[RFC] Add support for locally modified environment variables for windows-nat.c

["Pierre Muller" <pierre dot muller at ics-cnrs dot unistra dot fr>]

A while ago
Sebastian Puebla submitted a patch for 
support of locally modified environment variables.

http://sourceware.org/ml/gdb-patches/2010-05/msg00317.html
http://sourceware.org/ml/gdb-patches/2010-08/msg00026.html
http://sourceware.org/ml/gdb-patches/2010-11/msg00128.html

Nevertheless, I suspect that his patch would not have worked for Cygwin,
because Cygwin converts several environment variables
from windows style to POSIX style.

  Here is a patch that does support also Cygwin special variables.
This patch applies on top of my previously submitted patch
to separate out Cygwin/mingw and ANSI/Unicode specific code.
http://sourceware.org/ml/gdb-patches/2011-04/msg00328.html

  The patch allows to propagate locally modified
environment variables to inferior for both Cygwin and mingw
compilation hosts.

  There list of cygwin converted variables was
extracted from  from winsup/cygwin/environ.cc source,
from January 2011.

  Comments welcome,

Pierre Muller



2011-04-20  Pierre Muller  <muller@ics.u-strasbg.fr>

	Add support for locally modifed environment variables in windows
	native hosts.
	(win_env): New type.
	(conv_envvars): New array of type win_env.
	(cygwin_convert_envs, cywin_restore_envs): New functions using
	CONV_ENVVARS array to convert Cygwin environment variables
	back and forth to Windows style.
	(windows_create_inferior): Add support for setting 7th parameter
	of CreateProcess call containing possibly locally modified
	environment variables.

diff --git a/gdb/windows-nat.c b/gdb/windows-nat.c
index 9b49e6e..90e52af 100644
--- a/gdb/windows-nat.c
+++ b/gdb/windows-nat.c
@@ -1967,6 +1967,95 @@ windows_set_console_info (STARTUPINFO *si, DWORD
*flags)
   *flags |= CREATE_NEW_CONSOLE;
 }
 
+#ifdef __CYGWIN__
+/* List of names which are converted from dos to unix on the way in
+   and back again on the way out.
+   PATH needs to be here because CreateProcess uses it and gdb uses
+   CreateProcess.  HOME is here because most shells use it and would be
+   confused by Windows style path names.  */
+typedef struct struct_win_env {
+    char *name;
+    int in_index;
+    void *in_orig_val;
+    int is_list;
+} win_env;
+
+/* This list is extracted from cygwin/environ.cc source,
+   list from January 2011.  */
+static win_env conv_envvars[] =
+  {
+    {"PATH=", -1, NULL, 1},
+    {"HOME=", -1, NULL, 0},
+    {"LD_LIBRARY_PATH=", -1, NULL, 1},
+    {"TMPDIR=", -1, NULL, 0},
+    {"TMP=", -1, NULL, 0},
+    {"TEMP=", -1, NULL, 0},
+    {NULL, -1, NULL, 0}
+  };
+
+/* cgwin_convert_envs function uses conv_envvars array above to
+   convert Cygwin environment variables back to win32 format.  */
+
+static void
+cygwin_convert_envs (char **in_env)
+{
+  int i, j;
+
+  for (i = 0; in_env[i]; i++)
+    {
+      for (j = 0; conv_envvars[j].name; j++)
+	{
+	  char *name = conv_envvars[j].name;
+	  int nlen = strlen(name);
+
+	  if (strncmp (in_env[i], name, nlen) == 0)
+	    {
+	      char *conv;
+	      int len;
+
+	      /* We found this environment variable that we need to convert.
*/
+	      conv_envvars[j].in_index = i;
+	      conv_envvars[j].in_orig_val = in_env[i];
+	      if (conv_envvars[j].is_list)
+		{
+		  len = cygwin_conv_path_list (CCP_POSIX_TO_WIN_A,
+					       &in_env[i][nlen], NULL, 0);
+		  conv = (char *) alloca (len + nlen + 1);
+		  strcpy (conv, name);
+		  cygwin_conv_path_list (CCP_POSIX_TO_WIN_A,
+					 &in_env[i][nlen], &conv[nlen],
len);
+		}
+	      else
+		{
+		  conv = (char *) alloca (__PMAX + nlen);
+		  strcpy (conv, name);
+		  cygwin_conv_path (CCP_POSIX_TO_WIN_A,
+				    &in_env[i][nlen], &conv[nlen], __PMAX);
+		}
+	      in_env[i] = xstrdup (conv);
+	    }
+	}
+    }
+}
+
+/* cygwin_restore_envs function restores in_env elements to their
+   original value.  */
+
+static void
+cygwin_restore_envs (char **in_env)
+{
+  int i, j;
+
+  for (j = 0; conv_envvars[j].name; j++)
+    if (conv_envvars[j].in_index != -1)
+      {
+	xfree (in_env[conv_envvars[j].in_index]);
+        in_env[conv_envvars[j].in_index] = conv_envvars[j].in_orig_val;
+      }
+}
+
+#endif
+
 /* Start an inferior windows child process and sets inferior_ptid to its
pid.
    EXEC_FILE is the file to run.
    ALLARGS is a string containing the arguments to the program.
@@ -1983,6 +2072,9 @@ windows_create_inferior (struct target_ops *ops, char
*exec_file,
   win_buf_t *toexec;
   win_buf_t *cygallargs;
   win_buf_t *args;
+  size_t env_size;
+  int i;
+  win_buf_t *out_env;
 #ifdef __USEWIDE
   size_t len;
 #endif
@@ -2010,6 +2102,7 @@ windows_create_inferior (struct target_ops *ops, char
*exec_file,
     windows_set_console_info (&si, &flags);
 
