/*
 * Copyright 1993, 1995 Christopher Seiwald.
 *
 * This file is part of Jam - see jam.c for Copyright information.
 */

/*  This file is ALSO:
 *  Copyright 2001-2004 David Abrahams.
 *  Copyright 2007 Rene Rivera.
 *  Distributed under the Boost Software License, Version 1.0.
 *  (See accompanying file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
 */

# include "jam.h"
# include "lists.h"
# include "execcmd.h"
# include "pathsys.h"
# include "string.h"
# include "output.h"
# include <errno.h>
# include <assert.h>
# include <ctype.h>
# include <time.h>

# ifdef USE_EXECNT

# define WIN32_LEAN_AND_MEAN
# include <windows.h>
# include <process.h>
# include <tlhelp32.h>

/*
 * execnt.c - execute a shell command on Windows NT
 *
 * If $(JAMSHELL) is defined, uses that to formulate execvp()/spawnvp().
 * The default is:
 *
 *  /bin/sh -c %        [ on UNIX/AmigaOS ]
 *  cmd.exe /c %        [ on Windows NT ]
 *
 * Each word must be an individual element in a jam variable value.
 *
 * In $(JAMSHELL), % expands to the command string and ! expands to 
 * the slot number (starting at 1) for multiprocess (-j) invocations.
 * If $(JAMSHELL) doesn't include a %, it is tacked on as the last
 * argument.
 *
 * Don't just set JAMSHELL to /bin/sh or cmd.exe - it won't work!
 *
 * External routines:
 *  execcmd() - launch an async command execution
 *  execwait() - wait and drive at most one execution completion
 *
 * Internal routines:
 *  onintr() - bump intr to note command interruption
 *
 * 04/08/94 (seiwald) - Coherent/386 support added.
 * 05/04/94 (seiwald) - async multiprocess interface
 * 01/22/95 (seiwald) - $(JAMSHELL) support
 * 06/02/97 (gsar)    - full async multiprocess support for Win32
 */

/* get the maximum command line length according to the OS */
int maxline();

/* delete and argv list */
static void free_argv(char**);
/* Convert a command string into arguments for spawnvp. */
static char** string_to_args(const char*);
/* bump intr to note command interruption */
static void onintr(int);
/* If the command is suitable for execution via spawnvp */
long can_spawn(char*);
/* Add two 64-bit unsigned numbers, h1l1 and h2l2 */
static FILETIME add_64(
    unsigned long h1, unsigned long l1,
    unsigned long h2, unsigned long l2);
static FILETIME add_FILETIME(FILETIME t1, FILETIME t2);
static FILETIME negate_FILETIME(FILETIME t);
/* Convert a FILETIME to a number of seconds */
static double filetime_seconds(FILETIME t);
/* record the timing info for the process */
static void record_times(HANDLE, timing_info*);
/* calc the current running time of an *active* process */
static double running_time(HANDLE);
/* */
DWORD get_process_id(HANDLE);
/* terminate the given process, after terminating all its children */
static void kill_process_tree(DWORD, HANDLE);
/* waits for a command to complete or for the given timeout, whichever is first */
static int try_wait(int timeoutMillis);
/* reads any pending output for running commands */
static void read_output();
/* checks if a command ran out of time, and kills it */
static int try_kill_one();
/* */
static double creation_time(HANDLE);
/* Recursive check if first process is parent (directly or indirectly) of 
the second one. */
static int is_parent_child(DWORD, DWORD);
/* */
static void close_alert(HANDLE);
/* close any alerts hanging around */
static void close_alerts();

/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */

static int intr = 0;
static int cmdsrunning = 0;
static void (*istat)( int );

/* the list of commands we run */
static struct
{
    /* buffer to hold action */
    string action;
    /* buffer to hold target */
    string target;
    /* buffer to hold command being invoked */
    string command;
    /* the temporary batch file of the action, when needed */
    char *tempfile_bat;
    /* the pipes for the child process, parent reads from (0),
       child writes to (1) */
    HANDLE pipe_out[2];
    HANDLE pipe_err[2];
    /* buffers to hold stdout and stderr, if any */
    string buffer_out;
    string buffer_err;
    /* running process info */
    PROCESS_INFORMATION pi;
    /* when comand completes, the result value */
    DWORD exitcode;
    /* function called when the command completes */
    void (*func)( void *closure, int status, timing_info*, char *, char * );
    void *closure;
    /* when command completes, the reason it completed */
    int exit_reason;
} cmdtab[ MAXJOBS ] = {{0}};

