int
fflush(FILE *f)
{
if (f == NULL) { // flush all open streams
for (f = &files->fd[0]; f < &files->fd[OPEN_MAX]; f++)
if (filedesc_isopen(f))
fflush(f);
return 0;
}
assert(filedesc_isopen(f));
return fileino_flush(f->ino);
}
int
dup2(int oldfn, int newfn)
{
filedesc *oldfd = &files->fd[oldfn];
filedesc *newfd = &files->fd[newfn];
assert(filedesc_isopen(oldfd));
assert(filedesc_isvalid(newfd));
if (filedesc_isopen(newfd))
close(newfn);
*newfd = *oldfd;
return newfn;
}
int
feof(FILE *fd)
{
assert(filedesc_isopen(fd));
fileinode *fi = &files->fi[fd->ino];
return fd->ofs >= fi->size && !(fi->mode & S_IFPART);
}
int
isatty(int fn)
{
assert(filedesc_isopen(&files->fd[fn]));
return files->fd[fn].ino == FILEINO_CONSIN
|| files->fd[fn].ino == FILEINO_CONSOUT;
}
void
filedesc_close(filedesc *fd)
{
assert(filedesc_isopen(fd));
assert(fileino_isvalid(fd->ino));
fd->ino = FILEINO_NULL; // mark the fd free
}
// Find or create and open a file, optionally using a given file descriptor.
// The argument 'fd' must point to a currently unused file descriptor,
// or may be NULL, in which case this function finds an unused file descriptor.
// The 'openflags' determines whether the file is created, truncated, etc.
// Returns the opened file descriptor on success,
// or returns NULL and sets errno on failure.
filedesc *
filedesc_open(filedesc *fd, const char *path, int openflags, mode_t mode)
{
if (!fd && !(fd = filedesc_alloc()))
return NULL;
assert(fd->ino == FILEINO_NULL);
// Determine the complete file mode if it is to be created.
mode_t createmode = (openflags & O_CREAT) ? S_IFREG | (mode & 0777) : 0;
// Walk the directory tree to find the desired directory entry,
// creating an entry if it doesn't exist and O_CREAT is set.
int ino = dir_walk(path, createmode);
if (ino < 0)
return NULL;
assert(fileino_exists(ino));
// Refuse to open conflict-marked files;
// the user needs to resolve the conflict and clear the conflict flag,
// or just delete the conflicted file.
if (files->fi[ino].mode & S_IFCONF) {
errno = ECONFLICT;
return NULL;
}
// Truncate the file if we were asked to
if (openflags & O_TRUNC) {
if (!(openflags & O_WRONLY)) {
warn("filedesc_open: can't truncate non-writable file");
errno = EINVAL;
return NULL;
}
if (fileino_truncate(ino, 0) < 0)
return NULL;
}
// Initialize the file descriptor
fd->ino = ino;
fd->flags = openflags;
fd->ofs = (openflags & O_APPEND) ? files->fi[ino].size : 0;
fd->err = 0;
assert(filedesc_isopen(fd));
return fd;
}
// Scan an open directory filedesc and return the next entry.
// Returns a pointer to the next matching file inode's 'dirent' struct,
// or NULL if the directory being scanned contains no more entries.
struct dirent *readdir(DIR *dir)
{
#if SOL >= 4
assert(filedesc_isopen(dir));
int ino;
while ((ino = dir->ofs++) < FILE_INODES) {
if (!fileino_exists(ino) || files->fi[ino].dino != dir->ino)
continue;
return &files->fi[ino].de; // Return inode's dirent
}
return NULL; // End of directory
#else // ! SOL >= 4
// Lab 4: insert your directory scanning code here.
// Hint: a fileinode's 'dino' field indicates
// what directory the file is in;
// this function shouldn't return entries from other directories!
warn("readdir() not implemented");
return NULL;
#endif // ! SOL >= 4
}
// Seek the given file descriptor to a specificied position,
// which may be relative to the file start, end, or corrent position,
// depending on 'whence' (SEEK_SET, SEEK_CUR, or SEEK_END).
// Returns the resulting absolute file position,
// or returns -1 and sets errno appropriately on error.
off_t filedesc_seek(filedesc *fd, off_t offset, int whence)
{
assert(filedesc_isopen(fd));
assert(whence == SEEK_SET || whence == SEEK_CUR || whence == SEEK_END);
fileinode *fi = &files->fi[fd->ino];
#if SOL >= 4
off_t newofs = offset;
if (whence == SEEK_CUR)
newofs += fd->ofs;
else if (whence == SEEK_END)
newofs += fi->size;
assert(newofs >= 0);
fd->ofs = newofs;
return newofs;
#else // ! SOL >= 4
// Lab 4: insert your file descriptor seek implementation here.
warn("filedesc_seek() not implemented");
errno = EINVAL;
return -1;
#endif // ! SOL >= 4
}
FILE *
freopen(const char *path, const char *mode, FILE *fd)
{
assert(filedesc_isvalid(fd));
if (filedesc_isopen(fd))
fclose(fd);
// Parse the open mode string
int flags;
switch (*mode++) {
case 'r': flags = O_RDONLY; break;
case 'w': flags = O_WRONLY | O_CREAT | O_TRUNC; break;
case 'a': flags = O_WRONLY | O_CREAT | O_APPEND; break;
default: panic("freopen: unknown file mode '%c'\n", *--mode);
}
if (*mode == 'b') // binary flag - compatibility only
mode++;
if (*mode == '+')
flags |= O_RDWR;
if (filedesc_open(fd, path, flags, 0666) != fd)
return NULL;
return fd;
}
int
fileno(FILE *fd)
{
assert(filedesc_isopen(fd));
return fd - files->fd;
}
void
clearerr(FILE *fd)
{
assert(filedesc_isopen(fd));
fd->err = 0;
}
int
ferror(FILE *fd)
{
assert(filedesc_isopen(fd));
return fd->err;
}
long
ftell(FILE *fd)
{
assert(filedesc_isopen(fd));
return fd->ofs;
}
int
fsync(int fn)
{
assert(filedesc_isopen(&files->fd[fn]));
return fileino_flush(files->fd[fn].ino);
}
int
fstat(int fn, struct stat *statbuf)
{
assert(filedesc_isopen(&files->fd[fn]));
return fileino_stat(files->fd[fn].ino, statbuf);
}
int
ftruncate(int fn, off_t newlength)
{
assert(filedesc_isopen(&files->fd[fn]));
return fileino_truncate(files->fd[fn].ino, newlength);
}