pipe（）構造体を子から親に送ります。 read（）の中の象形。

Question

構造化されたデータを子プロセスから親に送信したい。親プロセスは、10個の測定データの平均を出力する必要があります。 funcs.hで

構造体のデータ：

struct data{ 
int nr; 
float temp; 
float bst; 
float abst; 
}; 

uebung2_1.c（メイン）：Linuxの割り込みを経由して

#include <stdio.h> 
#include <stdlib.h> 
#include <string.h> 
#include <unistd.h> 
#include <math.h> 
#include <time.h> 
#include <signal.h> 
#include <stdio.h> 
#include "funcs.h" 

#define READ_END 0 
#define WRITE_END 1 
#define CHILD "./sohn" 

int main(){ 
    int w_status, pid_fork, i, k; 
    double midT, midB, midA; 
    int pfd[2]; 
    struct data buf; 

    if(pipe(pfd) == -1){ 
     perror("ERROR creating a pipe\n"); 
     exit(EXIT_FAILURE); 
    } 

    pid_fork = fork(); 
    switch(pid_fork){ 
     case(-1): 
      perror("fork()"); 
      return EXIT_FAILURE; 
     case(0): 
      dup2(pfd[WRITE_END], STDOUT_FILENO); 
      close(pfd[READ_END]); 
      execlp(CHILD,CHILD,NULL); 
      perror("exec is failed"); 
      break; 
     default: 
      close(pfd[WRITE_END]); 
      printf("Sohn gestartet mit PID %d\n", pid_fork); 
      midT = midB = midA = 0; 
      i = k = 0; 
      while(1){ 
       read(pfd[READ_END],&buf,sizeof(struct data)); 
       midT += buf.temp; 
       midB += buf.bst; 
       midA += buf.abst; 
       i++; 
       if(i == 10){ 
        midT /=10; 
        midB /=10; 
        midA /=10; 
        printf("Messung. %4i: Temp.: %4.1lf, Beleucht.: %4lf, Abstand: %3.1lf\n",k++, midT, midB, midA); 
        midT = midB = midA = 0; 
        i = 0; 
       } 
      } 
      while(i != -1){ 
       i = wait(&w_status); 
       if(i != -1) 
        printf("\nSohn beendet. Exit Status: %x Nummer des Sohn-Prozesses %d", 
         (w_status>>8) & 0xff, i); 
        else 
         printf("\nLetzter Sohn beendet!\n"); 
      } 
     } 
    return 0; 
} 

子孫プロセスセンド測定データごとに500nsでの。私はそれを最初にchar配列でテストし、成功しました。

sohn.c：

#include <stdio.h> 
#include <stdlib.h> 
#include <string.h> 
#include <unistd.h> 
#include <math.h> 
#include <time.h> 
#include <signal.h> 
#include <stdio.h> 
#include <sys/time.h> 
#include "funcs.h" 

#define INTERVAL 500000 

int howmany = 0; 

void alarm_wakeup (int i) 
{ 
    struct itimerval tout_val; 
    howmany += INTERVAL; 
    tout_val.it_interval.tv_sec = 0; 
    tout_val.it_interval.tv_usec = 0; 
    tout_val.it_value.tv_sec = 0; 
    tout_val.it_value.tv_usec = INTERVAL; 
    setitimer(ITIMER_REAL, &tout_val,0); 
} 

void exit_func (int i) 
{ 
    signal(SIGINT,exit_func); 
    exit(0); 
} 



int main(){ 

    struct data mess; 
    struct itimerval tout_val; 
    tout_val.it_interval.tv_sec = 0; 
    tout_val.it_interval.tv_usec = 0; 
    tout_val.it_value.tv_sec = 0; 
    tout_val.it_value.tv_usec = INTERVAL; 
    setitimer(ITIMER_REAL, &tout_val,0); 
    signal(SIGALRM,alarm_wakeup); 
    signal(SIGINT,exit_func); 

    srand(time(0)); 
    mess.nr = 0; 
    while (1) { 
     mess.nr++; 
     mess.temp = (rand()%1001)/10 - 20; 
     mess.bst = rand()%1000 + 1; 
     mess.abst = rand()%26 + 4; 
     write(STDIN_FILENO,&mess, sizeof(struct data)); 
     sleep(10); 
    } 

    exit(0); 
} 

出力：私はプロセスを殺した

strace ./uebung2_1 
execve("./uebung2_1", ["./uebung2_1"], [/* 78 vars */]) = 0 
brk(0)         = 0x8320000 
access("/etc/ld.so.nohwcap", F_OK)  = -1 ENOENT (No such file or directory) 
mmap2(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7791000 
access("/etc/ld.so.preload", R_OK)  = -1 ENOENT (No such file or directory) 
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3 
fstat64(3, {st_mode=S_IFREG|0644, st_size=109872, ...}) = 0 
mmap2(NULL, 109872, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7776000 
close(3)        = 0 
access("/etc/ld.so.nohwcap", F_OK)  = -1 ENOENT (No such file or directory) 
open("/lib/i386-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3 
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\340\233\1\0004\0\0\0"..., 512) = 512 
fstat64(3, {st_mode=S_IFREG|0755, st_size=1754876, ...}) = 0 
mmap2(NULL, 1759868, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb75c8000 
mmap2(0xb7770000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1a8000) = 0xb7770000 
mmap2(0xb7773000, 10876, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb7773000 
close(3)        = 0 
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb75c7000 
set_thread_area({entry_number:-1 -> 6, base_addr:0xb75c7940, limit:1048575, seg_32bit:1, contents:0, read_exec_only:0, limit_in_pages:1, seg_not_present:0, useable:1}) = 0 
mprotect(0xb7770000, 8192, PROT_READ) = 0 
mprotect(0x8049000, 4096, PROT_READ) = 0 
mprotect(0xb77b7000, 4096, PROT_READ) = 0 
munmap(0xb7776000, 109872)    = 0 
pipe([3, 4])       = 0 
clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0xb75c79a8) = 3436 
close(4)        = 0 
fstat64(1, {st_mode=S_IFCHR|0600, st_rdev=makedev(136, 8), ...}) = 0 
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7790000 
write(1, "Sohn gestartet mit PID 3436\n", 28Sohn gestartet mit PID 3436 
) = 28 
read(3, �B�C�A@A4D�@ 
        B�D@AHB�nD�A�A�C�B�C`ApB�▒D��A'C@A ,B��C�A 
���C�A 
     �B$D�A 
PA�C�AB�LD�A<B��CA��@D ApA@gD�A�AD@A^CProcess 3435 detached 
<detached ...> 

：straceのと

Sohn gestartet mit PID 3488 
�BhB�A@��@�A�B�!DA@ATCpA�B@D A4B�C�A0A@#D0dB�sDA  4B��CpA 
��\D�A^C 

出力ctrl + cを押します。なぜ象形文字？

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アップデート：私は子供で書かれた （sohn.c） 標準入力に出力されますが、出力には出力されません。おかげでJoachim Pileborg

Answer 1

に子供（sohn.c）が書き込まれましたが、出力に出力されました。 Joachim Pileborg

のおかげで - 壊滅させる