/* execution unit tests */
void execnt_unit_test()
{
#if !defined(NDEBUG)        
    /* vc6 preprocessor is broken, so assert with these strings gets
     * confused. Use a table instead.
     */
    typedef struct test { char* command; int result; } test;
    test tests[] = {
        { "x", 0 },
        { "x\n ", 0 },
        { "x\ny", 1 },
        { "x\n\n y", 1 },
        { "echo x > foo.bar", 1 },
        { "echo x < foo.bar", 1 },
        { "echo x \">\" foo.bar", 0 },
        { "echo x \"<\" foo.bar", 0 },
        { "echo x \\\">\\\" foo.bar", 1 },
        { "echo x \\\"<\\\" foo.bar", 1 }
    };
    int i;
    for ( i = 0; i < sizeof(tests)/sizeof(*tests); ++i)
    {
        assert( !can_spawn( tests[i].command ) == tests[i].result );
    }

    {
        char* long_command = BJAM_MALLOC_ATOMIC(MAXLINE + 10);
        assert( long_command != 0 );
        memset( long_command, 'x', MAXLINE + 9 );
        long_command[MAXLINE + 9] = 0;
        assert( can_spawn( long_command ) == MAXLINE + 9);
        BJAM_FREE( long_command );
    }

    {
        /* Work around vc6 bug; it doesn't like escaped string
         * literals inside assert
         */
        char** argv = string_to_args("\"g++\" -c -I\"Foobar\"");
        char const expected[] = "-c -I\"Foobar\""; 
        
        assert(!strcmp(argv[0], "g++"));
        assert(!strcmp(argv[1], expected));
        free_argv(argv);
    }
#endif 
}

/* execcmd() - launch an async command execution */
void execcmd( 
    char *command,
    void (*func)( void *closure, int status, timing_info*, char *invoked_command, char *command_output),
    void *closure,
    LIST *shell,
    char *action,
    char *target )
{
    int slot;
    int raw_cmd = 0 ;
    char *argv_static[ MAXARGC + 1 ]; /* +1 for NULL */
    char **argv = argv_static;
    char *p;
    char* command_orig = command;
    
    /* Check to see if we need to hack around the line-length limitation. */
    /* Look for a JAMSHELL setting of "%", indicating that the command
     * should be invoked directly */
    if ( shell && !strcmp(shell->string,"%") && !list_next(shell) )
    {
        raw_cmd = 1;
        shell = 0;
    }

    /* Find a slot in the running commands table for this one. */
    for( slot = 0; slot < MAXJOBS; slot++ )
        if( !cmdtab[ slot ].pi.hProcess )
            break;
    if( slot == MAXJOBS )
    {
        printf( "no slots for child!\n" );
        exit( EXITBAD );
    }

    /* compute the name of a temp batch file, for possible use */
    if( !cmdtab[ slot ].tempfile_bat )
    {
        const char *tempdir = path_tmpdir();
        DWORD procID = GetCurrentProcessId();
  
        /* SVA - allocate 64 other just to be safe */
        cmdtab[ slot ].tempfile_bat = BJAM_MALLOC_ATOMIC( strlen( tempdir ) + 64 );
  
        sprintf(
            cmdtab[ slot ].tempfile_bat, "%s\\jam%d-%02d.bat", 
            tempdir, procID, slot );
    }

    /* Trim leading, -ending- white space */
    while( isspace( *command ) )
        ++command;

    /* Write to .BAT file unless the line would be too long and it
     * meets the other spawnability criteria.
     */
    if( raw_cmd && can_spawn( command ) >= MAXLINE )
    {
        if( DEBUG_EXECCMD )
            printf("Executing raw command directly\n");        
    }
    else
    {
        FILE *f = 0;
        int tries = 0;
        raw_cmd = 0;
        
        /* Write command to bat file. For some reason this open can
           fails intermitently. But doing some retries works. Most likely
           this is due to a previously existing file of the same name that
           happens to be opened by an active virus scanner. Pointed out,
           and fix by Bronek Kozicki. */
        for (; !f && tries < 4; ++tries)
        {
            f = fopen( cmdtab[ slot ].tempfile_bat, "w" );
            if ( !f && tries < 4 ) Sleep( 250 );
        }
        if (!f)
        {
            printf( "failed to write command file!\n" );
            exit( EXITBAD );
        }
        fputs( command, f );
        fclose( f );

        command = cmdtab[ slot ].tempfile_bat;
        
        if( DEBUG_EXECCMD )
        {
            if (shell)
                printf("using user-specified shell: %s", shell->string);
            else
                printf("Executing through .bat file\n");
        }
    }

