libuv 之《經過管道讀取子進程數據》

首先推薦一本 libuv 的書《An Introduction to libuv》

http://nikhilm.github.io/uvbook/

我遇到的問題是，打開一個子進程 ls -l /tmp，我想讀取輸出。這本書裏面是沒有提到的，我在 stackoverflow 找到了答案。

http://stackoverflow.com/questions/14751504/capture-a-child-processs-stdout-with-libuv

代碼以下：

#include <stdio.h>
#include <stdlib.h>
#include "../../libuv/include/uv.h"

uv_loop_t *loop;
uv_process_t child_req;
uv_process_options_t options;
uv_pipe_t apipe;

void on_child_exit(uv_process_t *req, int exit_status, int term_signal) {
    fprintf(stderr, "Process exited with status %d, signal %d\n", exit_status, term_signal);
    uv_close((uv_handle_t*) req, NULL);
}

uv_buf_t alloc_buffer(uv_handle_t *handle, size_t len) {
    printf("alloc_buffer called, requesting a %lu byte buffer\n");
    uv_buf_t buf;
    buf.base = malloc(len);
    buf.len = len;
    return buf;
}

void read_apipe(uv_stream_t* stream, ssize_t nread, uv_buf_t buf) {
    printf("read %li bytes in a %lu byte buffer\n", nread, buf.len);
    if (nread + 1 > buf.len) return;
    buf.base[nread] = '\0'; // turn it into a cstring
    printf("read: |%s|", buf.base);
}

int main(int argc, char *argv[]) {
    printf("spawn_test\n");
    loop = uv_default_loop();

    char* args[3];
    args[0] = "dummy";
    args[1] = NULL;
    args[2] = NULL;

    uv_pipe_init(loop, &apipe, 0);
    uv_pipe_open(&apipe, 0);

    options.stdio_count = 3;
    uv_stdio_container_t child_stdio[3];
    child_stdio[0].flags = UV_IGNORE;
    child_stdio[1].flags = UV_CREATE_PIPE | UV_READABLE_PIPE;
    child_stdio[1].data.stream = (uv_stream_t *) &apipe;
    child_stdio[2].flags = UV_IGNORE;
    options.stdio = child_stdio;

    options.exit_cb = on_child_exit;
    options.file = args[0];
    options.args = args;

    if (uv_spawn(loop, &child_req, options)) {
        fprintf(stderr, "%s\n", uv_strerror(uv_last_error(loop)));
        return 1;
    }
    uv_read_start((uv_stream_t*)&apipe, alloc_buffer, read_apipe);

    return uv_run(loop, UV_RUN_DEFAULT);
}