tar.c

/* vi: set sw=4 ts=4: */
/*
 * Mini tar implementation for busybox based on code taken from sash.
 *
 * Copyright (c) 1999 by David I. Bell
 * Permission is granted to use, distribute, or modify this source,
 * provided that this copyright notice remains intact.
 *
 * Permission to distribute this code under the GPL has been granted.
 *
 * Modified for busybox by Erik Andersen <andersee@debian.org>
 * Adjusted to grok stdin/stdout options.
 *
 * Modified to handle device special files by Matt Porter
 * <porter@debian.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 */


#include "internal.h"
#include <stdio.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <time.h>
#include <utime.h>
#include <sys/types.h>
#include <sys/sysmacros.h>
#include <sys/param.h>			/* for PATH_MAX */


#ifdef BB_FEATURE_TAR_CREATE

static const char tar_usage[] =
	"tar -[cxtvOf] [tarFileName] [FILE] ...\n\n"
	"Create, extract, or list files from a tar file.\n\n"
	"Options:\n"

	"\tc=create, x=extract, t=list contents, v=verbose,\n"
	"\tO=extract to stdout, f=tarfile or \"-\" for stdin\n";

#else

static const char tar_usage[] =
	"tar -[xtvOf] [tarFileName] [FILE] ...\n\n"
	"Extract, or list files stored in a tar file.  This\n"
	"version of tar does not support creation of tar files.\n\n"
	"Options:\n"

	"\tx=extract, t=list contents, v=verbose,\n"
	"\tO=extract to stdout, f=tarfile or \"-\" for stdin\n";

#endif


/* Tar file constants  */


/* POSIX tar Header Block, from POSIX 1003.1-1990  */
struct TarHeader
{
                                /* byte offset */
	char name[100];               /*   0 */
	char mode[8];                 /* 100 */
	char uid[8];                  /* 108 */
	char gid[8];                  /* 116 */
	char size[12];                /* 124 */
	char mtime[12];               /* 136 */
	char chksum[8];               /* 148 */
	char typeflag;                /* 156 */
	char linkname[100];           /* 157 */
	char magic[6];                /* 257 */
	char version[2];              /* 263 */
	char uname[32];               /* 265 */
	char gname[32];               /* 297 */
	char devmajor[8];             /* 329 */
	char devminor[8];             /* 337 */
	char prefix[155];             /* 345 */
	/* padding                       500 */
};
typedef struct TarHeader TarHeader;


/* A few useful constants */
#define TAR_MAGIC          "ustar"        /* ustar and a null */
#define TAR_VERSION        "00"           /* 00 and no null */
#define TAR_MAGIC_LEN       6
#define TAR_VERSION_LEN     2
#define TAR_NAME_LEN        100
#define TAR_BLOCK_SIZE      512

/* A nice enum with all the possible tar file content types */
enum TarFileType 
{
	REGTYPE  = '0',            /* regular file */
	REGTYPE0 = '\0',           /* regular file (ancient bug compat)*/
	LNKTYPE  = '1',            /* hard link */
	SYMTYPE  = '2',            /* symbolic link */
	CHRTYPE  = '3',            /* character special */
	BLKTYPE  = '4',            /* block special */
	DIRTYPE  = '5',            /* directory */
	FIFOTYPE = '6',            /* FIFO special */
	CONTTYPE = '7',            /* reserved */
};
typedef enum TarFileType TarFileType;

/* This struct ignores magic, non-numeric user name, 
 * non-numeric group name, and the checksum, since
 * these are all ignored by BusyBox tar. */ 
struct TarInfo
{
	int              tarFd;          /* An open file descriptor for reading from the tarball */
	char *           name;           /* File name */
	mode_t           mode;           /* Unix mode, including device bits. */
	uid_t            uid;            /* Numeric UID */
	gid_t            gid;            /* Numeric GID */
	size_t           size;           /* Size of file */
	time_t           mtime;          /* Last-modified time */
	enum TarFileType type;           /* Regular, directory, link, etc */
	char *           linkname;       /* Name for symbolic and hard links */
	dev_t            device;         /* Special device for mknod() */
};
typedef struct TarInfo TarInfo;

