unarchive.c

手机嵌入式Linux下可用的busybox源码

		if (fgetc(src_stream) != '\n') {
			error_msg("Invalid magic");
			return(NULL);
		}
		/* fix up the header, we started reading 1 byte too early */
		/* raw_header[60] wont be '\n' as it should, but it doesnt matter */
		memmove(ar.raw, &ar.raw[1], 59);
	}
		
	typed = (file_header_t *) xcalloc(1, sizeof(file_header_t));

	typed->size = (size_t) atoi(ar.formated.size);
	/* long filenames have '/' as the first character */
	if (ar.formated.name[0] == '/') {
		if (ar.formated.name[1] == '/') {
			/* If the second char is a '/' then this entries data section
			 * stores long filename for multiple entries, they are stored
			 * in static variable long_names for use in future entries */
			ar_long_names = (char *) xrealloc(ar_long_names, typed->size);
			fread(ar_long_names, 1, typed->size, src_stream);
			archive_offset += typed->size;
			/* This ar entries data section only contained filenames for other records
			 * they are stored in the static ar_long_names for future reference */
			return (get_header_ar(src_stream)); /* Return next header */
		} else if (ar.formated.name[1] == ' ') {
			/* This is the index of symbols in the file for compilers */
			seek_sub_file(src_stream, typed->size);
			return (get_header_ar(src_stream)); /* Return next header */
		} else {
			/* The number after the '/' indicates the offset in the ar data section
			(saved in variable long_name) that conatains the real filename */
			if (!ar_long_names) {
				error_msg("Cannot resolve long file name");
				return (NULL);
			}
			typed->name = xstrdup(ar_long_names + atoi(&ar.formated.name[1]));
		}
	} else {
		/* short filenames */
		typed->name = xcalloc(1, 16);
		strncpy(typed->name, ar.formated.name, 16);
	}
	typed->name[strcspn(typed->name, " /")]='\0';

	/* convert the rest of the now valid char header to its typed struct */	
	parse_mode(ar.formated.mode, &typed->mode);
	typed->mtime = atoi(ar.formated.date);
	typed->uid = atoi(ar.formated.uid);
	typed->gid = atoi(ar.formated.gid);

	return(typed);
}
#endif

#ifdef L_get_header_cpio
struct hardlinks {
	file_header_t *entry;
	int inode;
	struct hardlinks *next;
};

file_header_t *get_header_cpio(FILE *src_stream)
{
	file_header_t *cpio_entry = NULL;
	char cpio_header[110];
	int namesize;
 	char dummy[16];
 	int major, minor, nlink, inode;
 	static struct hardlinks *saved_hardlinks = NULL;
 	static int pending_hardlinks = 0;

	if (pending_hardlinks) { /* Deal with any pending hardlinks */
		struct hardlinks *tmp = saved_hardlinks, *oldtmp = NULL;
		while (tmp) {
			if (tmp->entry->link_name) { /* Found a hardlink ready to be extracted */
				cpio_entry = tmp->entry;
				if (oldtmp) oldtmp->next = tmp->next; /* Remove item from linked list */
				else saved_hardlinks = tmp->next;
				free(tmp);
				return (cpio_entry);
			}
			oldtmp = tmp;
			tmp = tmp->next;
		}
		pending_hardlinks = 0; /* No more pending hardlinks, read next file entry */
	}
  
	/* There can be padding before archive header */
	seek_sub_file(src_stream, (4 - (archive_offset % 4)) % 4);
	if (fread(cpio_header, 1, 110, src_stream) == 110) {
		archive_offset += 110;
		if (strncmp(cpio_header, "07070", 5) != 0) {
			error_msg("Unsupported format or invalid magic");
			return(NULL);
		}
		switch (cpio_header[5]) {
			case '2': /* "crc" header format */
				/* Doesnt do the crc check yet */
			case '1': /* "newc" header format */
				cpio_entry = (file_header_t *) xcalloc(1, sizeof(file_header_t));
				sscanf(cpio_header, "%6c%8x%8x%8x%8x%8x%8lx%8lx%16c%8x%8x%8x%8c",
					dummy, &inode, (unsigned int*)&cpio_entry->mode, 
					(unsigned int*)&cpio_entry->uid, (unsigned int*)&cpio_entry->gid,
					&nlink, &cpio_entry->mtime, (unsigned long*)&cpio_entry->size,
					dummy, &major, &minor, &namesize, dummy);

