synth_intr.c

eCos操作系统源码

    char        filename[BUFSIZE];
    const char* path = 0;
    int         i, j;
    cyg_bool    found   = false;
    int         to_aux_pipe[2];
    int         from_aux_pipe[2];
    int         child;
    int         aux_version;
#if 1
    // Check for a command line argument -io. Only run the auxiliary if this
    // argument is provided, i.e. default to traditional behaviour.
    for (i = 1; i < cyg_hal_sys_argc; i++) {
        const char* tmp = cyg_hal_sys_argv[i];
        if ('-' == *tmp) {
            // Arguments beyond -- are reserved for use by the application,
            // and should not be interpreted by the HAL itself or by ecosynth.
            if (('-' == tmp[1]) && ('\0' == tmp[2])) {
                break;
            }
            tmp++;
            if ('-' == *tmp) {
                // Do not distinguish between -io and --io
                tmp++;
            }
            if (('i' == tmp[0]) && ('o' == tmp[1]) && ('\0' == tmp[2])) {
                found = 1;
                break;
            }
        }
    }
    if (!found) {
        return;
    }
#else
    // Check for a command line argument -ni or -nio. Always run the
    // auxiliary unless this argument is given, i.e. default to full
    // I/O support.
    for (i = 1; i < cyg_hal_sys_argc; i++) {
        const char* tmp = cyg_hal_sys_argv[i];
        if ('-' == *tmp) {
            if (('-' == tmp[1]) && ('\0' == tmp[2])) {
                break;
            }
            tmp++;
            if ('-' == *tmp) {
                tmp++;
            }
            if ('n' == *tmp) {
                tmp++;
                if ('i' == *tmp) {
                    tmp++;
                    if ('\0' == *tmp) {
                        found = 1;  // -ni or --ni
                        break;
                    }
                    if (('o' == *tmp) && ('\0' == tmp[1])) {
                        found = 1;  // -nio or --nio
                        break;
                    }
                }
            }
        }
    }
    if (found) {
        return;
    }
#endif
    
    // The auxiliary must be found relative to the current search path,
    // so look for a PATH= environment variable.
    for (i = 0; (0 == path) && (0 != cyg_hal_sys_environ[i]); i++) {
        const char *var = cyg_hal_sys_environ[i];
        if (('P' == var[0]) && ('A' == var[1]) && ('T' == var[2]) && ('H' == var[3]) && ('=' == var[4])) {
            path = var + 5;
        }
    }
    if (0 == path) {
        // Very unlikely, but just in case.
        path = ".:/bin:/usr/bin";
    }

    found = 0;
    while (!found && ('\0' != *path)) {         // for every entry in the path
        char *tmp = AUXILIARY;
        
        j = 0;

        // As a special case, an empty string in the path corresponds to the
        // current directory.
        if (':' == *path) {
            filename[j++] = '.';
            path++;
        } else {
            while ((j < BUFSIZE) && ('\0' != *path) && (':' != *path)) {
                filename[j++] = *path++;
            }
            // If not at the end of the search path, move on to the next entry.
            if ('\0' != *path) {
                while ((':' != *path) && ('\0' != *path)) {
                    path++;
                }
                if (':' == *path) {
                    path++;
                }
            }
        }
        // Now append a directory separator, and then the name of the executable.
        if (j < BUFSIZE) {
            filename[j++] = '/';
        }
        while ((j < BUFSIZE) && ('\0' != *tmp)) {
            filename[j++] = *tmp++;
        }
        // If there has been a buffer overflow, skip this entry.
        if (j == BUFSIZE) {
            filename[BUFSIZE-1] = '\0';
            diag_printf("Warning: buffer limit reached while searching PATH for the I/O auxiliary.\n");
            diag_printf("       : skipping current entry.\n");
        } else {
            // filename now contains a possible match for the auxiliary.
            filename[j++]    = '\0';
            if (0 == cyg_hal_sys_access(filename, CYG_HAL_SYS_X_OK)) {
                found = true;
            }
        }
    }
#undef BUFSIZE

    if (!found) {
        diag_printf("Error: unable to find the I/O auxiliary program on the current search PATH\n");
        diag_printf("     : please install the appropriate host-side tools.\n");
        cyg_hal_sys_exit(1);
    }

    // An apparently valid executable exists (or at the very least it existed...),
    // so create the pipes that will be used for communication.
    if ((0 != cyg_hal_sys_pipe(to_aux_pipe)) ||
        (0 != cyg_hal_sys_pipe(from_aux_pipe))) {
        diag_printf("Error: unable to set up pipes for communicating with the I/O auxiliary.\n");
        cyg_hal_sys_exit(1);
    }
    
    // Time to fork().
    child = cyg_hal_sys_fork();
    if (child < 0) {
        diag_printf("Error: failed to fork() process for the I/O auxiliary.\n");
        cyg_hal_sys_exit(1);
    } else if (child == 0) {
        cyg_bool    found_dotdot;
        // There should not be any problems rearranging the file descriptors as desired...
        cyg_bool    unexpected_error = 0;
        