/* Static data  */
static const unsigned long TarChecksumOffset = (const unsigned long)&(((TarHeader *)0)->chksum);


/*
 * Static data.
 */
static int inHeader;			// <- check me
static int badHeader;
static int skipFileFlag;
static int warnedRoot;
static int eofFlag;
static long dataCc;
static int outFd;
static const char *outName;

static int mode;
static int uid;
static int gid;
static time_t mtime;

/*
 * Static data associated with the tar file.
 */
static int tarFd;
static dev_t tarDev;
static ino_t tarInode;


/*
 * Local procedures to restore files from a tar file.
 */
static int readTarFile(const char* tarName, int extractFlag, int listFlag, 
		int tostdoutFlag, int verboseFlag);
static void readData(const char *cp, int count);
static long getOctal(const char *cp, int len);
static int parseTarHeader(struct TarHeader *rawHeader, struct TarInfo *header);
static int wantFileName(const char *fileName,
						int argc, char **argv);

#ifdef BB_FEATURE_TAR_CREATE
/*
 * Local procedures to save files into a tar file.
 */
static void saveFile(const char *fileName, int seeLinks);
static void saveRegularFile(const char *fileName,
							const struct stat *statbuf);
static void saveDirectory(const char *fileName,
						  const struct stat *statbuf);
static void writeHeader(const char *fileName, const struct stat *statbuf);
static void writeTarFile(int argc, char **argv);
static void writeTarBlock(const char *buf, int len);
static int putOctal(char *cp, int len, long value);

#endif


extern int tar_main(int argc, char **argv)
{
	const char *tarName=NULL;
	const char *options;
	int listFlag     = FALSE;
	int extractFlag  = FALSE;
	int createFlag   = FALSE;
	int verboseFlag  = FALSE;
	int tostdoutFlag = FALSE;

	argc--;
	argv++;

	if (argc < 1)
		usage(tar_usage);

	/* Parse options  */
	if (**argv == '-')
		options = (*argv++) + 1;
	else
		options = (*argv++);
	argc--;

	for (; *options; options++) {
		switch (*options) {
		case 'f':
			if (tarName != NULL)
				fatalError( "Only one 'f' option allowed\n");

			tarName = *argv++;
			if (tarName == NULL)
				fatalError( "Option requires an argument: No file specified\n");
			argc--;

			break;

		case 't':
			if (extractFlag == TRUE || createFlag == TRUE)
				goto flagError;
			listFlag = TRUE;
			break;

		case 'x':
			if (listFlag == TRUE || createFlag == TRUE)
				goto flagError;
			extractFlag = TRUE;
			break;
		case 'c':
			if (extractFlag == TRUE || listFlag == TRUE)
				goto flagError;
			createFlag = TRUE;
			break;

		case 'v':
			verboseFlag = TRUE;
			break;

		case 'O':
			tostdoutFlag = TRUE;
			break;

		case '-':
			usage(tar_usage);
			break;

		default:
			fatalError( "Unknown tar flag '%c'\n" 
					"Try `tar --help' for more information\n", *options);
		}
	}

	/* 
	 * Do the correct type of action supplying the rest of the
	 * command line arguments as the list of files to process.
	 */
	if (createFlag == TRUE) {
#ifndef BB_FEATURE_TAR_CREATE
		fatalError( "This version of tar was not compiled with tar creation support.\n");
#else
		exit(writeTarFile(argc, argv));
#endif
	} else {
		exit(readTarFile(tarName, extractFlag, listFlag, tostdoutFlag, verboseFlag));
	}

  flagError:
	fatalError( "Exactly one of 'c', 'x' or 't' must be specified\n");
}
					
static void
tarExtractRegularFile(TarInfo *header, int extractFlag, int listFlag, int tostdoutFlag, int verboseFlag)
{

}


/*
 * Read a tar file and extract or list the specified files within it.
 * If the list is empty than all files are extracted or listed.
 */
static int readTarFile(const char* tarName, int extractFlag, int listFlag, 
		int tostdoutFlag, int verboseFlag)
{
	int status, tarFd=0;
	int errorFlag=FALSE;
	TarHeader rawHeader;
	TarInfo header;