    /* Formulate argv; If shell was defined, be prepared for % and ! subs. */
    /* Otherwise, use stock cmd.exe. */
    if( shell )
    {
        int i;
        char jobno[4];
        int gotpercent = 0;

        sprintf( jobno, "%d", slot + 1 );

        for( i = 0; shell && i < MAXARGC; i++, shell = list_next( shell ) )
        {
            switch( shell->string[0] )
            {
                case '%':   argv[i] = command; gotpercent++; break;
                case '!':   argv[i] = jobno; break;
                default:    argv[i] = shell->string;
            }
            if( DEBUG_EXECCMD )
                printf( "argv[%d] = '%s'\n", i, argv[i] );
        }

        if( !gotpercent )
            argv[i++] = command;

        argv[i] = 0;
    }
    else if (raw_cmd)
    {
        argv = string_to_args(command);
    }
    else
    {
        argv[0] = "cmd.exe";
        argv[1] = "/Q/C"; /* anything more is non-portable */
        argv[2] = command;
        argv[3] = 0;
    }

    /* Catch interrupts whenever commands are running. */

    if( !cmdsrunning++ )
        istat = signal( SIGINT, onintr );
    
    /* Start the command */
    {
        SECURITY_ATTRIBUTES sa
            = { sizeof(SECURITY_ATTRIBUTES), 0, 0 };
        SECURITY_DESCRIPTOR sd;
        STARTUPINFO si
            = { sizeof(STARTUPINFO), 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
        string cmd;

        /* init the security data */
        InitializeSecurityDescriptor( &sd, SECURITY_DESCRIPTOR_REVISION );
        SetSecurityDescriptorDacl( &sd, TRUE, NULL, FALSE );
        sa.lpSecurityDescriptor = &sd;
        sa.bInheritHandle = TRUE;

        /* create the stdout, which is also the merged out+err, pipe */
        if ( ! CreatePipe( &cmdtab[ slot ].pipe_out[0], &cmdtab[ slot ].pipe_out[1], &sa, 0 ) )
        {
            perror( "CreatePipe" );
            exit( EXITBAD );
        }

        /* create the stdout, which is also the merged out+err, pipe */
        if ( globs.pipe_action == 2 )
        {
            if ( ! CreatePipe( &cmdtab[ slot ].pipe_err[0], &cmdtab[ slot ].pipe_err[1], &sa, 0 ) )
            {
                perror( "CreatePipe" );
                exit( EXITBAD );
            }
        }

        /* set handle inheritance off for the pipe ends the parent reads from */
        SetHandleInformation( cmdtab[ slot ].pipe_out[0], HANDLE_FLAG_INHERIT, 0 );
        if ( globs.pipe_action == 2 )
        {
            SetHandleInformation( cmdtab[ slot ].pipe_err[0], HANDLE_FLAG_INHERIT, 0 );
        }

        /* hide the child window, if any */
        si.dwFlags |= STARTF_USESHOWWINDOW;
        si.wShowWindow = SW_HIDE;

        /* set the child outputs to the pipes */
        si.dwFlags |= STARTF_USESTDHANDLES;
        si.hStdOutput = cmdtab[ slot ].pipe_out[1];
        if ( globs.pipe_action == 2 )
        {
            /* pipe stderr to the action error output */
            si.hStdError = cmdtab[ slot ].pipe_err[1];
        }
        else if ( globs.pipe_action == 1 )
        {
            /* pipe stderr to the console error output */
            si.hStdError = GetStdHandle(STD_ERROR_HANDLE);
        }
        else
        {
            /* pipe stderr to the action merged output */
            si.hStdError = cmdtab[ slot ].pipe_out[1];
        }

        /* Save the operation for execwait() to find. */
        cmdtab[ slot ].func = func;
        cmdtab[ slot ].closure = closure;
        if (action && target)
        {
            string_copy( &cmdtab[ slot ].action, action );
            string_copy( &cmdtab[ slot ].target, target );
        }
        else
        {
            string_free( &cmdtab[ slot ].action );
            string_new( &cmdtab[ slot ].action );
            string_free( &cmdtab[ slot ].target );
            string_new( &cmdtab[ slot ].target );
        }
        string_copy( &cmdtab[ slot ].command, command_orig );
        
        /* put together the comman we run */
        {
            char ** argp = argv;
            string_new(&cmd);
            string_copy(&cmd,*(argp++));
            while( *argp != 0 )
            {
                string_push_back(&cmd,' ');
                string_append(&cmd,*(argp++));
            }
        }
        
        /* create the output buffers */
        string_new( &cmdtab[ slot ].buffer_out );
        string_new( &cmdtab[ slot ].buffer_err );

        /* run the command, by creating a sub-process for it */
        if (
            ! CreateProcess(
                NULL, /* application name */
                cmd.value, /* command line */
                NULL, /* process attributes */
                NULL, /* thread attributes */
                TRUE, /* inherit handles */
                CREATE_NEW_PROCESS_GROUP, /* create flags */
                NULL, /* env vars, null inherits env */
                NULL, /* current dir, null is our current dir */
                &si, /* startup info */
                &cmdtab[ slot ].pi /* the child process info, if created */
                )
            )
        {
            perror( "CreateProcess" );
            exit( EXITBAD );
        }
        
