/* this entry returns the inode pointed to by the given directory entry. It also
* handles redirecting for symbolic links */
struct inode *fs_dirent_readinode(struct dirent *dir, bool perms)
{
assert(dir);
if(perms) {
if(!vfs_inode_check_permissions(dir->parent, MAY_EXEC, 0))
return 0;
}
return vfs_icache_get(dir->filesystem, dir->ino);
}
ssize_t fs_inode_read(struct inode *node, size_t off, size_t count, unsigned char *buf)
{
if(!vfs_inode_check_permissions(node, MAY_READ, 0))
return -EACCES;
ssize_t ret;
ret = fs_callback_inode_read(node, off, count, buf);
return ret;
}
ssize_t fs_inode_write(struct inode *node, size_t off, size_t count, const unsigned char *buf)
{
if(S_ISDIR(node->mode))
return -EISDIR;
if(!vfs_inode_check_permissions(node, MAY_WRITE, 0))
return -EACCES;
ssize_t ret = fs_callback_inode_write(node, off, count, buf);
if(ret > 0) {
node->mtime = time_get_epoch();
vfs_inode_set_dirty(node);
}
return ret;
}
int sys_getdents(int fd, struct dirent_posix *dirs, unsigned int count)
{
struct file *f = file_get(fd);
if(!f) return -EBADF;
unsigned nex;
if(!vfs_inode_check_permissions(f->inode, MAY_READ, 0)) {
file_put(f);
return -EACCES;
}
rwlock_acquire(&f->inode->lock, RWL_READER);
int r = fs_callback_inode_getdents(f->inode, f->pos, dirs, count, &nex);
rwlock_release(&f->inode->lock, RWL_READER);
f->pos = nex;
file_put(f);
return r;
}
int fs_link(struct inode *dir, struct inode *target, const char *name, size_t namelen, bool allow_incomplete_directories)
{
if(!vfs_inode_check_permissions(dir, MAY_WRITE, 0))
return -EACCES;
if(!S_ISDIR(dir->mode))
return -ENOTDIR;
rwlock_acquire(&dir->lock, RWL_WRITER);
if(S_ISDIR(dir->mode) && (dir->nlink == 1) && !allow_incomplete_directories) {
rwlock_release(&dir->lock, RWL_WRITER);
return -ENOSPC;
}
rwlock_acquire(&target->metalock, RWL_WRITER);
int r = fs_callback_inode_link(dir, target, name, namelen);
if(!r)
atomic_fetch_add(&target->nlink, 1);
rwlock_release(&target->metalock, RWL_WRITER);
rwlock_release(&dir->lock, RWL_WRITER);
return r;
}
/* note that this function doesn't actually delete the dirent. It just sets a flag that
* says "hey, this was deleted". See vfs_dirent_release for more details. An important
* aspect is that on unlinking a directory, it does unlink the . and .. entries, even
* though the directory won't actually be deleted until vfs_dirent_release gets called
* and the last reference is released. */
static int do_fs_unlink(struct inode *node, const char *name, size_t namelen, int rec)
{
if(!vfs_inode_check_permissions(node, MAY_WRITE, 0))
return -EACCES;
struct dirent *dir = fs_dirent_lookup(node, name, namelen);
if(!dir)
return -ENOENT;
struct inode *target = fs_dirent_readinode(dir, true);
if(!target || (rec && S_ISDIR(target->mode) && !fs_inode_dirempty(target))) {
if(target)