	/* Open the tar file for reading.  */
	if (!strcmp(tarName, "-"))
		tarFd = fileno(stdin);
	else
		tarFd = open(tarName, O_RDONLY);
	if (tarFd < 0) {
		errorMsg( "Error opening '%s': %s", tarName, strerror(errno));
		return ( FALSE);
	}

	/* Read the tar file */
	while ( (status = fullRead(tarFd, (char*)&rawHeader, TAR_BLOCK_SIZE)) == TAR_BLOCK_SIZE ) {
		/* Now see if the header looks ok */
		if ( parseTarHeader(&rawHeader, &header) == FALSE ) {
			close( tarFd);
			if ( *(header.name) == '\0' ) {
				goto endgame;
			} else {
				errorFlag=TRUE;
				errorMsg("Bad tar header, skipping\n");
				continue;
			}
		}
		if ( *(header.name) == '\0' )
				goto endgame;

		/* If we got here, we can be certain we have a legitimate 
		 * header to work with.  So work with it.  */
		switch ( header.type ) {
			case REGTYPE:
			case REGTYPE0:
				/* If the name ends in a '/' then assume it is
				 * supposed to be a directory, and fall through */
				if (header.name[strlen(header.name)-1] != '/') {
					tarExtractRegularFile(&header, extractFlag, listFlag, tostdoutFlag, verboseFlag);
					break;
				}
#if 0
			case Directory:
				tarExtractDirectory( &header, extractFlag, listFlag, tostdoutFlag, verboseFlag);
				break;
			case HardLink:
				tarExtractHardLink( &header, extractFlag, listFlag, tostdoutFlag, verboseFlag);
				break;
			case SymbolicLink:
				tarExtractSymLink( &header, extractFlag, listFlag, tostdoutFlag, verboseFlag);
				break;
			case CharacterDevice:
			case BlockDevice:
			case FIFO:
				tarExtractSpecial( &header, extractFlag, listFlag, tostdoutFlag, verboseFlag);
				break;
#endif
			default:
				close( tarFd);
				return( FALSE);
		}
	}

	close(tarFd);
	if (status > 0) {
		/* Bummer - we read a partial header */
		errorMsg( "Error reading '%s': %s", tarName, strerror(errno));
		return ( FALSE);
	}
	else 
		return( status);

	/* Stuff we do when we know we are done with the file */
endgame:
	close( tarFd);
	if ( *(header.name) == '\0' ) {
		if (errorFlag==FALSE)
			return( TRUE);
	} 
	return( FALSE);
}

/*
 * Read an octal value in a field of the specified width, with optional
 * spaces on both sides of the number and with an optional null character
 * at the end.  Returns -1 on an illegal format.
 */
static long getOctal(const char *cp, int size)
{
	long val = 0;

	for(;(size > 0) && (*cp == ' '); cp++, size--);
	if ((size == 0) || !isOctal(*cp))
		return -1;
	for(; (size > 0) && isOctal(*cp); size--) {
		val = val * 8 + *cp++ - '0';
	}
	for (;(size > 0) && (*cp == ' '); cp++, size--);
	if ((size > 0) && *cp)
		return -1;
	return val;
}

/* Parse the tar header and fill in the nice struct with the details */
static int
parseTarHeader(struct TarHeader *rawHeader, struct TarInfo *header)
{
	long major, minor, chksum, sum;

	header->name  = rawHeader->name;
	header->mode  = getOctal(rawHeader->mode, sizeof(rawHeader->mode));
	header->uid   =  getOctal(rawHeader->uid, sizeof(rawHeader->uid));
	header->gid   =  getOctal(rawHeader->gid, sizeof(rawHeader->gid));
	header->size  = getOctal(rawHeader->size, sizeof(rawHeader->size));
	header->mtime = getOctal(rawHeader->mtime, sizeof(rawHeader->mtime));
	chksum = getOctal(rawHeader->chksum, sizeof(rawHeader->chksum));
	header->type  = rawHeader->typeflag;
	header->linkname  = rawHeader->linkname;
	header->device  = MAJOR(getOctal(rawHeader->devmajor, sizeof(rawHeader->devmajor))) |
		MINOR(getOctal(rawHeader->devminor, sizeof(rawHeader->devminor)));

