Introduce FEATURE_CYGWIN_TTY

This feature allows terminal-aware applications to access Cygwin-based
terminal emulator, like rxvt, by allowing access to termios structure
managed by Cygwin.

The way this works is really intrusive. It examines Cygwin's
(unofficial) shared information to find out termios data and
manipulate directly on that (without locking, for now).

Different Cygwin versions may change share info layout. This patch
only supports cygwin-1.7.0-46. Support for other versions can be added later.

5 files changed, 233 insertions, 3 deletions

diff --git a/include/mingw.h b/include/mingw.h
index b39d94a33..500308947 100644
--- a/include/mingw.h
+++ b/include/mingw.h
@@ -191,6 +191,9 @@ int mingw_getpagesize(void);
 #define getpagesize mingw_getpagesize
 #endif
 
+int mingw_isatty(int fd);
+#define isatty(fd) mingw_isatty(fd)
+
 /* Use mingw_lstat() instead of lstat()/stat() and
  * mingw_fstat() instead of fstat() on Windows.
  */
diff --git a/libbb/Config.in b/libbb/Config.in
index 112a3d658..a75fb58c0 100644
--- a/libbb/Config.in
+++ b/libbb/Config.in
@@ -26,6 +26,15 @@ config MD5_SIZE_VS_SPEED
           2                   3.0                5088
           3 (smallest)        5.1                4912
 
+config FEATURE_CYGWIN_TTY
+        bool "Support Cygwin tty"
+        default n
+        depends on MINGW32
+        help
+          Try to sneak in Cygwin shared structure to determine if
+          a file handle is Cygwin tty, useful if you want to use
+          a Cygwin-based terminal emulator.
+
 config FEATURE_EDITING
         bool "Command line editing"
         default n
diff --git a/libbb/termios.c b/libbb/termios.c
index f47593a49..5695e9ba2 100644
--- a/libbb/termios.c
+++ b/libbb/termios.c
@@ -4,8 +4,212 @@
 #include "strbuf.h"
 #include "cygwin_termios.h"
 
