_INVALID;
     }
     if ((flags & M_SETOPT_BACKUP) && set)
-        ensure_backup(config, co);
+        ensure_backup(&config->backup_opts, BACKUP_LOCAL, co);
 
     return set ? 2 : 1;
 }
@@ -577,6 +610,9 @@ int m_config_set_option_raw(struct m_config *config,
     if (!co->data)
         return flags & M_SETOPT_FROM_CMDLINE ? 0 : M_OPT_UNKNOWN;
 
+    if (config->profile_backup_tmp)
+        ensure_backup(config->profile_backup_tmp, config->profile_backup_flags, co);
+
     m_config_mark_co_flags(co, flags);
 
     m_option_copy(co->opt, co->data, data);
@@ -884,23 +920,26 @@ struct m_profile *m_config_add_profile(struct m_config *config, char *name)
     return p;
 }
 
-void m_profile_set_desc(struct m_profile *p, bstr desc)
-{
-    talloc_free(p->desc);
-    p->desc = bstrto0(p, desc);
-}
-
-void m_profile_set_cond(struct m_profile *p, bstr cond)
-{
-    TA_FREEP(&p->cond);
-    cond = bstr_strip(cond);
-    if (cond.len)
-        p->cond = bstrto0(p, cond);
-}
-
 int m_config_set_profile_option(struct m_config *config, struct m_profile *p,
                                 bstr name, bstr val)
 {
+    if (bstr_equals0(name, "profile-desc")) {
+        talloc_free(p->desc);
+        p->desc = bstrto0(p, val);
+        return 0;
+    }
+    if (bstr_equals0(name, "profile-cond")) {
+        TA_FREEP(&p->cond);
+        val = bstr_strip(val);
+        if (val.len)
+            p->cond = bstrto0(p, val);
+        return 0;
+    }
+    if (bstr_equals0(name, profile_restore_mode_opt.name)) {
+        return m_option_parse(config->log, &profile_restore_mode_opt, name, val,
+                              &p->restore_mode);
+    }
+
     int i = m_config_set_option_cli(config, name, val,
                                     M_SETOPT_CHECK_ONLY |
                                     M_SETOPT_FROM_CONFIG_FILE);
@@ -914,19 +953,32 @@ int m_config_set_profile_option(struct m_config *config, struct m_profile *p,
     return 1;
 }
 
-int m_config_set_profile(struct m_config *config, char *name, int flags)
+static struct m_profile *find_check_profile(struct m_config *config, char *name)
 {
     struct m_profile *p = m_config_get_profile0(config, name);
     if (!p) {
         MP_WARN(config, "Unknown profile '%s'.\n", name);
-        return M_OPT_INVALID;
+        return NULL;
     }
-    MP_VERBOSE(config, "Applying profile '%s'...\n", name);
-
     if (config->profile_depth > MAX_PROFILE_DEPTH) {
         MP_WARN(config, "WARNING: Profile inclusion too deep.\n");
+        return NULL;
+    }
+    return p;
+}
+
+int m_config_set_profile(struct m_config *config, char *name, int flags)
+{
+    MP_VERBOSE(config, "Applying profile '%s'...\n", name);
+    struct m_profile *p = find_check_profile(config, name);
+    if (!p)
         return M_OPT_INVALID;
+
+    if (!config->profile_backup_tmp && p->restore_mode) {
+        config->profile_backup_tmp = &p->backups;
+        config->profile_backup_flags = p->restore_mode == 2 ? BACKUP_NVAL : 0;
     }
+
     config->profile_depth++;
     for (int i = 0; i < p->num_opts; i++) {
         m_config_set_option_cli(config,
@@ -936,6 +988,31 @@ int m_config_set_profile(struct m_config *config, char *name, int flags)
     }
     config->profile_depth--;
 
