* cygcheck.cc (get_word, get_dword): Move to path.cc.

	(LINK_EXTENSION): New macro.
	(check_existence): New static function.
	(find_on_path): Check for symbolic links if asked.
	(dll_info): New error handling.
	(track_down): Only call dll_info() for executables, display
	an error for symlinks, and print magic number for others.
	(find_app_on_path): New static function.
	(cygcheck, dump_sysinfo): Call find_app_on_path() instead of
	find_on_path().
	* path.cc (cmp_shortcut_header): New static function.
	(get_word, get_dword): Moved from cygcheck.cc.
	(EXE_MAGIC, SHORTCUT_MAGIC, SYMLINK_COOKIE, SYMLINK_MAGIC): New
	macros.
	(is_exe, is_symlink, readlink): New functions.
	* path.h (is_exe, is_symlink, readlink): Declare.
	(get_word, get_dword): Ditto.

1 files changed, 200 insertions, 2 deletions

diff --git a/winsup/utils/path.cc b/winsup/utils/path.cc
index 57bd3a4ff..356a60f01 100644
--- a/winsup/utils/path.cc
+++ b/winsup/utils/path.cc
@@ -9,14 +9,16 @@ Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
 details. */
 
 /* The purpose of this file is to hide all the details about accessing
-   Cygwin's mount table.  If the format or location of the mount table
-   changes, this is the file to change to match it. */
+   Cygwin's mount table, shortcuts, etc.  If the format or location of
+   the mount table, or the shortcut format changes, this is the file to
+   change to match it. */
 
 #define str(a) #a
 #define scat(a,b) str(a##b)
 #include <windows.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include "path.h"
 #include "cygwin/include/cygwin/version.h"
 #include "cygwin/include/sys/mount.h"
 #include "cygwin/include/mntent.h"
@@ -29,6 +31,202 @@ details. */
    })
 
