/*-----------------------------------------------------------------------*
Name _LoadProg -- Load and Execute a program
Usage #include <_process.h>
int _LoadProg(int (* Func)(char *, char *, char *),
char *pathP,
char *argP[],
char *envV[],
int UsePath)
Prototype in _process.h
Description _Loadprog loads and runs another program, known as child
process.
The child process overlays the current program if _exec is
passed as Func argument, otherwise the calling parent
process regains control after program execution if _spawn
is passed as Func argument.
*pathP is the file name of the called child process.
_LoadProg searches for pathname using the standard MS-DOS
search algorithm:
. no extension or no period - search for exact file
name; if not successful, add .EXE and search
again
. extension given - search only for exact file name
. period given - search only for file name with no
extension
UsePath, if true, specifies that the function will search
for the child in those directories specified by the DOS
PATH environment variable. If false, _LoadProg only
searches the root and current working directory.
At execution time, the child process receives two
arguments:
- a command string built from argP
- an environment built from envV.
Return value A successful _exec does not return, and a successful _spawn
returns the exit code of the child process. On error,
_LoadProg returns -1, and errno is set to one of the
following:
E2BIG Argument list too long
EACCES Permission denied
EMFILE Too many open files
ENOENT Path or file name not found
ENOEXEC Exec format error
ENOMEM Not enough core
*------------------------------------------------------------------------*/
int near _LoadProg(int cdecl near (*Func)(char *, char *, char *), char *pathP,
char *argP[], char *envV[], int UsePath)
{
char *cmdP, *envP;
void *envSave;
int rc;
/* First, Check if the program exists */
if ((pathP = __searchpath(pathP, UsePath | _PROGRAM)) == NULL)
{
errno = ENOENT;
return -1;
}
/* Then, concatenate arguments to make the DOS command line */
if ((cmdP = __DOScmd(argP)) == NULL)
{
errno = ENOMEM;
return -1;
}
/* Then, concatenate environment strings */
if (envV == NULL)
envV = environ;
if ((envP = __DOSenv(envV, pathP, &envSave)) == NULL)
{
errno = ENOMEM;
free(cmdP);
return -1;
}
/* Flush all byte streams */
(*_exitbuf)();
/* Now, call the low level _exec/_spawn function */
rc = (*Func)(pathP, cmdP, envP);
/* Release all working buffers */
free(envSave);
free(cmdP);
return (rc);
}
/*-----------------------------------------------------------------------*
Name searchpath - searches the DOS path
Usage char *searchpath(const char *filename);
Prototype in dir.h
Description searchpath simply calls __searchpath to search the current
directory and MS DOS path for filename.
Return value see __searchpath in searchp.cas.
*------------------------------------------------------------------------*/
char * _CType searchpath(const char *file)
{
return __searchpath(file, _USEPATH);
}