+    if (config->profile_backup_tmp == &p->backups) {
+        config->profile_backup_tmp = NULL;
+
+        for (struct m_opt_backup *bc = p->backups; bc; bc = bc->next) {
+            if (bc && bc->nval)
+                m_option_copy(bc->co->opt, bc->nval, bc->co->data);
+            talloc_steal(p, bc);
+        }
+    }
+
+    return 0;
+}
+
+int m_config_restore_profile(struct m_config *config, char *name)
+{
+    MP_VERBOSE(config, "Restoring from profile '%s'...\n", name);
+    struct m_profile *p = find_check_profile(config, name);
+    if (!p)
+        return M_OPT_INVALID;
+
+    if (!p->backups)
+        MP_WARN(config, "Profile contains no restore data.\n");
+
+    restore_backups(&p->backups, config);
+
     return 0;
 }
 
@@ -960,6 +1037,12 @@ struct mpv_node m_config_get_profiles(struct m_config *config)
             node_map_add_string(entry, "profile-desc", profile->desc);
         if (profile->cond)
             node_map_add_string(entry, "profile-cond", profile->cond);
+        if (profile->restore_mode) {
+            char *s =
+                m_option_print(&profile_restore_mode_opt, &profile->restore_mode);
+            node_map_add_string(entry, profile_restore_mode_opt.name, s);
+            talloc_free(s);
+        }
 
         struct mpv_node *opts =
             node_map_add(entry, "options", MPV_FORMAT_NODE_ARRAY);
diff --git a/options/m_config_frontend.h b/options/m_config_frontend.h
index 81bc78b6e1..ee6b9aec46 100644
--- a/options/m_config_frontend.h
+++ b/options/m_config_frontend.h
@@ -70,6 +70,9 @@ typedef struct m_config {
     struct m_profile *profiles;
     // Depth when recursively including profiles.
     int profile_depth;
+    // Temporary during profile application.
+    struct m_opt_backup **profile_backup_tmp;
+    int profile_backup_flags;
 
     struct m_opt_backup *backup_opts;
 
@@ -224,17 +227,6 @@ void m_config_finish_default_profile(struct m_config *config, int flags);
  */
 struct m_profile *m_config_add_profile(struct m_config *config, char *name);
 
-/*  Set the description of a profile.
- *  Used by the config file parser when defining a profile.
- *
- *  \param p The profile object.
- *  \param arg The profile's name.
- */
-void m_profile_set_desc(struct m_profile *p, bstr desc);
-
-// Set auto profile condition of a profile.
-void m_profile_set_cond(struct m_profile *p, bstr cond);
-
 /*  Add an option to a profile.
  *  Used by the config file parser when defining a profile.
  *
@@ -256,6 +248,9 @@ int m_config_set_profile_option(struct m_config *config, struct m_profile *p,
  */
 int m_config_set_profile(struct m_config *config, char *name, int flags);
 
+// Attempt to "unset" a profile if possible.
+int m_config_restore_profile(struct m_config *config, char *name);
+
 struct mpv_node m_config_get_profiles(struct m_config *config);
 
 // Run async option updates here. This will call option_change_callback() on it.
diff --git a/options/parse_configfile.c b/options/parse_configfile.c
index 96b607d554..627c466948 100644
--- a/options/parse_configfile.c
+++ b/options/parse_configfile.c
@@ -127,16 +127,7 @@ int m_config_parse(m_config_t *config, const char *location, bstr data,
             goto error;
         }
 
-        int res;
-        if (bstr_equals0(option, "profile-desc")) {
-            m_profile_set_desc(profile, value);
-            res = 0;
-        } else if (bstr_equals0(option, "profile-cond")) {
-            m_profile_set_cond(profile, value);
-            res = 0;
-        } else {
-            res = m_config_set_profile_option(config, profile, option, value);
-        }
+        int res = m_config_set_profile_option(config, profile, option, value);
         if (res < 0) {
             MP_ERR(config, "%s setting option %.*s='%.*s' failed.\n",
                    loc, BSTR_P(option), BSTR_P(value));