	/* Check the checksum */
	sum = ' ' * sizeof(rawHeader->chksum);
	for ( i = TarChecksumOffset; i > 0; i-- )
		sum += *s++;
	s += sizeof(h->chksum);       
	for ( i = (512 - TarChecksumOffset - sizeof(h->chksum)); i > 0; i-- )
		sum += *s++;
	if (sum == checksum )
		return ( TRUE);
	return( FALSE);
}

#if 0
	if ((header->mode < 0) || (header->uid < 0) || 
			(header->gid < 0) || (header->size < 0)) {
		errorMsg(stderr, "Bad tar header, skipping\n");
		return( FALSE);
	}

	badHeader = FALSE;
	skipFileFlag = FALSE;
	devFileFlag = FALSE;

	/* 
	 * Check for the file modes.
	 */
	hardLink = ((hp->typeFlag == TAR_TYPE_HARD_LINK) ||
				(hp->typeFlag == TAR_TYPE_HARD_LINK - '0'));

	softLink = ((hp->typeFlag == TAR_TYPE_SOFT_LINK) ||
				(hp->typeFlag == TAR_TYPE_SOFT_LINK - '0'));

	/* 
	 * Check for a directory.
	 */
	if (outName[strlen(outName) - 1] == '/')
		mode |= S_IFDIR;

	/* 
	 * Check for absolute paths in the file.
	 * If we find any, then warn the user and make them relative.
	 */
	if (*outName == '/') {
		while (*outName == '/')
			outName++;

		if (warnedRoot == FALSE) {
			fprintf(stderr,
					"Absolute path detected, removing leading slashes\n");
		}

		warnedRoot = TRUE;
	}

	/* 
	 * See if we want this file to be restored.
	 * If not, then set up to skip it.
	 */
	if (wantFileName(outName, argc, argv) == FALSE) {
		if (!hardLink && !softLink && (S_ISREG(mode) || S_ISCHR(mode)
									   || S_ISBLK(mode) || S_ISSOCK(mode)
									   || S_ISFIFO(mode))) {
			inHeader = (size == 0) ? TRUE : FALSE;
			dataCc = size;
		}

		skipFileFlag = TRUE;

		return;
	}

	/* 
	 * This file is to be handled.
	 * If we aren't extracting then just list information about the file.
	 */
	if (extractFlag == FALSE) {
		if (verboseFlag == TRUE) {
			printf("%s %3d/%-d ", modeString(mode), uid, gid);
			if (S_ISCHR(mode) || S_ISBLK(mode))
				printf("%4d,%4d %s ", major, minor, timeString(mtime));
			else
				printf("%9ld %s ", size, timeString(mtime));
		}
		printf("%s", outName);

		if (hardLink)
			printf(" (link to \"%s\")", hp->linkName);
		else if (softLink)
			printf(" (symlink to \"%s\")", hp->linkName);
		else if (S_ISREG(mode) || S_ISCHR(mode) || S_ISBLK(mode) ||
				 S_ISSOCK(mode) || S_ISFIFO(mode)) {
			inHeader = (size == 0) ? TRUE : FALSE;
			dataCc = size;
		}

		printf("\n");

		return;
	}

	/* 
	 * We really want to extract the file.
	 */
	if (verboseFlag == TRUE)
		printf("x %s\n", outName);

	if (hardLink) {
		if (link(hp->linkName, outName) < 0) {
			perror(outName);
			return;
		}
		/* Set the file time */
		utb.actime = mtime;
		utb.modtime = mtime;
		utime(outName, &utb);
		/* Set the file permissions */
		chown(outName, uid, gid);
		chmod(outName, mode);
		return;
	}

	if (softLink) {
#ifdef	S_ISLNK
		if (symlink(hp->linkName, outName) < 0) {
			perror(outName);
			return;
		}
		/* Try to change ownership of the symlink.
		 * If libs doesn't support that, don't bother.
		 * Changing the pointed-to file is the Wrong Thing(tm).
		 */
#if (__GLIBC__ >= 2) && (__GLIBC_MINOR__ >= 1)
		lchown(outName, uid, gid);
#endif