+#if ENABLE_FEATURE_CYGWIN_TTY
+#include <ntdef.h>
+
+/* NtCreateDirectoryObject */
+#define DIRECTORY_QUERY                 1
+#define DIRECTORY_TRAVERSE              2
+#define DIRECTORY_CREATE_OBJECT         4
+#define DIRECTORY_CREATE_SUBDIRECTORY   8
+
+#define CYG_SHARED_DIR_ACCESS   (DIRECTORY_QUERY                 \
+                                 | DIRECTORY_TRAVERSE            \
+                                 | DIRECTORY_CREATE_SUBDIRECTORY \
+                                 | DIRECTORY_CREATE_OBJECT       \
+                                 | READ_CONTROL)
+
+typedef enum _OBJECT_INFORMATION_CLASS {
+        ObjectNameInformation = 1,
+} OBJECT_INFORMATION_CLASS;
+
+typedef struct _OBJECT_NAME_INFORMATION {
+        UNICODE_STRING Name;
+} OBJECT_NAME_INFORMATION;
+
+VOID NTAPI      RtlInitUnicodeString (PUNICODE_STRING, PCWSTR);
+NTSTATUS NTAPI  NtOpenSection (PHANDLE, ACCESS_MASK, POBJECT_ATTRIBUTES);
+NTSTATUS NTAPI  NtCreateDirectoryObject (PHANDLE, ACCESS_MASK, POBJECT_ATTRIBUTES);
+NTSTATUS NTAPI  NtQueryObject (HANDLE, OBJECT_INFORMATION_CLASS, VOID *, ULONG, ULONG *);
+
+/* Cygwin's shared_info */
+
+struct winsize {
+        unsigned short ws_row, ws_col;
+        unsigned short ws_xpixel, ws_ypixel;
+};
+
+struct tty_min {
+        pid_t sid;      /* Session ID of tty */
+        struct status_flags {
+                unsigned initialized : 1; /* Set if tty is initialized */
+                unsigned rstcons     : 1; /* Set if console needs to be set to "non-cooked" */
+        } status;
+
+        pid_t pgid;
+        int output_stopped;
+        int ntty;
+        DWORD last_ctrl_c;      /* tick count of last ctrl-c */
+        HWND hwnd;              /* Console window handle tty belongs to */
+
+        struct termios ti;
+        struct winsize winsize;
+
+        /* ioctl requests buffer */
+        int cmd;
+        union {
+                struct termios termios;
+                struct winsize winsize;
+                int value;
+                pid_t pid;
+        } arg;
+        /* XXX_retval variables holds master's completion codes. Error are stored as
+         * -ERRNO
+         */
+        int ioctl_retval;
+        int write_error;
+};
+
+struct tty {
+        struct tty_min tty_min;
+        pid_t master_pid;       /* PID of tty master process */
+
+        HANDLE from_master, to_master;
+
+        int read_retval;
+        int was_opened;         /* True if opened at least once. */
+};
+
+#define NTTYS           128
+struct tty_list {
+        struct tty ttys[NTTYS];
+};
+
+#define CYGWIN_PATH_MAX 4096
+struct shared_info {
+        DWORD version;
+        DWORD cb;
+        unsigned heap_chunk;
+        int heap_slop_inited;
+        unsigned heap_slop;
+        DWORD sys_mount_table_counter;
+        struct tty_list tty;
+        LONG last_used_bindresvport;
+        WCHAR installation_root[CYGWIN_PATH_MAX];
+        DWORD obcaseinsensitive;
+        /* mtinfo mt; */
+};
+
+/* Some magic to recognize shared_info */
+#define CYGWIN_VERSION_SHARED_DATA      5
+#define CYGWIN_VERSION_DLL_IDENTIFIER   L"cygwin1"
+#define CYGWIN_VERSION_API_MAJOR        0
+#define CYGWIN_VERSION_API_MINOR        210
+#define SHARED_INFO_CB                  39328
+#define CURR_SHARED_MAGIC               0x22f9ff0bU
+
+#define CYGWIN_VERSION_MAGIC(a, b) ((unsigned) ((((unsigned short) a) << 16) | (unsigned short) b))
+#define SHARED_VERSION (unsigned)(CYGWIN_VERSION_API_MAJOR << 8 | CYGWIN_VERSION_API_MINOR)
+#define SHARED_VERSION_MAGIC CYGWIN_VERSION_MAGIC (CURR_SHARED_MAGIC, SHARED_VERSION)
+
+static struct shared_info *get_shared_info()
+{
+        WCHAR buf[32];
+        HANDLE sh;
+        WCHAR base[MAX_PATH];
+        UNICODE_STRING uname;
+        HANDLE dir;
+        NTSTATUS status;
+        OBJECT_ATTRIBUTES attr;
+        static struct shared_info *si = NULL;
+
+        if (si)
+                return si;
+
+        swprintf(base, L"\\BaseNamedObjects\\%sS%d",
+                 CYGWIN_VERSION_DLL_IDENTIFIER,
+                 CYGWIN_VERSION_SHARED_DATA);
+        RtlInitUnicodeString (&uname, base);
+        InitializeObjectAttributes (&attr, &uname, OBJ_INHERIT | OBJ_OPENIF, NULL, NULL);
+        status = NtCreateDirectoryObject (&dir, CYG_SHARED_DIR_ACCESS, &attr);
+
+        swprintf(buf, L"%s.%d", L"shared", CYGWIN_VERSION_SHARED_DATA);
+        RtlInitUnicodeString(&uname, buf);
+        InitializeObjectAttributes (&attr, &uname, OBJ_CASE_INSENSITIVE, dir, NULL);
+        status = NtOpenSection (&sh, FILE_MAP_READ | FILE_MAP_WRITE, &attr);
+        si = MapViewOfFileEx(sh, FILE_MAP_READ | FILE_MAP_WRITE, 0, 0, 0, NULL);
+        //if (si->version == SHARED_VERSION_MAGIC && si->cb == SHARED_INFO_CB)
+        return si;
+}
+
+static int fd_to_tty(int fd)
+{
+        ULONG len = 0;
+        OBJECT_NAME_INFORMATION dummy_oni, *ntfn;
+        HANDLE h = _get_osfhandle(fd);
+        char buf[PATH_MAX];
+        int tty;
+
+        NtQueryObject (h, ObjectNameInformation, &dummy_oni, sizeof (dummy_oni), &len);
+        ntfn = malloc (len + sizeof (WCHAR));
+        NtQueryObject (h, ObjectNameInformation, ntfn, len, NULL);
+        wcstombs(buf, ntfn->Name.Buffer, 100);
+        tty = -1;
+        swscanf(ntfn->Name.Buffer, L"\\Device\\NamedPipe\\cygwin-tty%d-from-master", &tty);
+        free(ntfn);
+        return tty;
+}
+
+int is_cygwin_tty(int fd)
+{
+        return fd_to_tty(fd) >= 0 && get_shared_info() != NULL;
+}
+
+static int cygwin_tcgetattr(int fd, struct termios *t)
+{
+        int tty = fd_to_tty(fd);
+        struct shared_info *si = get_shared_info();
+        *t = si->tty.ttys[tty].tty_min.ti;
+        return 0;
+}
+
+
+static int cygwin_tcsetattr(int fd, int mode, const struct termios *t)
+{
+        int tty = fd_to_tty(fd);
+        struct shared_info *si;
+
+        if (tty < 0)
+                return -1;
+        si = get_shared_info();
+        si->tty.ttys[tty].tty_min.ti = *t;
+        return 0;
+}
+
+#else
+
+int is_cygwin_tty(int fd)
+{
+        return 0;
+}
+
+#define cygwin_tcgetattr(fd,t) -1
+#define cygwin_tcsetattr(fd,mode,t) -1
+
+#endif
+
+#undef isatty
+int mingw_isatty(int fd)
+{
+        return isatty(fd) || is_cygwin_tty(fd);
+}
+
 int tcgetattr(int fd, struct termios *t)
 {
+        int ret = cygwin_tcgetattr(fd, t);
+        if (ret >= 0)
+                return ret;
+        /* not cygwin tty, likely windows console */
         t->c_lflag = ECHO;
         return 0;
 }
@@ -13,7 +217,7 @@ int tcgetattr(int fd, struct termios *t)
 
