Develop a simple version of the I/O library function fgets() using Unix I/O system calls. Here is the description of fgets() from the manual:

Prototype: char *fgets(char *s, int size, FILE *stream)

fgets() reads in at most one less than size characters from stream and stores them into the buffer pointed to by s. Reading stops after an EOF or a newline. If a newline is read, it is stored into the buffer. A terminating null byte is stored after the last character in the buffer. fgets() return s on success, and NULL on error or when end of file occurs while no characters have been read.

Below is a test driver for the function myFgets() to be implemented.

#include  #include  #include  #include  

#ifndef _IOEOF #define _IOEOF 0020 #endif #ifndef _IOERR #define _IOERR 0040 #endif char *myFgets(char *buf, int size, FILE *fp); int main(int argc, char *argv[]){ 

FILE *fp; char buf[100], int cnt=0; 

if(argc == 1) // reading from keyboard fp=stdin; 

else if((fp = fopen(argv[1], "r")) == NULL){ 

 perror("Could not open input file"); 

exit(1); }

while(myFgets(buf, 100, fp) != NULL){ fputs(buf, stdout); cnt =+ strlen(buf); 

} if(feof(fp)) 

else

printf("The file size is %d ", cnt); perror("Reading not completed"); 

The function myFgets() must:

return NULL when an error or the end of file has occured, update the _flag of the FILE object accordingly(use the constants _IOEOF and _IOERR). obtain the file Unix descriptor using the function fileno(FILE *), e.g., fd=fileno(fp);.