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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 int flagSignalS = 0;
  10.  
  11. void signal_handler(int sig) {
  12.   char mes[] = "jumped into the signal handler, aborting.\n";
  13.   write(2, mes, sizeof(mes) - 1);
  14.   flagSignalS = 1;
  15. }
  16.  
  17. enum sigentry { INIT = 0, DISABLE, ENABLE };
  18. void signal_handling_entry(enum sigentry entry) {
  19.   sigset_t set;
  20.   static sigset_t defmaskS, restoreS;
  21.   struct sigaction act;
  22.   switch (entry) {
  23.   case INIT:
  24.     sigemptyset(&set);
  25.     sigaddset(&set, SIGINT);
  26.     sigaddset(&set, SIGQUIT);
  27.     sigaddset(&set, SIGTERM);
  28.     sigaddset(&set, SIGTSTP);
  29.     act.sa_handler = signal_handler;
  30.     act.sa_flags = set;
  31.     sigemptyset(&act.sa_mask);
  32.     sigaction(SIGINT, &act, 0);
  33.     sigaction(SIGQUIT, &act, 0);
  34.     sigaction(SIGTERM, &act, 0);
  35.     sigaction(SIGTSTP, &act, 0);
  36.     defmaskS = set;
  37.     return;
  38.  
  39.   case DISABLE:
  40.     sigprocmask(SIG_BLOCK, &defmaskS, &restoreS);
  41.     return;
  42.  
  43.   case ENABLE:
  44.     sigprocmask(SIG_SETMASK, &restoreS, 0);
  45.     return;
  46.  
  47.   default:
  48.     return;
  49.   }
  50. }
  51.  
  52. struct node {
  53.   char *data;
  54.   struct node *next;
  55.   struct node *prev;
  56. };
  57.  
  58. int push_head(struct node **root, char *data) {
  59.   struct node *p;
  60.   if ((p = malloc(sizeof(struct node))) != 0) {
  61.     p->data = data;
  62.     if (*root == 0) {
  63.       p->next = p;
  64.       p->prev = p;
  65.     } else {
  66.       p->next = *root;
  67.       p->prev = (*root)->prev;
  68.       p->prev->next = p;
  69.       p->next->prev = p;
  70.     }
  71.     *root = p;
  72.     return 1;
  73.   }
  74.   return 0;
  75. }
  76.  
  77. int push_tail(struct node **root, char *data) {
  78.   struct node *p;
  79.   if ((p = malloc(sizeof(struct node))) != 0) {
  80.     p->data = data;
  81.     if (*root == 0) {
  82.       p->next = p;
  83.       p->prev = p;
  84.       *root = p;
  85.     } else {
  86.       p->next = *root;
  87.       p->prev = (*root)->prev;
  88.       p->prev->next = p;
  89.       p->next->prev = p;
  90.     }
  91.     return 1;
  92.   }
  93.   return 0;
  94. }
  95.  
  96. char *pop(struct node **root) {
  97.   char *r;
  98.   struct node *p;
  99.   if (*root == 0)
  100.     return 0;
  101.   p = *root;
  102.   r = p->data;
  103.   if (p->next == p) {
  104.     *root = 0;
  105.     free(p);
  106.   } else {
  107.     p->next->prev = p->prev;
  108.     p->prev->next = p->next;
  109.     *root = p->next;
  110.     free(p);
  111.   }
  112.   return r;
  113. }
  114.  
  115. #define BUFFSIZE 1024
  116. int main(int argc, char *argv[]) {
  117.   struct node *rootS = 0;
  118.   static char buff[BUFFSIZE];
  119.   char *p;
  120.   int flag_reverse;
  121.   int flagsig;
  122.   if (argc != 2) {
  123.   usage:
  124.     fprintf(stderr, "usage: %s -r/f.\n option -r:reverse, -f:forward\n", argv[0]);
  125.     exit(1);
  126.   }
  127.   if (*argv[1] == '-') {
  128.     if (*(argv[1] + 1) == 'f')
  129.       flag_reverse = 0;
  130.     else if (*(argv[1] + 1) == 'r')
  131.       flag_reverse = 1;
  132.     else
  133.       goto usage;
  134.   } else {
  135.     goto usage;
  136.   }
  137.  
  138.   signal_handling_entry(INIT);
  139.   rootS = 0;
  140.   for (;;) {
  141.     signal_handling_entry(DISABLE);
  142.     flagsig = flagSignalS;
  143.     signal_handling_entry(ENABLE);
  144.     if (flagsig)
  145.       break;
  146.     if (fgets(buff, BUFFSIZE, stdin) == 0) {
  147.       if (errno != EINTR)
  148.         break;
  149.       else
  150.         continue;
  151.     }
  152.     if ((p = malloc(strlen(buff) + 1)) != 0) {
  153.       strcpy(p, buff);
  154.       if (flag_reverse) {
  155.         if (!push_head(&rootS, p))
  156.           free(p);
  157.       } else {
  158.         if (!push_tail(&rootS, p))
  159.           free(p);
  160.       }
  161.     }
  162.   }
  163.   putchar('\n');
  164.   for (;;) {
  165.     signal_handling_entry(DISABLE);
  166.     flagsig = flagSignalS;
  167.     signal_handling_entry(ENABLE);
  168.     if (flagsig)
  169.       break;
  170.     if((p = pop(&rootS)) == 0)
  171.       break;
  172.     printf("%s", p);
  173.     free(p);
  174.   }
  175.   while ((p = pop(&rootS)) != 0)
  176.     free(p);
  177.   return 0;
  178. }
  179. /* end */
  180.  
Compilation error #stdin compilation error #stdout 0s 0KB
comments (?)
stdin 
Standard input is empty
compilation info 
prog.c: In function ‘signal_handler’:
prog.c:13: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result
prog.c: In function ‘signal_handling_entry’:
prog.c:30: error: incompatible types in assignment
stdout 
Standard output is empty
https://ideone.com/ycqqcm
language:
C (gcc 8.3)
created:
12 years ago
visibility:
public

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