sys_execex.c

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#include "../fb.h"
#include "fb_private_console.h"
#include <sys/wait.h>

FBCALL int fb_ExecEx( FBSTRING *program, FBSTRING *args, int do_fork )
{
        char buffer[MAX_PATH+1], *application, *arguments, **argv, *p;
        int i, argc = 0, res = -1, status;
        ssize_t len_program, len_arguments;
        pid_t pid;

        if( (program == NULL) || (program->data == NULL) ) 
        {
                fb_hStrDelTemp( args );
                fb_hStrDelTemp( program );
                return -1;
        }

        application = fb_hGetShortPath( program->data, buffer, MAX_PATH );
        DBG_ASSERT( application!=NULL );
        if( application==program->data ) 
        {
                len_program = FB_STRSIZE( program );
                application = buffer;
                FB_MEMCPY(application, program->data, len_program );
                application[len_program] = 0;
        }

        fb_hConvertPath( application );

        if( args==NULL ) {
                arguments = "";
        } else {
                len_arguments = FB_STRSIZE( args );
                arguments = alloca( len_arguments + 1 );
                DBG_ASSERT( arguments!=NULL );
                arguments[len_arguments] = 0;
                if( len_arguments )
                        argc = fb_hParseArgs( arguments, args->data, len_arguments );
        }

        FB_STRLOCK();

        fb_hStrDelTemp_NoLock( args );
        fb_hStrDelTemp_NoLock( program );

        FB_STRUNLOCK();

        if( argc == -1 )
                return -1;

        argc++;                         /* add 1 for program name */

        argv = alloca( sizeof(char*) * (argc + 1 ));
        DBG_ASSERT( argv!=NULL );

        argv[0] = application;

        /* scan the processed args and set pointers */
        p = arguments;
        for( i=1 ; i<argc; i++) {
                argv[i] = p;    /* set pointer to current argument */
                while( *p++ );  /* skip to 1 char past next null char */
        }
        argv[argc] = NULL;


        /* Launch */
        FB_LOCK( );
        fb_hExitConsole();
        FB_UNLOCK( );

        if( do_fork ) {
                pid = fork();
                if( pid != -1 ) {
                        if (pid == 0) {
                                /* execvp() only returns if it failed */
                                execvp( application, argv );
                                /* HACK: execvp() failed, this must be communiated to the parent process *somehow*,
                                   so fb_ExecEx() can return -1 there */
                                /* Using _Exit() instead of exit() to prevent the child from flusing file I/O and
                                   running global destructors (especially the rtlib's own cleanup), which may try
                                   to wait on threads to finish (e.g. hinit.c::bg_thread()), but fork() doesn't
                                   duplicate other threads besides the current one, so their pthread handles will be
                                   invalid here in the child process. */
                                _Exit( 255 );
                                /* FIXME: won't be able to tell the difference if the exec'ed program returned 255.
                                   Maybe a pipe could be used instead of the 255 exit code? Unless that's too slow/has side-effects */
                        } else if( (waitpid(pid, &status, 0) > 0) && WIFEXITED(status) ) {
                                res = WEXITSTATUS(status);
                                if( res == 255 ) {
                                        /* See the HACK above */
                                        res = -1;
                                }
                        }
                }
        } else {
                res = execvp( application, argv );
        }

        FB_LOCK( );
        fb_hInitConsole();
        FB_UNLOCK( );

        return res;
}