C语言：子进程不会退出，也不会终止，也不会杀死我的父进程

Question

我无法退出或终止发送信号的子进程。

您能告诉我在这段代码中我做错了什么吗：

//###################################### INVERTER.C (main)   
#include <semaphore.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <math.h>
#include <errno.h>
#include <unistd.h>

#include "timeprofiler.h"
#include "ppmtools.h"

//Global vars:
int shmids[4], shmPixelId, *total_lines, *processed_lines, *next_line, *buf_vars;
//To share unnamed semaphores between processes, they must be allocated in a shared memory.
mem_struct *sh_mm;
//unnamed semaphores
sem_t *mutex1, *mutex2, *mutex3, *sem_remaining_lines;
//struct that will hold the image in shared memory
image_struct *image;
pid_t *workersPID;
header *h;

int main(int argc, char *argv[]) {
    int i, j, k, cur = 0, id;
    pixel *row;
    double start, stop, startms, stopms;

    if (argc < 3) {
        printf("Incorrect usage.\nPlease use \"./invert input_filename.ppm output_filename.ppm\"\n");
        return -1;
    }
    //BLOCK ALL SIGNAL
    sigset_t block_ctrlc;
    sigfillset(&block_ctrlc);
    sigdelset(&block_ctrlc, SIGINT);
    sigprocmask(SIG_BLOCK, &block_ctrlc, NULL);

    //start timer
    start = getCurrentTimeMicro();
    startms = getCurrentTimeMili();

    printf("Opening input file [%s]\n", argv[1]);
    FILE *fpin = fopen(argv[1], "r");
    if (fpin == NULL) {
        printf("Could not open input file\n");
        return -1;
    }

    printf("Opening output file [%s]\n", argv[2]);
    FILE *fpout = fopen(argv[2], "w");
    if (fpout == NULL) {
        printf("Could not open output file\n");
        return -1;
    }

    printf("Getting header\n");
    h = getImageHeader(fpin);
    if (h == NULL) {
        printf("Error getting header from file\n");
        return -1;
    }
    printf("Got file Header: %s - %u x %u - %u\n", h->type, h->width, h->height, h->depth);

    printf("Saving header to output file\n");
    if (writeImageHeader(h, fpout) == -1) {
        printf("Could not write to output file\n");
        return -1;
    }

    init();
    printf("After init...\n");
    //alloc mem space for one row (width * size of one pixel struct)
    row = (pixel *) malloc(h->width * sizeof (pixel));

    printf("Starting work\n");
    for (i = 0; i < h->height; i++) {
        printf("Reading row... \n");
        if (getImageRow(h->width, row, fpin) == -1) {
            printf("Error while reading row\n");
        }
        printf("Got row %d || \n", (i + 1));
        for (j = cur, k = 0; j < cur + h->width; j++, k++) {
            image->pixel_data[j].red = row[k].red;
            image->pixel_data[j].blue = row[k].blue;
            image->pixel_data[j].green = row[k].green;
        }
        cur += h->width;
    }

    /*Creates workers*/
    workersPID = (pid_t*) malloc(sizeof (pid_t) *((NUM_WORKERS)));
    for (i = 0; i < NUM_WORKERS; i++) {
        id = fork();
        if (id == -1) {
            printf("Error creating worker no %d\n", i);
            return (EXIT_FAILURE);
        } else if (id == 0) {
            workersPID[i] = getpid();
            printf("Launching son with pid %d\n", getpid());
            worker(i);
        }
    }
    cur = 0;
    sem_wait(mutex2);

    /*Writes the invert image on the output file*/
    for (i = 0; i < h->height; i++) {
        for (j = cur, k = 0; j < cur + h->width; j++, k++) {
            row[k].red = image->pixel_data[j].red;
            row[k].blue = image->pixel_data[j].blue;
            row[k].green = image->pixel_data[j].green;
        }
        cur += h->width;
        printf("Saving row... \n");
        if (writeRow(h->width, row, fpout) == -1) {
            printf("Error while writing row\n");
        }
        printf("Done\n");
    }

    printf("Cleaning up...\n");
    //clean up row
    free(row);
    //clean up header
    free(h);

    printf("Closing file pointers.\n");
    fclose(fpin);
    fclose(fpout);
    //stop timer
    stop = getCurrentTimeMicro();
    stopms = getCurrentTimeMili();

    for (i = 0; i < NUM_WORKERS; i++) {
        if (workersPID[i]) {
            kill(workersPID[i], SIGTERM); 
            waitpid(workersPID[i], NULL, 0);
        }
    }
    terminate();
    printTimeElapsed(start, stop, "microseconds");
    printTimeElapsed(startms, stopms, "miliseconds");
    printf("Done!\n");

    return 0;
}

void init() {

    //create shared memory to hold the source image:
    if ((shmids[0] = shmget(IPC_PRIVATE, sizeof (image_struct), IPC_CREAT | 0700)) == -1) {
        printf("shmget to allocate image struct failed. Errno returned:  %s\n", strerror(errno));
        exit(EXIT_FAILURE);
    }
    image = (image_struct*) shmat(shmids[0], NULL, 0);

