bad file descriptor from fread - c

Question

I try to use read() to get some characters from file just for learning this API. I have create a file called "file" in the same directory and it contains 1000 characters. But I got an error saying:
read: %m: Bad file descriptor
Here is the code:
#include <stdio.h>
#include <error.h>
int read_indent(int sockfd){
int sport, cport;
char user[2], rtype[2], addinfo[2];
char buffer[17];
if(read(sockfd, buffer, sizeof(buffer)) <= 0) {
perror("read: %m");
return -1;
}
buffer[sizeof(buffer)-1] = '\0';
sscanf(buffer, "%d:%d:%s:%s:%s", &sport, &cport, rtype, user, addinfo);
printf("%d:%d:%s:%s:%s", sport, cport, rtype, user, addinfo);
return 0;
}
int main(){
FILE *file_pt = fopen("file", "r");
if(file_pt == NULL) { printf("fopen error\n"); return -1;}
char buf[128];
int a = read_indent(file_pt);
fclose(file_pt);
return 0;
}
UPDATE 1: Compilation message
test.c: In function ‘main’:
test.c:27:2: warning: passing argument 1 of ‘read_indent’ makes integer from pointer without a cast [enabled by default]
int a = read_indent(file_pt);
^
test.c:4:5: note: expected ‘int’ but argument is of type ‘struct FILE *’
int read_indent(int sockfd){

Answer 1

Your read_indent function takes a file descriptor, but you're passing in a FILE* pointer. Try turning the FILE* pointer into a file descriptor using fileno:
int a = read_indent(fileno(file_pt));