        /* clean up temporary stuff */
        string_free(&cmd);
    }

    /* Wait until we're under the limit of concurrent commands. */
    /* Don't trust globs.jobs alone.                            */

    while( cmdsrunning >= MAXJOBS || cmdsrunning >= globs.jobs )
        if( !execwait() )
            break;
    
    if (argv != argv_static)
    {
        free_argv(argv);
    }
}



/* execwait()
    - wait and drive at most one execution completion
    * waits for one command to complete, while processing the io
      for all ongoing commands.
*/
int execwait()
{
    int i = -1;

    /* Handle naive make1() which doesn't know if cmds are running. */

    if( !cmdsrunning )
        return 0;
    
    /* wait for a command to complete, while snarfing up any output */
    do
    {
        /* read in the output of all running commands */
        read_output();
        /* close out pending debug style dialogs */
        close_alerts();
        /* check for a complete command, briefly */
        if ( i < 0 ) i = try_wait(500);
        /* check if a command ran out of time */
        if ( i < 0 ) i = try_kill_one();
    }
    while ( i < 0 );
    
    /* we have a command... process it */
    --cmdsrunning;
    {
        timing_info time;
        int rstat;
        
        /* the time data for the command */
        record_times(cmdtab[i].pi.hProcess, &time);

        /* Clear the temp file */
        if ( cmdtab[i].tempfile_bat )
        {
            unlink( cmdtab[ i ].tempfile_bat );
            BJAM_FREE(cmdtab[i].tempfile_bat);
            cmdtab[i].tempfile_bat = NULL;
        }

        /* the dispossition of the command */
        if( intr )
            rstat = EXEC_CMD_INTR;
        else if( cmdtab[i].exitcode != 0 )
            rstat = EXEC_CMD_FAIL;
        else
            rstat = EXEC_CMD_OK;
        
        /* output the action block */
        out_action(
            cmdtab[i].action.size > 0 ? cmdtab[i].action.value : 0,
            cmdtab[i].target.size > 0 ? cmdtab[i].target.value : 0,
            cmdtab[i].command.size > 0 ? cmdtab[i].command.value : 0,
            cmdtab[i].buffer_out.size > 0 ? cmdtab[i].buffer_out.value : 0,
            cmdtab[i].buffer_err.size > 0 ? cmdtab[i].buffer_err.value : 0,
            cmdtab[i].exit_reason);

        /* call the callback, may call back to jam rule land.
        assume -p0 in effect so only pass buffer containing
        merged output */
        (*cmdtab[ i ].func)(
            cmdtab[ i ].closure,
            rstat,
            &time,
            cmdtab[i].command.value,
            cmdtab[i].buffer_out.value );
        
        /* clean up the command data, process, etc. */
        string_free(&cmdtab[i].action); string_new(&cmdtab[i].action);
        string_free(&cmdtab[i].target); string_new(&cmdtab[i].target);
        string_free(&cmdtab[i].command); string_new(&cmdtab[i].command);
        if (cmdtab[i].pi.hProcess) { CloseHandle(cmdtab[i].pi.hProcess); cmdtab[i].pi.hProcess = 0; }
        if (cmdtab[i].pipe_out[0]) { CloseHandle(cmdtab[i].pipe_out[0]); cmdtab[i].pipe_out[0] = 0; }
        if (cmdtab[i].pipe_out[1]) { CloseHandle(cmdtab[i].pipe_out[1]); cmdtab[i].pipe_out[1] = 0; }
        if (cmdtab[i].pipe_err[0]) { CloseHandle(cmdtab[i].pipe_err[0]); cmdtab[i].pipe_err[0] = 0; }
        if (cmdtab[i].pipe_err[1]) { CloseHandle(cmdtab[i].pipe_err[1]); cmdtab[i].pipe_err[1] = 0; }
        string_free(&cmdtab[i].buffer_out); string_new(&cmdtab[i].buffer_out);
        string_free(&cmdtab[i].buffer_err); string_new(&cmdtab[i].buffer_err);
        cmdtab[i].exitcode = 0;
        cmdtab[i].exit_reason = EXIT_OK;
    }

    return 1;
}

/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */

static void free_argv( char** args )
{
    BJAM_FREE( args[0] );
    BJAM_FREE( args );
}

int maxline()
{
    OSVERSIONINFO os_info;
    os_info.dwOSVersionInfoSize = sizeof(os_info);
    GetVersionEx(&os_info);
    
    return (os_info.dwMajorVersion == 3)
        ? 996 /* NT 3.5.1 */
        : 2047 /* NT >= 4.x */
        ;
}

