squeezelite-esp32/components/spotify/cspot/bell/main/io/MGStreamAdapter.cpp

// MGStreamAdapter.cpp
#include "MGStreamAdapter.h"

mg_buf::mg_buf(struct mg_connection* _conn) : conn(_conn) {
    setp(buffer, buffer + BUF_SIZE - 1); // -1 to leave space for overflow '\0'
}

mg_buf::int_type mg_buf::overflow(int_type c) {
    if (c != EOF) {
        *pptr() = c;
        pbump(1);
    }

    if (flush_buffer() == EOF) {
        return EOF;
    }

    return c;
}

int mg_buf::flush_buffer() {
    int len = int(pptr() - pbase());
    if (mg_write(conn, buffer, len) != len) {
        return EOF;
    }
    pbump(-len); // reset put pointer accordingly
    return len;
}

int mg_buf::sync() {
    if (flush_buffer() == EOF) {
        return -1;  // return -1 on error
    }
    return 0;
}

MGStreamAdapter::MGStreamAdapter(struct mg_connection* _conn) : std::ostream(&buf), buf(_conn) {
    rdbuf(&buf);  // set the custom streambuf
}


mg_read_buf::mg_read_buf(struct mg_connection* _conn) : conn(_conn) {
    setg(buffer + BUF_SIZE,     // beginning of putback area
         buffer + BUF_SIZE,     // read position
         buffer + BUF_SIZE);    // end position
}

mg_read_buf::int_type mg_read_buf::underflow() {
    if (gptr() < egptr()) { // buffer not exhausted
        return traits_type::to_int_type(*gptr());
    }

    char* base = buffer;
    char* start = base;

    if (eback() == base) { // true when this isn't the first fill
        // Make arrangements for putback characters
        std::memmove(base, egptr() - 2, 2);
        start += 2;
    }

    // Read new characters
    int n = mg_read(conn, start, buffer + BUF_SIZE - start);
    if (n == 0) {
        return traits_type::eof();
    }

    // Set buffer pointers
    setg(base, start, start + n);

    // Return next character
    return traits_type::to_int_type(*gptr());
}

MGInputStreamAdapter::MGInputStreamAdapter(struct mg_connection* _conn) : std::istream(&buf), buf(_conn) {
    rdbuf(&buf);  // set the custom streambuf
}