config: add more generic config_GetSysDir()

A quick survey of used installation directories yields those:
datadir, libdir, localedir, pkgdatadir, pkglibdir, pkglibexecdir.

The current pair of functions is up to the requirements. This provides
a more generic function prototype, similar to what is done for user
directories.

Refs #19748, #19894.

include/vlc_configuration.h

@@ -297,7 +297,32 @@ VLC_API char *config_GetDataDir(void) VLC_USED VLC_MALLOC;
  */
 VLC_API char *config_GetLibDir(void) VLC_USED VLC_MALLOC;
 
-typedef enum vlc_userdir
+/**
+ * System directory identifiers
+ */
+typedef enum vlc_system_dir
+{
+    VLC_PKG_DATA_DIR, /**< Package-specific architecture-independent read-only
+                           data directory (e.g. /usr/local/data/vlc). */
+    VLC_PKG_LIB_DIR, /**< Package-specific architecture-dependent read-only
+                          data directory (e.g. /usr/local/lib/vlc). */
+} vlc_sysdir_t;
+
+/**
+ * Gets an installation directory.
+ *
+ * This function determines one of the installation directory.
+ *
+ * @param dir identifier of the directory (see \ref vlc_sysdir_t)
+ * @param filename name of a file or other object within the directory
+ *                 (or NULL to obtain the plain directory)
+ *
+ * @return a heap-allocated string (use free() to release it), or NULL on error
+ */
+VLC_API char *config_GetSysPath(vlc_sysdir_t dir, const char *filename)
+VLC_USED VLC_MALLOC;
+
+typedef enum vlc_user_dir
 {
     VLC_HOME_DIR, /* User's home */
     VLC_CONFIG_DIR, /* VLC-specific configuration directory */

src/darwin/dirs.c

@@ -108,6 +108,31 @@ char *config_GetDataDir (void)
     return datadir;
 }
 
+char *config_GetSysPath(vlc_sysdir_t type, const char *filename)
+{
+    char *dir;
+
+    switch (type)
+    {
+        case VLC_PKG_DATA_DIR:
+            dir = config_GetDataDir();
+            break;
+        case VLC_PKG_LIB_DIR:
+            dir = config_GetLibDir();
+            break;
+        default:
+            vlc_assert_unreachable();
+    }
+
+    if (filename == NULL || unlikely(dir == NULL))
+        return dir;
+
+    char *path;
+    asprintf(&path, "%s/%s", dir, filename);
+    free(dir);
+    return path;
+}
+
 static char *config_GetHomeDir (void)
 {
     const char *home = getenv ("HOME");

src/libvlccore.sym

@@ -54,6 +54,7 @@ config_FindConfig
 config_GetDataDir
 config_GetLibDir
 config_GetFloat
+config_GetSysPath
 config_GetUserDir
 config_GetInt
 config_GetIntChoices

src/os2/dirs.c

@@ -64,6 +64,31 @@ char *config_GetDataDir (void)
     return datadir;
 }
 
+char *config_GetSysPath(vlc_sysdir_t type, const char *filename)
+{
+    char *dir;
+
+    switch (type)
+    {
+        case VLC_PKG_DATA_DIR:
+            dir = config_GetDataDir();
+            break;
+        case VLC_PKG_LIB_DIR:
+            dir = config_GetLibDir();
+            break;
+        default:
+            vlc_assert_unreachable();
+    }
+
+    if (filename == NULL || unlikely(dir == NULL))
+        return dir;
+
+    char *path;
+    asprintf(&path, "%s/%s", dir, filename);
+    free(dir);
+    return path;
+}
+
 static char *config_GetHomeDir (void)
 {
     const char *home = getenv ("HOME");

src/posix/dirs.c

@@ -57,6 +57,32 @@ VLC_WEAK char *config_GetLibDir(void)
     return strdup((path != NULL) ? path : PKGLIBDIR);
 }
 
+char *config_GetSysPath(vlc_sysdir_t type, const char *filename)
+{
+    char *dir;
+
+    switch (type)
+    {
+        case VLC_PKG_DATA_DIR:
+            dir = config_GetDataDir();
+            break;
+        case VLC_PKG_LIB_DIR:
+            dir = config_GetLibDir();
+            break;
+        default:
+            vlc_assert_unreachable();
+    }
+
+    if (filename == NULL || unlikely(dir == NULL))
+        return dir;
+
+    char *path;
+    if (unlikely(asprintf(&path, "%s/%s", dir, filename) == -1))
+        path = NULL;
+    free(dir);
+    return path;
+}
+
 static char *config_GetHomeDir (void)
 {
     /* 1/ Try $HOME  */

src/win32/dirs.c

@@ -212,6 +212,32 @@ char *config_GetDataDir (void)
     return (path != NULL) ? strdup (path) : config_GetLibDir ();
 }
 
+char *config_GetSysPath(vlc_sysdir_t type, const char *filename)
+{
+    char *dir;
+
+    switch (type)
+    {
+        case VLC_PKG_DATA_DIR:
+            dir = config_GetDataDir();
+            break;
+        case VLC_PKG_LIB_DIR:
+            dir = config_GetLibDir();
+            break;
+        default:
+            vlc_assert_unreachable();
+    }
+
+    if (filename == NULL || unlikely(dir == NULL))
+        return dir;
+
+    char *path;
+    if (unlikely(asprintf(&path, "%s/%s", dir, filename) == -1))
+        path = NULL;
+    free(dir);
+    return path;
+}
+
 static char *config_GetShellDir (int csidl)
 {
     wchar_t wdir[MAX_PATH];