libtar/block.c - android_bootable_recovery - Gitiles

 /*
 **  Copyright 1998-2003 University of Illinois Board of Trustees
 **  Copyright 1998-2003 Mark D. Roth
 **  All rights reserved.
 **
 **  block.c - libtar code to handle tar archive header blocks
 **
 **  Mark D. Roth <roth@uiuc.edu>
 **  Campus Information Technologies and Educational Services
 **  University of Illinois at Urbana-Champaign
 */

 #include <internal.h>

 #include <errno.h>

 #ifdef STDC_HEADERS
 # include <string.h>
 # include <stdlib.h>
 #endif

 #define BIT_ISSET(bitmask, bit) ((bitmask) & (bit))

 // Used to identify selinux_context in extended ('x')
 // metadata. From RedHat implementation.
 #define SELINUX_TAG "RHT.security.selinux="
 #define SELINUX_TAG_LEN 21

 /* read a header block */
 int
 th_read_internal(TAR *t)
 {
 	int i;
 	int num_zero_blocks = 0;

 #ifdef DEBUG
 	printf("==> th_read_internal(TAR=\"%s\")\n", t->pathname);
 #endif

 	while ((i = tar_block_read(t, &(t->th_buf))) == T_BLOCKSIZE)
 	{
 		/* two all-zero blocks mark EOF */
 		if (t->th_buf.name[0] == '\0')
 		{
 			num_zero_blocks++;
 			if (!BIT_ISSET(t->options, TAR_IGNORE_EOT)
 			    && num_zero_blocks >= 2)
 				return 0;	/* EOF */
 			else
 				continue;
 		}

 		/* verify magic and version */
 		if (BIT_ISSET(t->options, TAR_CHECK_MAGIC)
 		    && strncmp(t->th_buf.magic, TMAGIC, TMAGLEN - 1) != 0)
 		{
 #ifdef DEBUG
 			puts("!!! unknown magic value in tar header");
 #endif
 			return -2;
 		}

 		if (BIT_ISSET(t->options, TAR_CHECK_VERSION)
 		    && strncmp(t->th_buf.version, TVERSION, TVERSLEN) != 0)
 		{
 #ifdef DEBUG
 			puts("!!! unknown version value in tar header");
 #endif
 			return -2;
 		}

 		/* check chksum */
 		if (!BIT_ISSET(t->options, TAR_IGNORE_CRC)
 		    && !th_crc_ok(t))
 		{
 #ifdef DEBUG
 			puts("!!! tar header checksum error");
 #endif
 			return -2;
 		}

 		break;
 	}

 #ifdef DEBUG
 	printf("<== th_read_internal(): returning %d\n", i);
 #endif
 	return i;
 }


 /* wrapper function for th_read_internal() to handle GNU extensions */
 int
 th_read(TAR *t)
 {
 	int i, j;
 	size_t sz;
 	char *ptr;

 #ifdef DEBUG
 	printf("==> th_read(t=0x%lx)\n", t);
 #endif

 	if (t->th_buf.gnu_longname != NULL)
 		free(t->th_buf.gnu_longname);
 	if (t->th_buf.gnu_longlink != NULL)
 		free(t->th_buf.gnu_longlink);
 #ifdef HAVE_SELINUX
 	if (t->th_buf.selinux_context != NULL)
 		free(t->th_buf.selinux_context);
 #endif

 	memset(&(t->th_buf), 0, sizeof(struct tar_header));

 	i = th_read_internal(t);
 	if (i == 0)
 		return 1;
 	else if (i != T_BLOCKSIZE)
 	{
 		if (i != -1)
 			errno = EINVAL;
 		return -1;
 	}

 	/* check for GNU long link extention */
 	if (TH_ISLONGLINK(t))
 	{
 		sz = th_get_size(t);
 		j = (sz / T_BLOCKSIZE) + (sz % T_BLOCKSIZE ? 1 : 0);
 #ifdef DEBUG
 		printf("    th_read(): GNU long linkname detected "
 		       "(%ld bytes, %d blocks)\n", sz, j);
 #endif
 		t->th_buf.gnu_longlink = (char *)malloc(j * T_BLOCKSIZE);
 		if (t->th_buf.gnu_longlink == NULL)
 			return -1;

