创建临时文件mkstemp()和tmpfile()

mkstemp 

#include <stdlib.h>

int mkstemp(char *template);

 实例：

#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <sys/types.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <getopt.h>
#include <sys/epoll.h>
#include <sys/uio.h>
#include <limits.h>

#define _DEBUG_INFO
#ifdef _DEBUG_INFO
#define DEBUG_INFO(format, ...) printf("%s:%d $$ " format "\n" \
,__func__,__LINE__ \
, ##__VA_ARGS__)
#else
#define DEBUG_INFO(format, ...)
#endif
static char *file_name = "writev.txt";
int main(int argc, char **argv)
{
    int fd ;
    char name[] = "/tmp/lkmao_XXXXXX";
    fd = mkstemp(name);
    if(fd < 0){
        perror("mkstemp");
        return -1;
    }
    DEBUG_INFO("mkstemp %s ok",name);
    unlink(name);
    close(fd);
    return 0;
}

FILE *tmpfile(void); 

#include <stdio.h>
FILE *tmpfile(void);

#include <stdio.h>
int fileno(FILE *stream);

测试代码：

#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <sys/types.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <getopt.h>
#include <sys/epoll.h>
#include <sys/uio.h>
#include <limits.h>

#define _DEBUG_INFO
#ifdef _DEBUG_INFO
#define DEBUG_INFO(format, ...) printf("%s:%d $$ " format "\n" \
,__func__,__LINE__ \
, ##__VA_ARGS__)
#else
#define DEBUG_INFO(format, ...)
#endif
static char *file_name = "writev.txt";
int main(int argc, char **argv)
{
    FILE* p = tmpfile();
    if(p == NULL){
        perror("tmpfile");
        return -1;
    }
    int fd = fileno(p);
    if(fd < 0){
        perror("fileno");
        return -1;
    }
    off_t offset = 0;
    pwrite(fd,"hello tmp",sizeof("hello tmp"),offset);
    char buf[100];
    int len = pread(fd,buf,sizeof(buf),offset);
    buf[len] = '\0';
    DEBUG_INFO("buf = %s",buf);

    DEBUG_INFO("after pread:offset = %ld",ftell(p));
    len = read(fd,buf,sizeof(buf));
    buf[len] = '\0';
    DEBUG_INFO("buf = %s",buf);

    DEBUG_INFO("after read:offset = %ld",ftell(p));

    fclose(p);
    return 0;
}

测试结果：

小结