/**************************************************************/

/*  tpax: a topological pax implementation                    */

/*  Copyright (C) 2020--2021  SysDeer Technologies, LLC       */

/*  Released under GPLv2 and GPLv3; see COPYING.TPAX.         */

/**************************************************************/

#include <stdint.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <fcntl.h>

#include <errno.h>

#include <grp.h>

#include <pwd.h>

#include <sys/mman.h>

#include <sys/stat.h>

#include <tpax/tpax.h>

#include <tpax/tpax_specs.h>

#include "tpax_driver_impl.h"

#include "tpax_getdents_impl.h"

#include "tpax_tmpfile_impl.h"

#include "tpax_errinfo_impl.h"

#ifndef ssizeof

#define ssizeof(x) (ssize_t)(sizeof(x))

#endif

static int tpax_archive_append_memory_data(

	int                             fdout,

	void *                          buf,

	ssize_t                         nbytes)

{

	ssize_t ret;

	char  * ch;

	for (ch=buf; nbytes; ch+=ret) {

		ret = write(fdout,ch,nbytes);

		while ((ret < 0) && (errno == EINTR))

			ret = write(fdout,ch,nbytes);

		if (ret < 0)

			return ret;

		nbytes -= ret;

	}

	return 0;

}

static char * tpax_append_prefix_item(

	const struct tpax_driver_ctx *  dctx,

	const char *                    prefix)

{

	struct tpax_driver_ctx_impl *   ictx;

	char **                         prefv;

	char **                         psrc;

	char **                         pdst;

	off_t                           elements;

	char *                          pitem;

	ictx = tpax_get_driver_ictx(dctx);

	for (psrc=ictx->prefixv; *psrc; psrc++)

		if (!strcmp(*psrc,prefix))

			return *psrc;

	if (ictx->prefixp == ictx->prefcap) {

		elements  = ictx->prefcap - ictx->prefixv;

		elements += 256;

		if (!(prefv = calloc(elements,sizeof(char *))))

			return 0;

		for (psrc=ictx->prefixv,pdst=prefv; *psrc; psrc++,pdst++)

			*pdst = *psrc;

		if (ictx->prefixv != ictx->prefptr)

			free(ictx->prefixv);

		ictx->prefixv = prefv;

		ictx->prefixp = pdst;

		ictx->prefcap = &prefv[--elements];

	}

	if (!(pitem = strdup(prefix)))

		return 0;

	*ictx->prefixp++ = pitem;

	return pitem;

}

static int tpax_archive_append_pad(

	const struct tpax_driver_ctx *  dctx,

	int                             fdout,

	const struct stat *             st)

{

	int     ret;

	off_t   cpos;

	ssize_t nbytes;

	char    buf[512];

	nbytes  = st->st_size;

	nbytes += 0x1ff;

	nbytes |= 0x1ff;

	nbytes ^= 0x1ff;

	nbytes -= st->st_size;

	memset(buf,0,nbytes);

	cpos  = tpax_get_driver_cpos(dctx);

	cpos += st->st_size + nbytes;

	if (!(ret = tpax_archive_append_memory_data(fdout,buf,nbytes)))

		tpax_set_driver_cpos(dctx,cpos);

	return ret;

}

static struct tpax_dirent_buffer * tpax_dirent_buf_first_alloc(

	const struct tpax_driver_ctx * dctx)

{

	void * addr;

	struct tpax_driver_ctx_impl * ictx;

	addr = (struct tpax_dirent_buffer *)mmap(

		0,TPAX_DIRENT_BUFLEN,

		PROT_READ|PROT_WRITE,

		MAP_PRIVATE|MAP_ANONYMOUS,

		-1,0);

	if (addr == MAP_FAILED)

		return 0;

	ictx                  = tpax_get_driver_ictx(dctx);

	ictx->dirents         = (struct tpax_dirent_buffer *)addr;

	ictx->dirents->cdent  = ictx->dirents->dbuf;

	ictx->dirents->size   = TPAX_DIRENT_BUFLEN;

	ictx->dirents->next   = 0;

	ictx->dirents->nfree  = TPAX_DIRENT_BUFLEN;

	ictx->dirents->nfree -= offsetof(struct tpax_dirent_buffer,dbuf);

	return ictx->dirents;

