我决定不那么懒惰，并通过编写一些代码来回答是否将数据最终写入磁盘的问题。答案是它将被编写。
#include <stdint.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
typedef struct {
char data[100];
uint16_t count;
} state_data;
const char *test_data = "test";
int main(int argc, const char *argv[]) {
int fd = open("test.mm", O_RDWR|O_CREAT|O_TRUNC, (mode_t)0700);
if (fd < 0) {
perror("Unable to open file 'test.mm'");
exit(1);
}
size_t data_length = sizeof(state_data);
if (ftruncate(fd, data_length) < 0) {
perror("Unable to truncate file 'test.mm'");
exit(1);
}
state_data *data = (state_data *)mmap(NULL, data_length, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_POPULATE, fd, 0);
if (MAP_Failed == data) {
perror("Unable to mmap file 'test.mm'");
close(fd);
exit(1);
}
memset(data, 0, data_length);
for (data->count = 0; data->count < 5; ++data->count) {
data->data[data->count] = test_data[data->count];
}
kill(getpid(), 9);
}
#include <stdint.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <assert.h>
typedef struct {
char data[100];
uint16_t count;
} state_data;
const char *test_data = "test";
int main(int argc, const char *argv[]) {
int fd = open("test.mm", O_RDONLY);
if (fd < 0) {
perror("Unable to open file 'test.mm'");
exit(1);
}
size_t data_length = sizeof(state_data);
state_data *data = (state_data *)mmap(NULL, data_length, PROT_READ, MAP_SHARED|MAP_POPULATE, fd, 0);
if (MAP_Failed == data) {
perror("Unable to mmap file 'test.mm'");
close(fd);
exit(1);
}
assert(5 == data->count);
unsigned index;
for (index = 0; index < 4; ++index) {
assert(test_data[index] == data->data[index]);
}
printf("Validated\n");
}
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