/* Convert a command string into arguments for spawnvp.  The original
 * code, inherited from ftjam, tried to break up every argument on the
 * command-line, dealing with quotes, but that's really a waste of
 * time on Win32, at least.  It turns out that all you need to do is
 * get the raw path to the executable in the first argument to
 * spawnvp, and you can pass all the rest of the command-line
 * arguments to spawnvp in one, un-processed string.
 *
 * New strategy: break the string in at most one place.
 */
static char** string_to_args( const char*  string )
{
    int src_len;
    int in_quote;
    char* line;
    char const* src;
    char* dst;
    char** argv;

    /* drop leading and trailing whitespace if any */
    while (isspace(*string))
        ++string;
  
    src_len = strlen( string );
    while ( src_len > 0 && isspace( string[src_len - 1] ) )
        --src_len;

    /* Copy the input string into a buffer we can modify
     */
    line = (char*)BJAM_MALLOC_ATOMIC( src_len+1 );
    if (!line)
        return 0;

    /* allocate the argv array.
     *   element 0: stores the path to the executable
     *   element 1: stores the command-line arguments to the executable
     *   element 2: NULL terminator
     */
    argv = (char**)BJAM_MALLOC( 3 * sizeof(char*) );
    if (!argv)
    {
        BJAM_FREE( line );
        return 0;
    }
    
    /* Strip quotes from the first command-line argument and find
     * where it ends.  Quotes are illegal in Win32 pathnames, so we
     * don't need to worry about preserving escaped quotes here.
     * Spaces can't be escaped in Win32, only enclosed in quotes, so
     * removing backslash escapes is also a non-issue.
     */
    in_quote = 0;
    for ( src = string, dst = line ; *src; src++ )
    {
        if (*src == '"')
            in_quote = !in_quote;
        else if (!in_quote && isspace(*src))
            break;
        else
            *dst++ = *src;
    }
    *dst++ = 0;
    argv[0] = line;

    /* skip whitespace in src */
    while (isspace(*src))
        ++src;

    argv[1] = dst;

    /* Copy the rest of the arguments verbatim */
    
    src_len -= src - string;

    /* Use strncat because it appends a trailing nul */
    *dst = 0;
    strncat(dst, src, src_len);

    argv[2] = 0;
    
    return argv;
}

static void onintr( int disp )
{
    intr++;
    printf( "...interrupted\n" );
}

/*
 * can_spawn() - If the command is suitable for execution via spawnvp,
 * return a number >= the number of characters it would occupy on the
 * command-line.  Otherwise, return zero.
 */
long can_spawn(char* command)
{
    char *p;
    
    char inquote = 0;

    /* Move to the first non-whitespace */
    command += strspn( command, " \t" );

    p = command;
    
    /* Look for newlines and unquoted i/o redirection */
    do
    {
        p += strcspn( p, "'\n\"<>|" );

        switch (*p)
        {
        case '\n':
            /* skip over any following spaces */
            while( isspace( *p ) )
                ++p;
            /* Must use a .bat file if there is anything significant
             * following the newline
             */
            if (*p)
                return 0;
            break;
            
        case '"':
        case '\'':
            if (p > command && p[-1] != '\\')
            {
                if (inquote == *p)
                    inquote = 0;
                else if (inquote == 0)
                    inquote = *p;
            }
                
            ++p;
            break;
            
        case '<':
        case '>':
        case '|':
            if (!inquote)
                return 0;
            ++p;
            break;
        }
    }
    while (*p);

    /* Return the number of characters the command will occupy
     */
    return p - command;
}

/* 64-bit arithmetic helpers */

/* Compute the carry bit from the addition of two 32-bit unsigned numbers */
#define add_carry_bit(a, b) ( (((a) | (b)) >> 31) & (~((a) + (b)) >> 31) & 0x1 )

/* Compute the high 32 bits of the addition of two 64-bit unsigned numbers, h1l1 and h2l2 */
#define add_64_hi(h1, l1, h2, l2) ((h1) + (h2) + add_carry_bit(l1, l2))

/* Add two 64-bit unsigned numbers, h1l1 and h2l2 */
static FILETIME add_64(
    unsigned long h1, unsigned long l1,
    unsigned long h2, unsigned long l2)
{
    FILETIME result;
    result.dwLowDateTime = l1 + l2;
    result.dwHighDateTime = add_64_hi(h1, l1, h2, l2);

    return result;
}

static FILETIME add_FILETIME(FILETIME t1, FILETIME t2)
{
    return add_64(
        t1.dwHighDateTime, t1.dwLowDateTime
      , t2.dwHighDateTime, t2.dwLowDateTime);
}
static FILETIME negate_FILETIME(FILETIME t)
{
    /* 2s complement negation */
    return add_64(~t.dwHighDateTime, ~t.dwLowDateTime, 0, 1);
}

