// SPDX-License-Identifier: GPL-2.0

  #include <linux/init.h>
  #include <linux/fs.h>
  #include <linux/slab.h>
  #include <linux/types.h>
  #include <linux/fcntl.h>
  #include <linux/delay.h>
  #include <linux/string.h>

  #include <linux/dirent.h>

  #include <linux/syscalls.h>

  #include <linux/utime.h>

  #include <linux/file.h>

  static ssize_t __init xwrite(int fd, const char *p, size_t count)
  {
  	ssize_t out = 0;
  
  	/* sys_write only can write MAX_RW_COUNT aka 2G-4K bytes at most */
  	while (count) {

  		ssize_t rv = ksys_write(fd, p, count);

  
  		if (rv < 0) {
  			if (rv == -EINTR || rv == -EAGAIN)
  				continue;
  			return out ? out : rv;
  		} else if (rv == 0)
  			break;
  
  		p += rv;
  		out += rv;
  		count -= rv;
  	}
  
  	return out;
  }

  static __initdata char *message;
  static void __init error(char *x)
  {
  	if (!message)
  		message = x;
  }

  /* link hash */

  #define N_ALIGN(len) ((((len) + 1) & ~3) + 2)

  static __initdata struct hash {
  	int ino, minor, major;

  	umode_t mode;

  	struct hash *next;

  	char name[N_ALIGN(PATH_MAX)];

  } *head[32];
  
  static inline int hash(int major, int minor, int ino)
  {
  	unsigned long tmp = ino + minor + (major << 3);
  	tmp += tmp >> 5;
  	return tmp & 31;
  }

  static char __init *find_link(int major, int minor, int ino,

  			      umode_t mode, char *name)

  {
  	struct hash **p, *q;
  	for (p = head + hash(major, minor, ino); *p; p = &(*p)->next) {
  		if ((*p)->ino != ino)
  			continue;
  		if ((*p)->minor != minor)
  			continue;
  		if ((*p)->major != major)
  			continue;

  		if (((*p)->mode ^ mode) & S_IFMT)
  			continue;

  		return (*p)->name;
  	}

  	q = kmalloc(sizeof(struct hash), GFP_KERNEL);

  	if (!q)
  		panic("can't allocate link hash entry");

  	q->major = major;

  	q->minor = minor;
  	q->ino = ino;
  	q->mode = mode;

  	strcpy(q->name, name);

  	q->next = NULL;
  	*p = q;
  	return NULL;
  }
  
  static void __init free_hash(void)
  {
  	struct hash **p, *q;
  	for (p = head; p < head + 32; p++) {
  		while (*p) {
  			q = *p;
  			*p = q->next;

  			kfree(q);

  		}
  	}
  }

  static long __init do_utime(char *filename, time64_t mtime)

  {

  	struct timespec64 t[2];

  
  	t[0].tv_sec = mtime;
  	t[0].tv_nsec = 0;
  	t[1].tv_sec = mtime;
  	t[1].tv_nsec = 0;
  
  	return do_utimes(AT_FDCWD, filename, t, AT_SYMLINK_NOFOLLOW);
  }
  
  static __initdata LIST_HEAD(dir_list);
  struct dir_entry {
  	struct list_head list;
  	char *name;

  	time64_t mtime;

  };

  static void __init dir_add(const char *name, time64_t mtime)

  {
  	struct dir_entry *de = kmalloc(sizeof(struct dir_entry), GFP_KERNEL);
  	if (!de)
  		panic("can't allocate dir_entry buffer");
  	INIT_LIST_HEAD(&de->list);
  	de->name = kstrdup(name, GFP_KERNEL);
  	de->mtime = mtime;
  	list_add(&de->list, &dir_list);
  }
  
  static void __init dir_utime(void)
  {
  	struct dir_entry *de, *tmp;
  	list_for_each_entry_safe(de, tmp, &dir_list, list) {
  		list_del(&de->list);
  		do_utime(de->name, de->mtime);
  		kfree(de->name);
  		kfree(de);
  	}
  }

  static __initdata time64_t mtime;

