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562 lines
16 KiB
562 lines
16 KiB
/***
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*popen.c - initiate a pipe and a child command
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*
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* Copyright (c) 1989-1993, Microsoft Corporation. All rights reserved.
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*
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*Purpose:
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* Defines _popen() and _pclose().
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*
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*Revision History:
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* 01-06-89 GJF Initial version (I plead temporary insanity).
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* 01-09-89 GJF Fixed several bugs.
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* 01-10-89 GJF Implemented several improvements from Trapper.
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* 01-12-89 GJF Added underscores to function names. Also, in _pclose,
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* pstream must be close before the cwait call if it is
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* attached to the write handle of the pipe (otherwise,
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* may get a deadlock).
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* 01-13-89 GJF Added multi-thread/dll support.
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* 02-09-89 GJF Prevent child process from inheriting unwanted handles.
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* Also, always close pstream before doing the cwait.
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* 05-10-89 GJF Ported to 386 (OS/2 2.0)
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* 08-14-89 GJF Use DOSCALLS.H for API prototypes, fixed _rotl call
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* in _pclose (rotate 24 bits for 386!), re-tested.
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* 11-16-89 GJF Changed DOS32SETFILEHSTATE to DOS32SETFHSTATE
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* 11-20-89 GJF Added const attribute to types of _popen()'s args.
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* Also, fixed copyright.
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* 03-19-90 GJF Replaced _LOAD_DS with _CALLTYPE1 and added #include
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* <cruntime.h>.
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* 03-26-90 GJF Made ibtab() and setinherit() _CALLTYPE4.
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* 07-25-90 SBM Compiles cleanly with -W3 (removed unreferenced
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* variables), removed '32' from API names
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* 08-13-90 SBM Compiles cleanly with -W3 with new build of compiler
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* 10-03-90 GJF New-style function declarators.
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* 12-04-90 SRW Changed to include <oscalls.h> instead of <doscalls.h>
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* 12-06-90 SRW Added _CRUISER_ and _WIN32 conditionals.
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* 01-18-91 GJF ANSI naming.
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* 02-25-91 SRW Renamed _get_free_osfhnd to be _alloc_osfhnd [_WIN32_]
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* 09-29-91 GJF Picked up NT implementation (_WIN32_).
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* 04-06-92 SRW Fixed to not rely on setinherit function (_WIN32_).
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* 04-28-92 DJM ifndef for POSIX
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* 05-06-92 GJF Set _osfile[stddup] so that _get_osfhandle knows it's
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* open (bug found by Markl).
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* 05-15-92 GJF Fixed regression Markl found - _close(stddup) to ensure
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* that _osfile[] entry is cleared.
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* 01-07-93 GJF Substantially revised: purged Cruiser support, removed
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* needlessly repeated API calls, closed down a pipe
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* handle accidently left open at end of _popen, removed
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* reduntant CloseHandle call from _pclose, tried to clean
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* up the format and reduce the number of silly casts,
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* and added or revised many comments.
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* 04-10-93 GJF Removed redundant close of child process handle in
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* _pclose().
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*
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*******************************************************************************/
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#ifndef _POSIX_
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#include <cruntime.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <malloc.h>
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#include <process.h>
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#include <io.h>
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#include <fcntl.h>
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#include <internal.h>
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#include <errno.h>
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#include <msdos.h>
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#include <os2dll.h>
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#include <oscalls.h>
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/* size for pipe buffer
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*/
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#define PSIZE 1024
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#define STDIN 0
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#define STDOUT 1
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/* definitions for table of stream pointer - process handle pairs. the table
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* is created, maintained and accessed by the idtab function. _popen and
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* _pclose gain access to table entries only by calling idtab. Note that the
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* table is expanded as necessary (by idtab) and free table entries are reused
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* (an entry is free if its stream field is NULL), but the table is never
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* contracted.
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*/
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typedef struct {
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FILE *stream;
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int prochnd;
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} IDpair;
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/* number of entries in idpairs table
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*/
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static unsigned idtabsiz = 0;
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/* pointer to first table entry
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*/
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static IDpair *idpairs = NULL;
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/* function to find specified table entries. also, creates and maintains
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* the table.
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*/
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static IDpair * _CRTAPI3 idtab(FILE *);
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/***
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*FILE *_popen(cmdstring,type) - initiate a pipe and a child command
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*
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*Purpose:
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* Creates a pipe and asynchronously executes a child copy of the command
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* processor with cmdstring (see system()). If the type string contains
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* an 'r', the calling process can read child command's standard output
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* via the returned stream. If the type string contains a 'w', the calling
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* process can write to the child command's standard input via the
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* returned stream.
