int
truncate(const char *path, off_t newlength)
{
int ino = dir_walk(path, 0);
if (ino < 0)
return -1;
return fileino_truncate(ino, newlength);
}
// 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;
}
int
ftruncate(int fn, off_t newlength)
{
assert(filedesc_isopen(&files->fd[fn]));
return fileino_truncate(files->fd[fn].ino, newlength);
}