Re: [PATCH 3/3] fhandler_pty_slave::setup_locale: respect charset == "UTF-8"

[Takashi Yano <takashi.yano@nifty.ne.jp>]

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Hi Corinna,

On Sat, 5 Sep 2020 20:15:06 +0900
Takashi Yano via Cygwin-patches <cygwin-patches@cygwin.com> wrote:
> On Sat, 5 Sep 2020 17:43:01 +0900
> Takashi Yano via Cygwin-patches <cygwin-patches@cygwin.com> wrote:
> > Hi Corinna,
> > 
> > On Fri, 4 Sep 2020 21:22:35 +0200
> > Corinna Vinschen wrote:
> > > Hi Takashi,
> > > 
> > > On Sep  4 23:50, Takashi Yano via Cygwin-patches wrote:
> > > > Hi Corinna,
> > > > 
> > > > On Fri, 4 Sep 2020 14:44:00 +0200
> > > > Corinna Vinschen wrote:
> > > > > On Sep  4 18:21, Takashi Yano via Cygwin-patches wrote:
> > > > > > I think I have found the answer to your request.
> > > > > > Patch attached. What do you think of this patch?
> > > > > > 
> > > > > > Calling initial_setlocale() is necessary because
> > > > > > nl_langinfo() always returns "ANSI_X3.4-1968"
> > > > > > regardless locale setting if this is not called.
> > > > > [...]
> > > > > However, the initial_setlocale() call in dll_crt0_1 calls
> > > > > internal_setlocale(), and *that* function sets the conversion functions
> > > > > for the internal conversions.  What it *doesn't* do yet at the moment is
> > > > > to store the charset name itself or, better, the equivalent codepage.
> > > > > 
> > > > > If we change that, setup_locale can simply go away.  Below is a patch
> > > > > doing just that.  Can you please check if that works in your test
> > > > > scenarios?
> > > > 
> > > > I tried your patch, but unfortunately it does not work.
> > > > cygheap->locale.term_code_page is 0 in pty master.
> > > > 
> > > > If the following lines are moved in internal_setlocale(),
> > > > 
> > > >   const char *charset = __locale_charset (__get_global_locale ());
> > > >   debug_printf ("Global charset set to %s", charset);
> > > >   /* Store codepage to be utilized by pseudo console code. */
> > > >   cygheap->locale.term_code_page =
> > > >             __eval_codepage_from_internal_charset (charset);
> > > > 
> > > > in internal_setlocale() before
> > > > 
> > > >   /* Don't do anything if the charset hasn't actually changed. */
> > > >   if (cygheap->locale.mbtowc == __get_global_locale ()->mbtowc)
> > > >     return;
> > > 
> > > Uh, that makes sense.
> > > 
> > > > cygheap->locale.term_code_page is always 65001 even if mintty is
> > > > startted by
> > > > mintty -o locale=ja_JP -o charset=CP932
> > > > or
> > > > mintty -o locale=ja_JP -o charset=EUCJP
> > > > 
> > > > Perhaps, this is because LANG is not set properly yet when mintty
> > > > is started.
> > > 
> > > Yeah, that's the reason.  The above settings of locale and charset on
> > > the CLI should only take over when mintty calls setlocale() with a
> > > matching string.  The fact that it sets the matching value in the
> > > environment, too, should only affect child processes, not mintty itself.
> > > 
> > > But it's incorrect to call initial_setlocale() from setup_locale()
> > > without resetting it to its original value.
> > > 
> > > Unfortunately that doesn't solve any problem with the pseudo console
> > > codepage.  Drat.  It sounds like you need the terminal's charset,
> > > rather than the one set in the environment.
> > > 
> > > So this boils down to the fact that term_code_page must be set
> > > after the application is already running and as soo as it creates
> > > the pty, me thinks.  What if __eval_codepage_from_internal_charset()
> > > is called at pty creation?  Or even on reading from /writing to
> > > the pty the first time?  That should always be late enough to fetch
> > > the correct codepage.
> > > 
> > > Patch attached.  Does that work as expected?
> > 
> > Thank you very much for the patch.
> > 
> > Your new additional patch works well except the test case such as:
> > 
> >   int pm = getpt();
> >   if (fork()) {
> >     [do the master operations]
> >   } else {
> >     int ps = open(ptsname(pm), O_RDWR|O_NOCTTY);
> >     close(pm);
> >     setsid();
> >     ioctl(ps, TIOCSCTTY, 1);
> >     dup2(ps, 0);
> >     dup2(ps, 1);
> >     dup2(ps, 2);
> >     close(ps);
> >     [exec non-cygwin process]
> >   }
> > 
> > If this test case is run in cygwin console (command prompt),
> > it causes garbled output due to term_code_page == 0.
> > 
> > The second additional patch attached fixes the isseu.
> 
> No. This does not fix enough.
> 
> In the test case above, if it does not call setlocale(),
> __eval_codepage_from_internal_charset() always returns "ASCII"
> regardless of locale setting. Therefore, output is garbled if
> the terminal charset is not UTF-8.

