convertjson.c

#include <stdio.h>
#include <time.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/event.h>
#include <ctype.h>

struct ReaderState {
    int initialized;
    int isInStr;
    unsigned int depth;
};

int convert(struct ReaderState *state, char *buffer, ssize_t lenRBytes, char *destBuffer, ssize_t *lenWBytes) {
    unsigned int curr = 0, oseek = 0;
    if (!state->initialized) {
        if (buffer[0] == '[') {
            state->initialized = 1;
            curr++;
        } else {
            return 0;
        }
    }
    while (curr < lenRBytes) {
        if (!state->isInStr) {
            if (buffer[curr] == '{') {
                state->depth++;
            } else if (buffer[curr] == '}') {
                state->depth--;
            } else if (buffer[curr] == '"' && (curr == 0 || buffer[curr - 1] != '\\')) {
                state->isInStr = 1;
            }
            if (buffer[curr] == ',' && (curr == 0 || buffer[curr - 1] == '}') && state->depth == 0) {
                destBuffer[oseek++] = '\n';
            } else if (buffer[curr] != ' ' && buffer[curr] != '\n' && buffer[curr] != '\t') {
                destBuffer[oseek++] = buffer[curr];
            }
        } else {
            if (buffer[curr] == '"' && (curr == 0 || buffer[curr - 1] != '\\')) {
                state->isInStr = 0;
            }
            if (buffer[curr] == '\n') {
                destBuffer[oseek++] = '\\';
                destBuffer[oseek++] = 'n';
            } else {
                destBuffer[oseek++] = buffer[curr];
            }
        }
        curr++;
    }
    *lenWBytes = oseek;
    return 1;
}

int main(int argc, char *argv[]) {
    struct ReaderState state = { 0, 0, 0 };
    struct kevent kEvent1, kEvent2;
    char buffer[4096], destBuffer[4096];

    int fd = fileno(stdin), ofd = fileno(stdout);

    int kq = kqueue();
    EV_SET(&kEvent1, fd, EVFILT_READ, EV_ADD, 0, 0, NULL);
    kevent(kq, &kEvent1, 1, NULL, 0, NULL);

    while (1) {
        int ret = kevent(kq, NULL, 0, &kEvent2, 1, NULL);
        if (ret == -1) {
            fprintf(stderr, "kevent error");
        }

        ssize_t readBytesLen = read(fd, buffer, sizeof(buffer));
        ssize_t writeBytesLen;
        if (readBytesLen== 0) {
            break;
        } else if (readBytesLen== -1) {
            fprintf(stderr, "IO error. (read)\n");
        }
        if (convert(&state, buffer, readBytesLen, destBuffer, &writeBytesLen)) {
            write(ofd, destBuffer, writeBytesLen);
        }
    }
    return 0;
}