Re: [RFA/mingw32] environment variables are case-insensitive on win32

[Jerome Guitton <guitton@adacore.com>]

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Joel Brobecker (brobecker@adacore.com):

>   1. Decide whether we want GDB to match environment variable names
>      using case-sensitive or case-insensentive functions on cygwin.
>      Right now, it's case-sensitive. FWIW, we are offering to change
>      that behavior, and it seems more user-friencly at the moment,
>      but either choice is fine with me. If no concensus can be reached
>      on this, then we'll revert to the original behavior.
> 
>   2. Commit Jerome's patch which implements the decision from (1),
>      letting a more elaborate handling of environment variables
>      as a followup patch for someone more involved in cygwin than
>      we are.

At this point my feeling is that there is something to clarify for
Cygwin; the symptom being that the new test I submitted for
testenv.exp fails on this platform. But for the moment I'd be inclined
to let Cygwin's situation unchanged and let an expert handle it. The patch
that I would submit would fix mingw32 only. So I guess that would be (2).

The corresponding patch is in attachment.





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commit 65a7d48d6ae3835fb63d2a7c6a40feee16572d95
Author: Jerome Guitton <guitton@adacore.com>
Date:   Thu May 24 18:19:23 2012 +0200

    environment variables are case-insensitive on mingw
    
    gdb/ChangeLog:
    
    	* environ.c (host_has_case_sensitive_env_vars)
    	(env_var_name_ncmp): New functions.
    	(get_in_environ, set_in_environ, unset_in_environ): Use
    	env_var_name_ncmp instead of strncmp.

diff --git a/gdb/environ.c b/gdb/environ.c
index 33426eb..98d8ca6 100644
--- a/gdb/environ.c
+++ b/gdb/environ.c
@@ -96,6 +96,48 @@ environ_vector (struct gdb_environ *e)
   return e->vector;
 }
 \f
+
+/* Return 1 if the names of environ variables are case sensitive
+   on host.  */
+
+static int
+host_has_case_sensitive_env_vars()
+{
+  static int result = -1;
+  char *value;
+
+  if (result != -1)
+    return result;
+
+#if defined(_WIN32) && !defined(__CYGWIN__)
+  putenv ("__GDB_TEST_CASE_SENSITIVITY=set");
+
+#else
+  setenv ("__GDB_TEST_CASE_SENSITIVITY", "set", 1);
+#endif
+
+  value = getenv ("__GDB_test_CASE_Sensitivity");
+
+  if (value && (strcmp (value, "set") == 0))
+    result = 0;
+  else
+    result = 1;
+
+  return result;
+}
+
+/* Compare the first LENGTH characters of the names of two
+   environment variable A and B.  */
+
+static int
+env_var_name_ncmp(const char *a, const char *b, int length)
+{
+  if (host_has_case_sensitive_env_vars())
+    return strncmp(a, b, length);
+  else
+    return strncasecmp (a, b, length);
+}
+
 /* Return the value in environment E of variable VAR.  */
 
 char *
@@ -106,7 +148,7 @@ get_in_environ (const struct gdb_environ *e, const char *var)
   char *s;
 
   for (; (s = *vector) != NULL; vector++)
-    if (strncmp (s, var, len) == 0 && s[len] == '=')
+    if (env_var_name_ncmp (s, var, len) == 0 && s[len] == '=')
       return &s[len + 1];
 
   return 0;
@@ -123,7 +165,7 @@ set_in_environ (struct gdb_environ *e, const char *var, const char *value)
   char *s;
 
   for (i = 0; (s = vector[i]) != NULL; i++)
-    if (strncmp (s, var, len) == 0 && s[len] == '=')
+    if (env_var_name_ncmp (s, var, len) == 0 && s[len] == '=')
       break;
 
   if (s == 0)
@@ -170,7 +212,7 @@ unset_in_environ (struct gdb_environ *e, char *var)
 
   for (; (s = *vector) != NULL; vector++)
     {
-      if (strncmp (s, var, len) == 0 && s[len] == '=')
+      if (env_var_name_ncmp (s, var, len) == 0 && s[len] == '=')
 	{
 	  xfree (s);
 	  /* Walk through the vector, shuffling args down by one, including