 		for (ptr = t->th_buf.gnu_longlink; j > 0;
 		     j--, ptr += T_BLOCKSIZE)
 		{
 #ifdef DEBUG
 			printf("    th_read(): reading long linkname "
 			       "(%d blocks left, ptr == %ld)\n", j, ptr);
 #endif
 			i = tar_block_read(t, ptr);
 			if (i != T_BLOCKSIZE)
 			{
 				if (i != -1)
 					errno = EINVAL;
 				return -1;
 			}
 #ifdef DEBUG
 			printf("    th_read(): read block == \"%s\"\n", ptr);
 #endif
 		}
 #ifdef DEBUG
 		printf("    th_read(): t->th_buf.gnu_longlink == \"%s\"\n",
 		       t->th_buf.gnu_longlink);
 #endif

 		i = th_read_internal(t);
 		if (i != T_BLOCKSIZE)
 		{
 			if (i != -1)
 				errno = EINVAL;
 			return -1;
 		}
 	}

 	/* check for GNU long name extention */
 	if (TH_ISLONGNAME(t))
 	{
 		sz = th_get_size(t);
 		j = (sz / T_BLOCKSIZE) + (sz % T_BLOCKSIZE ? 1 : 0);
 #ifdef DEBUG
 		printf("    th_read(): GNU long filename detected "
 		       "(%ld bytes, %d blocks)\n", sz, j);
 #endif
 		t->th_buf.gnu_longname = (char *)malloc(j * T_BLOCKSIZE);
 		if (t->th_buf.gnu_longname == NULL)
 			return -1;

 		for (ptr = t->th_buf.gnu_longname; j > 0;
 		     j--, ptr += T_BLOCKSIZE)
 		{
 #ifdef DEBUG
 			printf("    th_read(): reading long filename "
 			       "(%d blocks left, ptr == %ld)\n", j, ptr);
 #endif
 			i = tar_block_read(t, ptr);
 			if (i != T_BLOCKSIZE)
 			{
 				if (i != -1)
 					errno = EINVAL;
 				return -1;
 			}
 #ifdef DEBUG
 			printf("    th_read(): read block == \"%s\"\n", ptr);
 #endif
 		}
 #ifdef DEBUG
 		printf("    th_read(): t->th_buf.gnu_longname == \"%s\"\n",
 		       t->th_buf.gnu_longname);
 #endif

 		i = th_read_internal(t);
 		if (i != T_BLOCKSIZE)
 		{
 			if (i != -1)
 				errno = EINVAL;
 			return -1;
 		}
 	}

 #ifdef HAVE_SELINUX
 	if(TH_ISEXTHEADER(t))
 	{
 		sz = th_get_size(t);

 		if(sz >= T_BLOCKSIZE) // Not supported
 		{
 #ifdef DEBUG
 			printf("    th_read(): Extended header is too long!\n");
 #endif
 		}
 		else
 		{
 			char buf[T_BLOCKSIZE];
 			i = tar_block_read(t, buf);
 			if (i != T_BLOCKSIZE)
 			{
 				if (i != -1)
 					errno = EINVAL;
 				return -1;
 			}

 			// To be sure
 			buf[T_BLOCKSIZE-1] = 0;

 			int len = strlen(buf);
 			char *start = strstr(buf, SELINUX_TAG);
 			if(start && start+SELINUX_TAG_LEN < buf+len)
 			{
 				start += SELINUX_TAG_LEN;
 				char *end = strchr(start, '\n');
 				if(end)
 				{
 					t->th_buf.selinux_context = strndup(start, end-start);
 #ifdef DEBUG
 					printf("    th_read(): SELinux context xattr detected: %s\n", t->th_buf.selinux_context);
 #endif
 				}
 			}
 		}

 		i = th_read_internal(t);
 		if (i != T_BLOCKSIZE)
 		{
 			if (i != -1)
 				errno = EINVAL;
 			return -1;
 		}
 	}
 #endif

 #if 0
 	/*
 	** work-around for old archive files with broken typeflag fields
 	** NOTE: I fixed this in the TH_IS*() macros instead
 	*/

 	/*
 	** (directories are signified with a trailing '/')
 	*/
 	if (t->th_buf.typeflag == AREGTYPE
 	    && t->th_buf.name[strlen(t->th_buf.name) - 1] == '/')
 		t->th_buf.typeflag = DIRTYPE;

