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From: "Jonathan Kamens" <jik AT kamens DOT us>
To: <cygwin AT cygwin DOT com>
Subject: Bug report for run.exe with patch
Date: Fri, 31 Dec 2010 14:00:02 -0500
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Several people have reported problems with run.exe complaining about being
unable to execute programs.

The typical symptoms of the problem are that the user clicks on a link in
the Start menu that uses run.exe and gets back an error pop-up from run.exe
that looks like this:

Error could not start C:\cygwin\bin\emacs-X11.exe [some extra characters
here that shouldn=92t be] -display 127.0.0.1:0.0

I just encountered this issue and tracked down the root cause, which is that
run.exe doesn=92t null-terminate the data returned by readlink(). According=
 to
the readlink(3) man page on Linux, =93Conforming applications should not
assume that the returned contents of the symbolic link are null-terminated,=
=94
and indeed, at least in some circumstances they are not.

I have attached a patch.

Share and enjoy. :-)

Thanks,

=A0 Jonathan Kamens


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diff -rup run-1.1.12/src/run.c /tmp/run-1.1.12/src/run.c
--- old/run-1.1.12/src/run.c	2010-12-31 13:43:05.770732300 -0500
+++ run-1.1.12/src/run.c	2010-12-31 13:41:13.093732300 -0500
@@ -810,10 +810,16 @@ void process_execname(char *exec, const
       {
          if ((stbuf.st_mode & S_IFLNK) =3D=3D S_IFLNK)
          {
-	    if (readlink(sym_link_name, real_name, sizeof(real_name)) =3D=3D -1)
+	    ssize_t len;
+
+	    if ((len =3D readlink(sym_link_name, real_name, sizeof(real_name))) =
=3D=3D -1)
                error("problem reading symbolic link for %s",exec_tmp);
             else
             {
+		if (len < sizeof(real_name))
+		    real_name[len] =3D '\0';
+		else
+		    error("symlink pointed to by %s is too long", sym_link_name);
                 /* if realname starts with '/' it's a rootpath */
                 if (real_name[0] =3D=3D '/')
                     strcpy(exec_tmp2,real_name);


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