		/* Do not change permissions or date on symlink,
		 * since it changes the pointed to file instead.  duh. */
#else
		fprintf(stderr, "Cannot create symbolic links\n");
#endif
		return;
	}

	/* Set the umask for this process so it doesn't 
	 * screw things up. */
	umask(0);

	/* 
	 * If the file is a directory, then just create the path.
	 */
	if (S_ISDIR(mode)) {
		if (createPath(outName, mode) == TRUE) {
			/* make the final component, just in case it was
			 * omitted by createPath() (which will skip the
			 * directory if it doesn't have a terminating '/')
			 */
			mkdir(outName, mode);

			/* Set the file time */
			utb.actime = mtime;
			utb.modtime = mtime;
			utime(outName, &utb);
			/* Set the file permissions */
			chown(outName, uid, gid);
			chmod(outName, mode);
			return;
		}
		return;
	}

	/* 
	 * There is a file to write.
	 * First create the path to it if necessary with default permissions.
	 */
	createPath(outName, 0777);

	inHeader = (size == 0) ? TRUE : FALSE;
	dataCc = size;

	/* 
	 * Start the output file.
	 */
	if (tostdoutFlag == TRUE)
		outFd = fileno(stdout);
	else {
		if (S_ISCHR(mode) || S_ISBLK(mode) || S_ISSOCK(mode)) {
			devFileFlag = TRUE;
			outFd = mknod(outName, mode, makedev(major, minor));
		} else if (S_ISFIFO(mode)) {
			devFileFlag = TRUE;
			outFd = mkfifo(outName, mode);
		} else {
			outFd = open(outName, O_WRONLY | O_CREAT | O_TRUNC, mode);
		}
		if (outFd < 0) {
			perror(outName);
			skipFileFlag = TRUE;
			return;
		}
		/* Set the file time */
		utb.actime = mtime;
		utb.modtime = mtime;
		utime(outName, &utb);
		/* Set the file permissions */
		chown(outName, uid, gid);
		chmod(outName, mode);
	}


	/* 
	 * If the file is empty, then that's all we need to do.
	 */
	if (size == 0 && (tostdoutFlag == FALSE) && (devFileFlag == FALSE)) {
		close(outFd);
		outFd = -1;
	}
}


/*
 * Handle a data block of some specified size that was read.
 */
static void readData(const char *cp, int count)
{
	/* 
	 * Reduce the amount of data left in this file.
	 * If there is no more data left, then we need to read
	 * the header again.
	 */
	dataCc -= count;

	if (dataCc <= 0)
		inHeader = TRUE;

	/* 
	 * If we aren't extracting files or this file is being
	 * skipped then do nothing more.
	 */
	if (extractFlag == FALSE || skipFileFlag == TRUE)
		return;

	/* 
	 * Write the data to the output file.
	 */
	if (fullWrite(outFd, cp, count) < 0) {
		perror(outName);
		if (tostdoutFlag == FALSE) {
			close(outFd);
			outFd = -1;
		}
		skipFileFlag = TRUE;
		return;
	}

	/* 
	 * Check if we are done writing to the file now.
	 */
	if (dataCc <= 0 && tostdoutFlag == FALSE) {
		struct utimbuf utb;

		if (close(outFd))
			perror(outName);

		/* Set the file time */
		utb.actime = mtime;
		utb.modtime = mtime;
		utime(outName, &utb);
		/* Set the file permissions */
		chown(outName, uid, gid);
		chmod(outName, mode);

		outFd = -1;
	}
}


/*
 * See if the specified file name belongs to one of the specified list
 * of path prefixes.  An empty list implies that all files are wanted.
 * Returns TRUE if the file is selected.
 */
static int
wantFileName(const char *fileName, int argc, char **argv)
{
	const char *pathName;
	int fileLength;
	int pathLength;

	/* 
	 * If there are no files in the list, then the file is wanted.
	 */
	if (argc == 0)
		return TRUE;

	fileLength = strlen(fileName);