  /* cpio header parsing */
  
  static __initdata unsigned long ino, major, minor, nlink;

  static __initdata umode_t mode;

  static __initdata unsigned long body_len, name_len;
  static __initdata uid_t uid;
  static __initdata gid_t gid;
  static __initdata unsigned rdev;
  
  static void __init parse_header(char *s)
  {
  	unsigned long parsed[12];
  	char buf[9];
  	int i;
  
  	buf[8] = '\0';
  	for (i = 0, s += 6; i < 12; i++, s += 8) {
  		memcpy(buf, s, 8);
  		parsed[i] = simple_strtoul(buf, NULL, 16);
  	}
  	ino = parsed[0];
  	mode = parsed[1];
  	uid = parsed[2];
  	gid = parsed[3];
  	nlink = parsed[4];

  	mtime = parsed[5]; /* breaks in y2106 */

  	body_len = parsed[6];
  	major = parsed[7];
  	minor = parsed[8];
  	rdev = new_encode_dev(MKDEV(parsed[9], parsed[10]));
  	name_len = parsed[11];
  }
  
  /* FSM */
  
  static __initdata enum state {
  	Start,
  	Collect,
  	GotHeader,
  	SkipIt,
  	GotName,
  	CopyFile,
  	GotSymlink,
  	Reset
  } state, next_state;
  
  static __initdata char *victim;

  static unsigned long byte_count __initdata;

  static __initdata loff_t this_header, next_header;

  static inline void __init eat(unsigned n)

  {
  	victim += n;
  	this_header += n;

  	byte_count -= n;

  }

  static __initdata char *vcollected;

  static __initdata char *collected;

  static long remains __initdata;

  static __initdata char *collect;
  
  static void __init read_into(char *buf, unsigned size, enum state next)
  {

  	if (byte_count >= size) {

  		collected = victim;
  		eat(size);
  		state = next;
  	} else {
  		collect = collected = buf;
  		remains = size;
  		next_state = next;
  		state = Collect;
  	}
  }
  
  static __initdata char *header_buf, *symlink_buf, *name_buf;
  
  static int __init do_start(void)
  {
  	read_into(header_buf, 110, GotHeader);
  	return 0;
  }
  
  static int __init do_collect(void)
  {

  	unsigned long n = remains;

  	if (byte_count < n)
  		n = byte_count;

  	memcpy(collect, victim, n);
  	eat(n);
  	collect += n;
  	if ((remains -= n) != 0)
  		return 1;
  	state = next_state;
  	return 0;
  }
  
  static int __init do_header(void)
  {

  	if (memcmp(collected, "070707", 6)==0) {
  		error("incorrect cpio method used: use -H newc option");
  		return 1;
  	}

  	if (memcmp(collected, "070701", 6)) {
  		error("no cpio magic");
  		return 1;
  	}
  	parse_header(collected);
  	next_header = this_header + N_ALIGN(name_len) + body_len;
  	next_header = (next_header + 3) & ~3;

  	state = SkipIt;
  	if (name_len <= 0 || name_len > PATH_MAX)
  		return 0;
  	if (S_ISLNK(mode)) {
  		if (body_len > PATH_MAX)
  			return 0;
  		collect = collected = symlink_buf;
  		remains = N_ALIGN(name_len) + body_len;
  		next_state = GotSymlink;
  		state = Collect;
  		return 0;
  	}
  	if (S_ISREG(mode) || !body_len)
  		read_into(name_buf, N_ALIGN(name_len), GotName);
  	return 0;
  }
  
  static int __init do_skip(void)
  {

  	if (this_header + byte_count < next_header) {
  		eat(byte_count);

  		return 1;
  	} else {
  		eat(next_header - this_header);
  		state = next_state;
  		return 0;
  	}
  }
  
  static int __init do_reset(void)
  {

  	while (byte_count && *victim == '\0')

  		eat(1);

  	if (byte_count && (this_header & 3))

  		error("broken padding");
  	return 1;
  }

  static void __init clean_path(char *path, umode_t fmode)