 	/*
 	** fallback to using mode bits
 	*/
 	if (t->th_buf.typeflag == AREGTYPE)
 	{
 		mode = (mode_t)oct_to_int(t->th_buf.mode);

 		if (S_ISREG(mode))
 			t->th_buf.typeflag = REGTYPE;
 		else if (S_ISDIR(mode))
 			t->th_buf.typeflag = DIRTYPE;
 		else if (S_ISFIFO(mode))
 			t->th_buf.typeflag = FIFOTYPE;
 		else if (S_ISCHR(mode))
 			t->th_buf.typeflag = CHRTYPE;
 		else if (S_ISBLK(mode))
 			t->th_buf.typeflag = BLKTYPE;
 		else if (S_ISLNK(mode))
 			t->th_buf.typeflag = SYMTYPE;
 	}
 #endif

 	return 0;
 }


 /* write a header block */
 int
 th_write(TAR *t)
 {
 	int i, j;
 	char type2;
 	size_t sz, sz2;
 	char *ptr;
 	char buf[T_BLOCKSIZE];

 #ifdef DEBUG
 	printf("==> th_write(TAR=\"%s\")\n", t->pathname);
 	th_print(t);
 #endif

 	if ((t->options & TAR_GNU) && t->th_buf.gnu_longlink != NULL)
 	{
 #ifdef DEBUG
 		printf("th_write(): using gnu_longlink (\"%s\")\n",
 		       t->th_buf.gnu_longlink);
 #endif
 		/* save old size and type */
 		type2 = t->th_buf.typeflag;
 		sz2 = th_get_size(t);

 		/* write out initial header block with fake size and type */
 		t->th_buf.typeflag = GNU_LONGLINK_TYPE;
 		sz = strlen(t->th_buf.gnu_longlink);
 		th_set_size(t, sz);
 		th_finish(t);
 		i = tar_block_write(t, &(t->th_buf));
 		if (i != T_BLOCKSIZE)
 		{
 			if (i != -1)
 				errno = EINVAL;
 			return -1;
 		}

 		/* write out extra blocks containing long name */
 		for (j = (sz / T_BLOCKSIZE) + (sz % T_BLOCKSIZE ? 1 : 0),
 		     ptr = t->th_buf.gnu_longlink; j > 1;
 		     j--, ptr += T_BLOCKSIZE)
 		{
 			i = tar_block_write(t, ptr);
 			if (i != T_BLOCKSIZE)
 			{
 				if (i != -1)
 					errno = EINVAL;
 				return -1;
 			}
 		}
 		memset(buf, 0, T_BLOCKSIZE);
 		strncpy(buf, ptr, T_BLOCKSIZE);
 		i = tar_block_write(t, &buf);
 		if (i != T_BLOCKSIZE)
 		{
 			if (i != -1)
 				errno = EINVAL;
 			return -1;
 		}

 		/* reset type and size to original values */
 		t->th_buf.typeflag = type2;
 		th_set_size(t, sz2);
 	}

 	if ((t->options & TAR_GNU) && t->th_buf.gnu_longname != NULL)
 	{
 #ifdef DEBUG
 		printf("th_write(): using gnu_longname (\"%s\")\n",
 		       t->th_buf.gnu_longname);
 #endif
 		/* save old size and type */
 		type2 = t->th_buf.typeflag;
 		sz2 = th_get_size(t);

 		/* write out initial header block with fake size and type */
 		t->th_buf.typeflag = GNU_LONGNAME_TYPE;
 		sz = strlen(t->th_buf.gnu_longname);
 		th_set_size(t, sz);
 		th_finish(t);
 		i = tar_block_write(t, &(t->th_buf));
 		if (i != T_BLOCKSIZE)
 		{
 			if (i != -1)
 				errno = EINVAL;
 			return -1;
 		}

 		/* write out extra blocks containing long name */
 		for (j = (sz / T_BLOCKSIZE) + (sz % T_BLOCKSIZE ? 1 : 0),
 		     ptr = t->th_buf.gnu_longname; j > 1;
 		     j--, ptr += T_BLOCKSIZE)
 		{
 			i = tar_block_write(t, ptr);
 			if (i != T_BLOCKSIZE)
 			{
 				if (i != -1)
 					errno = EINVAL;
 				return -1;
 			}
 		}
 		memset(buf, 0, T_BLOCKSIZE);
 		strncpy(buf, ptr, T_BLOCKSIZE);
 		i = tar_block_write(t, &buf);
 		if (i != T_BLOCKSIZE)
 		{
 			if (i != -1)
 				errno = EINVAL;
 			return -1;
 		}

