MINGW: fix tmpnam giving filenames in the root directory

Window's tmpnam expects that you will prepend it with the temporary
directory.  Using _tempnam gives a path that is already prepended
with a temporary directory.

* NEWS: updated
* libguile/posix.c [_WIN32](scm_tmpnam): use _tempnam to create
    a temporary filename
* test-suite/tests/posix.test ("tmpnam"): new test

NEWS

@@ -54,7 +54,7 @@ by libtool, such as libfoo-1.dll.
 
 Also, it has been updated to do library renaming for MSYS.  On Cygwin,
 when the #:rename-on-cygwin? option is #t, it already had the capability
-to search for "libfoo" as "cygfoo.dll".  It has been updated to add the
+to search for "libfo[[Oo" as "cygfoo.dll".  It has been updated to add the
 capability to search for "libfoo" as "msys-foo.dll" on MSYS.
 
 The load-foreign-library option #:rename-on-cygwin? has been changed to
@@ -171,6 +171,7 @@ text files.
    GC-related closes to produce spurious "log" events in other tests.
 ** getsockopt no longer risks a buffer overrun with timestamps
    (<https://bugs.gnu.org/76907>)
+** In MinGW, fix tmpnam returning names in root directory
 
 
 Changes in 3.0.10 (since 3.0.9)
@@ -399,6 +400,14 @@ have them.  Send any bug reports to bug-guile@gnu.org.
 ** Hashing of UTF-8 symbols with non-ASCII characters avoids corruption
    (<https://bugs.gnu.org/56413>)
 
+This issue could cause `scm_from_utf8_symbol' and
+`scm_from_utf8_symboln` to incorrectly conclude that the symbol hadn't
+already been interned, and then create a new one, which of course
+wouldn't be `eq?' to the other(s).  The incorrect hash was the result of
+a buffer overrun, and so might vary.  This problem affected a number of
+other operations, given the internal use of those functions.
+
+
 Hearty thanks to Arne Babenhauserheide, Arsen Arsenović, Bruno Victal,
 Christopher Baines, Daniel Llorens, Denis 'GNUtoo' Carikli, Ekaitz
 Zarraga, Jonas Hahnfeld, Jorge Gomez, Josselin Poiret, Juliana Sims,

libguile/posix.c

@@ -1799,11 +1799,24 @@ SCM_DEFINE (scm_tmpnam, "tmpnam", 0, 0, 0,
   scm_c_issue_deprecation_warning
       ("Use of tmpnam is deprecated.  Use mkstemp instead.");
 
+#ifndef _WIN32
   SCM_SYSCALL (rv = tmpnam (name));
+#else
+  /* _tempnam properly prepends the temp directory path. */
+  SCM_SYSCALL (rv = _tempnam (NULL, ""));
+#endif
+
   if (rv == NULL)
     /* not SCM_SYSERROR since errno probably not set.  */
     SCM_MISC_ERROR ("tmpnam failed", SCM_EOL);
+
+#ifndef _WIN32
   return scm_from_locale_string (name);
+#else
+  SCM ret = scm_from_locale_string (rv);
+  free (rv);
+  return ret;
+#endif
 }
 #undef FUNC_NAME
 

test-suite/tests/posix.test

@@ -58,6 +58,22 @@
 ;;   (pass-if-exception "./nosuchprog" '(system-error . ".*")
 ;;     (execle "./nosuchprog" '("FOO=1" "BAR=2") "./nosuchprog" "some arg")))
 
+;;
+;; tmpnam
+;;
+
+(with-test-prefix "tmpnam"
+  (pass-if "returns usable location"
+    (unless (defined? 'tmpnam)
+      ;; tmpnam is deprecated
+      (throw 'unsupported))
+    (let* ((filename (tmpnam))
+           (outport (open-output-file filename)))
+      (display "\n" outport)
+      (close-port outport)
+      (let ((result (access? filename R_OK)))
+        (delete-file filename)
+        result))))
   
 ;;
 ;; mkstemp