				cpio_entry->name = (char *) xcalloc(1, namesize);
				fread(cpio_entry->name, 1, namesize, src_stream); /* Read in filename */
				archive_offset += namesize;
				/* Skip padding before file contents */
				seek_sub_file(src_stream, (4 - (archive_offset % 4)) % 4);
				if (strcmp(cpio_entry->name, "TRAILER!!!") == 0) {
					printf("%d blocks\n", (int) (archive_offset % 512 ? (archive_offset / 512) + 1 : archive_offset / 512)); /* Always round up */
					if (saved_hardlinks) { /* Bummer - we still have unresolved hardlinks */
						struct hardlinks *tmp = saved_hardlinks, *oldtmp = NULL;
						while (tmp) {
							error_msg("%s not created: cannot resolve hardlink", tmp->entry->name);
							oldtmp = tmp;
							tmp = tmp->next;
							free (oldtmp->entry->name);
							free (oldtmp->entry);
							free (oldtmp);
						}
						saved_hardlinks = NULL;
						pending_hardlinks = 0;
					}
					return(NULL);
				}

				if (S_ISLNK(cpio_entry->mode)) {
					cpio_entry->link_name = (char *) xcalloc(1, cpio_entry->size + 1);
					fread(cpio_entry->link_name, 1, cpio_entry->size, src_stream);
					archive_offset += cpio_entry->size;
					cpio_entry->size = 0; /* Stop possiable seeks in future */
				}
				if (nlink > 1 && !S_ISDIR(cpio_entry->mode)) {
					if (cpio_entry->size == 0) { /* Put file on a linked list for later */
						struct hardlinks *new = xmalloc(sizeof(struct hardlinks));
						new->next = saved_hardlinks;
						new->inode = inode;
						new->entry = cpio_entry;
						saved_hardlinks = new;
					return(get_header_cpio(src_stream)); /* Recurse to next file */
					} else { /* Found the file with data in */
						struct hardlinks *tmp = saved_hardlinks;
						pending_hardlinks = 1;
						while (tmp) {
							if (tmp->inode == inode) {
								tmp->entry->link_name = xstrdup(cpio_entry->name);
								nlink--;
							}
							tmp = tmp->next;
						}
						if (nlink > 1) error_msg("error resolving hardlink: did you create the archive with GNU cpio 2.0-2.2?");
					}
				}
				cpio_entry->device = (major << 8) | minor;
				break;
			default:
				error_msg("Unsupported format");
				return(NULL);
		}
		if (ferror(src_stream) || feof(src_stream)) {
			perror_msg("Stream error");
			return(NULL);
		}
	}
	return(cpio_entry);
}
#endif

#ifdef L_get_header_tar
file_header_t *get_header_tar(FILE *tar_stream)
{
	union {
		unsigned char raw[512];
		struct {
			char name[100];		/*   0-99 */
			char mode[8];		/* 100-107 */
			char uid[8];		/* 108-115 */
			char gid[8];		/* 116-123 */
			char size[12];		/* 124-135 */
			char mtime[12];		/* 136-147 */
			char chksum[8];		/* 148-155 */
			char typeflag;		/* 156-156 */
			char linkname[100];	/* 157-256 */
			char magic[6];		/* 257-262 */
			char version[2];	/* 263-264 */
			char uname[32];		/* 265-296 */
			char gname[32];		/* 297-328 */
			char devmajor[8];	/* 329-336 */
			char devminor[8];	/* 337-344 */
			char prefix[155];	/* 345-499 */
			char padding[12];	/* 500-512 */
		} formated;
	} tar;
	file_header_t *tar_entry = NULL;
	long i;
	long sum = 0;

	if (archive_offset % 512 != 0) {
		seek_sub_file(tar_stream, 512 - (archive_offset % 512));
	}

	if (fread(tar.raw, 1, 512, tar_stream) != 512) {
		/* Unfortunatly its common for tar files to have all sorts of
		 * trailing garbage, fail silently */
//		error_msg("Couldnt read header");
		return(NULL);
	}
	archive_offset += 512;

