linux下c错误控制

#include<stdio.h>
#include<stdlib.h>
#include<errno.h>
#include<string.h>


int main()
{
    FILE* fp = fopen("test.txt","r");

    if(fp == NULL)
    {   
        fprintf(stderr,"error in open file test.txt,errno %s\n",strerror(errno));//strerror函数显示errno对应的具体错误
        exit(-1);
    }   

    return 0;
}

#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<string.h>
#include<errno.h>
#include<fcntl.h>

int readFromFile(const char* fileName,size_t length)
{
    size_t bufferRead;
    char *buffer = (char *)malloc(length);
    if(buffer == NULL)
    {   
        fprintf(stderr,"error in alloc memory buffer:%s\n",strerror(errno));
        abort();
    }   
    int fd = open(fileName,O_RDONLY);

    if(fd == -1) 
    {   
        free(buffer);
        fprintf(stderr,"error in open file %s:%s\n",fileName,strerror(errno));
        return -1; 
    }   

    while((bufferRead = read(fd,buffer,length)) != 0)
    {   
        printf("%s\n",buffer);
    }   

    close(fd);
    free(buffer);
    return 0;
}

int main()
{
     readFromFile("test.txt",5);
    return 0;
}