        // In the child process. Close unwanted file descriptors, then some dup2'ing,
        // and execve() the I/O auxiliary. The auxiliary will inherit stdin,
        // stdout and stderr from the eCos application, so that functions like
        // printf() work as expected. In addition fd 3 will be the pipe from
        // the eCos application and fd 4 the pipe to the application. It is possible
        // that the eCos application was run from some process other than a shell
        // and hence that file descriptors 3 and 4 are already in use, but that is not
        // supported. One possible workaround would be to close all file descriptors
        // >= 3, another would be to munge the argument vector passing the file
        // descriptors actually being used.
        unexpected_error |= (0 != cyg_hal_sys_close(to_aux_pipe[1]));
        unexpected_error |= (0 != cyg_hal_sys_close(from_aux_pipe[0]));
        
        if (3 != to_aux_pipe[0]) {
            if (3 == from_aux_pipe[1]) {
                // Because to_aux_pipe[] was set up first it should have received file descriptors 3 and 4.
                diag_printf("Internal error: file descriptors have been allocated in an unusual order.\n");
                cyg_hal_sys_exit(1);
            } else {
                unexpected_error |= (3 != cyg_hal_sys_dup2(to_aux_pipe[0], 3));
                unexpected_error |= (0 != cyg_hal_sys_close(to_aux_pipe[0]));
            }
        }
        if (4 != from_aux_pipe[1]) {
            unexpected_error |= (4 != cyg_hal_sys_dup2(from_aux_pipe[1], 4));
            unexpected_error |= (0 != cyg_hal_sys_close(from_aux_pipe[1]));
        }
        if (unexpected_error) {
            diag_printf("Error: internal error in auxiliary process, failed to manipulate pipes.\n");
            cyg_hal_sys_exit(1);
        }
        // The arguments passed to the auxiliary are mostly those for
        // the synthetic target application, except for argv[0] which
        // is replaced with the auxiliary's pathname. The latter
        // currently holds at least one ../, and cleaning this up is
        // useful.
        //
        // If the argument vector contains -- then that and subsequent
        // arguments are not passed to the auxiliary. Instead such
        // arguments are reserved for use by the application.
        do {
            int len;
            for (len = 0; '\0' != filename[len]; len++)
                ;
            found_dotdot = false;
            for (i = 0; i < (len - 4); i++) {
                if (('/' == filename[i]) && ('.' == filename[i+1]) && ('.' == filename[i+2]) && ('/' == filename[i+3])) {
                    j = i + 3;
                    for ( --i; (i >= 0) && ('/' != filename[i]); i--) {
                        CYG_EMPTY_STATEMENT;
                    }
                    if (i >= 0) {
                        found_dotdot = true;
                        do {
                            i++; j++;
                            filename[i] = filename[j];
                        } while ('\0' != filename[i]);
                    }
                }
            }
        } while(found_dotdot);
        
        cyg_hal_sys_argv[0] = filename;

        for (i = 1; i < cyg_hal_sys_argc; i++) {
            const char* tmp = cyg_hal_sys_argv[i];
            if (('-' == tmp[0]) && ('-' == tmp[1]) && ('\0' == tmp[2])) {
                cyg_hal_sys_argv[i] = (const char*) 0;
                break;
            }
        }
        cyg_hal_sys_execve(filename, cyg_hal_sys_argv, cyg_hal_sys_environ);

        // An execute error has occurred. Report this here, then exit. The
        // parent will detect a close on the pipe without having received
        // any data, and it will assume that a suitable diagnostic will have
        // been displayed already.
        diag_printf("Error: failed to execute the I/O auxiliary.\n");
        cyg_hal_sys_exit(1);
    } else {
        int     rc;
        char    buf[1];
        
        // Still executing the eCos application.
        // Do some cleaning-up.
        to_aux      = to_aux_pipe[1];
        from_aux    = from_aux_pipe[0];
        if ((0 != cyg_hal_sys_close(to_aux_pipe[0]))  ||
            (0 != cyg_hal_sys_close(from_aux_pipe[1]))) {
            diag_printf("Error: internal error in main process, failed to manipulate pipes.\n");
            cyg_hal_sys_exit(1);
        }

        // It is now a good idea to block until the auxiliary is
        // ready, i.e. give it a chance to read in its configuration
        // files, load appropriate scripts, pop up windows, ... This
        // may take a couple of seconds or so. Once the auxiliary is
        // ready it will write a single byte down the pipe. This is
        // the only time that the auxiliary will write other than when
        // responding to a request.
        do {
            rc = cyg_hal_sys_read(from_aux, buf, 1);
        } while (-CYG_HAL_SYS_EINTR == rc);

        if (1 != rc) {
            // The auxiliary has not started up successfully, so exit
            // immediately. It should have generated appropriate
            // diagnostics.
            cyg_hal_sys_exit(1);
        }
    }

