Linux：libc库简单设计

简单设计MyFopen，MyFclose，MyFwrite，MyFFlush

mystdio.h

#pragma once
#include<stdio.h>#define MAX 1024
#define NONE_FLUSH 1<<0
#define LINE_FLUSH 1<<1
#define FULL_FLUSH 1<<2typedef struct IO_FILE
{int fileno;int flag;char outbuffer[MAX];int bufferlen;int flush_method;
}MyFile;MyFile* MyFopen(const char* path, const char* mode);
void MyFclose(MyFile*);
int MyFwrite(MyFile*, void* str, int len);
void MyFFlush(MyFile*);

mystdio.c

#include"mystdio.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>static MyFile* BuyFile(int fd, int flag)
{MyFile* f = (MyFile*)malloc(sizeof(MyFile));if (f == NULL) return NULL;f->fileno = fd;f->flag = flag;f->bufferlen = 0;f->flush_method = LINE_FLUSH;memset(f->outbuffer, 0, sizeof(f->outbuffer));return f;
};MyFile* MyFopen(const char* path, const char* mode)
{int fd = -1;int flag = 0;if (strcmp(mode, "w") == 0){flag = O_CREAT | O_WRONLY | O_TRUNC;fd = open(path, flag, 0666);}else if (strcmp(mode, "a") == 0){flag = O_CREAT | O_WRONLY | O_APPEND;fd = open(path, flag, 0666);}else if (strcmp(mode, "r") == 0){flag = O_RDWR;fd = open(path, flag);}else{}if (fd < 0)return NULL;return BuyFile(fd, flag);
}void MyFclose(MyFile* file)
{if (file->fileno < 0) return;MyFFlush(file);close(file->fileno);free(file);
}int MyFwrite(MyFile* file, void* str, int len)
{memcpy(file->outbuffer + file->bufferlen, str, len);file->bufferlen += len;if (file->flush_method & LINE_FLUSH && file->outbuffer[file->bufferlen - 1] == '\n'){MyFFlush(file);}return 0;
}void MyFFlush(MyFile* file)
{if (file->bufferlen <= 0) return;int n = write(file->fileno, file->outbuffer, file->bufferlen);(void)n;fsync(file->fileno);file->bufferlen = 0;
}

usercode.c

#include "mystdio.h"
#include <string.h>
#include <unistd.h>int main()
{MyFile* filep = MyFopen("./log.txt", "a");if (!filep){printf("fopen error!\n");return 1;}int cnt = 10;while (cnt--){char* msg = (char*)"hello myfile!!!";MyFwrite(filep, msg, strlen(msg));MyFFlush(filep);printf("buffer: %s\n", filep->outbuffer);sleep(1);}MyFclose(filep); // FILE *fpreturn 0;
}