New additional patch against your patches is attached.
In the end, essentially what was being done in the original
code has been restored.

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>

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diff --git a/winsup/cygwin/cygheap.h b/winsup/cygwin/cygheap.h
index 2b84f4252..8877cc358 100644
--- a/winsup/cygwin/cygheap.h
+++ b/winsup/cygwin/cygheap.h
@@ -341,7 +341,6 @@ struct cygheap_debug
 struct cygheap_locale
 {
   mbtowc_p mbtowc;
-  UINT term_code_page;
 };
 
 struct user_heap_info
diff --git a/winsup/cygwin/fhandler.h b/winsup/cygwin/fhandler.h
index af619df5f..b4ba9428a 100644
--- a/winsup/cygwin/fhandler.h
+++ b/winsup/cygwin/fhandler.h
@@ -2336,6 +2336,7 @@ class fhandler_pty_slave: public fhandler_pty_common
   void set_switch_to_pcon (void);
   void reset_switch_to_pcon (void);
   void mask_switch_to_pcon_in (bool mask);
+  void setup_locale (void);
 };
 
 #define __ptsname(buf, unit) __small_sprintf ((buf), "/dev/pty%d", (unit))
diff --git a/winsup/cygwin/fhandler_tty.cc b/winsup/cygwin/fhandler_tty.cc
index feb014175..ed1c34a5f 100644
--- a/winsup/cygwin/fhandler_tty.cc
+++ b/winsup/cygwin/fhandler_tty.cc
@@ -635,9 +635,9 @@ fhandler_pty_slave::open (int flags, mode_t)
 
   fhandler_console::need_invisible ();
 
-#if 1 /* Let's try this first */
-  if (!cygheap->locale.term_code_page)
-    cygheap->locale.term_code_page = __eval_codepage_from_internal_charset ();
+#if 0 /* Let's try this first */
+  if (!get_ttyp ()->term_code_page)
+    get_ttyp ()->term_code_page = __eval_codepage_from_internal_charset ();
 #endif
 
   set_open_status ();
@@ -1615,8 +1615,8 @@ fhandler_pty_master::write (const void *ptr, size_t len)
     return (ssize_t) bg;
 
 #if 0 /* Let's try this if setting codepage at pty open time is not enough */
-  if (!cygheap->locale.term_code_page)
-    cygheap->locale.term_code_page = __eval_codepage_from_internal_charset ();
+  if (!get_ttyp ()->term_code_page)
+    get_ttyp ()->term_code_page = __eval_codepage_from_internal_charset ();
 #endif
 
   push_process_state process_state (PID_TTYOU);
@@ -1627,7 +1627,7 @@ fhandler_pty_master::write (const void *ptr, size_t len)
     {
       size_t nlen;
       char *buf = convert_mb_str (CP_UTF8, &nlen,
-				  cygheap->locale.term_code_page,
+				  get_ttyp ()->term_code_page,
 				  (const char *) ptr, len);
 
       WaitForSingleObject (input_mutex, INFINITE);
@@ -1795,6 +1795,13 @@ fhandler_pty_common::set_close_on_exec (bool val)
   close_on_exec (val);
 }
 