 		/* reset type and size to original values */
 		t->th_buf.typeflag = type2;
 		th_set_size(t, sz2);
 	}

 #ifdef HAVE_SELINUX
 	if((t->options & TAR_STORE_SELINUX) && t->th_buf.selinux_context != NULL)
 	{
 #ifdef DEBUG
 		printf("th_write(): using selinux_context (\"%s\")\n",
 		       t->th_buf.selinux_context);
 #endif
 		/* save old size and type */
 		type2 = t->th_buf.typeflag;
 		sz2 = th_get_size(t);

 		/* write out initial header block with fake size and type */
 		t->th_buf.typeflag = TH_EXT_TYPE;

 		/* setup size - EXT header has format "*size of this whole tag as ascii numbers* *space* *content* *newline* */
 		//                                                       size   newline
 		sz = SELINUX_TAG_LEN + strlen(t->th_buf.selinux_context) + 3  +    1;

 		if(sz >= 100) // another ascci digit for size
 			++sz;

 		if(sz >= T_BLOCKSIZE) // impossible
 		{
 			errno = EINVAL;
 			return -1;
 		}

 		th_set_size(t, sz);
 		th_finish(t);
 		i = tar_block_write(t, &(t->th_buf));
 		if (i != T_BLOCKSIZE)
 		{
 			if (i != -1)
 				errno = EINVAL;
 			return -1;
 		}

 		memset(buf, 0, T_BLOCKSIZE);
 		snprintf(buf, T_BLOCKSIZE, "%d "SELINUX_TAG"%s\n", sz, t->th_buf.selinux_context);
 		i = tar_block_write(t, &buf);
 		if (i != T_BLOCKSIZE)
 		{
 			if (i != -1)
 				errno = EINVAL;
 			return -1;
 		}

 		/* reset type and size to original values */
 		t->th_buf.typeflag = type2;
 		th_set_size(t, sz2);
 	}
 #endif

 	th_finish(t);

 #ifdef DEBUG
 	/* print tar header */
 	th_print(t);
 #endif

 	i = tar_block_write(t, &(t->th_buf));
 	if (i != T_BLOCKSIZE)
 	{
 		if (i != -1)
 			errno = EINVAL;
 		return -1;
 	}

 #ifdef DEBUG
 	puts("th_write(): returning 0");
 #endif
 	return 0;
 }
	/*
	** Copyright 1998-2003 University of Illinois Board of Trustees
	** Copyright 1998-2003 Mark D. Roth
	** All rights reserved.
	**
	** block.c - libtar code to handle tar archive header blocks
	**
	** Mark D. Roth <roth@uiuc.edu>
	** Campus Information Technologies and Educational Services
	** University of Illinois at Urbana-Champaign
	*/

	#include <internal.h>

	#include <errno.h>

	#ifdef STDC_HEADERS
	# include <string.h>
	# include <stdlib.h>
	#endif

	#define BIT_ISSET(bitmask, bit) ((bitmask) & (bit))

	// Used to identify selinux_context in extended ('x')
	// metadata. From RedHat implementation.
	#define SELINUX_TAG "RHT.security.selinux="
	#define SELINUX_TAG_LEN 21

	/* read a header block */
	int
	th_read_internal(TAR *t)
	{
	int i;
	int num_zero_blocks = 0;

	#ifdef DEBUG
	printf("==> th_read_internal(TAR=\"%s\")\n", t->pathname);
	#endif

	while ((i = tar_block_read(t, &(t->th_buf))) == T_BLOCKSIZE)
	{
	/* two all-zero blocks mark EOF */
	if (t->th_buf.name[0] == '\0')
	{
	num_zero_blocks++;
	if (!BIT_ISSET(t->options, TAR_IGNORE_EOT)
	&& num_zero_blocks >= 2)
	return 0; /* EOF */
	else
	continue;
	}