vfs_icache_put(target);
vfs_dirent_release(dir);
return -ENOTEMPTY;
}
atomic_fetch_or_explicit(&dir->flags, DIRENT_UNLINK, memory_order_release);
if(S_ISDIR(target->mode) && rec) {
do_fs_unlink(target, "..", 2, 0);
do_fs_unlink(target, ".", 1, 0);
}
vfs_icache_put(target);
vfs_dirent_release(dir);
return 0;
}
/* This function returns the directory entry associated with the name 'name' under
* the inode 'node'. It must be careful to lookup the entry in the cache first. */
struct dirent *fs_dirent_lookup(struct inode *node, const char *name, size_t namelen)
{
if(!vfs_inode_check_permissions(node, MAY_READ, 0))
return 0;
if(!S_ISDIR(node->mode))
return 0;
if(node == current_process->root && !strncmp(name, "..", 2) && namelen == 2)
return fs_dirent_lookup(node, ".", 1);
mutex_acquire(dirent_cache_lock);
rwlock_acquire(&node->lock, RWL_WRITER);
struct dirent *dir = vfs_inode_get_dirent(node, name, namelen);
if(!dir) {
dir = vfs_dirent_create(node);
dir->count = 1;
strncpy(dir->name, name, namelen);
dir->namelen = namelen;
int r = fs_callback_inode_lookup(node, name, namelen, dir);
if(r) {
dir->count = 0;
vfs_dirent_destroy(dir);
rwlock_release(&node->lock, RWL_WRITER);
mutex_release(dirent_cache_lock);
return 0;
}
vfs_inode_get(node);
vfs_inode_add_dirent(node, dir);
} else {
if(atomic_fetch_add(&dir->count, 1) == 0) {
fs_dirent_remove_lru(dir);
vfs_inode_get(node);
}
}
rwlock_release(&node->lock, RWL_WRITER);
mutex_release(dirent_cache_lock);
return dir;
}
int do_exec(char *path, char **argv, char **env, int shebanged /* oh my */)
{
unsigned int i=0;
addr_t end, eip;
unsigned int argc=0, envc=0;
char **backup_argv=0, **backup_env=0;
/* Sanity */
if(!path || !*path)
return -EINVAL;
/* Load the file, and make sure that it is valid and accessible */
if(EXEC_LOG == 2)
printk(0, "[%d]: Checking executable file (%s)\n", current_process->pid, path);
struct file *efil;
int err_open;
efil = fs_file_open(path, _FREAD, 0, &err_open);
if(!efil)
return err_open;
/* are we allowed to execute it? */
if(!vfs_inode_check_permissions(efil->inode, MAY_EXEC, 0))
{
file_put(efil);
return -EACCES;
}
/* is it a valid elf? */
int header_size = 0;
#if CONFIG_ARCH == TYPE_ARCH_X86_64
header_size = sizeof(elf64_header_t);
#elif CONFIG_ARCH == TYPE_ARCH_X86
header_size = sizeof(elf32_header_t);
#endif
/* read in the ELF header, and check if it's a shebang */
if(header_size < 2) header_size = 2;
unsigned char mem[header_size];
fs_file_pread(efil, 0, mem, header_size);
if(__is_shebang(mem))
return loader_do_shebang(efil, argv, env);
int other_bitsize=0;
if(!is_valid_elf(mem, 2) && !other_bitsize) {
file_put(efil);
return -ENOEXEC;
}
if(EXEC_LOG == 2)
printk(0, "[%d]: Copy data\n", current_process->pid);
/* okay, lets back up argv and env so that we can
* clear out the address space and not lose data...
