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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <string.h>
  4. /*-------------------*/
  5. #include <signal.h>
  6. #include <unistd.h>
  7. #include <errno.h>
  8.  
  9. static volatile sig_atomic_t flagSignalS = 0;
  10.  
  11. void signal_handler(int sig) {
  12.   int errsrv = errno;
  13.   char mes[] = "\njumped into the signal handler, ignored.\n";
  14.   write(2, mes, sizeof(mes) - 1);
  15.   errno = errsrv;
  16.   flagSignalS = 1;
  17. }
  18.  
  19. enum sigentry { INIT = 0, DISABLE, ENABLE };
  20. void signal_handling_entry(enum sigentry entry) {
  21.   sigset_t set;
  22.   static sigset_t defmaskS, restoreS;
  23.   struct sigaction act;
  24.   switch (entry) {
  25.   case INIT:
  26.     sigemptyset(&set);
  27.     sigaddset(&set, SIGINT);
  28.     sigaddset(&set, SIGQUIT);
  29.     sigaddset(&set, SIGTERM);
  30.     sigaddset(&set, SIGTSTP);
  31.     act.sa_handler = signal_handler;
  32.     act.sa_mask = set;
  33.     sigemptyset(&act.sa_mask);
  34.     sigaction(SIGINT, &act, 0);
  35.     sigaction(SIGQUIT, &act, 0);
  36.     sigaction(SIGTERM, &act, 0);
  37.     sigaction(SIGTSTP, &act, 0);
  38.     defmaskS = set;
  39.     return;
  40.  
  41.   case DISABLE:
  42.     sigprocmask(SIG_BLOCK, &defmaskS, &restoreS);
  43.     return;
  44.  
  45.   case ENABLE:
  46.     sigprocmask(SIG_SETMASK, &restoreS, 0);
  47.     return;
  48.  
  49.   default:
  50.     return;
  51.   }
  52. }
  53.  
  54. int getSignalS(void) {
  55.   int flag_sig;
  56.   signal_handling_entry(DISABLE);
  57.   flag_sig = flagSignalS;
  58.   signal_handling_entry(ENABLE);
  59.   return flag_sig;
  60. }
  61.  
  62. void clearSignalS(void) {
  63.   signal_handling_entry(DISABLE);
  64.   flagSignalS = 0;  
  65.   signal_handling_entry(ENABLE);
  66. }
  67.  
  68. /*-------------------*/
  69.  
  70. struct node {
  71.   char *data;
  72.   struct node *next;
  73.   struct node *prev;
  74. };
  75.  
  76. int push_head(struct node **root, char *data) {
  77.   struct node *p;
  78.   if ((p = malloc(sizeof(struct node))) != 0) {
  79.     p->data = data;
  80.     if (*root == 0) {
  81.       p->next = p;
  82.       p->prev = p;
  83.     } else {
  84.       p->next = *root;
  85.       p->prev = (*root)->prev;
  86.       p->prev->next = p;
  87.       p->next->prev = p;
  88.     }
  89.     *root = p;
  90.     return 1;
  91.   }
  92.   return 0;
  93. }
  94.  
  95. int push_tail(struct node **root, char *data) {
  96.   struct node *p;
  97.   if ((p = malloc(sizeof(struct node))) != 0) {
  98.     p->data = data;
  99.     if (*root == 0) {
  100.       p->next = p;
  101.       p->prev = p;
  102.       *root = p;
  103.     } else {
  104.       p->next = *root;
  105.       p->prev = (*root)->prev;
  106.       p->prev->next = p;
  107.       p->next->prev = p;
  108.     }
  109.     return 1;
  110.   }
  111.   return 0;
  112. }
  113.  
  114. char *pop(struct node **root) {
  115.   char *r;
  116.   struct node *p;
  117.   if (*root == 0)
  118.     return 0;
  119.   p = *root;
  120.   r = p->data;
  121.   if (p->next == p) {
  122.     *root = 0;
  123.     free(p);
  124.   } else {
  125.     p->next->prev = p->prev;
  126.     p->prev->next = p->next;
  127.     *root = p->next;
  128.     free(p);
  129.   }
  130.   return r;
  131. }
  132.  
  133.  
  134. #define BUFFSIZE 1024
  135. int main(int argc, char *argv[]) {
  136.   struct node *rootS = 0;
  137.   static char buff[BUFFSIZE];
  138.   char *p;
  139.   int flag_reverse;
  140.   if (argc != 2) {
  141.   usage:
  142.     fprintf(stderr, "usage: %s -r/f.\n option -r:reverse, -f:forward\n", argv[0]);
  143.     exit(1);
  144.   }
  145.   if (*argv[1] == '-') {
  146.     if (*(argv[1] + 1) == 'f')
  147.       flag_reverse = 0;
  148.     else if (*(argv[1] + 1) == 'r')
  149.       flag_reverse = 1;
  150.     else
  151.       goto usage;
  152.   } else {
  153.     goto usage;
  154.   }
  155.  
  156.   signal_handling_entry(INIT);
  157.   rootS = 0;
  158.   for (;;) {
  159.     printf(">> ");
  160.     if (fgets(buff, BUFFSIZE, stdin) == 0) {
  161.       if (ferror(stdin)) {
  162.         if (getSignalS()) { clearSignalS(); clearerr(stdin); continue; } else {
  163.           fprintf(stderr, "error occured in fgets(), aborting.\n");
  164.           break;
  165.         }
  166.       } else
  167.         break;
  168.     }
  169.     while (!(p = malloc(strlen(buff) + 1)))
  170.       if (getSignalS()) { clearSignalS(); continue; }
  171.     if (p != 0) {
  172.       strcpy(p, buff);
  173.       if (flag_reverse) {
  174.         while (!push_head(&rootS, p))
  175.           if (getSignalS()) { clearSignalS(); continue; } else {
  176.             free(p); goto label_exit;
  177.           }
  178.       } else {
  179.         while (!push_tail(&rootS, p))
  180.           if (getSignalS()) { clearSignalS(); continue; } else {
  181.             free(p); goto label_exit;
  182.           }
  183.       }
  184.     }
  185.   } /* for(;;) */
  186.   putchar('\n');
  187.   while ((p = pop(&rootS)) != 0) {
  188.     while (printf("%s", p) < 0)
  189.       if (getSignalS()) { clearSignalS(); continue; } else
  190.         break;
  191.     free(p);
  192.   }
  193. label_exit:
  194.   while ((p = pop(&rootS)) != 0)
  195.     free(p);
  196.   return 0;
  197. }
  198. /* end */
  199.  
Runtime error #stdin #stdout 0.01s 1672KB
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https://ideone.com/DKgnoQ
language:
C (gcc 8.3)
created:
12 years ago
visibility:
public

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