	/* verify magic and version */
	if (BIT_ISSET(t->options, TAR_CHECK_MAGIC)
	&& strncmp(t->th_buf.magic, TMAGIC, TMAGLEN - 1) != 0)
	{
	#ifdef DEBUG
	puts("!!! unknown magic value in tar header");
	#endif
	return -2;
	}

	if (BIT_ISSET(t->options, TAR_CHECK_VERSION)
	&& strncmp(t->th_buf.version, TVERSION, TVERSLEN) != 0)
	{
	#ifdef DEBUG
	puts("!!! unknown version value in tar header");
	#endif
	return -2;
	}

	/* check chksum */
	if (!BIT_ISSET(t->options, TAR_IGNORE_CRC)
	&& !th_crc_ok(t))
	{
	#ifdef DEBUG
	puts("!!! tar header checksum error");
	#endif
	return -2;
	}

	break;
	}

	#ifdef DEBUG
	printf("<== th_read_internal(): returning %d\n", i);
	#endif
	return i;
	}


	/* wrapper function for th_read_internal() to handle GNU extensions */
	int
	th_read(TAR *t)
	{
	int i, j;
	size_t sz;
	char *ptr;

	#ifdef DEBUG
	printf("==> th_read(t=0x%lx)\n", t);
	#endif

	if (t->th_buf.gnu_longname != NULL)
	free(t->th_buf.gnu_longname);
	if (t->th_buf.gnu_longlink != NULL)
	free(t->th_buf.gnu_longlink);
	#ifdef HAVE_SELINUX
	if (t->th_buf.selinux_context != NULL)
	free(t->th_buf.selinux_context);
	#endif

	memset(&(t->th_buf), 0, sizeof(struct tar_header));

	i = th_read_internal(t);
	if (i == 0)
	return 1;
	else if (i != T_BLOCKSIZE)
	{
	if (i != -1)
	errno = EINVAL;
	return -1;
	}

	/* check for GNU long link extention */
	if (TH_ISLONGLINK(t))
	{
	sz = th_get_size(t);
	j = (sz / T_BLOCKSIZE) + (sz % T_BLOCKSIZE ? 1 : 0);
	#ifdef DEBUG
	printf(" th_read(): GNU long linkname detected "
	"(%ld bytes, %d blocks)\n", sz, j);
	#endif
	t->th_buf.gnu_longlink = (char )malloc(j T_BLOCKSIZE);
	if (t->th_buf.gnu_longlink == NULL)
	return -1;

	for (ptr = t->th_buf.gnu_longlink; j > 0;
	j--, ptr += T_BLOCKSIZE)
	{
	#ifdef DEBUG
	printf(" th_read(): reading long linkname "
	"(%d blocks left, ptr == %ld)\n", j, ptr);
	#endif
	i = tar_block_read(t, ptr);
	if (i != T_BLOCKSIZE)
	{
	if (i != -1)
	errno = EINVAL;
	return -1;
	}
	#ifdef DEBUG
	printf(" th_read(): read block == \"%s\"\n", ptr);
	#endif
	}
	#ifdef DEBUG
	printf(" th_read(): t->th_buf.gnu_longlink == \"%s\"\n",
	t->th_buf.gnu_longlink);
	#endif

	i = th_read_internal(t);
	if (i != T_BLOCKSIZE)
	{
	if (i != -1)
	errno = EINVAL;
	return -1;
	}
	}

	/* check for GNU long name extention */
	if (TH_ISLONGNAME(t))
	{
	sz = th_get_size(t);
	j = (sz / T_BLOCKSIZE) + (sz % T_BLOCKSIZE ? 1 : 0);
	#ifdef DEBUG
	printf(" th_read(): GNU long filename detected "
	"(%ld bytes, %d blocks)\n", sz, j);
	#endif
	t->th_buf.gnu_longname = (char )malloc(j T_BLOCKSIZE);
	if (t->th_buf.gnu_longname == NULL)
	return -1;

	for (ptr = t->th_buf.gnu_longname; j > 0;
	j--, ptr += T_BLOCKSIZE)
	{
	#ifdef DEBUG
	printf(" th_read(): reading long filename "
	"(%d blocks left, ptr == %ld)\n", j, ptr);
	#endif
	i = tar_block_read(t, ptr);
	if (i != T_BLOCKSIZE)
	{
	if (i != -1)
	errno = EINVAL;
	return -1;
	}
	#ifdef DEBUG
	printf(" th_read(): read block == \"%s\"\n", ptr);
	#endif
	}
	#ifdef DEBUG
	printf(" th_read(): t->th_buf.gnu_longname == \"%s\"\n",
	t->th_buf.gnu_longname);
	#endif

	i = th_read_internal(t);
	if (i != T_BLOCKSIZE)
	{
	if (i != -1)
	errno = EINVAL;
	return -1;
	}
	}

