On Mar 10 10:25, Corinna Vinschen wrote:
> execv (argv[1], args);
> bash$ gcc -o exec exec.c
> bash$ ./exec /bin/echo
> abc
> bash$ ./exec C:\\cygwin\\bin\\echo
> abc
Thanks for trying a test case. I am attaching a new test case that
shows that the trouble was with execvp(), not exec(). Only execvp()
calls find_exec() which fails to find a file in backslash notation,
find_exec (path, buf, "PATH=", FE_NNF)
Another call to find_exec in spawnvpe() seems to succeed,
find_exec (file, buf)
So, perhaps, another way to address the issue is to call find_exec()
without the 2 extra parameters. I find it confusing that the
function did not work despite its numerous options and its usage of
isdrive() implying attempts to handle Windows native paths.
--
#include <process.h> // for spawnvpe() (not specified by The Open Group)
#include <unistd.h> // for execvp()
#include <stdio.h> // for printf()
#include <errno.h> // for errno
#include <string.h> // for strdup(), strerror()
#include <stdlib.h> // for getenv()
int
main (int argc, const char *argv[])
{
const char const *args[3];
char *mutable_args[3];
// See http://c-faq.com/ansi/constmismatch.html explaining that a promise
// of constness of values pointed to by pointer elements requires constness
// of pointers as well. In other words, a const char** parameter cannot
// accept a char ** argument.
const char *envp[2];
const char *pathvalue = NULL;
char *pathenv = NULL;
int ec;
if ( argc < 2 ) {
return 2;
}
args[ 0 ] = argv[1];
args[ 1 ] = "abc";
args[ 2 ] = NULL;
mutable_args[ 0 ] = strdup( args[ 0 ] );
mutable_args[ 1 ] = strdup( args[ 1 ] );
mutable_args[ 2 ] = NULL;
pathvalue = getenv( "PATH" );
if (pathvalue) {
int pathlen = strlen( pathvalue );
pathenv = malloc( 5 + pathlen + 1 );
if ( pathenv ) {
memcpy( pathenv, "PATH=", 5 );
memcpy( pathenv + 5, pathvalue, pathlen + 1 );
}
}
envp[ 0 ] = pathenv;
envp[ 1 ] = NULL;
setbuf( stdout, NULL );
setbuf( stderr, NULL );
printf( "Spawning %s with search in $PATH and a limited environment...\n",
args[ 0 ] );
ec = spawnvpe( _P_WAIT, args[ 0 ], args, envp );
printf( "Exit code: %d\n\n", ec );
printf( "Loading %s with search in $PATH and inherited environment...\n",
args[ 0 ] );
// The prototype in unistd.h differs from the one in process.h. The former
// does not promise to keep the pointers intact.
execvp( args[ 0 ], mutable_args );
ec = errno;
printf( "Load error: %s (%d)\n", strerror( ec ), ec );
return ec;
}
C:\WORK>.\exec.exe ..\echo.exe
Spawning ..\echo.exe with search in $PATH and a limited environment...
abc
Exit code: 0
Loading ..\echo.exe with search in $PATH and inherited environment...
Load error: No such file or directory (2)
C:\WORK>copy \cygwin\bin\cygwin1.dll.new \cygwin\bin\cygwin1.dll
Overwrite \cygwin\bin\cygwin1.dll? (Yes/No/All): y
1 file(s) copied.
C:\WORK>.\exec.exe ..\echo.exe
Spawning ..\echo.exe with search in $PATH and a limited environment...
abc
Exit code: 0
Loading ..\echo.exe with search in $PATH and inherited environment...
abc
C:\WORK>
--
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