/* Convert a FILETIME to a number of seconds */
static double filetime_seconds(FILETIME t)
{
    return t.dwHighDateTime * (double)(1UL << 31) * 2 + t.dwLowDateTime * 1.0e-7;
}

static void record_times(HANDLE process, timing_info* time)
{
    FILETIME creation, exit, kernel, user;
    
    if (GetProcessTimes(process, &creation, &exit, &kernel, &user))
    {
        /* Compute the elapsed time */
        #if 0 /* We don't know how to get this number on Unix */
        time->elapsed = filetime_seconds(
            add_FILETIME( exit, negate_FILETIME(creation) )
            );
        #endif 
        time->system = filetime_seconds(kernel);
        time->user = filetime_seconds(user);            
    }
        
    /* CloseHandle((HANDLE)pid); */
}

#define IO_BUFFER_SIZE (16*1024)

static char ioBuffer[IO_BUFFER_SIZE+1];

static void read_pipe(
    HANDLE in, /* the pipe to read from */
    string * out
    )
{
    DWORD bytesInBuffer = 0;
    DWORD bytesAvailable = 0;
    
    do
    {
        /* check if we have any data to read */
        if ( ! PeekNamedPipe( in, ioBuffer, IO_BUFFER_SIZE, &bytesInBuffer, &bytesAvailable, NULL ) )
        {
            bytesAvailable = 0;
        }
        
        /* read in the available data */
        if ( bytesAvailable > 0 )
        {
            /* we only read in the available bytes, to avoid blocking */
            if (
                ReadFile( in, ioBuffer,
                    bytesAvailable <= IO_BUFFER_SIZE ? bytesAvailable : IO_BUFFER_SIZE,
                    &bytesInBuffer, NULL )
                )
            {
                if ( bytesInBuffer > 0 )
                {
                    /* clean up non-ascii chars */
                    int i;
                    for ( i = 0; i < bytesInBuffer; ++i )
                    {
                        if ((unsigned char)ioBuffer[i] < 1 ||
                            (unsigned char)ioBuffer[i] > 127 )
                        {
                            ioBuffer[i] = '?';
                        }
                    }
                    /* null, terminate */
                    ioBuffer[bytesInBuffer] = '\0';
                    /* append to the output */
                    string_append(out,ioBuffer);
                    /* subtract what we read in */
                    bytesAvailable -= bytesInBuffer;
                }
                else
                {
                    /* likely read a error, bail out. */
                    bytesAvailable = 0;
                }
            }
            else
            {
                /* definitely read a error, bail out. */
                bytesAvailable = 0;
            }
        }
    }
    while ( bytesAvailable > 0 );
}

static void read_output()
{
    int i;
    
    for ( i = 0; i < globs.jobs && i < MAXJOBS; ++i )
    {
        /* read stdout data */
        if (cmdtab[i].pipe_out[0])
            read_pipe( cmdtab[i].pipe_out[0], & cmdtab[i].buffer_out );
        /* read stderr data */
        if (cmdtab[i].pipe_err[0])
            read_pipe( cmdtab[i].pipe_err[0], & cmdtab[i].buffer_err );
    }
}

/*  waits for a single child process command to complete, or the
    timeout, whichever is first. returns the index of the completed
    command, or -1. */
static int try_wait(int timeoutMillis)
{
    int i, num_active, waiting;
    HANDLE active_handles[MAXJOBS];
    int active_procs[MAXJOBS];

    for ( waiting = 1; waiting;  )
    {
        /* find the first completed child process */
        for ( num_active = 0, i = 0; i < globs.jobs; ++i )
        {
            /* if we have an already dead process, return it. */
            cmdtab[i].exitcode = 0;
            if ( GetExitCodeProcess( cmdtab[i].pi.hProcess, &cmdtab[i].exitcode ) )
            {
                if ( STILL_ACTIVE != cmdtab[i].exitcode )
                {
                    return i;
                }
            }
            /* it's running, add it to the list to watch for */
            active_handles[num_active] = cmdtab[i].pi.hProcess;
            active_procs[num_active] = i;
            num_active += 1;
        }
        
        /* wait for a child to complete, or for our timeout window to expire */
        if ( waiting )
        {
            WaitForMultipleObjects( num_active, active_handles, FALSE, timeoutMillis );
            waiting = 0;
        }
    }
    
    return -1;
}

static int try_kill_one()
{
    /* only need to check if a timeout was specified with the -l option. */
    if ( globs.timeout > 0 )
    {
        int i;
        
        for ( i = 0; i < globs.jobs; ++i )
        {
            double t = running_time(cmdtab[i].pi.hProcess);
            if ( t > (double)globs.timeout )
            {
                /* the job may have left an alert dialog around,
                try and get rid of it before killing */
                close_alert(cmdtab[i].pi.hProcess);
                /* we have a "runaway" job, kill it */
                kill_process_tree(0,cmdtab[i].pi.hProcess);
                /* and return it as complete, with the failure code */
                GetExitCodeProcess( cmdtab[i].pi.hProcess, &cmdtab[i].exitcode );
                /* mark it as a timeout */
                cmdtab[i].exit_reason = EXIT_TIMEOUT;
                return i;
            }
        }
    }
    return -1;
}

