Linux通过AIO进行异步读文件，下面列出源代码：

#include
#include
#include

#include
#include
#include
#include
#include

static char *memBuffer;
static int sFileDesc;
static struct sigaction sOldSigAction;

static void MySigQuitHandler(int sig)
{
? ? printf("Signal Quit! The number is: %d\n", sig);
}

static void MyFileReadCompleteProcedure(int sig, siginfo_t *si, void *ucontext)
{
? ? printf("The file length is: %zu, and the content is: %s\n", strlen(memBuffer), memBuffer);
? ? int status = close(sFileDesc);
? ? if(status == 0)
? ? ? ? puts("File closed successfully!");
? ? else
? ? ? ? printf("The error code is: %d\n", status);

? ? free(memBuffer);

? ? // 还原原来的SIGUSR1信号行为
? ? if(sigaction(SIGUSR1, &sOldSigAction, NULL) == -1)
? ? ? ? puts("SIGUSR1 signal restore failed!");
}

int main(void)
{
? ? struct sigaction sigAction = { .sa_flags = SA_RESTART, .sa_handler = &MySigQuitHandler };

? ? sigemptyset(&sigAction.sa_mask);

? ? if (sigaction(SIGQUIT, &sigAction, NULL) == -1)
? ? {
? ? ? ? puts("Signal failed!");
? ? ? ? return -1;
? ? }

? ? sigAction.sa_sigaction = &MyFileReadCompleteProcedure;
? ? if(sigaction(SIGUSR1, &sigAction, &sOldSigAction) == -1)
? ? {
? ? ? ? puts("Signal failed!");
? ? ? ? return -1;
? ? }

? ? const char *filePath = "myfile.txt";

? ? const mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
? ? sFileDesc = open(filePath, O_RDONLY, mode);
? ? if(sFileDesc == -1)
? ? {
? ? ? ? printf("The file: %s cannot be opened!\n", filePath);
? ? ? ? return -1;
? ? }

? ? const long fileLength = lseek(sFileDesc, 0, SEEK_END);
? ? lseek(sFileDesc, 0, SEEK_SET);

? ? memBuffer = malloc(fileLength + 1);
? ? memBuffer[fileLength] = '\0';

? ? struct aiocb aioBuffer;
? ? aioBuffer.aio_fildes = sFileDesc;
? ? aioBuffer.aio_offset = 0;
? ? aioBuffer.aio_buf = memBuffer;
? ? aioBuffer.aio_nbytes = fileLength;
? ? aioBuffer.aio_reqprio = 0;
? ? aioBuffer.aio_sigevent = (struct sigevent){.sigev_notify = SIGEV_SIGNAL, .sigev_signo = SIGUSR1, .sigev_value.sival_ptr = memBuffer };

? ? aio_read(&aioBuffer);

? ? getchar();

? ? return 0;
}

其中，上述代码实现中采用SIGUSR1信号进行捕获文件读完成事件，当然，这里也可以用SIGIO信号。

另外，在编译链接时必须添加-lrt命令选项，因为rt库才包含了系统底层的API。