[Patch] "strace ./app.exe" probably runs application from /bin

[Christian Franke]

Running an application with strace from current directory may not work 
as expected.
The "./" is not passed to CreateProcess() and the default app search 
rules apply

(1. strace.exe directory,  2. cwd, ..., 6. PATH)

Therefore, an old version of the same app already installed in /bin may 
be run instead.



Testcase:

$ cd /tmp

$ cp /bin/date.exe ./uname.exe

$ date
Sat Jun  2 16:34:23 2007

$ uname
CYGWIN_NT-5.1

$ ./uname
Sat Jun  2 16:34:24 2007

$ strace -o nul ./uname
CYGWIN_NT-5.1

Workaround:

$ strace -o nul ././uname
Sat Jun  2 16:34:25 2007


The attached patch should fix this.

2007-06-02  Christian Franke <[EMAIL PROTECTED]>

* strace.cc (create_child): Don't remove current directory
from application path.


Christian

--- cygwin-1.5.24-2.orig/winsup/utils/strace.cc 2006-05-24 18:50:50.00100 
+0200
+++ cygwin-1.5.24-2/winsup/utils/strace.cc  2007-06-02 16:04:39.28125 
+0200
@@ -313,7 +313,19 @@ create_child (char **argv)
   BOOL ret;
   DWORD flags;
 
-  *argv = cygpath (*argv, NULL);
+  if (strncmp(*argv, "./", 2) == 0)
+{
+  // cygpath() removes "./". Add another to avoid that
+  // CreateProcess() uses its application search rules
+  // (1. app dir, 2. cwd, ..., 6. PATH).
+  char arg0[2 + strlen(*argv) + 1];
+  strcpy (arg0, "./");
+  strcpy (arg0+2, *argv);
+  *argv = cygpath (arg0, NULL);
+}
+  else
+*argv = cygpath (*argv, NULL);
+
   memset (&si, 0, sizeof (si));
   si.cb = sizeof (si);
 

Re: [Patch] "strace ./app.exe" probably runs application from /bin

[Christopher Faylor]

On Sat, Jun 02, 2007 at 04:51:31PM +0200, Christian Franke wrote:
>Running an application with strace from current directory may not work 
>as expected.
>The "./" is not passed to CreateProcess() and the default app search 
>rules apply
>(1. strace.exe directory,  2. cwd, ..., 6. PATH)
>
>Therefore, an old version of the same app already installed in /bin may 
>be run instead.
>
>
>Testcase:
>
>$ cd /tmp
>
>$ cp /bin/date.exe ./uname.exe
>
>$ date
>Sat Jun  2 16:34:23 2007
>
>$ uname
>CYGWIN_NT-5.1
>
>$ ./uname
>Sat Jun  2 16:34:24 2007
>
>$ strace -o nul ./uname
>CYGWIN_NT-5.1
>
>Workaround:
>
>$ strace -o nul ././uname
>Sat Jun  2 16:34:25 2007
>
>
>The attached patch should fix this.
>
>2007-06-02  Christian Franke <[EMAIL PROTECTED]>
>
>   * strace.cc (create_child): Don't remove current directory
>   from application path.

Thanks for the problem report and test case but this is pretty clearly
not the right way to deal with the issue.  Putting a special case catch
of "./" around a function call which is intended to deal with paths is
pretty clearly a band-aid.

Let me rephrase the problem:

"cygpath does not properly deal with the current directory"

Thanks for the patch but we won't be applying it in this form.

cgf

Re: [Patch] "strace ./app.exe" probably runs application from /bin

[Christian Franke]

Christopher Faylor wrote:

...
  
Thanks for the problem report and test case but this is pretty clearly

not the right way to deal with the issue.  Putting a special case catch
of "./" around a function call which is intended to deal with paths is
pretty clearly a band-aid.
  


Yes.



Let me rephrase the problem:

"cygpath does not properly deal with the current directory"

  


It depends. Removing "./" from a path is usually OK. Except when 
application search should be enabled if a path is missing.


I don't know whether this current behaviour of path.cc:cygpath() is 
required somewhere else

(cygcheck.cc, dump_setup.cc ...).

Thats the reason why I didn't modify cygpath() itself and used this 
(workaround|hack) instead.


Christian

Re: [Patch] "strace ./app.exe" probably runs application from /bin

[Brian Dessent]

Christopher Faylor wrote:

> Let me rephrase the problem:
> 
> "cygpath does not properly deal with the current directory"
> 
> Thanks for the patch but we won't be applying it in this form.

I've been meaning to take a look at fixing this myself, because I'm
tired of:

$ cd /usr/bin

$ cygcheck ./ls
.\.\.\.\ - Cannot open

$ cygcheck ls
 - Cannot open
Error: could not find ls

$ cygcheck ls.exe
 - Cannot open
Error: could not find ls.exe

$ cygcheck ./ls.exe
.\ls.exe
  .\cygwin1.dll
C:\WINXP\system32\ADVAPI32.DLL
  C:\WINXP\system32\ntdll.dll
  C:\WINXP\system32\KERNEL32.dll
  C:\WINXP\system32\RPCRT4.dll
  .\cygintl-8.dll
.\cygiconv-2.dll

Brian