	/* 
	 * Check each of the test paths.
	 */
	while (argc-- > 0) {
		pathName = *argv++;

		pathLength = strlen(pathName);

		if (fileLength < pathLength)
			continue;

		if (memcmp(fileName, pathName, pathLength) != 0)
			continue;

		if ((fileLength == pathLength) || (fileName[pathLength] == '/')) {
			return TRUE;
		}
	}

	return FALSE;
}


/* From here to the end of the file is the tar writing stuff.
 * If you do not have BB_FEATURE_TAR_CREATE defined, this will
 * not be built.
 * */
#ifdef BB_FEATURE_TAR_CREATE

/*
 * Write a tar file containing the specified files.
 */
static void writeTarFile(int argc, char **argv)
{
	struct stat statbuf;

	/* 
	 * Make sure there is at least one file specified.
	 */
	if (argc <= 0) {
		fprintf(stderr, "No files specified to be saved\n");
		errorFlag = TRUE;
	}

	/* 
	 * Create the tar file for writing.
	 */
	if ((tarName == NULL) || !strcmp(tarName, "-")) {
		tostdoutFlag = TRUE;
		tarFd = fileno(stdout);
	} else
		tarFd = open(tarName, O_WRONLY | O_CREAT | O_TRUNC, 0666);

	if (tarFd < 0) {
		perror(tarName);
		errorFlag = TRUE;
		return;
	}

	/* 
	 * Get the device and inode of the tar file for checking later.
	 */
	if (fstat(tarFd, &statbuf) < 0) {
		perror(tarName);
		errorFlag = TRUE;
		goto done;
	}

	tarDev = statbuf.st_dev;
	tarInode = statbuf.st_ino;

	/* 
	 * Append each file name into the archive file.
	 * Follow symbolic links for these top level file names.
	 */
	while (errorFlag == FALSE && (argc-- > 0)) {
		saveFile(*argv++, FALSE);
	}

	/* 
	 * Now write an empty block of zeroes to end the archive.
	 */
	writeTarBlock("", 1);


  done:
	/* 
	 * Close the tar file and check for errors if it was opened.
	 */
	if ((tostdoutFlag == FALSE) && (tarFd >= 0) && (close(tarFd) < 0))
		perror(tarName);
}

/*
 * Save one file into the tar file.
 * If the file is a directory, then this will recursively save all of
 * the files and directories within the directory.  The seeLinks
 * flag indicates whether or not we want to see symbolic links as
 * they really are, instead of blindly following them.
 */
static void saveFile(const char *fileName, int seeLinks)
{
	int status;
	struct stat statbuf;

	if (verboseFlag == TRUE)
		printf("a %s\n", fileName);

	/* 
	 * Check that the file name will fit in the header.
	 */
	if (strlen(fileName) >= TAR_NAME_SIZE) {
		fprintf(stderr, "%s: File name is too long\n", fileName);

		return;
	}

	/* 
	 * Find out about the file.
	 */
#ifdef	S_ISLNK
	if (seeLinks == TRUE)
		status = lstat(fileName, &statbuf);
	else
#endif
		status = stat(fileName, &statbuf);

	if (status < 0) {
		perror(fileName);

		return;
	}

	/* 
	 * Make sure we aren't trying to save our file into itself.
	 */
	if ((statbuf.st_dev == tarDev) && (statbuf.st_ino == tarInode)) {
		fprintf(stderr, "Skipping saving of archive file itself\n");

		return;
	}

	/* 
	 * Check the type of file.
	 */
	mode = statbuf.st_mode;

	if (S_ISDIR(mode)) {
		saveDirectory(fileName, &statbuf);

		return;
	}
	if (S_ISREG(mode)) {
		saveRegularFile(fileName, &statbuf);

		return;
	}

	/* Some day add support for tarring these up... but not today. :) */
//  if (S_ISLNK(mode) || S_ISFIFO(mode) || S_ISBLK(mode) || S_ISCHR (mode) ) {
//  fprintf (stderr, "%s: This version of tar can't store this type of file\n", fileName);
//  }

