Using lseek() prints out repeated characters - c

Question

char x[3];
char buff, c;
x[0]='y';
int offset, i;
int fd;
fd = open("test1.txt", O_RDONLY);
if(fd==-1){ printf("Error on fopen."); exit(1); }
offset = lseek(fd, 1, SEEK_END);
printf("Size of file is: %d. \n", offset);
for(i=offset-1; i>=0; i--)
{
c = read(fd, &buff, 1);
printf("The character is: %c. \n", c);
}
close(fd);
Running this gives me.
Size of file is: 6.
The character is: .
The character is: .
The character is: .
The character is: .
The character is: .
The character is: .
The test file contains only the word "TEST". I want to be able to print the word backwards.

Answer 1

read reads at the current position, and moves the current position forward by the amount read.
There needs to be further seeks. Also lseek( ..., 1, SEEK_END); probably ought to be lseek(...,0, SEEK_END); I would be uncomfortable with seeking to beyond the file.
for( i = ... ) {
lseek(fd, size - i, SEEK_BEGIN );
read(...);
}

Answer 2

Use fstat() to get the file size, as lseek() to SEEK_END is not guaranteed to return the size of a file, and you can use pread() to read a file in reverse without having to do any seeking at all. This is without any error checking - which should be added to any code that's going to be used:
struct stat sb;
int fd = open("test1.txt", O_RDONLY);
fstat( fd, &sb );
while ( sb.st_size > 0 )
{
char buff;
sb.st_size--;
pread( fd, &buff, sizeof( buff ), sb.st_size );
printf( "Char read: %c\n", buff );
}
close( fd );