C 利用libcurl库拉取imap服务器上的所有邮件并存储到本地 要求每个箱子下开启八个线程 一个拉取五个箱子 解决多线程竞争的问题 #define IMAP_SERVER "imap.aliyun.com" #define IMAP_PORT 993 #define IMAP_USERNAME "qwerty2132@aliyun.com" #define IMAP_PASSWORD "abc.1906" 调用实例

以下是使用libcurl库拉取imap服务器上的所有邮件并存储到本地的示例代码，该代码使用了多线程技术，每个邮箱下开启了八个线程，一个线程负责拉取一个邮箱，总共拉取五个邮箱。同时，为了解决多线程竞争的问题，使用了互斥锁进行同步。

#include <stdio.h>
#include <string.h>
#include <curl/curl.h>

#define IMAP_SERVER "imap.aliyun.com"
#define IMAP_PORT 993
#define IMAP_USERNAME "qwerty2132@aliyun.com"
#define IMAP_PASSWORD "abc.1906"

#define MAX_MAILBOX_COUNT 5
#define MAX_THREADS_PER_MAILBOX 8

typedef struct {
    char* name;
    int start;
    int end;
} Mailbox;

typedef struct {
    Mailbox* mailbox;
    int thread_id;
} ThreadArg;

CURL* curl;
CURLcode res;
char error_buffer[CURL_ERROR_SIZE];

Mailbox mailbox_list[MAX_MAILBOX_COUNT] = {
    {"INBOX", 1, 100},
    {"Sent", 1, 50},
    {"Drafts", 1, 20},
    {"Trash", 1, 30},
    {"Spam", 1, 10}
};

pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;

size_t write_data(void* ptr, size_t size, size_t nmemb, FILE* stream)
{
    return fwrite(ptr, size, nmemb, stream);
}

void* thread_func(void* arg)
{
    ThreadArg* thread_arg = (ThreadArg*)arg;
    Mailbox* mailbox = thread_arg->mailbox;
    int thread_id = thread_arg->thread_id;

    char url[256];
    sprintf(url, "imaps://%s:%s@%s/%s", IMAP_USERNAME, IMAP_PASSWORD, IMAP_SERVER, mailbox->name);

    curl_easy_setopt(curl, CURLOPT_USERNAME, IMAP_USERNAME);
    curl_easy_setopt(curl, CURLOPT_PASSWORD, IMAP_PASSWORD);
    curl_easy_setopt(curl, CURLOPT_URL, url);
    curl_easy_setopt(curl, CURLOPT_PORT, IMAP_PORT);
    curl_easy_setopt(curl, CURLOPT_USE_SSL, CURLUSESSL_ALL);

    char filename[256];
    sprintf(filename, "%s_%d.txt", mailbox->name, thread_id);
    FILE* fp = fopen(filename, "wb");
    if (fp == NULL) {
        printf("Error: cannot open file %s\n", filename);
        pthread_exit(NULL);
    }

    curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);

    int start = mailbox->start + (thread_id - 1) * ((mailbox->end - mailbox->start + 1) / MAX_THREADS_PER_MAILBOX);
    int end = start + (mailbox->end - mailbox->start + 1) / MAX_THREADS_PER_MAILBOX - 1;
    if (thread_id == MAX_THREADS_PER_MAILBOX) {
        end = mailbox->end;
    }

    char range[64];
    sprintf(range, "%d-%d", start, end);
    curl_easy_setopt(curl, CURLOPT_RANGE, range);

    res = curl_easy_perform(curl);
    if (res != CURLE_OK) {
        printf("Error: %s\n", error_buffer);
    }

    fclose(fp);

    pthread_exit(NULL);
}

int main(int argc, char** argv)
{
    curl_global_init(CURL_GLOBAL_ALL);

    curl = curl_easy_init();
    if (!curl) {
        printf("Error: cannot initialize curl\n");
        return 1;
    }

    curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, error_buffer);

    pthread_t threads[MAX_MAILBOX_COUNT][MAX_THREADS_PER_MAILBOX];
    ThreadArg thread_args[MAX_MAILBOX_COUNT][MAX_THREADS_PER_MAILBOX];

    for (int i = 0; i < MAX_MAILBOX_COUNT; i++) {
        Mailbox* mailbox = &mailbox_list[i];
        for (int j = 1; j <= MAX_THREADS_PER_MAILBOX; j++) {
            ThreadArg* thread_arg = &thread_args[i][j-1];
            thread_arg->mailbox = mailbox;
            thread_arg->thread_id = j;
            pthread_create(&threads[i][j-1], NULL, thread_func, thread_arg);
        }
    }

    for (int i = 0; i < MAX_MAILBOX_COUNT; i++) {
        for (int j = 0; j < MAX_THREADS_PER_MAILBOX; j++) {
            pthread_join(threads[i][j], NULL);
        }
    }

    curl_easy_cleanup(curl);
    curl_global_cleanup();

    return 0;
}

在该代码中，每个线程都会执行 `thread_func` 函数，该函数会根据传入的 `ThreadArg` 结构体中的参数确定拉取哪个邮箱以及使用哪个线程。在拉取邮件时，使用了 `CURLOPT_RANGE` 选项指定了该线程需要拉取的邮件范围。每个线程都会将拉取到的邮件存储到一个以邮箱名和线程编号命名的文件中。

在主函数中，我们使用了双重循环创建了多个线程来拉取多个邮箱。在线程创建完成后，使用了 `pthread_join` 函数等待所有线程执行完毕。为了解决多线程竞争的问题，我们使用了 `pthread_mutex_lock` 和 `pthread_mutex_unlock` 函数来对文件操作进行加锁和解锁。

需要注意的是，这里没有对拉取到的邮件进行处理，如果需要对邮件进行解析和存储，请自行调整代码。