/***
*execvpe.c - execute a file with given environ; search along PATH
*
*       Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved.
*
*Purpose:
*       defines _execvpe() - execute a file with given environ
*
*Revision History:
*       10-17-83  RN    written
*       10-29-85  TC    added execvpe capability
*       11-19-86  SKS   handle both kinds of slashes
*       12-01-86  JMB   added Kanji file name support under conditional KANJI
*                       switches, corrected header info
*                       removed bogus check for env = b after call to strncpy().
*       12-11-87  JCR   Added "_LOAD_DS" to declaration
*       09-05-88  SKS   Treat EACCES the same as ENOENT -- keep trying
*       10-18-88  GJF   Removed copy of PATH string to local array, changed
*                       bbuf to be a malloc-ed buffer. Removed bogus limits
*                       on the size of that PATH string.
*       10-26-88  GJF   Don't search PATH when relative pathname is given (per
*                       Stevesa). Also, if the name built from PATH component
*                       and filename is a UNC name, allow any error.
*       11-20-89  GJF   Fixed copyright. Added const attribute to types of
*                       filename, argvector and envptr. Also, added "#include
*                       <jstring.h>" under KANJI switch (same as 5-17-89 change
*                       to CRT version).
*       03-08-90  GJF   Replaced _LOAD_DS with _CALLTYPE1, added #include
*                       <cruntime.h> and removed #include <register.h>. Also,
*                       cleaned up the formatting a bit.
*       07-24-90  SBM   Removed redundant includes, replaced <assertm.h> by
*                       <assert.h>
*       09-27-90  GJF   New-style function declarator.
*       01-17-91  GJF   ANSI naming.
*       11-30-92  KRS   Port _MBCS code from 16-bit tree.
*       04-06-93  SKS   Replace _CRTAPI* with __cdecl
*       12-07-93  CFW   Wide char enable.
*       01-10-95  CFW   Debug CRT allocs.
*       02-06-95  CFW   assert -> _ASSERTE.
*       02-06-98  GJF   Changes for Win64: changed return type to intptr_t.
*
*******************************************************************************/

#include <cruntime.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <process.h>
#include <mbstring.h>
#include <tchar.h>
#include <dbgint.h>

#define SLASHCHAR _T('\\')
#define XSLASHCHAR _T('/')

#define SLASH _T("\\")
#define DELIMITER _T(";")

#ifdef _MBCS
/* note, the macro below assumes p is to pointer to a single-byte character
 * or the 1st byte of a double-byte character, in a string.
 */
#define ISPSLASH(p)     ( ((p) == _mbschr((p), SLASHCHAR)) || ((p) == \
_mbschr((p), XSLASHCHAR)) )
#else
#define ISSLASH(c)      ( ((c) == SLASHCHAR) || ((c) == XSLASHCHAR) )
#endif


/***
*int _execvpe(filename, argvector, envvector) - execute a file
*
*Purpose:
*       Executes a file with given arguments and environment.
*       try to execute the file. start with the name itself (directory '.'),
*       and if that doesn't work start prepending pathnames from the
*       environment until one works or we run out. if the file is a pathname,
*       don't go to the environment to get alternate paths. If a needed text
*       file is busy, wait a little while and try again before despairing
*       completely
*
*Entry:
*       _TSCHAR *filename        - file to execute
*       _TSCHAR **argvector - vector of arguments
*       _TSCHAR **envvector - vector of environment variables
*
*Exit:
*       destroys the calling process (hopefully)
*       if fails, returns -1
*
*Exceptions:
*
*******************************************************************************/

intptr_t __cdecl _texecvpe (
        REG3 const _TSCHAR *filename,
        const _TSCHAR * const *argvector,
        const _TSCHAR * const *envptr
        )
{
        REG1 _TSCHAR *env;
        _TSCHAR *bbuf = NULL;
        REG2 _TSCHAR *buf;
        _TSCHAR *pfin;

        _ASSERTE(filename != NULL);
        _ASSERTE(*filename != _T('\0'));
        _ASSERTE(argvector != NULL);
        _ASSERTE(*argvector != NULL);
        _ASSERTE(**argvector != _T('\0'));

        _texecve(filename,argvector,envptr);

        if ( (errno != ENOENT)
        || (_tcschr(filename, SLASHCHAR) != NULL)
        || (_tcschr(filename, XSLASHCHAR) != NULL)
        || *filename && *(filename+1) == _T(':')
        || !(env=_tgetenv(_T("PATH"))) )
                goto reterror;

        /* allocate a buffer to hold alternate pathnames for the executable
         */
        if ( (buf = bbuf = _malloc_crt(_MAX_PATH * sizeof(_TSCHAR))) == NULL )
            goto reterror;

        do {
                /* copy a component into bbuf[], taking care not to overflow it
                 */
                /* UNDONE: make sure ';' isn't 2nd byte of DBCS char */
                while ( (*env) && (*env != _T(';')) && (buf < bbuf+(_MAX_PATH-2)*sizeof(_TSCHAR)) )
                        *buf++ = *env++;

                *buf = _T('\0');
                pfin = --buf;
                buf = bbuf;

#ifdef _MBCS
                if (*pfin == SLASHCHAR) {
                        if (pfin != _mbsrchr(buf,SLASHCHAR))
                                /* *pfin is the second byte of a double-byte
                                 * character
                                 */
                                strcat( buf, SLASH );
                }
                else if (*pfin != XSLASHCHAR)
                        strcat(buf, SLASH);
#else
                if (*pfin != SLASHCHAR && *pfin != XSLASHCHAR)
                        _tcscat(buf, SLASH);
#endif

                /* check that the final path will be of legal size. if so,
                 * build it. otherwise, return to the caller (return value
                 * and errno rename set from initial call to _execve()).
                 */
                if ( (_tcslen(buf) + _tcslen(filename)) < _MAX_PATH )
                        _tcscat(buf, filename);
                else
                        break;

                _texecve(buf, argvector, envptr);

                if ( (errno != ENOENT)
#ifdef _MBCS
                && (!ISPSLASH(buf) || !ISPSLASH(buf+1)) )
#else
                && (!ISSLASH(*buf) || !ISSLASH(*(buf+1))) )
#endif
                        break;
        } while ( *env && env++ );

reterror:
        if (bbuf != NULL)
                _free_crt(bbuf);

        return(-1);
}