* If this call if coming from a shebang, then we don't check the pointers,
* since they won't be from userspace */
size_t total_args_len = 0;
if((shebanged || mm_is_valid_user_pointer(SYS_EXECVE, argv, 0)) && argv) {
while((shebanged || mm_is_valid_user_pointer(SYS_EXECVE, argv[argc], 0)) && argv[argc] && *argv[argc])
argc++;
backup_argv = (char **)kmalloc(sizeof(addr_t) * argc);
for(i=0;i<argc;i++) {
backup_argv[i] = (char *)kmalloc(strlen(argv[i]) + 1);
_strcpy(backup_argv[i], argv[i]);
total_args_len += strlen(argv[i])+1 + sizeof(char *);
}
}
if((shebanged || mm_is_valid_user_pointer(SYS_EXECVE, env, 0)) && env) {
while((shebanged || mm_is_valid_user_pointer(SYS_EXECVE, env[envc], 0)) && env[envc] && *env[envc]) envc++;
backup_env = (char **)kmalloc(sizeof(addr_t) * envc);
for(i=0;i<envc;i++) {
backup_env[i] = (char *)kmalloc(strlen(env[i]) + 1);
_strcpy(backup_env[i], env[i]);
total_args_len += strlen(env[i])+1 + sizeof(char *);
}
}
total_args_len += 2 * sizeof(char *);
/* and the path too! */
char *path_backup = (char *)kmalloc(strlen(path) + 1);
_strcpy((char *)path_backup, path);
path = path_backup;
/* Preexec - This is the point of no return. Here we close out unneeded
* file descs, free up the page directory and clear up the resources
* of the task */
if(EXEC_LOG)
printk(0, "Executing (p%dt%d, cpu %d, tty %d): %s\n", current_process->pid, current_thread->tid, current_thread->cpu->knum, current_process->pty ? current_process->pty->num : 0, path);
preexec();
/* load in the new image */
strncpy((char *)current_process->command, path, 128);
if(!loader_parse_elf_executable(mem, efil, &eip, &end))
eip=0;
/* do setuid and setgid */
if(efil->inode->mode & S_ISUID) {
current_process->effective_uid = efil->inode->uid;
}
if(efil->inode->mode & S_ISGID) {
current_process->effective_gid = efil->inode->gid;
}
/* we don't need the file anymore, close it out */
file_put(efil);
file_close_cloexec();
if(!eip) {
printk(5, "[exec]: Tried to execute an invalid ELF file!\n");
free_dp(backup_argv, argc);
free_dp(backup_env, envc);
kfree(path);
tm_thread_exit(0);
}
if(EXEC_LOG == 2)
printk(0, "[%d]: Updating task values\n", current_process->pid);
/* Setup the task with the proper values (libc malloc stack) */
addr_t end_l = end;
end = ((end-1)&PAGE_MASK) + PAGE_SIZE;
total_args_len += PAGE_SIZE;
/* now we need to copy back the args and env into userspace
* writeable memory...yippie. */
addr_t args_start = end + PAGE_SIZE;
addr_t env_start = args_start;
addr_t alen = 0;
mm_mmap(end, total_args_len,
PROT_READ | PROT_WRITE, MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, 0, 0, 0);
if(backup_argv) {
memcpy((void *)args_start, backup_argv, sizeof(addr_t) * argc);
alen += sizeof(addr_t) * argc;
*(addr_t *)(args_start + alen) = 0; /* set last argument value to zero */
alen += sizeof(addr_t);
argv = (char **)args_start;
for(i=0;i<argc;i++)
{
char *old = argv[i];
char *new = (char *)(args_start+alen);
unsigned len = strlen(old) + 4;
argv[i] = new;
_strcpy(new, old);
kfree(old);
alen += len;
}
kfree(backup_argv);
}
env_start = args_start + alen;
alen = 0;
if(backup_env) {
memcpy((void *)env_start, backup_env, sizeof(addr_t) * envc);
alen += sizeof(addr_t) * envc;
*(addr_t *)(env_start + alen) = 0; /* set last argument value to zero */
alen += sizeof(addr_t);
env = (char **)env_start;
for(i=0;i<envc;i++)
{
char *old = env[i];
char *new = (char *)(env_start+alen);
unsigned len = strlen(old) + 1;
env[i] = new;
_strcpy(new, old);
kfree(old);
alen += len;
}
kfree(backup_env);
}
end = (env_start + alen) & PAGE_MASK;
current_process->env = env;
current_process->argv = argv;
kfree(path);
/* set the heap locations, and map in the start */
current_process->heap_start = current_process->heap_end = end + PAGE_SIZE*2;
addr_t ret = mm_mmap(end + PAGE_SIZE, PAGE_SIZE,
PROT_READ | PROT_WRITE, MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, 0, 0, 0);
/* now, we just need to deal with the syscall return stuff. When the syscall
* returns, it'll just jump into the entry point of the new process */
tm_thread_lower_flag(current_thread, THREAD_SCHEDULE);
/* the kernel cares if it has executed something or not */
if(!(kernel_state_flags & KSF_HAVEEXECED))
set_ksf(KSF_HAVEEXECED);
arch_loader_exec_initializer(argc, eip);
if(EXEC_LOG == 2)
printk(0, "[%d]: Performing call\n", current_process->pid);
return 0;
}
/* This is possibly the lengthiest function in the VFS (possibly in the entire kernel!).
