Replica of file_get_contents() function in PHP

file_get_contents.c

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

char *file_get_contents();

int main() {
    char *str = file_get_contents( "test.txt" );
    printf( "%s", str );
    free( str );

    return 0;
}

char *file_get_contents( char file[] ) {
    FILE *f = fopen( file, "r" );
    int str_size = sizeof( char ) * 4;
    char *content = ( char* ) malloc( str_size );

    if( f == NULL ) {
        perror( "Unable to open file" );
        return "";
    }
    
    if( content != NULL ) {
        char str_content[ str_size ];
        int i = 1;
        while( fgets( str_content, str_size, f ) != NULL ) {
            content = ( char * ) realloc( content, ( str_size * i ) );
            strcat( content, str_content );
            i++;
        }

        return content;
    }

    return "";
}