我在使用以下代码时遇到问题。因此，在 logger.c 文件中，我创建了一个记录器子进程，它将继续循环等待读取。每当跑步时，我什么也得不到，它只是等待。 我真的不明白我做错了什么。 该记录器文件基本上记录sensor_db.c文件的活动，即每当sensor_db打开、写入一个值以及每当它关闭时记录一条消息。
sensor_db.c 文件：
#include <stdio.h>
#include <stdbool.h>
#include "config.h"
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include "logger.h"
#include <fcntl.h>
#include <sys/wait.h>
// status 1: file opening error
// status 2: fork failure
// status 3: writing to db file failure
// status 4: file failed to close
// status 5: pipe creation failure
/* definition of global vars */
FILE* open_db(char *filename, bool append) {
FILE *fp;
if (append == true) {
fp = fopen(filename, "a");
} else {
fp = fopen(filename, "w");
}
create_log_process();
// Error handling for file opening
if (fp == NULL) {
// create_log_process();
write_to_log_process("ERROR: could not open db file.");
perror("Error occurred during file opening");
exit(1);
}
// Communicate with the log process
// create_log_process(); // Create the log process once before opening the data file
write_to_log_process("Data file opened.");
// end_log_process();
return fp;
}
int insert_sensor(FILE * f, sensor_id_t id, sensor_value_t value, sensor_ts_t ts) {
if (fprintf(f, "%d, %lf, %ld \n", id, value, ts) < 0) {
// create_log_process();
write_to_log_process("ERROR: could not write to db file.");
// end_log_process();
perror("Error writing to file");
fclose(f);
exit(3);
}
// Communicate with the log process
// create_log_process();
write_to_log_process("Data inserted.");
// end_log_process();
return 0;
}
int close_db(FILE * f) {
if ( fclose(f) == EOF) {
// create_log_process();
write_to_log_process("ERROR: could not close db file.");
// end_log_process();
perror("Error closing file");
exit(4);
};
// Communicate with the log process
// create_log_process();
write_to_log_process("Data file closed.");
end_log_process();
return 0;
}
logger.c 文件：
#include <time.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/wait.h>
#include <string.h>
#include <errno.h>
#define BUFFER_SIZE 1000
// status 1: file opening error
// status 2: fork failure
// status 3: writing to log file failure
// status 4: file failed to close
// status 5: pipe creation failure
// status 6: writing to log file failure
/*global variables (for file opening + pipe)*/
FILE *fp;
int fd[2], pid;
int i = 0;
int create_log_process() {
// log file opening
fp = fopen("gateway.log", "a");
if (fp == NULL) {
perror("Error occurred during log file opening");
exit(1);
}
// creation of communication and child process
if (pipe(fd) == -1) {
perror("Error occurred during pipe creation");
exit(5);
};
pid = fork();
// error handle
if (pid == -1) {
perror("fork failed");
exit(2);
} else if (pid == 0) {
close(fd[1]); // closing write_end.
char received_message[BUFFER_SIZE];
ssize_t bytes_read;
while ((bytes_read = read(fd[0], received_message, BUFFER_SIZE - 1)) > 0) {
// received_message[bytes_read] = '\0'; // Null-terminate the received data
printf("test\n");
printf("child process reads: %s \n", received_message);
// timestamp creation.
time_t timer;
time(&timer);
struct tm *timestamp_info;
timestamp_info = localtime(&timer);
char timestamp[20];
strftime(timestamp, sizeof(timestamp), "%a %b %d %X %Y", timestamp_info);
// writing message to log file.
if (fprintf(fp, "%d - %s - %s\n", i++, timestamp, received_message) < 0) {
perror("Error occurred during writing to log file");
fclose(fp);
};
printf("test\n");
}
close(fd[0]);
fclose(fp);
exit(0);
} else {
// close(fd[0]);
}
return 0;
}
int write_to_log_process(char *msg) {
if (pid > 0) {
char message[BUFFER_SIZE];
strncpy(message, msg, sizeof(message) - 1);
message[sizeof(message) - 1] = '\0'; // Ensure null-termination
if (write(fd[1], message, strlen(message) + 1) == -1) {
perror("Error occurred during writing to pipe");
exit(3);
}
// opmerking!!! sizeof(msg) don't use, = size of the pointer! use buffer_size...
// with buffer_size you know for sure the nbytes you want to copy at most + is configurable.
}
return 0;
}
int end_log_process() {
close(fd[0]);
close(fd[1]);
wait(NULL);
return 0;
}
我尝试对其进行调试，但每当我到达记录器文件中定义的子进程中的 read() 函数时，调试器就会停止运行。
另外..这是使用的测试代码：
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <stdbool.h>
#include <time.h>
#include <sys/types.h>
#include "sensor_db.h"
#include "logger.h"
#include "config.h"
int main()
{
FILE *f = open_db("sensor_db.csv", true);
sleep(1);
sensor_id_t id = 1;
sensor_value_t v = 0.001;
sensor_ts_t ts = time(NULL);
insert_sensor(f, id, v, ts);
id = 2;
v = 0.002;
ts = time(NULL);
insert_sensor(f, id, v, ts);
id = 3;
v = 0.003;
ts = time(NULL);
insert_sensor(f, id, v, ts);
sleep(5);
insert_sensor(f, 4, v, ts);
close_db(f);
return 0;
}
问题在于
messagewrite_to_log_process()sizeof(*msg) == sizeof(char) == 1messagemsg应该是
strlen(msg)+1msgint write_to_log_process(char *msg) {
if (write(fd[1], msg, strlen(msg) + 1) == -1) { // +1 to include the null terminator
// opmerking!!! sizeof(msg) don't use, = size of the pointer! use buffer_size...
// with buffer_size you know for sure the nbytes you want to copy at most + is configurable.
perror("Error occurred during writing to pipe");
exit(3);
}
return 0;
}