|Subject:||Process::Create() not searching PATH for partial executable name|
|Date:||Tue, 26 Dec 2006 08:58:05 -0800|
|To:||bug-libwin32 [...] rt.cpan.org|
|From:||Greg Ercolano <erco [...] 3dsite.com>|
[as reported on bugs.activestate.com, bug #65241] ActivePerl 5.8.5 build 804 on Windows 2000 and Windows XP [full output of 'perl -V' at end] DESCRIPTION ----------- It seems Win32::Process::Create() does not support WIN32 CreateProcess()'s ability to set $appname to NULL (0), and set a partial name for $cmdline, so that the full path to the executable need not be specified. In C++, CreateProcess() can run an executable with a partial name (ie. without a pathname or extension specified) if 'appname' is NULL, eg: CreateProcess(NULL, // appname "netstat -an", // commandline NULL, ..) ..which works, as per Microsoft's docs for CreateProcess(), indicating it searches the PATH when a partial name is specified. In Perl's Process::Create(), the equivalent apparently doesn't work: Win32::Process::Create($pobj, 0, # appname "netstat -an", # commandline 1, # inherit handles NORMAL_PRIORITY_CLASS, # etc.. "."); ..this fails with "The system cannot find the file specified." I also tried 'undef', "" and "0" for the "appname" field with same results. This is hard to work around, without a brute force walk of the PATH's components to seek out the absolute path to the executable, which can be expensive and non-trivial, esp. when the PATH is large, and contains network components. SOLUTION -------- It would be good if the perl Process::Create() worked consistently with the Win32 equivalent, as often the absolute pathname to the executable is not known to the script, such as when the executable is a third party app. ATTEMPTED WORKAROUNDS --------------------- I tried invoking cmd.exe with an absolute path, passing my command as arguments to that, so that cmd.exe would do the search for the executable. Trouble is, involving cmd.exe introduces a different problem where if the cwd is a UNC path, cmd.exe prints a warning that UNC paths aren't supported (!) and falls back to using C:\windows as the CWD before running my command, fatal to some of my user's situations. :/ So avoiding calling cmd.exe is important, hence the approach of trying to invoke my command with CreateProcess(). I also can't use system() because even though it tries to avoid using cmd.exe, it has the problem with -1 exit codes (reported as bug #60738 which was reattached to bug #45337). So I'm kinda cornered into either writing a custom extension, or trying to troubleshoot/repair the Win32::Create::Process() module. OUTPUT OF 'perl -V' ------------------- Summary of my perl5 (revision 5 version 8 subversion 0) configuration: Platform: osname=MSWin32, osvers=4.0, archname=MSWin32-x86-multi-thread uname='' config_args='undef' hint=recommended, useposix=true, d_sigaction=undef usethreads=undef use5005threads=undef useithreads=define usemultiplicity=define useperlio=define d_sfio=undef uselargefiles=define usesocks=undef use64bitint=undef use64bitall=undef uselongdouble=undef usemymalloc=n, bincompat5005=undef Compiler: cc='cl', ccflags ='-nologo -Gf -W3 -MD -DNDEBUG -O1 -DWIN32 -D_CONSOLE -DNO_STRICT -DHAVE_DES_FCRYPT -DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -DUSE_PERLIO -DPERL_MSVCRT_READFIX', optimize='-MD -DNDEBUG -O1', cppflags='-DWIN32' ccversion='', gccversion='', gccosandvers='' intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234 d_longlong=undef, longlongsize=8, d_longdbl=define, longdblsize=10 ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='__int64', lseeksize=8 alignbytes=8, prototype=define Linker and Libraries: ld='link', ldflags ='-nologo -nodefaultlib -release -libpath:"C:\Perl\lib\CORE" -machine:x86' libpth="C:\Program Files\Microsoft Visual Studio .NET\FrameworkSDK\Lib\" "C:\Perl\lib\CORE" libs= oldnames.lib kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib netapi32.lib uuid.lib wsock32.lib mpr.lib winmm.lib version.lib odbc32.lib odbccp32.lib msvcrt.lib perllibs= oldnames.lib kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib netapi32.lib uuid.lib wsock32.lib mpr.lib winmm.lib version.lib odbc32.lib odbccp32.lib msvcrt.lib libc=msvcrt.lib, so=dll, useshrplib=yes, libperl=perl58.lib gnulibc_version='undef' Dynamic Linking: dlsrc=dl_win32.xs, dlext=dll, d_dlsymun=undef, ccdlflags=' ' cccdlflags=' ', lddlflags='-dll -nologo -nodefaultlib -release -libpath:"C:\Perl\lib\CORE" -machine:x86' Characteristics of this binary (from libperl): Compile-time options: MULTIPLICITY USE_ITHREADS USE_LARGE_FILES PERL_IMPLICIT_CONTEXT PERL_IMPLICIT_SYS Locally applied patches: ActivePerl Build 804 Built under MSWin32 Compiled at Dec 1 2002 23:15:13 @INC: C:/Perl/lib C:/Perl/site/lib .