103 lines
2.1 KiB
C
103 lines
2.1 KiB
C
#include <errno.h>
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#include <fcntl.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#define CPS 10
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#define BUFSIZE CPS
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#define BURST 100 //!! token上限
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// static volatile int token = 0;
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static volatile sig_atomic_t token = 0; //!!! 保证原子
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static void alrm_handler(int s)
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{
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alarm(1); //!! 产生新的alarm
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token++;
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if (token > BURST)
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token = BURST;
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}
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/***********************************************************************
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* @brief slowcat
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* @details 流量控制，令牌桶实现
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* @param argc
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* @param argv
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* @return int
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***********************************************************************/
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int main(int argc, char **argv)
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{
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int sfd, dfd = 1;
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char buf[BUFSIZE];
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int len, ret, pos;
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if (argc < 2)
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{
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fprintf(stderr, "Usage: %s <src>\n", argv[0]);
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exit(1);
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}
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signal(SIGALRM, alrm_handler);
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alarm(1);
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do //!!!
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{
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sfd = open(argv[1], O_RDONLY);
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if (sfd < 0)
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{
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//!!!
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if (errno != EINTR)
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{
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perror("open");
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exit(1);
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}
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}
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} while (sfd < 0);
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while (1)
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{
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while (token <= 0)
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pause( ); //!
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token--; //!!! 这条指令不一定原子
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//* 阻塞在这里的时候，token会自增
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while ((len = read(sfd, buf, BUFSIZE)) < 0)
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{
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//!!!
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if (EINTR == errno)
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continue;
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perror("read");
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break;
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}
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if (len == 0)
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break;
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pos = 0;
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while (len > 0)
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{
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/* 可能没写完被别的中断打断 */
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ret = write(dfd, buf + pos, len);
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if (ret < 0)
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{
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//!!!
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if (EINTR == errno)
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continue;
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perror("write");
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exit(1);
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}
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pos += ret;
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len -= ret;
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}
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// sleep(1); //! 能实现，但是移植性不好
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}
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close(sfd);
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exit(0);
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}
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