}

static struct tpax_dirent_buffer * tpax_dirent_buf_next_alloc(

	struct tpax_dirent_buffer * current)

{

	void * addr;

	addr = (struct tpax_dirent_buffer *)mmap(

		0,TPAX_DIRENT_BUFLEN,

		PROT_READ|PROT_WRITE,

		MAP_PRIVATE|MAP_ANONYMOUS,

		-1,0);

	if (addr == MAP_FAILED)

		return 0;

	current->next         = (struct tpax_dirent_buffer *)addr;

	current->next->cdent  = current->next->dbuf;

	current->next->size   = TPAX_DIRENT_BUFLEN;

	current->next->next   = 0;

	current->next->nfree  = TPAX_DIRENT_BUFLEN;

	current->next->nfree -= offsetof(struct tpax_dirent_buffer,dbuf);

	return current->next;

}

static int tpax_archive_append_ret(

	int                     ret,

	struct tpax_unit_ctx *  unit)

{

	if (unit)

		tpax_free_unit_ctx(unit);

	return ret;

}

static int tpax_archive_append_queue_item(

	const struct tpax_driver_ctx *  dctx,

	const struct dirent *           dirent,

	const struct tpax_dirent *      parent,

	const char *                    prefix,

	int                             depth,

	int                             flags,

	int                             fd,

	bool *                          fkeep)

{

	struct tpax_dirent_buffer *     dentbuf;

	struct tpax_dirent *            cdent;

	const char *                    src;

	char *                          dst;

	char *                          cap;

	size_t                          needed;

	if (!(dentbuf = tpax_get_driver_dirents(dctx)))

		if (!(dentbuf = tpax_dirent_buf_first_alloc(dctx)))

			return tpax_archive_append_ret(

				TPAX_SYSTEM_ERROR(dctx),

				0);

	needed  = dirent->d_reclen;

	needed += offsetof(struct tpax_dirent,dirent);

	needed += 0x7;

	needed |= 0x7;

	needed ^= 0x7;

	for (; dentbuf->next && (dentbuf->nfree < needed); )

		dentbuf = dentbuf->next;

	if (dentbuf->nfree < needed)

		if (!(dentbuf = tpax_dirent_buf_next_alloc(dentbuf)))

			return tpax_archive_append_ret(

				TPAX_SYSTEM_ERROR(dctx),

				0);

	*fkeep        = true;

	cdent         = dentbuf->cdent;

	cdent->fdat   = fd;

	cdent->depth  = depth;

	cdent->flags  = flags;

	cdent->nsize  = needed;

	cdent->parent = parent;

	cdent->prefix = prefix;

	memset(&cdent->dirent,0,offsetof(struct dirent,d_name));

	cdent->dirent.d_ino    = dirent->d_ino;

	cdent->dirent.d_type   = dirent->d_type;

	cdent->dirent.d_reclen = dirent->d_reclen;

	src  = dirent->d_name;

	dst  = cdent->dirent.d_name;

	cap  = dst - offsetof(struct dirent,d_name);

	cap -= offsetof(struct tpax_dirent,dirent);

	cap += needed;

	for (; *src; )

		*dst++ = *src++;

	for (; dst

		*dst++ = 0;

	dentbuf->cdent  = (struct tpax_dirent *)cap;

	dentbuf->nfree -= needed;

	return 0;

}

static int tpax_archive_append_dir_entries(

	const struct tpax_driver_ctx *  dctx,

	struct tpax_dirent *            dent)

{

	int                             fd;

	int                             fdat;

	int                             depth;

	bool                            fkeep;

	long                            nbytes;

	struct dirent *                 dirent;

	struct dirent *                 dirents;

	struct tpax_unit_ctx *          uctx;

	struct stat                     st;

	uintptr_t                       addr;

	/* init */

	fdat  = dent->fdat;

	depth = dent->depth;

	/* uctx on the fly */

	if (tpax_get_unit_ctx(

			dctx,fdat,

			dent->dirent.d_name,

			&uctx) < 0)

		return TPAX_NESTED_ERROR(dctx);

	/* verify that recursion item is still a directory */

	if (!S_ISDIR(uctx->st->st_mode))

		return tpax_archive_append_ret(

			TPAX_CUSTOM_ERROR(dctx,TPAX_ERR_FLOW_ERROR),

			uctx);