 
+static const GUID GUID_shortcut
+			= { 0x00021401L, 0, 0, 0xc0, 0, 0, 0, 0, 0, 0, 0x46 };
+
+enum {
+  WSH_FLAG_IDLIST = 0x01,	/* Contains an ITEMIDLIST. */
+  WSH_FLAG_FILE = 0x02,		/* Contains a file locator element. */
+  WSH_FLAG_DESC = 0x04,		/* Contains a description. */
+  WSH_FLAG_RELPATH = 0x08,	/* Contains a relative path. */
+  WSH_FLAG_WD = 0x10,		/* Contains a working dir. */
+  WSH_FLAG_CMDLINE = 0x20,	/* Contains command line args. */
+  WSH_FLAG_ICON = 0x40		/* Contains a custom icon. */
+};
+
+struct win_shortcut_hdr
+  {
+    DWORD size;		/* Header size in bytes.  Must contain 0x4c. */
+    GUID magic;		/* GUID of shortcut files. */
+    DWORD flags;	/* Content flags.  See above. */
+
+    /* The next fields from attr to icon_no are always set to 0 in Cygwin
+       and U/Win shortcuts. */
+    DWORD attr;	/* Target file attributes. */
+    FILETIME ctime;	/* These filetime items are never touched by the */
+    FILETIME mtime;	/* system, apparently. Values don't matter. */
+    FILETIME atime;
+    DWORD filesize;	/* Target filesize. */
+    DWORD icon_no;	/* Icon number. */
+
+    DWORD run;		/* Values defined in winuser.h. Use SW_NORMAL. */
+    DWORD hotkey;	/* Hotkey value. Set to 0.  */
+    DWORD dummy[2];	/* Future extension probably. Always 0. */
+  };
+
+static bool
+cmp_shortcut_header (win_shortcut_hdr *file_header)
+{
+  /* A Cygwin or U/Win shortcut only contains a description and a relpath.
+     Cygwin shortcuts also might contain an ITEMIDLIST. The run type is
+     always set to SW_NORMAL. */
+  return file_header->size == sizeof (win_shortcut_hdr)
+      && !memcmp (&file_header->magic, &GUID_shortcut, sizeof GUID_shortcut)
+      && (file_header->flags & ~WSH_FLAG_IDLIST)
+	 == (WSH_FLAG_DESC | WSH_FLAG_RELPATH)
+      && file_header->run == SW_NORMAL;
+}
+
+int
+get_word (HANDLE fh, int offset)
+{
+  unsigned short rv;
+  unsigned r;
+
+  SetLastError(NO_ERROR);
+  if (SetFilePointer (fh, offset, 0, FILE_BEGIN) == INVALID_SET_FILE_POINTER
+      && GetLastError () != NO_ERROR)
+    return -1;
+
+  if (!ReadFile (fh, &rv, 2, (DWORD *) &r, 0))
+    return -1;
+
+  return rv;
+}
+
+/*
+ * Check the value of GetLastError() to find out whether there was an error.
+ */
+int
+get_dword (HANDLE fh, int offset)
+{
+  int rv;
+  unsigned r;
+
+  SetLastError(NO_ERROR);
+  if (SetFilePointer (fh, offset, 0, FILE_BEGIN) == INVALID_SET_FILE_POINTER
+      && GetLastError () != NO_ERROR)
+    return -1;
+
+  if (!ReadFile (fh, &rv, 4, (DWORD *) &r, 0))
+    return -1;
+
+  return rv;
+}
+
+#define EXE_MAGIC ((int)*(unsigned short *)"MZ")
+#define SHORTCUT_MAGIC ((int)*(unsigned short *)"L\0")
+#define SYMLINK_COOKIE "!<symlink>"
+#define SYMLINK_MAGIC ((int)*(unsigned short *)SYMLINK_COOKIE)
+
+bool
+is_exe (HANDLE fh)
+{
+  int magic = get_word (fh, 0x0);
+  return magic == EXE_MAGIC;
+}
+
+bool
+is_symlink (HANDLE fh)
+{
+  int magic = get_word (fh, 0x0);
+  if (magic != SHORTCUT_MAGIC && magic != SYMLINK_MAGIC)
+    return false;
+  DWORD got;
+  BY_HANDLE_FILE_INFORMATION local;
+  if (!GetFileInformationByHandle (fh, &local))
+    return false;
+  if (magic == SHORTCUT_MAGIC)
+    {
+      DWORD size;
+      if (!local.dwFileAttributes & FILE_ATTRIBUTE_READONLY)
+	return false; /* Not a Cygwin symlink. */
+      if ((size = GetFileSize (fh, NULL)) > 8192)
+	return false; /* Not a Cygwin symlink. */
+      char buf[size];
+      SetFilePointer (fh, 0, 0, FILE_BEGIN);
+      if (!ReadFile (fh, buf, size, &got, 0))
+	return false;
+      if (got != size || !cmp_shortcut_header ((win_shortcut_hdr *) buf))
+	return false; /* Not a Cygwin symlink. */
+      /* TODO: check for invalid path contents
+         (see symlink_info::check() in ../cygwin/path.cc) */
+    }
+  else /* magic == SYMLINK_MAGIC */
+    {
+      if (!local.dwFileAttributes & FILE_ATTRIBUTE_SYSTEM)
+	return false; /* Not a Cygwin symlink. */
+      char buf[sizeof (SYMLINK_COOKIE) - 1];
+      SetFilePointer (fh, 0, 0, FILE_BEGIN);
+      if (!ReadFile (fh, buf, sizeof (buf), &got, 0))
+	return false;
+      if (got != sizeof (buf) ||
+          memcmp (buf, SYMLINK_COOKIE, sizeof (buf)) != 0)
+	return false; /* Not a Cygwin symlink. */
+    }
+  return true;
+}
+
+/* Assumes is_symlink(fh) is true */
+bool
+readlink (HANDLE fh, char *path, int maxlen)
+{
+  int got;
+  int magic = get_word (fh, 0x0);
+
+  if (magic == SHORTCUT_MAGIC)
+    {
+      int offset = get_word (fh, 0x4c);
+      int slen = get_word (fh, 0x4c + offset + 2);
+      if (slen >= maxlen)
+	{
+	  SetLastError (ERROR_FILENAME_EXCED_RANGE);
+	  return false;
+	}
+      if (SetFilePointer (fh, 0x4c + offset + 4, 0, FILE_BEGIN) ==
+          INVALID_SET_FILE_POINTER && GetLastError () != NO_ERROR)
+        return false;
+
+      if (!ReadFile (fh, path, slen, (DWORD *) &got, 0))
+        return false;
+      else if (got < slen)
+	{
+	  SetLastError (ERROR_READ_FAULT);
+	  return false;
+	}
+      else
+	path[got] = '\0';
+    }
+  else if (magic == SYMLINK_MAGIC)
+    {
+      char cookie_buf[sizeof (SYMLINK_COOKIE) - 1];
+
+      if (SetFilePointer (fh, 0, 0, FILE_BEGIN) == INVALID_SET_FILE_POINTER
+	  && GetLastError () != NO_ERROR)
+        return false;
+
+      if (!ReadFile (fh, cookie_buf, sizeof (cookie_buf), (DWORD *) &got, 0))
+        return false;
+      else if (got == sizeof (cookie_buf)
+	       && memcmp (cookie_buf, SYMLINK_COOKIE, sizeof (cookie_buf)) == 0)
+	{
+	  if (!ReadFile (fh, path, maxlen, (DWORD *) &got, 0))
+            return false;
+	  else if (got >= maxlen)
+	    {
+	      SetLastError (ERROR_FILENAME_EXCED_RANGE);
+	      path[0] = '\0';
+	      return false;
+	    }
+	  else
+	    path[got] = '\0';
+	}
+    }
+  else
+    return false;
+  return true;
+}
+
 static struct mnt
   {
     const char *native;