    //shared memory to allocate the pointer to pointer pixel_data
    if ((shmids[1] = shmget(IPC_PRIVATE, h->width * h->height * sizeof (pixel), IPC_CREAT | 0700)) == -1) {
        printf("shmget to allocate pixel_data array failed. Errno returned: %s\n", strerror(errno));
        exit(EXIT_FAILURE);
    }
    image->pixel_data = (pixel*) shmat(shmids[1], NULL, 0);

    /*Shared Memory segment for 3 integers*/
    if ((shmids[2] = shmget(IPC_PRIVATE, 3 * sizeof (int), IPC_CREAT | 0700)) == -1) {
        printf("shmget to allocate the 3 integers failed. Errno returned;  %s\n", strerror(errno));
        exit(EXIT_FAILURE);
    }
    buf_vars = (int*) shmat(shmids[2], NULL, 0);
    total_lines = &buf_vars[0];
    processed_lines = &buf_vars[1];
    next_line = &buf_vars[2];

    *processed_lines = *next_line = 0;
    *total_lines = h->height;

    if ((shmids[3] = shmget(IPC_PRIVATE, sizeof (mem_struct), IPC_CREAT | 0700)) == -1) {
        printf("shmget to allocate mem_Struct for semaphores failed. Errno returned %s\n", strerror(errno));
        exit(EXIT_FAILURE);
    }
    sh_mm = (mem_struct*) shmat(shmids[3], NULL, 0);
    if (sem_init(&sh_mm->mutex1, 1, 1) == -1) {
        printf("Error initializing semaphore mutex1.Errno returned: %s\n", strerror(errno));
        exit(EXIT_FAILURE);
    }
    mutex1 = &sh_mm->mutex1;

    if (sem_init(&sh_mm->mutex2, 1, 0) == -1) {
        printf("Error initializing semaphore mutex2.Errno returned: %s\n", strerror(errno));
        exit(EXIT_FAILURE);
    }
    mutex2 = &sh_mm->mutex2;

    if (sem_init(&sh_mm->mutex3, 1, 1) == -1) {
        printf("Error initializing semaphore mutex3.Errno returned: %s\n", strerror(errno));
        exit(EXIT_FAILURE);
    }
    mutex3 = &sh_mm->mutex3;

    if (sem_init(&sh_mm->sem_remaining_lines, 1, h->height) == -1) {
        printf("Error initializing semaphore sem_remaining_lines.Errno returned: %s\n", strerror(errno));
        exit(EXIT_FAILURE);
    }
    sem_remaining_lines = &sh_mm->sem_remaining_lines;
}

/*Worker process*/
void worker(int id) {
    int i, k, cur = 0;
    pixel *row;
    //Block all signals, except SIGINT and SIGKILL which are handled
    sigset_t block_ctrlc;
    sigfillset(&block_ctrlc);
    sigdelset(&block_ctrlc, SIGINT);
    sigdelset(&block_ctrlc, SIGTERM);
    sigprocmask(SIG_BLOCK, &block_ctrlc, NULL);
    signal(SIGINT, handle_signal);
    signal(SIGTERM, handle_signal);
    while (sem_wait(sem_remaining_lines)!= -1) { //if there are still lines to read, go on
        sem_wait(mutex3);
        cur = *next_line; //current image's line
        *next_line += h->width; //refreshs line for the next worker
        sem_post(mutex3);
        row = (pixel *) malloc(h->width * sizeof (pixel));
        for (i = cur, k = 0; i < cur + h->width; i++, k++) {
            row[k].red = image->pixel_data[i].red;
            row[k].blue = image->pixel_data[i].blue;
            row[k].green = image->pixel_data[i].green;
        }
        //printf("% - Inverting row... \n",id);
        invertRow(h->width, row); //invert 
        //printf("Done || \n");
        for (i = cur, k = 0; i < cur + h->width; i++, k++) {
            image->pixel_data[i].red = row[k].red;
            image->pixel_data[i].blue = row[k].blue;
            image->pixel_data[i].green = row[k].green;
        }
        sem_wait(mutex1);
        *processed_lines += 1; //increases the number of inverted lines
        if (*processed_lines == *total_lines) { //check if it reaches last line
            sem_post(mutex2); //if so, wakes the master telling that is ready
        }
        sem_post(mutex1);
    }
    //printf("Son %d is exiting\n",id);
    exit(0);
}

void handle_signal(int signum) {
    if(signum == SIGINT)
        signal(SIGINT, handle_signal);
    else
        signal(SIGTERM, handle_signal);
    exit(0);
}

void terminate() {
    int i;
    //close semaphores
    sem_destroy(mutex1);
    sem_destroy(mutex2);
    sem_destroy(mutex3);
    sem_destroy(sem_remaining_lines);

    //cleans up shared memory = removes shared memory segments
    for (i = 0; i < 4; i++) {
        shmctl(shmids[i], IPC_RMID, NULL);
    }

}

我将在这里留下作业的解释（顺便说一句，它已经完成了）：
1 页 pdf

Answer 1

您的工作线程已被 SIGTERM 阻塞（因为它在 main 中被阻塞，并且 sigprocmask 不会从阻塞集中删除信号，除非明确告知这样做）

您可能想在工作线程中执行类似的操作：

sigemptyset(&block_ctrlc);
sigaddset(&block_ctrlc, SIGINT);
sigaddset(&block_ctrlc, SIGTERM);
sigprocmask(SIG_UNBLOCK, &block_ctrlc, NULL);

或者，使用 SIG_SETMASK 调用 sigprocmask。