 #ifdef __CYGWIN__
+  cygwin_convert_envs (in_env);
   if (!useshell)
 #endif
     {
@@ -2071,15 +2164,43 @@ windows_create_inferior (struct target_ops *ops,
char *exec_file,
   wcscpy (args, toexec);
   wcscat (args, L" ");
   wcscat (args, cygallargs);
+  env_size = 1;
+  for (i = 0; in_env[i]; i++)
+    {
+      env_size += mbstowcs (NULL, in_env[i], 0) + 1;
+    }
+  out_env = (win_buf_t *) alloca (env_size * sizeof (win_buf_t *));
+  env_size = 0;
+  for (i = 0; in_env[i]; i++)
+    {
+      int len = mbstowcs (NULL, in_env[i], 0) + 1;
+      mbstowcs (&out_env[env_size], in_env[i], len);
+      env_size += len;
+    }
+  out_env[env_size] = L'\0';
+  flags |= CREATE_UNICODE_ENVIRONMENT;
 #else
   args = (win_buf_t *) alloca (strlen (toexec) + strlen (cygallargs) + 2);
   strcpy (args, toexec);
   strcat (args, " ");
   strcat (args, cygallargs);
+  env_size = 1;
+  for (i = 0; in_env[i]; i++)
+    {
+      env_size += strlen(in_env[i]) + 1;
+    }
+  out_env = (win_buf_t *) alloca (env_size * sizeof (win_buf_t *));
+  env_size = 0;
+  for (i = 0; in_env[i]; i++)
+    {
+      int len = strlen(in_env[i]) + 1;
+      strcpy (&out_env[env_size], in_env[i]);
+      env_size += len;
+    }
+  out_env[env_size] = '\0';
 #endif
 
 #ifdef __CYGWIN__
-  /* Prepare the environment vars for CreateProcess.  */
   cygwin_internal (CW_SYNC_WINENV);
 
   if (!inferior_io_terminal)
@@ -2137,11 +2258,13 @@ windows_create_inferior (struct target_ops *ops,
char *exec_file,
 		       NULL,	/* thread */
 		       TRUE,	/* inherit handles */
 		       flags,	/* start flags */
-		       NULL,	/* environment */
+		       out_env,	/* environment */
 		       NULL,	/* current directory */
 		       &si,
 		       &pi);
 #ifdef __CYGWIN__
+  cygwin_restore_envs (in_env);
+
   if (tty >= 0)
     {
       close (tty);