win32: optimize mp_vfprintf a little

- remove redundant strlen/wcslen
- reuse allocated temporary buffers

The difference is not big, but it satisfies me to remove those
redundancies.

osdep/io.c

@@ -307,8 +307,6 @@ static int mp_vfprintf(FILE *stream, const char *format, va_list args)
 
 static int mp_vfprintf(FILE *stream, const char *format, va_list args)
 {
-    int done = 0;
-
     HANDLE wstream = INVALID_HANDLE_VALUE;
 
     if (stream == stdout || stream == stderr) {
@@ -316,20 +314,10 @@ static int mp_vfprintf(FILE *stream, const char *format, va_list args)
                                STD_OUTPUT_HANDLE : STD_ERROR_HANDLE);
     }
 
-    if (mp_check_console(wstream)) {
-        size_t len = vsnprintf(NULL, 0, format, args) + 1;
-        char *buf = talloc_array(NULL, char, len);
+    if (mp_check_console(wstream))
+        return mp_write_console_ansi(wstream, format, args);
 
-        if (buf) {
-            done = vsnprintf(buf, len, format, args);
-            mp_write_console_ansi(wstream, buf);
-        }
-        talloc_free(buf);
-    } else {
-        done = vfprintf(stream, format, args);
-    }
-
-    return done;
+    return vfprintf(stream, format, args);
 }
 #endif
 

osdep/terminal-dummy.c

@@ -1,5 +1,7 @@
 #include "terminal.h"
 
+#include "misc/bstr.h"
+
 void terminal_init(void)
 {
 }
@@ -25,8 +27,9 @@ void terminal_get_size2(int *rows, int *cols, int *px_width, int *px_height)
 {
 }
 
-void mp_write_console_ansi(void *wstream, char *buf)
+int mp_write_console_ansi(void *wstream, const char *format, va_list args)
 {
+    return 0;
 }
 
 bool terminal_try_attach(void)

osdep/terminal-win.c

@@ -204,6 +204,12 @@ void terminal_setup_getch(struct input_ctx *ictx)
     }
 }
 
+DWORD tmp_buffers_key = FLS_OUT_OF_INDEXES;
+struct tmp_buffers {
+    bstr write_console_buf;
+    wchar_t *write_console_wbuf;
+};
+
 void terminal_uninit(void)
 {
     if (running) {
@@ -212,6 +218,7 @@ void terminal_uninit(void)
         input_ctx = NULL;
         running = false;
     }
+    FlsFree(tmp_buffers_key);
 }
 
 bool terminal_in_background(void)
@@ -219,14 +226,20 @@ bool terminal_in_background(void)
     return false;
 }
 
-void mp_write_console_ansi(HANDLE wstream, char *buf)
+int mp_write_console_ansi(HANDLE wstream, const char *format, va_list args)
 {
-    wchar_t *wbuf = mp_from_utf8(NULL, buf);
-    wchar_t *pos = wbuf;
+    struct tmp_buffers *buffers = FlsGetValue(tmp_buffers_key);
+    if (!buffers)
+        buffers = talloc_zero(NULL, struct tmp_buffers);
+
+    buffers->write_console_buf.len = 0;
+    bstr_xappend_vasprintf(buffers, &buffers->write_console_buf, format, args);
+    int wlen = bstr_to_wchar(buffers, buffers->write_console_buf, &buffers->write_console_wbuf);
+    wchar_t *pos = buffers->write_console_wbuf;
 
     while (*pos) {
         if (is_native_out_vt(wstream)) {
-            WriteConsoleW(wstream, pos, wcslen(pos), NULL, NULL);
+            WriteConsoleW(wstream, pos, wlen, NULL, NULL);
             break;
         }
         wchar_t *next = wcschr(pos, '\033');
@@ -365,7 +378,12 @@ void mp_write_console_ansi(HANDLE wstream, char *buf)
         pos = next;
     }
 
-    talloc_free(wbuf);
+    int ret = buffers->write_console_buf.len;
+
+    if (!FlsSetValue(tmp_buffers_key, buffers))
+        talloc_free(buffers);
+
+    return ret;
 }
 
 static bool is_a_console(HANDLE h)
@@ -455,4 +473,6 @@ void terminal_init(void)
 
     GetConsoleScreenBufferInfo(hSTDOUT, &cinfo);
     stdoutAttrs = cinfo.wAttributes;
+
+    tmp_buffers_key = FlsAlloc((PFLS_CALLBACK_FUNCTION)talloc_free);
 }

osdep/terminal.h

@@ -20,8 +20,10 @@
 #ifndef MPLAYER_GETCH2_H
 #define MPLAYER_GETCH2_H
 
+#include <stdarg.h>
 #include <stdbool.h>
-#include <stdio.h>
+
+#include "misc/bstr.h"
 
 #define TERM_ESC_GOTO_YX            "\033[%d;%df"
 #define TERM_ESC_HIDE_CURSOR        "\033[?25l"
@@ -52,7 +54,7 @@ void terminal_get_size(int *w, int *h);
 void terminal_get_size2(int *rows, int *cols, int *px_width, int *px_height);
 
 // Windows only.
-void mp_write_console_ansi(void *wstream, char *buf);
+int mp_write_console_ansi(void *wstream, const char *format, va_list args);
 bool mp_check_console(void *handle);
 
 /* Windows-only function to attach to the parent process's console */

test/test_utils.c

@@ -107,7 +107,7 @@ void mp_msg(struct mp_log *log, int lev, const char *format, ...) {};
 int mp_msg_find_level(const char *s) {return 0;};
 int mp_msg_level(struct mp_log *log) {return 0;};
 void mp_msg_set_max_level(struct mp_log *log, int lev) {};
-void mp_write_console_ansi(void *wstream, char *buf) {};
+int mp_write_console_ansi(void *wstream, const char *format, va_list args) {return 0;};
 bool mp_check_console(void *handle) { return false; };
 void mp_set_avdict(AVDictionary **dict, char **kv) {};
 struct mp_log *mp_log_new(void *talloc_ctx, struct mp_log *parent,