    // At this point the auxiliary is up and running. It should not
    // generate any interrupts just yet since none of the devices have
    // been initialized. Remember that the auxiliary is now running,
    // so that the initialization routines for those devices can
    // figure out that they should interact with the auxiliary rather
    // than attempt anything manually.
    synth_auxiliary_running   = true;

    // Make sure that the auxiliary is the right version.
    synth_auxiliary_xchgmsg(SYNTH_DEV_AUXILIARY, SYNTH_AUXREQ_GET_VERSION, 0, 0,
                            (const unsigned char*) 0, 0,
                            &aux_version, (unsigned char*) 0, (int*) 0, 0);
    if (SYNTH_AUXILIARY_PROTOCOL_VERSION != aux_version) {
        synth_auxiliary_running = false;
        diag_printf("Error: an incorrect version of the I/O auxiliary is installed\n"
                    "    Expected version %d, actual version %d\n"
                    "    Installed binary is %s\n",
                    SYNTH_AUXILIARY_PROTOCOL_VERSION, aux_version, filename);
        cyg_hal_sys_exit(1);
    }
}

// Write a request to the I/O auxiliary, and optionally get back a
// reply. The dev_id is 0 for messages intended for the auxiliary
// itself, for example a device instantiation or a request for the
// current interrupt sate. Otherwise it identifies a specific device.
// The request code is specific to the device, and the two optional
// arguments are specific to the request.
void
synth_auxiliary_xchgmsg(int devid, int reqcode, int arg1, int arg2,
                        const unsigned char* txdata, int txlen,
                        int* result, 
                        unsigned char* rxdata, int* actual_rxlen, int rxlen)
{
    unsigned char   request[SYNTH_REQUEST_LENGTH];
    unsigned char   reply[SYNTH_REPLY_LENGTH];
    int             rc;
    int             reply_rxlen;
    cyg_bool_t      old_isrstate;

    CYG_ASSERT(devid >= 0, "A valid device id should be supplied");
    CYG_ASSERT((0 == txlen) || ((const unsigned char*)0 != txdata), "Data transmits require a transmit buffer");
    CYG_ASSERT((0 == rxlen) || ((unsigned char*)0 != rxdata), "Data receives require a receive buffer");
    CYG_ASSERT((0 == rxlen) || ((int*)0 != result), "If a reply is expected then space must be allocated");

    // I/O interactions with the auxiliary must be atomic: a context switch in
    // between sending the header and the actual data would be bad.
    HAL_DISABLE_INTERRUPTS(old_isrstate);

    // The auxiliary should be running for the duration of this
    // exchange. However the auxiliary can disappear asynchronously,
    // so it is not possible for higher-level code to be sure that the
    // auxiliary is still running.
    //
    // If the auxiliary disappears during this call then usually this
    // will cause a SIGCHILD or SIGPIPE, both of which result in
    // termination. The exception is when the auxiliary decides to
    // shut down stdout for some reason without exiting - that has to
    // be detected in the read loop.
    if (synth_auxiliary_running) {
        request[SYNTH_REQUEST_DEVID_OFFSET + 0]     = (devid >>  0) & 0x0FF;
        request[SYNTH_REQUEST_DEVID_OFFSET + 1]     = (devid >>  8) & 0x0FF;
        request[SYNTH_REQUEST_DEVID_OFFSET + 2]     = (devid >> 16) & 0x0FF;
        request[SYNTH_REQUEST_DEVID_OFFSET + 3]     = (devid >> 24) & 0x0FF;
        request[SYNTH_REQUEST_REQUEST_OFFSET + 0]   = (reqcode >>  0) & 0x0FF;
        request[SYNTH_REQUEST_REQUEST_OFFSET + 1]   = (reqcode >>  8) & 0x0FF;
        request[SYNTH_REQUEST_REQUEST_OFFSET + 2]   = (reqcode >> 16) & 0x0FF;
        request[SYNTH_REQUEST_REQUEST_OFFSET + 3]   = (reqcode >> 24) & 0x0FF;
        request[SYNTH_REQUEST_ARG1_OFFSET + 0]      = (arg1 >>  0) & 0x0FF;
        request[SYNTH_REQUEST_ARG1_OFFSET + 1]      = (arg1 >>  8) & 0x0FF;
        request[SYNTH_REQUEST_ARG1_OFFSET + 2]      = (arg1 >> 16) & 0x0FF;
        request[SYNTH_REQUEST_ARG1_OFFSET + 3]      = (arg1 >> 24) & 0x0FF;
        request[SYNTH_REQUEST_ARG2_OFFSET + 0]      = (arg2 >>  0) & 0x0FF;
        request[SYNTH_REQUEST_ARG2_OFFSET + 1]      = (arg2 >>  8) & 0x0FF;
        request[SYNTH_REQUEST_ARG2_OFFSET + 2]      = (arg2 >> 16) & 0x0FF;
        request[SYNTH_REQUEST_ARG2_OFFSET + 3]      = (arg2 >> 24) & 0x0FF;
        request[SYNTH_REQUEST_TXLEN_OFFSET + 0]     = (txlen >>  0) & 0x0FF;