busybox/archival/libunarchive/data_extract_all.c

/* vi: set sw=4 ts=4: */
/*
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

#include "libbb.h"
#include "unarchive.h"

void FAST_FUNC data_extract_all(archive_handle_t *archive_handle)
{
	file_header_t *file_header = archive_handle->file_header;
	int dst_fd;
	int res;

#if ENABLE_FEATURE_TAR_SELINUX
	char *sctx = archive_handle->tar__next_file_sctx;
	if (!sctx)
		sctx = archive_handle->tar__global_sctx;
	if (sctx) { /* setfscreatecon is 4 syscalls, avoid if possible */
		setfscreatecon(sctx);
		free(archive_handle->tar__next_file_sctx);
		archive_handle->tar__next_file_sctx = NULL;
	}
#endif

	if (archive_handle->ah_flags & ARCHIVE_CREATE_LEADING_DIRS) {
		char *slash = strrchr(file_header->name, '/');
		if (slash) {
			*slash = '\0';
			bb_make_directory(file_header->name, -1, FILEUTILS_RECUR);
			*slash = '/';
		}
	}

	if (archive_handle->ah_flags & ARCHIVE_UNLINK_OLD) {
		/* Remove the entry if it exists */
		if (!S_ISDIR(file_header->mode)) {
			/* Is it hardlink?
			 * We encode hard links as regular files of size 0 with a symlink */
			if (S_ISREG(file_header->mode)
			 && file_header->link_target
			 && file_header->size == 0
			) {
				/* Ugly special case:
				 * tar cf t.tar hardlink1 hardlink2 hardlink1
				 * results in this tarball structure:
				 * hardlink1
				 * hardlink2 -> hardlink1
				 * hardlink1 -> hardlink1 <== !!!
				 */
				if (strcmp(file_header->link_target, file_header->name) == 0)
					goto ret;
			}
			/* Proceed with deleting */
			if (unlink(file_header->name) == -1
			 && errno != ENOENT
			) {
				bb_perror_msg_and_die("can't remove old file %s",
						file_header->name);
			}
		}
	}
	else if (archive_handle->ah_flags & ARCHIVE_EXTRACT_NEWER) {
		/* Remove the existing entry if its older than the extracted entry */
		struct stat existing_sb;
		if (lstat(file_header->name, &existing_sb) == -1) {
			if (errno != ENOENT) {
				bb_perror_msg_and_die("can't stat old file");
			}
		}
		else if (existing_sb.st_mtime >= file_header->mtime) {
			if (!(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)) {
				bb_error_msg("%s not created: newer or "
					"same age file exists", file_header->name);
			}
			data_skip(archive_handle);
			goto ret;
		}
		else if ((unlink(file_header->name) == -1) && (errno != EISDIR)) {
			bb_perror_msg_and_die("can't remove old file %s",
					file_header->name);
		}
	}

	/* Handle hard links separately
	 * We encode hard links as regular files of size 0 with a symlink */
	if (S_ISREG(file_header->mode)
	 && file_header->link_target
	 && file_header->size == 0
	) {
		/* hard link */
		res = link(file_header->link_target, file_header->name);
		if ((res == -1) && !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)) {
			bb_perror_msg("can't create %slink "
					"from %s to %s", "hard",
					file_header->name,
					file_header->link_target);
		}
		/* Hardlinks have no separate mode/ownership, skip chown/chmod */
		goto ret;
	}

	/* Create the filesystem entry */
	switch (file_header->mode & S_IFMT) {
	case S_IFREG: {
		/* Regular file */
		int flags = O_WRONLY | O_CREAT | O_EXCL;
		if (archive_handle->ah_flags & ARCHIVE_O_TRUNC)
			flags = O_WRONLY | O_CREAT | O_TRUNC;
		dst_fd = xopen3(file_header->name,
			flags,
			file_header->mode
			);
		bb_copyfd_exact_size(archive_handle->src_fd, dst_fd, file_header->size);
		close(dst_fd);
		break;
	}
	case S_IFDIR:
		res = mkdir(file_header->name, file_header->mode);
		if ((res == -1)
		 && (errno != EISDIR) /* btw, Linux doesn't return this */
		 && (errno != EEXIST)
		 && !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)
		) {
			bb_perror_msg("can't make dir %s", file_header->name);
		}
		break;
	case S_IFLNK:
		/* Symlink */
		res = symlink(file_header->link_target, file_header->name);
		if ((res == -1)
		 && !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)
		) {
			bb_perror_msg("can't create %slink "
				"from %s to %s", "sym",
				file_header->name,
				file_header->link_target);
		}
		break;
	case S_IFSOCK:
	case S_IFBLK:
	case S_IFCHR:
	case S_IFIFO:
		res = mknod(file_header->name, file_header->mode, file_header->device);
		if ((res == -1)
		 && !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)
		) {
			bb_perror_msg("can't create node %s", file_header->name);
		}
		break;
	default:
		bb_error_msg_and_die("unrecognized file type");
	}

	if (!S_ISLNK(file_header->mode)) {
		if (!(archive_handle->ah_flags & ARCHIVE_DONT_RESTORE_OWNER)) {
			uid_t uid = file_header->uid;
			gid_t gid = file_header->gid;
#if ENABLE_FEATURE_TAR_UNAME_GNAME
			if (!(archive_handle->ah_flags & ARCHIVE_NUMERIC_OWNER)) {
				if (file_header->tar__uname) {
//TODO: cache last name/id pair?
					struct passwd *pwd = getpwnam(file_header->tar__uname);
					if (pwd) uid = pwd->pw_uid;
				}
				if (file_header->tar__gname) {
					struct group *grp = getgrnam(file_header->tar__gname);
					if (grp) gid = grp->gr_gid;
				}
			}
#endif
			/* GNU tar 1.15.1 uses chown, not lchown */
			chown(file_header->name, uid, gid);
		}
		/* uclibc has no lchmod, glibc is even stranger -
		 * it has lchmod which seems to do nothing!
		 * so we use chmod... */
		if (!(archive_handle->ah_flags & ARCHIVE_DONT_RESTORE_PERM)) {
			chmod(file_header->name, file_header->mode);
		}
		if (archive_handle->ah_flags & ARCHIVE_RESTORE_DATE) {
			struct timeval t[2];

			t[1].tv_sec = t[0].tv_sec = file_header->mtime;
			t[1].tv_usec = t[0].tv_usec = 0;
			utimes(file_header->name, t);
		}
	}

 ret: ;
#if ENABLE_FEATURE_TAR_SELINUX
	if (sctx) {
		/* reset the context after creating an entry */
		setfscreatecon(NULL);
	}
#endif
}