+void
+fhandler_pty_slave::setup_locale (void)
+{
+  if (!get_ttyp ()->term_code_page)
+    get_ttyp ()->term_code_page = __eval_codepage_from_internal_charset ();
+}
+
 void
 fhandler_pty_slave::fixup_after_fork (HANDLE parent)
 {
@@ -1811,6 +1818,9 @@ fhandler_pty_slave::fixup_after_exec ()
   if (!close_on_exec ())
     fixup_after_fork (NULL);	/* No parent handle required. */
 
+  /* Set locale */
+  setup_locale ();
+
   /* Hook Console API */
 #define DO_HOOK(module, name) \
   if (!name##_Orig) \
@@ -1982,8 +1992,8 @@ fhandler_pty_master::pty_master_fwd_thread ()
   char outbuf[65536];
 
 #if 0 /* Let's try this if setting codepage at pty open time is not enough */
-  if (!cygheap->locale.term_code_page)
-    cygheap->locale.term_code_page = __eval_codepage_from_internal_charset ();
+  if (!get_ttyp ()->term_code_page)
+    get_ttyp ()->term_code_page = __eval_codepage_from_internal_charset ();
 #endif
 
   termios_printf ("Started.");
@@ -2041,7 +2051,7 @@ fhandler_pty_master::pty_master_fwd_thread ()
 	      state = 0;
 
 	  size_t nlen;
-	  char *buf = convert_mb_str (cygheap->locale.term_code_page,
+	  char *buf = convert_mb_str (get_ttyp ()->term_code_page,
 				      &nlen, CP_UTF8, ptr, wlen);
 
 	  ptr = buf;
@@ -2064,7 +2074,7 @@ fhandler_pty_master::pty_master_fwd_thread ()
 	  continue;
 	}
       size_t nlen;
-      char *buf = convert_mb_str (cygheap->locale.term_code_page, &nlen,
+      char *buf = convert_mb_str (get_ttyp ()->term_code_page, &nlen,
 				  GetConsoleOutputCP (), ptr, wlen);
 
       ptr = buf;
diff --git a/winsup/cygwin/nlsfuncs.cc b/winsup/cygwin/nlsfuncs.cc
index 6bffc77c9..dd82b7f49 100644
--- a/winsup/cygwin/nlsfuncs.cc
+++ b/winsup/cygwin/nlsfuncs.cc
@@ -1455,7 +1455,17 @@ __set_charset_from_locale (const char *locale, char *charset)
 UINT
 __eval_codepage_from_internal_charset ()
 {
-  const char *charset = __locale_charset (__get_global_locale ());
+  const char *env = __get_locale_env (_REENT, LC_CTYPE);
+  char locale[ENCODING_LEN + 1];
+  strncpy (locale, env, ENCODING_LEN);
+  locale[ENCODING_LEN] = '\0';
+  __locale_t loc;
+  memset (&loc, 0, sizeof (loc));
+  const char *charset;
+  if (__loadlocale (&loc, LC_CTYPE, locale))
+    charset = __locale_charset (&loc);
+  else
+    charset = __locale_charset (__get_global_locale ());
   UINT codepage = CP_UTF8; /* Default UTF8 */
 
   /* The internal charset names are well defined, so we can use shortcuts. */
diff --git a/winsup/cygwin/spawn.cc b/winsup/cygwin/spawn.cc
index 02c4207ab..92d190d1a 100644
--- a/winsup/cygwin/spawn.cc
+++ b/winsup/cygwin/spawn.cc
@@ -619,6 +619,18 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv,
 	    }
 	}
 
+      if (!iscygwin ())
+	{
+	  cfd.rewind ();
+	  while (cfd.next () >= 0)
+	    if (cfd->get_major () == DEV_PTYS_MAJOR)
+	      {
+		fhandler_pty_slave *ptys =
+		  (fhandler_pty_slave *)(fhandler_base *) cfd;
+		ptys->setup_locale ();
+	      }
+	}
+
       /* Set up needed handles for stdio */
       si.dwFlags = STARTF_USESTDHANDLES;
       si.hStdInput = handle ((in__stdin < 0 ? 0 : in__stdin), false);