	/* 
	 * The file is a strange type of file, ignore it.
	 */
	fprintf(stderr, "%s: not a directory or regular file\n", fileName);
}


/*
 * Save a regular file to the tar file.
 */
static void
saveRegularFile(const char *fileName, const struct stat *statbuf)
{
	int sawEof;
	int fileFd;
	int cc;
	int dataCount;
	long fullDataCount;
	char data[TAR_BLOCK_SIZE * 16];

	/* 
	 * Open the file for reading.
	 */
	fileFd = open(fileName, O_RDONLY);

	if (fileFd < 0) {
		perror(fileName);

		return;
	}

	/* 
	 * Write out the header for the file.
	 */
	writeHeader(fileName, statbuf);

	/* 
	 * Write the data blocks of the file.
	 * We must be careful to write the amount of data that the stat
	 * buffer indicated, even if the file has changed size.  Otherwise
	 * the tar file will be incorrect.
	 */
	fullDataCount = statbuf->st_size;
	sawEof = FALSE;

	while (fullDataCount > 0) {
		/* 
		 * Get the amount to write this iteration which is
		 * the minumum of the amount left to write and the
		 * buffer size.
		 */
		dataCount = sizeof(data);

		if (dataCount > fullDataCount)
			dataCount = (int) fullDataCount;

		/* 
		 * Read the data from the file if we haven't seen the
		 * end of file yet.
		 */
		cc = 0;

		if (sawEof == FALSE) {
			cc = fullRead(fileFd, data, dataCount);

			if (cc < 0) {
				perror(fileName);

				(void) close(fileFd);
				errorFlag = TRUE;

				return;
			}

			/* 
			 * If the file ended too soon, complain and set
			 * a flag so we will zero fill the rest of it.
			 */
			if (cc < dataCount) {
				fprintf(stderr, "%s: Short read - zero filling", fileName);

				sawEof = TRUE;
			}
		}

		/* 
		 * Zero fill the rest of the data if necessary.
		 */
		if (cc < dataCount)
			memset(data + cc, 0, dataCount - cc);

		/* 
		 * Write the buffer to the TAR file.
		 */
		writeTarBlock(data, dataCount);

		fullDataCount -= dataCount;
	}

	/* 
	 * Close the file.
	 */
	if ((tostdoutFlag == FALSE) && close(fileFd) < 0)
		fprintf(stderr, "%s: close: %s\n", fileName, strerror(errno));
}


/*
 * Save a directory and all of its files to the tar file.
 */
static void saveDirectory(const char *dirName, const struct stat *statbuf)
{
	DIR *dir;
	struct dirent *entry;
	int needSlash;
	char fullName[PATH_MAX + 1];

	/* 
	 * Construct the directory name as used in the tar file by appending
	 * a slash character to it.
	 */
	strcpy(fullName, dirName);
	strcat(fullName, "/");

	/* 
	 * Write out the header for the directory entry.
	 */
	writeHeader(fullName, statbuf);

	/* 
	 * Open the directory.
	 */
	dir = opendir(dirName);

	if (dir == NULL) {
		fprintf(stderr, "Cannot read directory \"%s\": %s\n",
				dirName, strerror(errno));

		return;
	}

	/* 
	 * See if a slash is needed.
	 */
	needSlash = (*dirName && (dirName[strlen(dirName) - 1] != '/'));

	/* 
	 * Read all of the directory entries and check them,
	 * except for the current and parent directory entries.
	 */
	while (errorFlag == FALSE && ((entry = readdir(dir)) != NULL)) {
		if ((strcmp(entry->d_name, ".") == 0) ||
			(strcmp(entry->d_name, "..") == 0)) {
			continue;
		}

		/* 
		 * Build the full path name to the file.
		 */
		strcpy(fullName, dirName);

		if (needSlash)
			strcat(fullName, "/");

		strcat(fullName, entry->d_name);

		/* 
		 * Write this file to the tar file, noticing whether or not
		 * the file is a symbolic link.
		 */
		saveFile(fullName, TRUE);
	}