static void close_alerts()
{
    /* we only attempt this every 5 seconds, or so, because it's
    not a cheap operation, and we'll catch the alerts eventually.
    this check uses floats as some compilers define CLOCKS_PER_SEC
    as a float or double. */
    if ( ((float)clock() / (float)(CLOCKS_PER_SEC*5)) < (1.0/5.0) )
    {
        int i;
        for ( i = 0; i < globs.jobs; ++i )
        {
            close_alert(cmdtab[i].pi.hProcess);
        }
    }
}

/* calc the current running time of an *active* process */
static double running_time(HANDLE process)
{
    FILETIME creation, exit, kernel, user, current;
    if (GetProcessTimes(process, &creation, &exit, &kernel, &user))
    {
        /* Compute the elapsed time */
        GetSystemTimeAsFileTime(&current);
        {
            double delta = filetime_seconds(
                add_FILETIME( current, negate_FILETIME(creation) )
                );
            return delta;
        }
    }
    return 0.0;
}

/* it's just stupidly silly that one has to do this! */
typedef struct PROCESS_BASIC_INFORMATION__ {
    LONG ExitStatus;
    PVOID PebBaseAddress;
    ULONG AffinityMask;
    LONG BasePriority;
    ULONG UniqueProcessId;
    ULONG InheritedFromUniqueProcessId;
    } PROCESS_BASIC_INFORMATION_;
typedef LONG (__stdcall * NtQueryInformationProcess__)(
    HANDLE ProcessHandle,
    LONG ProcessInformationClass,
    PVOID ProcessInformation,
    ULONG ProcessInformationLength,
    PULONG ReturnLength);
static NtQueryInformationProcess__ NtQueryInformationProcess_ = NULL;
static HMODULE NTDLL_ = NULL;
DWORD get_process_id(HANDLE process)
{
    PROCESS_BASIC_INFORMATION_ pinfo;
    if ( ! NtQueryInformationProcess_ )
    {
        if ( ! NTDLL_ )
        {
            NTDLL_ = GetModuleHandleA("ntdll");
        }
        if ( NTDLL_ )
        {
            NtQueryInformationProcess_
                = (NtQueryInformationProcess__)GetProcAddress( NTDLL_,"NtQueryInformationProcess" );
        }
    }
    if ( NtQueryInformationProcess_ )
    {
        LONG r = (*NtQueryInformationProcess_)(
            process,/* ProcessBasicInformation == */ 0,&pinfo,sizeof(PROCESS_BASIC_INFORMATION_),NULL);
        return pinfo.UniqueProcessId;
    }
    else
    {
        return 0;
    }
}

/* not really optimal, or efficient, but it's easier this way, and it's not
like we are going to be killing thousands, or even tens of processes. */
static void kill_process_tree(DWORD pid, HANDLE process)
{
    HANDLE process_snapshot_h = INVALID_HANDLE_VALUE;
    if ( !pid )
    {
        pid = get_process_id(process);
    }
    process_snapshot_h = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS,0);
    
    if (INVALID_HANDLE_VALUE != process_snapshot_h)
    {
        BOOL ok = TRUE;
        PROCESSENTRY32 pinfo;
        pinfo.dwSize = sizeof(PROCESSENTRY32);
        for (
            ok = Process32First(process_snapshot_h,&pinfo);
            TRUE == ok;
            ok = Process32Next(process_snapshot_h,&pinfo) )
        {
            if (pinfo.th32ParentProcessID == pid)
            {
                /* found a child, recurse to kill it and anything else below it */
                HANDLE ph = OpenProcess(PROCESS_ALL_ACCESS,FALSE,pinfo.th32ProcessID);
                if (NULL != ph)
                {
                    kill_process_tree(pinfo.th32ProcessID,ph);
                    CloseHandle(ph);
                }
            }
        }
        CloseHandle(process_snapshot_h);
    }
    /* now that the children are all dead, kill the root */
    TerminateProcess(process,-2);
}

static double creation_time(HANDLE process)
{
    FILETIME creation, exit, kernel, user, current;
    if (GetProcessTimes(process, &creation, &exit, &kernel, &user))
    {
        return filetime_seconds(creation);
    }
    return 0.0;
}