	#ifdef HAVE_SELINUX
	if(TH_ISEXTHEADER(t))
	{
	sz = th_get_size(t);

	if(sz >= T_BLOCKSIZE) // Not supported
	{
	#ifdef DEBUG
	printf(" th_read(): Extended header is too long!\n");
	#endif
	}
	else
	{
	char buf[T_BLOCKSIZE];
	i = tar_block_read(t, buf);
	if (i != T_BLOCKSIZE)
	{
	if (i != -1)
	errno = EINVAL;
	return -1;
	}

	// To be sure
	buf[T_BLOCKSIZE-1] = 0;

	int len = strlen(buf);
	char *start = strstr(buf, SELINUX_TAG);
	if(start && start+SELINUX_TAG_LEN < buf+len)
	{
	start += SELINUX_TAG_LEN;
	char *end = strchr(start, '\n');
	if(end)
	{
	t->th_buf.selinux_context = strndup(start, end-start);
	#ifdef DEBUG
	printf(" th_read(): SELinux context xattr detected: %s\n", t->th_buf.selinux_context);
	#endif
	}
	}
	}

	i = th_read_internal(t);
	if (i != T_BLOCKSIZE)
	{
	if (i != -1)
	errno = EINVAL;
	return -1;
	}
	}
	#endif

	#if 0
	/*
	** work-around for old archive files with broken typeflag fields
	** NOTE: I fixed this in the TH_IS*() macros instead
	*/

	/*
	** (directories are signified with a trailing '/')
	*/
	if (t->th_buf.typeflag == AREGTYPE
	&& t->th_buf.name[strlen(t->th_buf.name) - 1] == '/')
	t->th_buf.typeflag = DIRTYPE;

	/*
	** fallback to using mode bits
	*/
	if (t->th_buf.typeflag == AREGTYPE)
	{
	mode = (mode_t)oct_to_int(t->th_buf.mode);

	if (S_ISREG(mode))
	t->th_buf.typeflag = REGTYPE;
	else if (S_ISDIR(mode))
	t->th_buf.typeflag = DIRTYPE;
	else if (S_ISFIFO(mode))
	t->th_buf.typeflag = FIFOTYPE;
	else if (S_ISCHR(mode))
	t->th_buf.typeflag = CHRTYPE;
	else if (S_ISBLK(mode))
	t->th_buf.typeflag = BLKTYPE;
	else if (S_ISLNK(mode))
	t->th_buf.typeflag = SYMTYPE;
	}
	#endif

	return 0;
	}


	/* write a header block */
	int
	th_write(TAR *t)
	{
	int i, j;
	char type2;
	size_t sz, sz2;
	char *ptr;
	char buf[T_BLOCKSIZE];

	#ifdef DEBUG
	printf("==> th_write(TAR=\"%s\")\n", t->pathname);
	th_print(t);
	#endif

	if ((t->options & TAR_GNU) && t->th_buf.gnu_longlink != NULL)
	{
	#ifdef DEBUG
	printf("th_write(): using gnu_longlink (\"%s\")\n",
	t->th_buf.gnu_longlink);
	#endif
	/* save old size and type */
	type2 = t->th_buf.typeflag;
	sz2 = th_get_size(t);

	/* write out initial header block with fake size and type */
	t->th_buf.typeflag = GNU_LONGLINK_TYPE;
	sz = strlen(t->th_buf.gnu_longlink);
	th_set_size(t, sz);
	th_finish(t);
	i = tar_block_write(t, &(t->th_buf));
	if (i != T_BLOCKSIZE)
	{
	if (i != -1)
	errno = EINVAL;
	return -1;
	}