 int tcsetattr(int fd, int mode, const struct termios *t)
 {
-        return 0;
+        return cygwin_tcsetattr(fd, mode, t);
 }
 
 static int get_wincon_width_height(const int fd, int *width, int *height)
@@ -36,6 +240,18 @@ static int get_wincon_width_height(const int fd, int *width, int *height)
 
 int get_terminal_width_height(const int fd, int *width, int *height)
 {
+#if ENABLE_FEATURE_CYGWIN_TTY
+        int tty = fd_to_tty(fd);
+        struct shared_info *si = get_shared_info();
+
+        if (tty >= 0 && si) {
+                if (width)
+                        *width = si->tty.ttys[tty].tty_min.winsize.ws_col;
+                if (height)
+                        *height = si->tty.ttys[tty].tty_min.winsize.ws_row;
+                return 0;
+        }
+#endif
         return get_wincon_width_height(fd, width, height);
 }
 
diff --git a/libbb/winansi.c b/libbb/winansi.c
index f3a304436..0e139432d 100644
--- a/libbb/winansi.c
+++ b/libbb/winansi.c
@@ -4,6 +4,7 @@
 
 #include <windows.h>
 #include "libbb.h"
+#include "cygwin_termios.h"
 
 /*
  Functions to be wrapped:
@@ -278,7 +279,7 @@ int winansi_fputs(const char *str, FILE *stream)
 {
         int rv;
 
-        if (!isatty(fileno(stream)))
+        if (!isatty(fileno(stream)) || is_cygwin_tty(fileno(stream)))
                 return fputs(str, stream);
 
         init();
@@ -301,7 +302,7 @@ static int winansi_vfprintf(FILE *stream, const char *format, va_list list)
         char *buf = small_buf;
         va_list cp;
 
-        if (!isatty(fileno(stream)))
+        if (!isatty(fileno(stream)) || is_cygwin_tty(fileno(stream)))
                 goto abort;
 
         init();
diff --git a/scripts/trylink b/scripts/trylink
index 63132eda9..6cca80c11 100755
--- a/scripts/trylink
+++ b/scripts/trylink
@@ -11,6 +11,7 @@ try() {
 }
 
 try "-lws2_32" "$@"
+try "-lws2_32 -lntdll" "$@"
 try "" "$@"
 try "-lm" "$@"
 try "-lcrypt" "$@"