/*
* Attaches BitMap to memory mapped file that is created in indices/ directory.
* file name is based on nmap name, so bit map name should be valid linux file
* name.
*
* File is created immidietly and space is allocated to match requested bit map
* size. Previously allocated bit map space is freed without copying it!
*/
BitMap bm_attach_to_file(BitMap self) {
int fname_length = strlen(self->name) + 8 + 4 + 1; // length of 'indices/' + length of '.idx' + 1 for 0
char* fname = malloc(fname_length);
struct stat buffer;
int fsize = self->part_length * sizeof (BitMapPart);
sprintf(fname, "indices/%s.idx", self->name);
if (self->parts) free(self->parts);
try_io(self->fd = open(fname, O_RDWR | O_CREAT | O_TRUNC, 0600));
try_io(fstat(self->fd, &buffer));
if (buffer.st_size < fsize) {
try_io(lseek(self->fd, fsize - 1, SEEK_SET));
try_io(write(self->fd, "\0", 1));
}
try_io(self->parts = mmap(NULL, fsize, PROT_WRITE | PROT_READ, MAP_SHARED, self->fd, 0));
free(fname);
return (self);
}
/*
* Resizes bitmap to new bit length. If bit length falls into same part length,
* then nothing is changed besides bit_length.
*
* realloc and mremap are used - both claim to copy data, but they might change
* address of parts pointer. Becouse of that, client should not store pointers
* to arbitrary parts, instead store index of part relative to first part.
*
*/
BitMap bm_resize(BitMap self, int new_bit_length) {
int new_part_length = bm_part_length(new_bit_length);
int new_byte_size = new_part_length * sizeof (BitMapPart);
if (new_part_length != self->part_length) {
if (self->persisted) {
try_io(lseek(self->fd, new_byte_size - 1, SEEK_SET));
try_io(write(self->fd, "\0", 1));
self->parts = mremap(
self->parts,
self->part_length * sizeof (BitMapPart),
new_byte_size,
MREMAP_MAYMOVE
);
} else {
self->parts = realloc(self->parts, new_byte_size);
}
}
self->bit_length = new_bit_length;
self->part_length = new_part_length;
return (self);
}
void
priv_vfs_readwrite_fother(int asroot, int injail, struct test *test)
{
try_io("priv_vfs_readwrite_fother(none, O_RDONLY)", fpath_none,
asroot, injail, O_RDONLY, asroot ? 0 : -1, EACCES);
try_io("priv_vfs_readwrite_fother(none, O_WRONLY)", fpath_none,
asroot, injail, O_WRONLY, asroot ? 0 : -1, EACCES);
try_io("priv_vfs_readwrite_fother(none, O_RDWR)", fpath_none,
asroot, injail, O_RDWR, asroot ? 0 : -1, EACCES);
try_io("priv_vfs_readwrite_fother(read, O_RDONLY)", fpath_read,
asroot, injail, O_RDONLY, 0, 0);
try_io("priv_vfs_readwrite_fother(read, O_WRONLY)", fpath_read,
asroot, injail, O_WRONLY, asroot ? 0 : -1, EACCES);
try_io("priv_vfs_readwrite_fother(read, O_RDWR)", fpath_read,
asroot, injail, O_RDWR, asroot ? 0 : -1, EACCES);
try_io("priv_vfs_readwrite_fother(write, O_RDONLY)", fpath_write,
asroot, injail, O_RDONLY, asroot ? 0 : -1, EACCES);
try_io("priv_vfs_readwrite_fother(write, O_WRONLY)", fpath_write,
asroot, injail, O_WRONLY, 0, 0);
try_io("priv_vfs_readwrite_fother(write, O_RDWR)", fpath_write,
asroot, injail, O_RDWR, asroot ? 0 : -1, EACCES);
try_io("priv_vfs_readwrite_fother(write, O_RDONLY)", fpath_readwrite,
asroot, injail, O_RDONLY, 0, 0);
try_io("priv_vfs_readwrite_fother(write, O_WRONLY)", fpath_readwrite,
asroot, injail, O_WRONLY, 0, 0);
try_io("priv_vfs_readwrite_fother(write, O_RDWR)", fpath_readwrite,
asroot, injail, O_RDWR, 0, 0);
}