* It resolves a path until the last name in the path string, and then tries to create
* a new file with that name. It requires a lot of in-sequence checks for permission,
* existance, is-a-directory, and so forth. */
struct inode *fs_path_resolve_create_get(const char *path, int flags, mode_t mode, int *result, struct dirent **dirent)
{
// Step 1: Split the path up into directory to create in, and name of new file.
int len = strlen(path) + 1;
char tmp[len];
memcpy(tmp, path, len);
char *del = strrchr(tmp, '/');
if(del)
*del = 0;
char *dirpath = del ? tmp : ".";
char *name = del ? del + 1 : tmp;
if(dirpath[0] == 0)
dirpath = "/";
if(dirent)
*dirent = 0;
if(result)
*result = 0;
// Step 2: Resolve the target directory.
struct inode *dir = fs_path_resolve_inode(dirpath, flags, result);
if(!dir)
return 0;
if(!S_ISDIR(dir->mode)) {
if(result) *result = -ENOTDIR;
return 0;
}
// Step 3: Try to look up the file that we're trying to create.
struct dirent *test = fs_dirent_lookup(dir, name, strlen(name));
if(test) {
// If it was found, return it and its inode.
if(dirent)
*dirent = test;
struct inode *ret = fs_dirent_readinode(test, true);
if(ret)
ret = fs_resolve_mount(ret);
if(!ret) {
if(dirent)
*dirent = 0;
if(result)
*result = -EIO;
vfs_dirent_release(test);
} else {
if(!dirent)
vfs_dirent_release(test);
if(result)
*result = 0;
}
vfs_icache_put(dir);
return ret;
}
// Didn't find the entry. Step 4: Create one.
if(!vfs_inode_check_permissions(dir, MAY_WRITE, 0)) {
if(result) *result = -EACCES;
vfs_icache_put(dir);
return 0;
}
if(dir->nlink == 1) {
if(result) *result = -ENOSPC;
vfs_icache_put(dir);
return 0;
}
uint32_t id;
// Step 4a: Allocate an inode.
int r = fs_callback_fs_alloc_inode(dir->filesystem, &id);
if(r) {
if(result) *result = r;
vfs_icache_put(dir);
return 0;
}
// Step 4b: Read in that inode, and set some initial values (like creation time).
struct inode *node = vfs_icache_get(dir->filesystem, id);
if(!node) {
vfs_icache_put(dir);
if(result) *result = -EIO;
return 0;
}
node->mode = mode;
node->length = 0;
node->ctime = node->mtime = time_get_epoch();
vfs_inode_set_dirty(node);
// If we're making a directory, create the . and .. entries.
if(S_ISDIR(mode)) {
// Create . and ..
if(fs_link(node, node, ".", 1, true))
r = -EPERM;
if(fs_link(node, dir, "..", 2, true))
r = -EMLINK;
}
// Step 4c: Create the link for the directory entry to the inode.
r = fs_link(dir, node, name, strlen(name), false);
if(result)
*result = !r ? 1 : r;
if(dirent && !r) {
*dirent = fs_dirent_lookup(dir, name, strlen(name));
if(!*dirent && node) {
vfs_icache_put(node);
vfs_icache_put(dir);
if(result)
*result = -EIO;
return 0;
}
}
vfs_icache_put(dir);
return r ? 0 : node;
}
