山本です。bcc32 の fopen, fdopen, fsopen が正しく errno を設定しない
件ですが、やっぱりパッチを当ててもいいでしょうか？落ちるのはあんまりな気がしてきました。
>> [ruby-dev:23743]

/////////////////////////////////
// パッチを当てる前

E:\ruby-cvs\ruby>..\miniruby.exe -e "IO.for_fd(-1)"
-e:1:in `for_fd': Invalid argument (Errno::EINVAL)
        from -e:1

E:\ruby-cvs\ruby>..\miniruby.exe -e "p 100.times { open('makefile') }"
-e:1: [BUG] rb_sys_fail(makefile) - errno == 0
ruby 1.9.0 (2004-07-23) [i386-bccwin32]


Abnormal program termination

E:\ruby-cvs\ruby>..\miniruby.exe -e "Array.new(100) { open('makefile') }"
-e:1: [BUG] rb_sys_fail(makefile) - errno == 0
ruby 1.9.0 (2004-07-23) [i386-bccwin32]


Abnormal program termination

/////////////////////////////////
// パッチを当てた後

E:\ruby-cvs\ruby>miniruby.exe -e "IO.for_fd(-1)"
-e:1:in `for_fd': Bad file number (Errno::EBADF)
        from -e:1

E:\ruby-cvs\ruby>miniruby.exe -e "p 100.times { open('makefile') }"
100 # EMFILE のとき GC を行うので、問題なく終了している

E:\ruby-cvs\ruby>miniruby.exe -e "Array.new(100) { open('makefile') }"
-e:1:in `initialize': Too many open files (Errno::EMFILE)
 - makefile     from -e:1:in `open'
        from -e:1
        from -e:1:in `initialize'
        from -e:1:in `new'
        from -e:1

//////////////////////////////////
// パッチ

Index: win32.c
===================================================================
RCS file: /var/cvs/src/ruby/win32/win32.c,v
retrieving revision 1.117
diff -u -w -b -p -r1.117 win32.c
--- win32.c	21 Jun 2004 00:27:39 -0000	1.117
+++ win32.c	24 Jul 2004 09:08:34 -0000
@@ -3330,3 +3330,51 @@ rb_w32_snprintf(char *buf, size_t size, 
     va_end(va);
     return ret;
 }
+
+#ifdef __BORLANDC__
+static int
+too_many_files()
+{
+    FILE *f;
+    for (f = _streams; f < _streams + _nfile; f++) {
+	if (f->fd < 0) return 0;
+    }
+    return 1;
+}
+
+#undef fopen
+FILE *
+rb_w32_fopen(const char *path, const char *mode)
+{
+    FILE *f = (errno = 0, fopen(path, mode));
+    if (f == NULL && errno == 0) {
+	if (too_many_files())
+	    errno = EMFILE;
+    }
+    return f;
+}
+
+FILE *
+rb_w32_fdopen(int handle, char *type)
+{
+    FILE *f = (errno = 0, _fdopen(handle, type));
+    if (f == NULL && errno == 0) {
+	if (handle < 0)
+	    errno = EBADF;
+	else if (too_many_files())
+	    errno = EMFILE;
+    }
+    return f;
+}
+
+FILE *
+rb_w32_fsopen(const char *path, const char *mode, int shflags)
+{
+    FILE *f = (errno = 0, _fsopen(path, mode, shflags));
+    if (f == NULL && errno == 0) {
+	if (too_many_files())
+	    errno = EMFILE;
+    }
+    return f;
+}
+#endif
Index: win32.h
===================================================================
RCS file: /var/cvs/src/ruby/win32/win32.h,v
retrieving revision 1.51
diff -u -w -b -p -r1.51 win32.h
--- win32.h	19 Feb 2004 09:08:23 -0000	1.51
+++ win32.h	24 Jul 2004 08:57:25 -0000
@@ -115,6 +115,12 @@ extern "C++" {
 #define sopen			_sopen
 #undef fstat
 #define fstat(fd,st)		rb_w32_fstat(fd,st)
+#undef fopen
+#define fopen(p, m)		rb_w32_fopen(p, m)
+#undef fdopen
+#define fdopen(h, m)		rb_w32_fdopen(h, m)
+#undef fsopen
+#define fsopen(p, m, sh)	rb_w32_fsopen(p, m, sh)
 #endif
 #define fsync(h)		_commit(h)
 #undef stat
@@ -178,6 +184,13 @@ extern int rb_w32_spawn(int, const char 
 extern int rb_w32_aspawn(int, const char *, char *const *);
 extern int kill(int, int);
 extern pid_t rb_w32_getpid(void);
+
+#ifdef __BORLANDC__
+extern int rb_w32_fstat(int, struct stat *);
+extern FILE *rb_w32_fopen(const char *, const char *);
+extern FILE *rb_w32_fdopen(int, char *);
+extern FILE *rb_w32_fsopen(const char *, const char *, int);
+#endif
 
 #include <float.h>
 #if !defined __MINGW32__ || defined __NO_ISOCEXT