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exec.h
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exec.h
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/*
--- Version 3.2 91-09-03 22:31 ---
EXEC.H: EXEC function with memory swap - Main function header file.
Public domain software by
Thomas Wagner
Ferrari electronic GmbH
Beusselstrasse 27
D-1000 Berlin 21
Germany
*/
extern int do_exec(char * xfn, char * pars, int spawn, unsigned needed,
char ** envp);
/*
The EXEC function.
Parameters:
xfn is a string containing the name of the file
to be executed. If the string is empty,
the COMSPEC environment variable is used to
load a copy of COMMAND.COM or its equivalent.
If the filename does not include a path, the
current PATH is searched after the default.
If the filename does not include an extension,
the path is scanned for a COM, EXE, or BAT file
in that order.
pars The program parameters.
spawn If 0, the function will terminate after the
EXECed program returns, the function will not return.
NOTE: If the program file is not found, the function
will always return with the appropriate error
code, even if 'spawn' is 0.
If non-0, the function will return after executing the
program. If necessary (see the "needed" parameter),
memory will be swapped out before executing the program.
For swapping, spawn must contain a combination of the
following flags:
USE_EMS (0x01) - allow EMS swap
USE_XMS (0x02) - allow XMS swap
USE_FILE (0x04) - allow File swap
The order of trying the different swap methods can be
controlled with one of the flags
EMS_FIRST (0x00) - EMS, XMS, File (default)
XMS_FIRST (0x10) - XMS, EMS, File
If swapping is to File, the attribute of the swap file
can be set to "hidden", so users are not irritated by
strange files appearing out of nowhere with the flag
HIDE_FILE (0x40) - create swap file as hidden
and the behaviour on Network drives can be changed with
NO_PREALLOC (0x100) - don't preallocate
CHECK_NET (0x200) - don't preallocate if file on net.
This checking for Network is mainly to compensate for
a strange slowdown on Novell networks when preallocating
a file. You can either set NO_PREALLOC to avoid allocation
in any case, or let the prep_swap routine decide whether
to do preallocation or not depending on the file being
on a network drive (this will only work with DOS 3.1 or
later).
needed The memory needed for the program in paragraphs (16 Bytes).
If not enough memory is free, the program will
be swapped out.
Use 0 to never swap, 0xffff to always swap.
If 'spawn' is 0, this parameter is irrelevant.
envp The environment to be passed to the spawned
program. If this parameter is NULL, a copy
of the parent's environment is used (i.e.
'putenv' calls have no effect). If non-NULL,
envp must point to an array of pointers to
strings, terminated by a NULL pointer (the
standard variable 'environ' may be used).
Return value:
0x0000..00FF: The EXECed Program's return code
0x0101: Error preparing for swap: no space for swapping
0x0102: Error preparing for swap: program too low in memory
0x0200: Program file not found
0x0201: Program file: Invalid drive
0x0202: Program file: Invalid path
0x0203: Program file: Invalid name
0x0204: Program file: Invalid drive letter
0x0205: Program file: Path too long
0x0206: Program file: Drive not ready
0x0207: Batchfile/COMMAND: COMMAND.COM not found
0x0208: Error allocating temporary buffer
0x03xx: DOS-error-code xx calling EXEC
0x0400: Error allocating environment buffer
0x0500: Swapping requested, but prep_swap has not
been called or returned an error.
0x0501: MCBs don't match expected setup
0x0502: Error while swapping out
0x0600: Redirection syntax error
0x06xx: DOS error xx on redirection
*/
/* Return codes (only upper byte significant) */
#define RC_PREPERR 0x0100
#define RC_NOFILE 0x0200
#define RC_EXECERR 0x0300
#define RC_ENVERR 0x0400
#define RC_SWAPERR 0x0500
#define RC_REDIRERR 0x0600
/* Swap method and option flags */
#define USE_EMS 0x01
#define USE_XMS 0x02
#define USE_FILE 0x04
#define EMS_FIRST 0x00
#define XMS_FIRST 0x10
#define HIDE_FILE 0x40
#define NO_PREALLOC 0x100
#define CHECK_NET 0x200
#define USE_ALL (USE_EMS | USE_XMS | USE_FILE)
/*
The function pointed to by "spawn_check" will be called immediately
before doing the actual swap/exec, provided that
- the preparation code did not detect an error, and
- "spawn_check" is not NULL.
The function definition is
int name (int cmdbat, int swapping, char *execfn, char *progpars)
The parameters passed to this function are
cmdbat 1: Normal EXE/COM file
2: Executing BAT file via COMMAND.COM
3: Executing COMMAND.COM (or equivalent)
swapping < 0: Exec, don't swap
0: Spawn, don't swap
> 0: Spawn, swap
execfn the file name to execute (complete with path)
progpars the program parameter string
If the routine returns anything other than 0, the swap/exec will
not be executed, and do_exec will return with this code.
You can use this function to output messages (for example, the
usual "enter EXIT to return" message when loading COMMAND.COM)
and to do clean-up and additional checking.
CAUTION: If swapping is > 0, the routine may not modify the
memory layout, i.e. it may not call any memory allocation or
deallocation routines.
"spawn_check" is initialized to NULL.
*/
typedef int (spawn_check_proc)(int cmdbat, int swapping, char * execfn, char * progpars);
extern spawn_check_proc * spawn_check;
/*
The 'swap_prep' variable can be accessed from the spawn_check
call-back routine for additional information on the nature and
parameters of the swap. This variable will ONLY hold useful
information if the 'swapping' parameter to spawn_check is > 0.
The contents of this variable may not be changed.
The 'swapmethod' field will contain one of the flags USE_FILE,
USE_XMS, or USE_EMS.
Caution: The module using this data structure must be compiled
with structure packing on byte boundaries on, i.e. with /Zp1 for
MSC, or -a- for Turbo/Borland.
*/
typedef struct {
long xmm; /* XMM entry address */
int first_mcb; /* Segment of first MCB */
int psp_mcb; /* Segment of MCB of our PSP */
int env_mcb; /* MCB of Environment segment */
int noswap_mcb; /* MCB that may not be swapped */
int ems_pageframe; /* EMS page frame address */
int handle; /* EMS/XMS/File handle */
int total_mcbs; /* Total number of MCBs */
char swapmethod; /* Method for swapping */
char swapfilename[81]; /* Swap file name if swapping to file */
} prep_block;
extern prep_block swap_prep;