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*
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*Entry:
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* char *cmdstring - command to be executed
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* char *type - string of the form "r|w[b|t]", determines the mode
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* of the returned stream (i.e., read-only vs write-only,
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* binary vs text mode)
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*
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*Exit:
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* If successful, returns a stream associated with one end of the created
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* pipe (the other end of the pipe is associated with either the child
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* command's standard input or standard output).
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*
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* If an error occurs, NULL is returned.
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*
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*Exceptions:
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*
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*******************************************************************************/
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FILE * _CRTAPI1 _popen (
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const char *cmdstring,
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const char *type
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)
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{
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int phdls[2]; /* I/O handles for pipe */
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int ph_open[2]; /* flags, set if correspond phdls is open */
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int i1; /* index into phdls[] */
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int i2; /* index into phdls[] */
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int tm = 0; /* flag indicating text or binary mode */
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int stdhdl; /* either STDIN or STDOUT */
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HANDLE osfhndsv1; /* used to save _osfhnd[stdhdl] */
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long osfhndsv2; /* used to save _osfhnd[phdls[i2] */
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char osfilesv1; /* used to save _osfile[stdhdl] */
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char osfilesv2; /* used to save _osfile[phdls[i2]] */
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HANDLE oldhnd; /* used to hold OS file handle values... */
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HANDLE newhnd; /* ...in calls to DuplicateHandle API */
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FILE *pstream; /* stream to be associated with pipe */
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HANDLE prochnd; /* handle for current process */
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char *cmdexe; /* pathname for the command processor */
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int childhnd; /* handle for child process (cmd.exe) */
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IDpair *locidpair; /* pointer to IDpair table entry */
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/* first check for errors in the arguments
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*/
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if ( (cmdstring == NULL) || (type == NULL) || ((*type != 'w') &&
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(*type != 'r')) )
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goto error1;
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/* do the _pipe(). note that neither of the resulting handles will
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* be inheritable.
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*/
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if ( *(type + 1) == 't' )
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tm = _O_TEXT;
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else if ( *(type + 1) == 'b' )
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tm = _O_BINARY;
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tm |= _O_NOINHERIT;
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if ( _pipe( phdls, PSIZE, tm ) == -1 )
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goto error1;
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/* test *type and set stdhdl, i1 and i2 accordingly.
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*/
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if ( *type == 'w' ) {
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stdhdl = STDIN;
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i1 = 0;
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i2 = 1;
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}
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else {
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stdhdl = STDOUT;
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i1 = 1;
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i2 = 0;
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}
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/* the pipe now exists. the following steps must be carried out before
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* the child process (cmd.exe) may be spawned:
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*
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* 1. save a non-inheritable dup of stdhdl
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*
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* 2. force stdhdl to be a dup of ph[i1]. close both ph[i1] and
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* the original OS handle underlying stdhdl
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*
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* 3. associate a stdio-level stream with ph[i2].
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*/
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/* set flags to indicate pipe handles are open. note, these are only
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* used for error recovery.
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*/
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ph_open[ 0 ] = ph_open[ 1 ] = 1;
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/* get the process handle, it will be needed in some API calls
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*/
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prochnd = GetCurrentProcess();
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/* MULTI-THREAD: ASSERT LOCK ON STDHDL HERE!!!!
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*/
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_lock_fh( stdhdl );
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/* save a non-inheritable copy of stdhdl for later restoration.
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*/
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oldhnd = (HANDLE)_osfhnd[ stdhdl ];
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if ( (oldhnd == INVALID_HANDLE_VALUE) ||
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!DuplicateHandle( prochnd,
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oldhnd,
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prochnd,
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&osfhndsv1,
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0L,
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FALSE, /* non-inheritable */
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DUPLICATE_SAME_ACCESS )
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) {
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goto error2;
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}
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osfilesv1 = _osfile[ stdhdl ];
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/* force stdhdl to an inheritable dup of phdls[i1] (i.e., force
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* STDIN to the pipe read handle or STDOUT to the pipe write handle)
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* and close phdls[i1] (so there won't be a stray open handle on the
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* pipe after a _pclose). also, clear ph_open[i1] flag so that error
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* recovery won't try to close it again.
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*/
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if ( !DuplicateHandle( prochnd,
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(HANDLE)_osfhnd[ phdls[i1] ],
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prochnd,
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&newhnd,
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0L,
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TRUE, /* inheritable */
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DUPLICATE_SAME_ACCESS )
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) {
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goto error3;
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}
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(void)CloseHandle( (HANDLE)_osfhnd[stdhdl] );
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_free_osfhnd( stdhdl );
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_set_osfhnd( stdhdl, (long)newhnd );
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_osfile[ stdhdl ] = _osfile[ phdls[i1] ];
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(void)_close( phdls[i1] );
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ph_open[ i1 ] = 0;
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/* associate a stream with phdls[i2]. note that if there are no
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* errors, pstream is the return value to the caller.
