-
-/*
- * Make MSVCRT's internal file descriptor control structure accessible
- * so that we can tweak OS handles and flags directly (we need MSVCRT
- * to treat our pipe handle as if it were a console).
- *
- * We assume that the ioinfo structure (exposed by MSVCRT.dll via
- * __pioinfo) starts with the OS handle and the flags. The exact size
- * varies between MSVCRT versions, so we try different sizes until
- * toggling the FDEV bit of _pioinfo(1)->osflags is reflected in
- * isatty(1).
- */
-typedef struct {
- HANDLE osfhnd;
- char osflags;
-} ioinfo;
-
-extern __declspec(dllimport) ioinfo *__pioinfo[];
-
-static size_t sizeof_ioinfo = 0;
-
-#define IOINFO_L2E 5
-#define IOINFO_ARRAY_ELTS (1 << IOINFO_L2E)
-
-#define FPIPE 0x08
-#define FDEV 0x40
-
-static inline ioinfo* _pioinfo(int fd)
-{
- return (ioinfo*)((char*)__pioinfo[fd >> IOINFO_L2E] +
- (fd & (IOINFO_ARRAY_ELTS - 1)) * sizeof_ioinfo);
-}
-
-static int init_sizeof_ioinfo(void)
-{
- int istty, wastty;
- /* don't init twice */
- if (sizeof_ioinfo)
- return sizeof_ioinfo >= 256;
-
- sizeof_ioinfo = sizeof(ioinfo);
- wastty = isatty(1);
- while (sizeof_ioinfo < 256) {
- /* toggle FDEV flag, check isatty, then toggle back */
- _pioinfo(1)->osflags ^= FDEV;
- istty = isatty(1);
- _pioinfo(1)->osflags ^= FDEV;
- /* return if we found the correct size */
- if (istty != wastty)
- return 0;
- sizeof_ioinfo += sizeof(void*);
- }
- error("Tweaking file descriptors doesn't work with this MSVCRT.dll");
- return 1;
-}
-