  {

  	struct kstat st;

  	if (!vfs_lstat(path, &st) && (st.mode ^ fmode) & S_IFMT) {
  		if (S_ISDIR(st.mode))

  			ksys_rmdir(path);

  		else

  			ksys_unlink(path);

  	}
  }

  static int __init maybe_link(void)
  {
  	if (nlink >= 2) {
  		char *old = find_link(major, minor, ino, mode, collected);
  		if (old) {
  			clean_path(collected, 0);
  			return (ksys_link(old, collected) < 0) ? -1 : 1;
  		}
  	}
  	return 0;
  }

  static __initdata int wfd;
  
  static int __init do_name(void)
  {
  	state = SkipIt;
  	next_state = Reset;
  	if (strcmp(collected, "TRAILER!!!") == 0) {
  		free_hash();
  		return 0;
  	}

  	clean_path(collected, mode);

  	if (S_ISREG(mode)) {

  		int ml = maybe_link();
  		if (ml >= 0) {
  			int openflags = O_WRONLY|O_CREAT;
  			if (ml != 1)
  				openflags |= O_TRUNC;

  			wfd = ksys_open(collected, openflags, mode);

  			if (wfd >= 0) {

  				ksys_fchown(wfd, uid, gid);

  				ksys_fchmod(wfd, mode);

  				if (body_len)

  					ksys_ftruncate(wfd, body_len);

  				vcollected = kstrdup(collected, GFP_KERNEL);

  				state = CopyFile;
  			}
  		}
  	} else if (S_ISDIR(mode)) {

  		ksys_mkdir(collected, mode);

  		ksys_chown(collected, uid, gid);

  		ksys_chmod(collected, mode);

  		dir_add(collected, mtime);

  	} else if (S_ISBLK(mode) || S_ISCHR(mode) ||
  		   S_ISFIFO(mode) || S_ISSOCK(mode)) {
  		if (maybe_link() == 0) {

  			ksys_mknod(collected, mode, rdev);

  			ksys_chown(collected, uid, gid);

  			ksys_chmod(collected, mode);

  			do_utime(collected, mtime);

  		}
  	}
  	return 0;
  }
  
  static int __init do_copy(void)
  {

  	if (byte_count >= body_len) {

  		if (xwrite(wfd, victim, body_len) != body_len)
  			error("write error");

  		ksys_close(wfd);

  		do_utime(vcollected, mtime);
  		kfree(vcollected);

  		eat(body_len);
  		state = SkipIt;
  		return 0;
  	} else {

  		if (xwrite(wfd, victim, byte_count) != byte_count)

  			error("write error");

  		body_len -= byte_count;
  		eat(byte_count);

  		return 1;
  	}
  }
  
  static int __init do_symlink(void)
  {
  	collected[N_ALIGN(name_len) + body_len] = '\0';

  	clean_path(collected, 0);

  	ksys_symlink(collected + N_ALIGN(name_len), collected);

  	ksys_lchown(collected, uid, gid);

  	do_utime(collected, mtime);

  	state = SkipIt;
  	next_state = Reset;
  	return 0;
  }
  
  static __initdata int (*actions[])(void) = {
  	[Start]		= do_start,
  	[Collect]	= do_collect,
  	[GotHeader]	= do_header,
  	[SkipIt]	= do_skip,
  	[GotName]	= do_name,
  	[CopyFile]	= do_copy,
  	[GotSymlink]	= do_symlink,
  	[Reset]		= do_reset,
  };

  static long __init write_buffer(char *buf, unsigned long len)

  {

  	byte_count = len;

  	victim = buf;
  
  	while (!actions[state]())
  		;

  	return len - byte_count;

  }

  static long __init flush_buffer(void *bufv, unsigned long len)

  {

  	char *buf = (char *) bufv;

  	long written;
  	long origLen = len;

  	if (message)

  		return -1;

  	while ((written = write_buffer(buf, len)) < len && !message) {
  		char c = buf[written];
  		if (c == '0') {
  			buf += written;
  			len -= written;
  			state = Start;
  		} else if (c == 0) {
  			buf += written;
  			len -= written;
  			state = Reset;
  		} else

  			error("junk within compressed archive");