	/* obtain buffer for file-system directory entries */

	dirents = tpax_get_driver_getdents_buffer(dctx);

	dirent  = dirents;

	fkeep   = false;

	nbytes  = 0;

	depth++;

	/* open directory and obtain first directory entries */

	if ((fd = openat(fdat,dent->dirent.d_name,O_RDONLY|O_DIRECTORY|O_CLOEXEC,0)) < 0)

		return tpax_archive_append_ret(

			TPAX_SYSTEM_ERROR(dctx),

			uctx);

	nbytes = tpax_getdents(fd,dirents,TPAX_DIRENT_BUFLEN);

	while ((nbytes == -EINTR) || ((nbytes < 0) && (errno == EINTR)))

		nbytes = tpax_getdents(fd,dirents,TPAX_DIRENT_BUFLEN);

	if (nbytes < 0)

		return tpax_archive_append_ret(

			TPAX_SYSTEM_ERROR(dctx),

			uctx);

	/* iterate */

	for (; nbytes>0; ) {

		if (!strcmp(dirent->d_name,".")) {

			(void)0;

		} else if (!strcmp(dirent->d_name,"..")) {

			(void)0;

		} else {

			if (dirent->d_type == DT_UNKNOWN) {

				if (fstatat(fd,dirent->d_name,&st,AT_SYMLINK_NOFOLLOW))

					return tpax_archive_append_ret(

						TPAX_SYSTEM_ERROR(dctx),

						uctx);

				if (S_ISDIR(st.st_mode)) {

					dirent->d_type = DT_DIR;

				}

			}

			if (tpax_archive_append_queue_item(

					dctx,dirent,

					dent,0,depth,

					TPAX_ITEM_IMPLICIT,

					fd,&fkeep) < 0)

				return tpax_archive_append_ret(

					TPAX_NESTED_ERROR(dctx),

					uctx);

		}

		addr    = (uintptr_t)dirent;

		addr   += dirent->d_reclen;

		nbytes -= dirent->d_reclen;

		dirent  = (struct dirent *)addr;

		if (nbytes == 0) {

			nbytes = tpax_getdents(fd,dirents,TPAX_DIRENT_BUFLEN);

			while ((nbytes == -EINTR) || ((nbytes < 0) && (errno == EINTR)))

				nbytes = tpax_getdents(fd,dirents,TPAX_DIRENT_BUFLEN);

			if (nbytes < 0)

				tpax_archive_append_ret(

					TPAX_SYSTEM_ERROR(dctx),

					uctx);

			dirent = dirents;

		}

	}

	/* all done */

	return tpax_archive_append_ret(

		fkeep ? 0 : close(fd),

		uctx);

}

int tpax_archive_append_item(

	const struct tpax_driver_ctx *  dctx,

	const struct tpax_unit_ctx *    uctx)

{

	(void)dctx;

	(void)uctx;

	(void)tpax_archive_append_dir_entries;

	(void)tpax_append_prefix_item;

	return 0;

}

int tpax_archive_seal(const struct tpax_driver_ctx * dctx)

{

	int     fdout;

	off_t   cpos;

	ssize_t nbytes;

	ssize_t nwritten;

	ssize_t blksize;

	char    buf[512];

	blksize = tpax_get_archive_block_size(dctx);

	cpos    = tpax_get_driver_cpos(dctx);

	if (cpos % 512)

		return TPAX_CUSTOM_ERROR(dctx,TPAX_ERR_FLOW_ERROR);

	fdout = tpax_driver_fdout(dctx);

	memset(buf,0,sizeof(buf));

	switch (cpos % blksize) {

		case 0:

			nbytes = cpos + blksize;

			break;

		default:

			nbytes  = cpos / blksize;

			nbytes *= blksize;

			nbytes += blksize;

			if (nbytes-cpos == 512)

				nbytes += blksize;

	}

	for (nwritten=cpos; nwritten

		if (tpax_archive_append_memory_data(fdout,buf,512) < 0)

			return TPAX_SYSTEM_ERROR(dctx);

		tpax_set_driver_cpos(dctx,nwritten);

	}

	return 0;

}