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

/*  tpax: a topological pax implementation                    */

/*  Copyright (C) 2020--2024  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/stat.h>

#include <tpax/tpax.h>

#include <tpax/tpax_specs.h>

#include "tpax_driver_impl.h"

#include "tpax_errinfo_impl.h"

#include "tpax_ftime_impl.h"

#ifndef ssizeof

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

#endif

int tpax_io_create_memory_snapshot(

	const struct tpax_driver_ctx *  dctx,

	int                             fdat,

	const char *                    path,

	const struct stat *             srcst,

	void *                          addr)

{

	int          fd;

	char *       ch;

	char *       cap;

	ssize_t      nread;

	struct stat  dstst;

	/* record errors */

	tpax_driver_set_ectx(

		dctx,0,path);

	/* memory snapshot internal limit */

	if (srcst->st_size >= 0x80000000)

		return TPAX_CUSTOM_ERROR(dctx,TPAX_ERR_REGION_SIZE);

	/* open */

	if ((fd = openat(fdat,path,O_CLOEXEC|O_NOCTTY|O_NOFOLLOW,0)) < 0)

		return TPAX_SYSTEM_ERROR(dctx);

	/* stat compare */

	if ((fstat(fd,&dstst)) < 0) {

		close(fd);

		return TPAX_SYSTEM_ERROR(dctx);

	} else if (tpax_util_stat_compare(srcst,&dstst)) {

		close(fd);

		return TPAX_CUSTOM_ERROR(dctx,TPAX_ERR_FILE_CHANGED);

	}

	/* read loop */

	ch  = addr;

	cap = &ch[srcst->st_size];

	while (ch < cap) {

		nread = read(fd,ch,cap-ch);

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

			nread = read(fd,ch,cap-ch);

		if (nread < 0) {

			tpax_ftime_restore_and_close(dctx,fd,&dstst);

			return TPAX_SYSTEM_ERROR(dctx);

		} else if (nread == 0) {

			tpax_ftime_restore_and_close(dctx,fd,&dstst);

			return TPAX_CUSTOM_ERROR(dctx,TPAX_ERR_FLOW_ERROR);

		} else {

			ch += nread;

		}

	}

	/* preserve last data access time as needed */

	tpax_ftime_restore(dctx,fd,&dstst);

	/* stat compare */

	if ((fstat(fd,&dstst)) < 0) {

		close(fd);

		return TPAX_SYSTEM_ERROR(dctx);

	} else if (tpax_util_stat_compare(srcst,&dstst)) {

		close(fd);

		return TPAX_CUSTOM_ERROR(dctx,TPAX_ERR_FILE_CHANGED);

	}

	/* yay */

	close(fd);

	return 0;

}