  	}

  	return origLen;

  }

  static unsigned long my_inptr; /* index of next byte to be processed in inbuf */

  #include <linux/decompress/generic.h>

  static char * __init unpack_to_rootfs(char *buf, unsigned long len)

  {

  	long written;

  	decompress_fn decompress;

  	const char *compress_name;
  	static __initdata char msg_buf[64];

  	header_buf = kmalloc(110, GFP_KERNEL);
  	symlink_buf = kmalloc(PATH_MAX + N_ALIGN(PATH_MAX) + 1, GFP_KERNEL);
  	name_buf = kmalloc(N_ALIGN(PATH_MAX), GFP_KERNEL);

  
  	if (!header_buf || !symlink_buf || !name_buf)

  		panic("can't allocate buffers");

  	state = Start;
  	this_header = 0;
  	message = NULL;
  	while (!message && len) {
  		loff_t saved_offset = this_header;
  		if (*buf == '0' && !(this_header & 3)) {
  			state = Start;
  			written = write_buffer(buf, len);
  			buf += written;
  			len -= written;
  			continue;
  		}
  		if (!*buf) {
  			buf++;
  			len--;
  			this_header++;
  			continue;
  		}
  		this_header = 0;

  		decompress = decompress_method(buf, len, &compress_name);

  		pr_debug("Detected %s compressed data
  ", compress_name);

  		if (decompress) {

  			int res = decompress(buf, len, NULL, flush_buffer, NULL,

  				   &my_inptr, error);

  			if (res)
  				error("decompressor failed");
  		} else if (compress_name) {

  			if (!message) {
  				snprintf(msg_buf, sizeof msg_buf,
  					 "compression method %s not configured",
  					 compress_name);
  				message = msg_buf;
  			}

  		} else

  			error("invalid magic at start of compressed archive");

  		if (state != Reset)

  			error("junk at the end of compressed archive");

  		this_header = saved_offset + my_inptr;
  		buf += my_inptr;
  		len -= my_inptr;

  	}

  	dir_utime();

  	kfree(name_buf);
  	kfree(symlink_buf);
  	kfree(header_buf);

  	return message;
  }

  static int __initdata do_retain_initrd;
  
  static int __init retain_initrd_param(char *str)
  {
  	if (*str)
  		return 0;
  	do_retain_initrd = 1;
  	return 1;
  }
  __setup("retain_initrd", retain_initrd_param);

  #ifdef CONFIG_ARCH_HAS_KEEPINITRD
  static int __init keepinitrd_setup(char *__unused)
  {
  	do_retain_initrd = 1;
  	return 1;
  }
  __setup("keepinitrd", keepinitrd_setup);
  #endif

  extern char __initramfs_start[];
  extern unsigned long __initramfs_size;

  #include <linux/initrd.h>

  #include <linux/kexec.h>

  void __weak free_initrd_mem(unsigned long start, unsigned long end)
  {

  	free_reserved_area((void *)start, (void *)end, POISON_FREE_INITMEM,
  			"initrd");

  }

  #ifdef CONFIG_KEXEC_CORE

  static bool kexec_free_initrd(void)
  {

  	unsigned long crashk_start = (unsigned long)__va(crashk_res.start);
  	unsigned long crashk_end   = (unsigned long)__va(crashk_res.end);
  
  	/*
  	 * If the initrd region is overlapped with crashkernel reserved region,
  	 * free only memory that is not part of crashkernel region.
  	 */

  	if (initrd_start >= crashk_end || initrd_end <= crashk_start)
  		return false;
  
  	/*
  	 * Initialize initrd memory region since the kexec boot does not do.
  	 */
  	memset((void *)initrd_start, 0, initrd_end - initrd_start);
  	if (initrd_start < crashk_start)
  		free_initrd_mem(initrd_start, crashk_start);
  	if (initrd_end > crashk_end)
  		free_initrd_mem(crashk_end, initrd_end);
  	return true;