	/* Check header has valid magic, unfortunately some tar files
	 * have empty (0'ed) tar entries at the end, which will
	 * cause this to fail, so fail silently for now
	 */
	if (strncmp(tar.formated.magic, "ustar", 5) != 0) {
		return(NULL);
	}

	/* Do checksum on headers */
	for (i =  0; i < 148 ; i++) {
		sum += tar.raw[i];
	}
	sum += ' ' * 8;
	for (i =  156; i < 512 ; i++) {
		sum += tar.raw[i];
	}
	if (sum != strtol(tar.formated.chksum, NULL, 8)) {
		error_msg("Invalid tar header checksum");
		return(NULL);
	}

	/* convert to type'ed variables */
	tar_entry = xcalloc(1, sizeof(file_header_t));
	tar_entry->name = xstrdup(tar.formated.name);

	parse_mode(tar.formated.mode, &tar_entry->mode);
	tar_entry->uid   = strtol(tar.formated.uid, NULL, 8);
	tar_entry->gid   = strtol(tar.formated.gid, NULL, 8);
	tar_entry->size  = strtol(tar.formated.size, NULL, 8);
	tar_entry->mtime = strtol(tar.formated.mtime, NULL, 8);
	tar_entry->link_name  = strlen(tar.formated.linkname) ? 
	    xstrdup(tar.formated.linkname) : NULL;
	tar_entry->device = (strtol(tar.formated.devmajor, NULL, 8) << 8) +
		strtol(tar.formated.devminor, NULL, 8);

	return(tar_entry);
}
#endif

#ifdef L_deb_extract
char *deb_extract(const char *package_filename, FILE *out_stream, 
	const int extract_function, const char *prefix, const char *filename)
{
	FILE *deb_stream;
	FILE *uncompressed_stream = NULL;
	file_header_t *ar_header = NULL;
	char **file_list = NULL;
	char *output_buffer = NULL;
	char *ared_file = NULL;
	char ar_magic[8];
	int gunzip_pid;

	if (filename != NULL) {
		file_list = xmalloc(sizeof(char *) * 2);
		file_list[0] = xstrdup(filename);
		file_list[1] = NULL;
	}
	
	if (extract_function & extract_control_tar_gz) {
		ared_file = xstrdup("control.tar.gz");
	}
	else if (extract_function & extract_data_tar_gz) {		
		ared_file = xstrdup("data.tar.gz");
	}

	/* open the debian package to be worked on */
	deb_stream = wfopen(package_filename, "r");
	if (deb_stream == NULL) {
		return(NULL);
	}
	/* set the buffer size */
	setvbuf(deb_stream, NULL, _IOFBF, 0x8000);

	/* check ar magic */
	fread(ar_magic, 1, 8, deb_stream);
	if (strncmp(ar_magic,"!<arch>",7) != 0) {
		error_msg_and_die("invalid magic");
	}
	archive_offset = 8;

	while ((ar_header = get_header_ar(deb_stream)) != NULL) {
		if (strcmp(ared_file, ar_header->name) == 0) {
			/* open a stream of decompressed data */
			uncompressed_stream = gz_open(deb_stream, &gunzip_pid);
			archive_offset = 0;
			output_buffer = unarchive(uncompressed_stream, out_stream, get_header_tar, extract_function, prefix, file_list);
		}
		seek_sub_file(deb_stream, ar_header->size);
	}
	gz_close(gunzip_pid);
	fclose(deb_stream);
	fclose(uncompressed_stream);
	free(ared_file);
	return(output_buffer);
}
#endif