lseek error

I'm just learning the unix system calls and have used lseek a few times and never had a problem with it. It's a pretty straight forward system call but this one is getting me. I'm getting the error "problem with lseek in lchars: 1 : Illegal seek"
I've used the system call in this exact way but am getting this error for one reason or another. Probably overlooking something.

Code:

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#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <ctype.h>

int
main(int argc, char **argv)
{
        int fd1, fd2;
        int i;
        char buf[1];

        if (fd1 = open(argv[1], O_RDONLY) == -1) {
                perror("problem with open in lchars: 1");
                exit(-1);
        }
        if (fd2 = open(argv[2], O_CREAT|O_WRONLY, 0664) == -1) {
                perror("problem with open in lchars: 2");
                exit(-1);
        }

        i = 1;
        if (lseek(fd1, (off_t)-i, SEEK_END) == -1) {
                perror("problem with lseek in lchars: 1");
                exit(-1);
        }

        /* strip spaces at end of file */
        read(fd1, buf, sizeof(buf));
        while (isspace(buf[i])) {
                ++i;
                lseek(fd1, (off_t)-i, SEEK_END);
                read(fd1, buf, sizeof(buf));
        }

        for (i; i < (i + 10); ++i) {
                write(fd2, buf, sizeof(buf));
                lseek(fd1, (off_t)-i, SEEK_END);
                read(fd1, buf, sizeof(buf));
        }

        return 0;
}

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Are you trying to seek in an empty file?

And what is the command you are using to invoke your program?

no, I was sure the file wasn't empty and tried it on a couple files. the command was
programname /etc/passwd file.txt
programname program.c file.txt
Both have read permissions for the user.

Quote:

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Originally Posted by crash88

Code:

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        if (fd1 = open(argv[1], O_RDONLY) == -1) {
                perror("problem with open in lchars: 1");
                exit(-1);
        }
        if (fd2 = open(argv[2], O_CREAT|O_WRONLY, 0664) == -1) {
                perror("problem with open in lchars: 2");
                exit(-1);
        }

---

---

Try changing this to:

Code:

---

        if ((fd1 = open(argv[1], O_RDONLY)) == -1) {
                perror("problem with open in lchars: 1");
                exit(-1);
        }
        if ((fd2 = open(argv[2], O_CREAT|O_WRONLY, 0664)) == -1) {
                perror("problem with open in lchars: 2");
                exit(-1);
        }

---