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*/
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if ( (pstream = _fdopen( phdls[i2], type )) == NULL )
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goto error4;
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/* MULTI-THREAD: ASSERT LOCK ON IDPAIRS HERE!!!!
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*/
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_mlock( _POPEN_LOCK );
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/* next, set locidpair to a free entry in the idpairs table.
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*/
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if ( (locidpair = idtab( NULL )) == NULL )
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goto error5;
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/* temporarily change the _osfhnd[] and _osfile[] entries so that
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* the child doesn't get any entries for phdls[i2].
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*/
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osfhndsv2 = _osfhnd[ phdls[i2] ];
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_osfhnd[ phdls[i2] ] = (long)INVALID_HANDLE_VALUE;
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osfilesv2 = _osfile[ phdls[i2] ];
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_osfile[ phdls[i2] ] = 0;
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/* spawn the child copy of cmd.exe. the algorithm is adapted from
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* SYSTEM.C, and behaves the same way.
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*/
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if ( ((cmdexe = getenv("COMSPEC")) == NULL) ||
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(((childhnd = _spawnl( _P_NOWAIT,
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cmdexe,
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cmdexe,
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"/c",
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cmdstring,
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NULL ))
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== -1) && ((errno == ENOENT) || (errno == EACCES))) ) {
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/* either COMSPEC wasn't defined, or the spawn failed because
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* cmdexe wasn't found or was inaccessible. in either case,
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* try to spawn "cmd.exe" instead. note that spawnlp is used
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* here so that the path is searched.
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*/
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cmdexe = "cmd.exe";
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childhnd = _spawnlp( _P_NOWAIT,
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cmdexe,
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cmdexe,
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"/c",
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cmdstring,
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NULL);
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}
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_osfhnd[ phdls[i2] ] = osfhndsv2;
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_osfile[ phdls[i2] ] = osfilesv2;
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/* check if the last (perhaps only) spawn attempt was successful
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*/
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if ( childhnd == -1 )
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goto error6;
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/* restore stdhdl for the current process, set value of *locidpair,
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* close osfhndsv1 (note that CloseHandle must be used instead of close)
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* and return pstream to the caller
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*/
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(void)DuplicateHandle( prochnd,
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osfhndsv1,
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prochnd,
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&newhnd,
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0L,
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TRUE, /* inheritable */
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DUPLICATE_CLOSE_SOURCE | /* close osfhndsv1 */
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DUPLICATE_SAME_ACCESS );
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(void)CloseHandle( (HANDLE)_osfhnd[stdhdl] );
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_free_osfhnd( stdhdl );
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_set_osfhnd( stdhdl, (long)newhnd );
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_osfile[stdhdl] = osfilesv1;
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/* MULTI-THREAD: RELEASE LOCK ON STDHDL HERE!!!!
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*/
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_unlock_fh( stdhdl );
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locidpair->prochnd = childhnd;
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locidpair->stream = pstream;
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/* MULTI-THREAD: RELEASE LOCK ON IDPAIRS HERE!!!!
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*/
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_munlock( _POPEN_LOCK );
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/* all successful calls to _popen return to the caller via this return
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* statement!
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*/
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return( pstream );
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/**
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* error handling code. all detected errors end up here, entering
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* via a goto one of the labels. note that the logic is currently
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* a straight fall-thru scheme (e.g., if entered at error5, the
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* code for error5, error4,...,error1 is all executed).
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**********************************************************************/
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error6: /* make sure locidpair is reusable
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*/
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locidpair->stream = NULL;
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error5: /* close pstream (also, clear ph_open[i2] since the stream
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* close will also close the pipe handle)
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*/
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(void)fclose( pstream );
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ph_open[ i2 ] = 0;
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/* MULTI-THREAD: RELEASE LOCK ON IDPAIRS HERE!!!!
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*/
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_munlock(_POPEN_LOCK);
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error4: /* restore stdhdl
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*/
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(void)DuplicateHandle( prochnd,
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osfhndsv1,
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prochnd,
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&newhnd,
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0L,
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TRUE,
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DUPLICATE_SAME_ACCESS );
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(void)CloseHandle( (HANDLE)_osfhnd[stdhdl] );
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_free_osfhnd( stdhdl );
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_set_osfhnd( stdhdl, (long)newhnd );
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_osfile[ stdhdl ] = osfilesv1;
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/* MULTI-THREAD: RELEASE LOCK ON STDHDL HERE!!!!
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*/
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_unlock_fh( stdhdl );
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error3: /* close osfhndsv1
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*/
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CloseHandle( osfhndsv1 );
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error2: /* close handles on pipe (if they are still open)
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*/
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if ( ph_open[i1] )
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_close( phdls[i1] );
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if ( ph_open[i2] )
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_close( phdls[i2] );
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error1: /* return NULL to the caller indicating failure
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*/
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return( NULL );
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}
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/***
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*int _pclose(pstream) - wait on a child command and close the stream on the
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* associated pipe
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*
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*Purpose:
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* Closes pstream then waits on the associated child command. The
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* argument, pstream, must be the return value from a previous call to
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* _popen. _pclose first looks up the process handle of child command
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* started by that _popen and does a cwait on it. Then, it closes pstream
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* and returns the exit status of the child command to the caller.