/* Recursive check if first process is parent (directly or indirectly) of 
the second one. Both processes are passed as process ids, not handles.
Special return value 2 means that the second process is smss.exe and its 
parent process is System (first argument is ignored) */
static int is_parent_child(DWORD parent, DWORD child)
{
    HANDLE process_snapshot_h = INVALID_HANDLE_VALUE;

    if (!child)
        return 0;
    if (parent == child)
        return 1;

    process_snapshot_h = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS,0);
    if (INVALID_HANDLE_VALUE != process_snapshot_h)
    {
        BOOL ok = TRUE;
        PROCESSENTRY32 pinfo;
        pinfo.dwSize = sizeof(PROCESSENTRY32);
        for (
            ok = Process32First(process_snapshot_h, &pinfo); 
            ok == TRUE; 
            ok = Process32Next(process_snapshot_h, &pinfo) )
        {
            if (pinfo.th32ProcessID == child)
            {
                /*
                Unfortunately, process ids are not really unique. There might 
                be spurious "parent and child" relationship match between
                two non-related processes if real parent process of a given
                process has exited (while child process kept running as an 
                "orphan") and the process id of such parent process has been 
                reused by internals of the operating system when creating 
                another process. Thus additional check is needed - process
                creation time. This check may fail (ie. return 0) for system 
                processes due to insufficient privileges, and that's OK. */
                double tchild = 0.0;
                double tparent = 0.0;
                HANDLE hchild = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, pinfo.th32ProcessID);

                CloseHandle(process_snapshot_h);

                /* csrss.exe may display message box like following:
                    xyz.exe - Unable To Locate Component
                    This application has failed to start because 
                    boost_foo-bar.dll was not found. Re-installing the 
                    application may fix the problem
                This actually happens when starting test process that depends
                on a dynamic library which failed to build. We want to 
                automatically close these message boxes even though csrss.exe
                is not our child process. We may depend on the fact that (in
                all current versions of Windows) csrss.exe is directly 
                child of smss.exe process, which in turn is directly child of
                System process, which always has process id == 4 .
                This check must be performed before comparison of process 
                creation time */
                if (stricmp(pinfo.szExeFile, "csrss.exe") == 0
                    && is_parent_child(parent, pinfo.th32ParentProcessID) == 2)
                {
                    return 1;
                }
                else if (stricmp(pinfo.szExeFile, "smss.exe") == 0
                    && pinfo.th32ParentProcessID == 4)
                {
                    return 2;
                }

                if (hchild != 0)
                {
                    HANDLE hparent = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, pinfo.th32ParentProcessID);
                    if (hparent != 0)
                    {
                        tchild = creation_time(hchild);
                        tparent = creation_time(hparent);
                        
                        CloseHandle(hparent);
                    }
                    CloseHandle(hchild);
                }

                /* return 0 if one of the following is true:
                1. we failed to read process creation time
                2. child was created before alleged parent */
                if (tchild == 0.0 || tparent == 0.0 || tchild < tparent)
                    return 0;

                return is_parent_child(parent, pinfo.th32ParentProcessID) & 1;
            }
        }

        CloseHandle(process_snapshot_h);
    }

    return 0;
}

typedef struct PROCESS_HANDLE_ID {HANDLE h; DWORD pid;} PROCESS_HANDLE_ID;

/* This function is called by the operating system for each topmost window. */
BOOL CALLBACK close_alert_window_enum(HWND hwnd, LPARAM lParam)
{
    char buf[7] = {0};
    PROCESS_HANDLE_ID p = *((PROCESS_HANDLE_ID*) (lParam));
    DWORD pid = 0;
    DWORD tid = 0;

    /* we want to find and close any window that:
    1. is visible and
    2. is a dialog and
    3. is displayed by any of our child processes */
    if (!IsWindowVisible(hwnd))
        return TRUE;

    if (!GetClassNameA(hwnd, buf, sizeof(buf)))
        return TRUE; /* failed to read class name; presume it's not a dialog */
 
    if (strcmp(buf, "#32770") != 0)
        return TRUE; /* not a dialog */

    /* GetWindowThreadProcessId returns 0 on error, otherwise thread id
    of window message pump thread */
    tid = GetWindowThreadProcessId(hwnd, &pid);
 
    if (tid && is_parent_child(p.pid, pid))
    {
        /* ask really nice */
        PostMessageA(hwnd, WM_CLOSE, 0, 0);
        /* now wait and see if it worked. If not, insist */
        if (WaitForSingleObject(p.h, 200) == WAIT_TIMEOUT)
        {
            PostThreadMessageA(tid, WM_QUIT, 0, 0);
            WaitForSingleObject(p.h, 300);
        }
        
        /* done, we do not want to check any other window now */
        return FALSE;
    }

    return TRUE;
}

static void close_alert(HANDLE process)
{
    DWORD pid = get_process_id(process);
    /* If process already exited or we just cannot get its process id, do not 
    go any further */
    if (pid)
    {
        PROCESS_HANDLE_ID p;
        p.h = process;
       	p.pid = pid;
        EnumWindows(&close_alert_window_enum, (LPARAM) &p);
    }
}

# endif /* USE_EXECNT */