	/* write out extra blocks containing long name */
	for (j = (sz / T_BLOCKSIZE) + (sz % T_BLOCKSIZE ? 1 : 0),
	ptr = t->th_buf.gnu_longlink; j > 1;
	j--, ptr += T_BLOCKSIZE)
	{
	i = tar_block_write(t, ptr);
	if (i != T_BLOCKSIZE)
	{
	if (i != -1)
	errno = EINVAL;
	return -1;
	}
	}
	memset(buf, 0, T_BLOCKSIZE);
	strncpy(buf, ptr, T_BLOCKSIZE);
	i = tar_block_write(t, &buf);
	if (i != T_BLOCKSIZE)
	{
	if (i != -1)
	errno = EINVAL;
	return -1;
	}

	/* reset type and size to original values */
	t->th_buf.typeflag = type2;
	th_set_size(t, sz2);
	}

	if ((t->options & TAR_GNU) && t->th_buf.gnu_longname != NULL)
	{
	#ifdef DEBUG
	printf("th_write(): using gnu_longname (\"%s\")\n",
	t->th_buf.gnu_longname);
	#endif
	/* save old size and type */
	type2 = t->th_buf.typeflag;
	sz2 = th_get_size(t);

	/* write out initial header block with fake size and type */
	t->th_buf.typeflag = GNU_LONGNAME_TYPE;
	sz = strlen(t->th_buf.gnu_longname);
	th_set_size(t, sz);
	th_finish(t);
	i = tar_block_write(t, &(t->th_buf));
	if (i != T_BLOCKSIZE)
	{
	if (i != -1)
	errno = EINVAL;
	return -1;
	}

	/* write out extra blocks containing long name */
	for (j = (sz / T_BLOCKSIZE) + (sz % T_BLOCKSIZE ? 1 : 0),
	ptr = t->th_buf.gnu_longname; j > 1;
	j--, ptr += T_BLOCKSIZE)
	{
	i = tar_block_write(t, ptr);
	if (i != T_BLOCKSIZE)
	{
	if (i != -1)
	errno = EINVAL;
	return -1;
	}
	}
	memset(buf, 0, T_BLOCKSIZE);
	strncpy(buf, ptr, T_BLOCKSIZE);
	i = tar_block_write(t, &buf);
	if (i != T_BLOCKSIZE)
	{
	if (i != -1)
	errno = EINVAL;
	return -1;
	}

	/* reset type and size to original values */
	t->th_buf.typeflag = type2;
	th_set_size(t, sz2);
	}

	#ifdef HAVE_SELINUX
	if((t->options & TAR_STORE_SELINUX) && t->th_buf.selinux_context != NULL)
	{
	#ifdef DEBUG
	printf("th_write(): using selinux_context (\"%s\")\n",
	t->th_buf.selinux_context);
	#endif
	/* save old size and type */
	type2 = t->th_buf.typeflag;
	sz2 = th_get_size(t);

	/* write out initial header block with fake size and type */
	t->th_buf.typeflag = TH_EXT_TYPE;

	/* setup size - EXT header has format "size of this whole tag as ascii numbers space content newline */
	// size newline
	sz = SELINUX_TAG_LEN + strlen(t->th_buf.selinux_context) + 3 + 1;

	if(sz >= 100) // another ascci digit for size
	++sz;

	if(sz >= T_BLOCKSIZE) // impossible
	{
	errno = EINVAL;
	return -1;
	}

	th_set_size(t, sz);
	th_finish(t);
	i = tar_block_write(t, &(t->th_buf));
	if (i != T_BLOCKSIZE)
	{
	if (i != -1)
	errno = EINVAL;
	return -1;
	}

	memset(buf, 0, T_BLOCKSIZE);
	snprintf(buf, T_BLOCKSIZE, "%d "SELINUX_TAG"%s\n", sz, t->th_buf.selinux_context);
	i = tar_block_write(t, &buf);
	if (i != T_BLOCKSIZE)
	{
	if (i != -1)
	errno = EINVAL;
	return -1;
	}

	/* reset type and size to original values */
	t->th_buf.typeflag = type2;
	th_set_size(t, sz2);
	}
	#endif

	th_finish(t);

	#ifdef DEBUG
	/* print tar header */
	th_print(t);
	#endif

	i = tar_block_write(t, &(t->th_buf));
	if (i != T_BLOCKSIZE)
	{
	if (i != -1)
	errno = EINVAL;
	return -1;
	}

	#ifdef DEBUG
	puts("th_write(): returning 0");
	#endif
	return 0;
	}