  }

  #else
  static inline bool kexec_free_initrd(void)
  {
  	return false;
  }
  #endif /* CONFIG_KEXEC_CORE */

  #ifdef CONFIG_BLK_DEV_RAM

  #define BUF_SIZE 1024
  static void __init clean_rootfs(void)
  {
  	int fd;
  	void *buf;
  	struct linux_dirent64 *dirp;

  	int num;

  	fd = ksys_open("/", O_RDONLY, 0);

  	WARN_ON(fd < 0);
  	if (fd < 0)
  		return;
  	buf = kzalloc(BUF_SIZE, GFP_KERNEL);
  	WARN_ON(!buf);
  	if (!buf) {

  		ksys_close(fd);

  		return;
  	}
  
  	dirp = buf;

  	num = ksys_getdents64(fd, dirp, BUF_SIZE);

  	while (num > 0) {
  		while (num > 0) {

  			struct kstat st;

  			int ret;

  			ret = vfs_lstat(dirp->d_name, &st);

  			WARN_ON_ONCE(ret);
  			if (!ret) {

  				if (S_ISDIR(st.mode))

  					ksys_rmdir(dirp->d_name);

  				else

  					ksys_unlink(dirp->d_name);

  			}

  			num -= dirp->d_reclen;

  			dirp = (void *)dirp + dirp->d_reclen;
  		}
  		dirp = buf;
  		memset(buf, 0, BUF_SIZE);

  		num = ksys_getdents64(fd, dirp, BUF_SIZE);

  	}

  	ksys_close(fd);

  	kfree(buf);
  }

  #else
  static inline void clean_rootfs(void)
  {
  }
  #endif /* CONFIG_BLK_DEV_RAM */

  #ifdef CONFIG_BLK_DEV_RAM

  static void __init populate_initrd_image(char *err)

  {
  	ssize_t written;
  	int fd;
  
  	unpack_to_rootfs(__initramfs_start, __initramfs_size);
  
  	printk(KERN_INFO "rootfs image is not initramfs (%s); looks like an initrd
  ",
  			err);
  	fd = ksys_open("/initrd.image", O_WRONLY | O_CREAT, 0700);
  	if (fd < 0)
  		return;
  
  	written = xwrite(fd, (char *)initrd_start, initrd_end - initrd_start);
  	if (written != initrd_end - initrd_start)
  		pr_err("/initrd.image: incomplete write (%zd != %ld)
  ",
  		       written, initrd_end - initrd_start);
  	ksys_close(fd);
  }

  #else

  static void __init populate_initrd_image(char *err)

  {
  	printk(KERN_EMERG "Initramfs unpacking failed: %s
  ", err);
  }

  #endif /* CONFIG_BLK_DEV_RAM */

  static int __init populate_rootfs(void)

  {

  	/* Load the built in initramfs */

  	char *err = unpack_to_rootfs(__initramfs_start, __initramfs_size);

  	if (err)

  		panic("%s", err); /* Failed to decompress INTERNAL initramfs */

  
  	if (!initrd_start || IS_ENABLED(CONFIG_INITRAMFS_FORCE))
  		goto done;
  
  	if (IS_ENABLED(CONFIG_BLK_DEV_RAM))

  		printk(KERN_INFO "Trying to unpack rootfs image as initramfs...
  ");

  	else
  		printk(KERN_INFO "Unpacking initramfs...
  ");

  	err = unpack_to_rootfs((char *)initrd_start, initrd_end - initrd_start);
  	if (err) {

  		clean_rootfs();

  		populate_initrd_image(err);

  	}

  done:

  	/*
  	 * If the initrd region is overlapped with crashkernel reserved region,
  	 * free only memory that is not part of crashkernel region.
  	 */

  	if (!do_retain_initrd && initrd_start && !kexec_free_initrd())

  		free_initrd_mem(initrd_start, initrd_end);
  	initrd_start = 0;
  	initrd_end = 0;

  	flush_delayed_fput();

  	return 0;

  }

  rootfs_initcall(populate_rootfs);