	/* 
	 * All done, close the directory.
	 */
	closedir(dir);
}


/*
 * Write a tar header for the specified file name and status.
 * It is assumed that the file name fits.
 */
static void writeHeader(const char *fileName, const struct stat *statbuf)
{
	long checkSum;
	const unsigned char *cp;
	int len;
	TarHeader header;

	/* 
	 * Zero the header block in preparation for filling it in.
	 */
	memset((char *) &header, 0, sizeof(header));

	/* 
	 * Fill in the header.
	 */
	strcpy(header.name, fileName);

	strncpy(header.magic, TAR_MAGIC, sizeof(header.magic));
	strncpy(header.version, TAR_VERSION, sizeof(header.version));

	putOctal(header.mode, sizeof(header.mode), statbuf->st_mode & 0777);
	putOctal(header.uid, sizeof(header.uid), statbuf->st_uid);
	putOctal(header.gid, sizeof(header.gid), statbuf->st_gid);
	putOctal(header.size, sizeof(header.size), statbuf->st_size);
	putOctal(header.mtime, sizeof(header.mtime), statbuf->st_mtime);

	header.typeFlag = TAR_TYPE_REGULAR;

	/* 
	 * Calculate and store the checksum.
	 * This is the sum of all of the bytes of the header,
	 * with the checksum field itself treated as blanks.
	 */
	memset(header.checkSum, ' ', sizeof(header.checkSum));

	cp = (const unsigned char *) &header;
	len = sizeof(header);
	checkSum = 0;

	while (len-- > 0)
		checkSum += *cp++;

	putOctal(header.checkSum, sizeof(header.checkSum), checkSum);

	/* 
	 * Write the tar header.
	 */
	writeTarBlock((const char *) &header, sizeof(header));
}


/*
 * Write data to one or more blocks of the tar file.
 * The data is always padded out to a multiple of TAR_BLOCK_SIZE.
 * The errorFlag static variable is set on an error.
 */
static void writeTarBlock(const char *buf, int len)
{
	int partialLength;
	int completeLength;
	char fullBlock[TAR_BLOCK_SIZE];

	/* 
	 * If we had a write error before, then do nothing more.
	 */
	if (errorFlag == TRUE)
		return;

	/* 
	 * Get the amount of complete and partial blocks.
	 */
	partialLength = len % TAR_BLOCK_SIZE;
	completeLength = len - partialLength;

	/* 
	 * Write all of the complete blocks.
	 */
	if ((completeLength > 0) && !fullWrite(tarFd, buf, completeLength)) {
		perror(tarName);

		errorFlag = TRUE;

		return;
	}

	/* 
	 * If there are no partial blocks left, we are done.
	 */
	if (partialLength == 0)
		return;

	/* 
	 * Copy the partial data into a complete block, and pad the rest
	 * of it with zeroes.
	 */
	memcpy(fullBlock, buf + completeLength, partialLength);
	memset(fullBlock + partialLength, 0, TAR_BLOCK_SIZE - partialLength);

	/* 
	 * Write the last complete block.
	 */
	if (!fullWrite(tarFd, fullBlock, TAR_BLOCK_SIZE)) {
		perror(tarName);

		errorFlag = TRUE;
	}
}


/*
 * Put an octal string into the specified buffer.
 * The number is zero and space padded and possibly null padded.
 * Returns TRUE if successful.
 */
static int putOctal(char *cp, int len, long value)
{
	int tempLength;
	char *tempString;
	char tempBuffer[32];

	/* 
	 * Create a string of the specified length with an initial space,
	 * leading zeroes and the octal number, and a trailing null.
	 */
	tempString = tempBuffer;

	sprintf(tempString, " %0*lo", len - 2, value);

	tempLength = strlen(tempString) + 1;

	/* 
	 * If the string is too large, suppress the leading space.
	 */
	if (tempLength > len) {
		tempLength--;
		tempString++;
	}

	/* 
	 * If the string is still too large, suppress the trailing null.
	 */
	if (tempLength > len)
		tempLength--;

	/* 
	 * If the string is still too large, fail.
	 */
	if (tempLength > len)
		return FALSE;

	/* 
	 * Copy the string to the field.
	 */
	memcpy(cp, tempString, len);

	return TRUE;
}
#endif

/* END CODE */
#endif