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*
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*Entry:
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* FILE *pstream - file stream returned by a previous call to _popen
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*
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*Exit:
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* If successful, _pclose returns the exit status of the child command.
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* The format of the return value is that same as for cwait, except that
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* the low order and high order bytes are swapped.
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*
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* If an error occurs, -1 is returned.
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*
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*Exceptions:
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*
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*******************************************************************************/
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|
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int _CRTAPI1 _pclose (
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FILE *pstream
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)
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{
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IDpair *locidpair; /* pointer to entry in idpairs table */
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int termstat; /* termination status word */
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int retval = -1; /* return value (to caller) */
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|
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/* MULTI-THREAD: LOCK IDPAIRS HERE!!!!
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*/
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_mlock(_POPEN_LOCK);
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if ( (pstream == NULL) || ((locidpair = idtab(pstream)) == NULL) )
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/* invalid pstream, exit with retval == -1
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*/
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goto done;
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|
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/* close pstream
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*/
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(void)fclose(pstream);
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|
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/* wait on the child (copy of the command processor) and all of its
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* children.
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*/
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if ( (_cwait(&termstat, locidpair->prochnd, _WAIT_GRANDCHILD) != -1) ||
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(errno == EINTR) )
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retval = termstat;
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/* Mark the IDpairtable entry as free (note: prochnd was closed by the
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* preceding call to _cwait).
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*/
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locidpair->stream = NULL;
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locidpair->prochnd = 0;
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/* only return path!
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*/
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done:
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/* MULTI-THREAD: RELEASE LOCK ON IDPAIRS HERE!!!!
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*/
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_munlock(_POPEN_LOCK);
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return(retval);
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}
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|
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/***
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|
* static IDpair * idtab(FILE *pstream) - find an idpairs table entry
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|
*
|
|
*Purpose:
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|
* Find an entry in the idpairs table. This function finds the entry the
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|
* idpairs table entry corresponding to pstream. In the case where pstream
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* is NULL, the entry being searched for is any free entry. In this case,
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* idtab will create the idpairs table if it doesn't exist, or expand it (by
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* exactly one entry) if there are no free entries.
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|
*
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* [MTHREAD NOTE: This routine assumes that the caller has acquired the
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* idpairs table lock.]
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|
*
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*Entry:
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* FILE *pstream - stream corresponding to table entry to be found (if NULL
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|
* then find any free table entry)
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|
*
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|
*Exit:
|
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* if successful, returns a pointer to the idpairs table entry. otherwise,
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* returns NULL.
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*
|
|
*Exceptions:
|
|
*
|
|
*******************************************************************************/
|
|
|
|
static IDpair * _CRTAPI3 idtab (
|
|
FILE *pstream
|
|
)
|
|
{
|
|
|
|
IDpair * pairptr; /* ptr to entry */
|
|
IDpair * newptr; /* ptr to newly malloc'd memory */
|
|
|
|
|
|
/* search the table. if table is empty, appropriate action should
|
|
* fall out automatically.
|
|
*/
|
|
for ( pairptr = idpairs ; pairptr < (idpairs+idtabsiz) ; pairptr++ )
|
|
if ( pairptr->stream == pstream )
|
|
break;
|
|
|
|
/* if we found an entry, return it.
|
|
*/
|
|
if ( pairptr < (idpairs + idtabsiz) )
|
|
return(pairptr);
|
|
|
|
/* did not find an entry in the table. if pstream was NULL, then try
|
|
* creating/expanding the table. otherwise, return NULL. note that
|
|
* when the table is created or expanded, exactly one new entry is
|
|
* produced. this must not be changed unless code is added to mark
|
|
* the extra entries as being free (i.e., set their stream fields to
|
|
* to NULL).
|
|
*/
|
|
if ( (pstream != NULL) || ((newptr = (IDpair *)realloc((void *)idpairs,
|
|
(idtabsiz + 1)*sizeof(IDpair))) == NULL) )
|
|
/* either pstream was non-NULL or the attempt to create/expand
|
|
* the table failed. in either case, return a NULL to indicate
|
|
* failure.
|
|
*/
|
|
return( NULL );
|
|
|
|
idpairs = newptr; /* new table ptr */
|
|
pairptr = newptr + idtabsiz; /* first new entry */
|
|
idtabsiz++; /* new table size */
|
|
|
|
return( pairptr );
|
|
|
|
}
|
|
|
|
|
|
#endif /* _POSIX_ */
|