mingw: make isatty() recognize MSYS2's pseudo terminals (/dev/pty*)

MSYS2 emulates pseudo terminals via named pipes, and isatty() returns 0
for such file descriptors. Therefore, some interactive functionality
(such as launching a pager, asking if a failed unlink should be repeated
etc.) doesn't work when run in a terminal emulator that uses MSYS2's
ptys (such as mintty).

However, MSYS2 uses special names for its pty pipes ('msys-*-pty*'),
which allows us to distinguish them from normal piped input / output.

On startup, check if stdin / stdout / stderr are connected to such pipes
using the NtQueryObject API from NTDll.dll. If the names match, adjust
the flags in MSVCRT's ioinfo structure accordingly.

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/compat/winansi.c b/compat/winansi.c
index 5dfa5ed61f49c4032d82c5825c0c43c86e04799f..3be60ce1c6fc0b5a6d96fdbe1101ed99e28b3585 100644 (file)
--- a/compat/winansi.c
+++ b/compat/winansi.c
@@ -483,6 +483,7 @@ 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)
@@ -530,6 +531,45 @@ static HANDLE swap_osfhnd(int fd, HANDLE new_handle)
        return old_handle;
 }
 
+#ifdef DETECT_MSYS_TTY
+
+#include <winternl.h>
+#include <ntstatus.h>
+
+static void detect_msys_tty(int fd)
+{
+       ULONG result;
+       BYTE buffer[1024];
+       POBJECT_NAME_INFORMATION nameinfo = (POBJECT_NAME_INFORMATION) buffer;
+       PWSTR name;
+
+       /* check if fd is a pipe */
+       HANDLE h = (HANDLE) _get_osfhandle(fd);
+       if (GetFileType(h) != FILE_TYPE_PIPE)
+               return;
+
+       /* get pipe name */
+       if (!NT_SUCCESS(NtQueryObject(h, ObjectNameInformation,
+                       buffer, sizeof(buffer) - 2, &result)))
+               return;
+       name = nameinfo->Name.Buffer;
+       name[nameinfo->Name.Length] = 0;
+
+       /* check if this could be a MSYS2 pty pipe ('msys-XXXX-ptyN-XX') */
+       if (!wcsstr(name, L"msys-") || !wcsstr(name, L"-pty"))
+               return;
+
+       /* init ioinfo size if we haven't done so */
+       if (init_sizeof_ioinfo())
+               return;
+
+       /* set FDEV flag, reset FPIPE flag */
+       _pioinfo(fd)->osflags &= ~FPIPE;
+       _pioinfo(fd)->osflags |= FDEV;
+}
+
+#endif
+
 void winansi_init(void)
 {
        int con1, con2;
@@ -538,8 +578,15 @@ void winansi_init(void)
        /* check if either stdout or stderr is a console output screen buffer */
        con1 = is_console(1);
        con2 = is_console(2);
-       if (!con1 && !con2)
+       if (!con1 && !con2) {
+#ifdef DETECT_MSYS_TTY
+               /* check if stdin / stdout / stderr are MSYS2 pty pipes */
+               detect_msys_tty(0);
+               detect_msys_tty(1);
+               detect_msys_tty(2);
+#endif
                return;
+       }
 
        /* create a named pipe to communicate with the console thread */
        xsnprintf(name, sizeof(name), "\\\\.\\pipe\\winansi%lu", GetCurrentProcessId());
@@ -575,8 +622,11 @@ void winansi_init(void)
 HANDLE winansi_get_osfhandle(int fd)
 {
        HANDLE hnd = (HANDLE) _get_osfhandle(fd);
-       if ((fd == 1 || fd == 2) && isatty(fd)
-           && GetFileType(hnd) == FILE_TYPE_PIPE)
-               return (fd == 1) ? hconsole1 : hconsole2;
+       if (isatty(fd) && GetFileType(hnd) == FILE_TYPE_PIPE) {
+               if (fd == 1 && hconsole1)
+                       return hconsole1;
+               else if (fd == 2 && hconsole2)
+                       return hconsole2;
+       }
        return hnd;
 }

diff --git a/config.mak.uname b/config.mak.uname
index 40d6b29eeef9a9b89b02100bb087fe9f37a3a7d6..a88f13989ac9c2cbb303e2ae5f9ed43c9a5f778f 100644 (file)
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -557,7 +557,8 @@ else
                        BASIC_LDFLAGS += -Wl,--large-address-aware
                endif
                CC = gcc
-               COMPAT_CFLAGS += -D__USE_MINGW_ANSI_STDIO=0
+               COMPAT_CFLAGS += -D__USE_MINGW_ANSI_STDIO=0 -DDETECT_MSYS_TTY
+               EXTLIBS += -lntdll
                INSTALL = /bin/install
                NO_R_TO_GCC_LINKER = YesPlease
                INTERNAL_QSORT = YesPlease