cpio: fix a bug where we do not extract zero-sized hardlinks

(spotted at http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=466771).
Add testsuite entry for that, and another one for another bug:
we do not list hardlinks in cpio -t (not fixed).

function                                             old     new   delta
get_header_cpio                                      884     909     +25
static.saved_hardlinks_created                         -       4      +4
static.pending_hardlinks                               4       -      -4
static.inode                                           4       -      -4
cpio_main                                           1122    1060     -62

3 files changed, 98 insertions, 93 deletions

diff --git a/archival/libunarchive/data_extract_all.c b/archival/libunarchive/data_extract_all.c
index 4df9c09a7..29a224bbc 100644
--- a/archival/libunarchive/data_extract_all.c
+++ b/archival/libunarchive/data_extract_all.c
@@ -20,7 +20,7 @@ void data_extract_all(archive_handle_t *archive_handle)
 
 	/* Check if the file already exists */
 	if (archive_handle->flags & ARCHIVE_EXTRACT_UNCONDITIONAL) {
-		/* Remove the existing entry if it exists */
+		/* Remove the entry if it exists */
 		if (((file_header->mode & S_IFMT) != S_IFDIR)
 		 && (unlink(file_header->name) == -1)
 		 && (errno != ENOENT)
diff --git a/archival/libunarchive/get_header_cpio.c b/archival/libunarchive/get_header_cpio.c
index 3f5135512..b97b53b20 100644
--- a/archival/libunarchive/get_header_cpio.c
+++ b/archival/libunarchive/get_header_cpio.c
@@ -8,70 +8,32 @@
 #include "unarchive.h"
 
 typedef struct hardlinks_s {
-	char *name;
-	int inode;
 	struct hardlinks_s *next;
+	int inode; /* TODO: must match maj/min too! */
+	int mode ;
+	int mtime; /* These three are useful only in corner case */
+	int uid  ; /* of hardlinks with zero size body */
+	int gid  ;
+	char name[1];
 } hardlinks_t;
 
 char get_header_cpio(archive_handle_t *archive_handle)
 {
 	static hardlinks_t *saved_hardlinks = NULL;
-	static unsigned pending_hardlinks = 0;
-	static int inode;
+	static hardlinks_t *saved_hardlinks_created = NULL;
 
 	file_header_t *file_header = archive_handle->file_header;
 	char cpio_header[110];
-	int namesize;
 	char dummy[16];
-	int major, minor, nlink;
-
-	if (pending_hardlinks) { /* Deal with any pending hardlinks */
-		hardlinks_t *tmp, *oldtmp;
-
-		tmp = saved_hardlinks;
-		oldtmp = NULL;
-
-		file_header->link_target = file_header->name;
-		file_header->size = 0;
-
-		while (tmp) {
-			if (tmp->inode != inode) {
-				tmp = tmp->next;
-				continue;
-			}
-
-			file_header->name = tmp->name;
-
-			if (archive_handle->filter(archive_handle) == EXIT_SUCCESS) {
-				archive_handle->action_data(archive_handle);
-				archive_handle->action_header(archive_handle->file_header);
-			}
-
-			pending_hardlinks--;
-
-			oldtmp = tmp;
-			tmp = tmp->next;
-			free(oldtmp->name);
-			free(oldtmp);
-			if (oldtmp == saved_hardlinks)
-				saved_hardlinks = tmp;
-		}
-
-		file_header->name = file_header->link_target;
-
-		if (pending_hardlinks > 1) {
-			bb_error_msg("error resolving hardlink: archive made by GNU cpio 2.0-2.2?");
-		}
-
-		/* No more pending hardlinks, read next file entry */
-		pending_hardlinks = 0;
-	}
+	int namesize;
+	int major, minor, nlink, mode, inode;
+	unsigned size, uid, gid, mtime;
 
 	/* There can be padding before archive header */
 	data_align(archive_handle, 4);
 
 	if (archive_xread_all_eof(archive_handle, (unsigned char*)cpio_header, 110) == 0) {
-		return EXIT_FAILURE;
+		goto create_hardlinks;
 	}
 	archive_handle->offset += 110;
 
@@ -81,17 +43,19 @@ char get_header_cpio(archive_handle_t *archive_handle)
 		bb_error_msg_and_die("unsupported cpio format, use newc or crc");
 	}
 
-	{
-		unsigned long tmpsize;
-		sscanf(cpio_header, "%6c%8x%8x%8x%8x%8x%8lx%8lx%16c%8x%8x%8x%8c",
-		    dummy, &inode, (unsigned int*)&file_header->mode,
-		    (unsigned int*)&file_header->uid, (unsigned int*)&file_header->gid,
-		    &nlink, &file_header->mtime, &tmpsize,
-		    dummy, &major, &minor, &namesize, dummy);
-		file_header->size = tmpsize;
-	}
+	sscanf(cpio_header + 6,
+			"%8x" "%8x" "%8x" "%8x"
+			"%8x" "%8x" "%8x" /*maj,min:*/ "%16c"
+			/*rmaj,rmin:*/"%8x" "%8x" "%8x" /*chksum:*/ "%8c",
+			&inode, &mode, &uid, &gid,
+			&nlink, &mtime, &size, dummy,
+			&major, &minor, &namesize, dummy);
+	file_header->mode = mode;
+	file_header->uid = uid;
+	file_header->gid = gid;
+	file_header->mtime = mtime;
+	file_header->size = size;
 
-	free(file_header->name);
 	file_header->name = xzalloc(namesize + 1);
 	/* Read in filename */
 	xread(archive_handle->src_fd, file_header->name, namesize);
@@ -101,25 +65,9 @@ char get_header_cpio(archive_handle_t *archive_handle)
 	data_align(archive_handle, 4);
 
 	if (strcmp(file_header->name, "TRAILER!!!") == 0) {
-		/* Always round up */
-		printf("%d blocks\n", (int) (archive_handle->offset % 512 ?
-		                             archive_handle->offset / 512 + 1 :
-		                             archive_handle->offset / 512
-		                            ));
-		if (saved_hardlinks) { /* Bummer - we still have unresolved hardlinks */
-			hardlinks_t *tmp = saved_hardlinks;
-			hardlinks_t *oldtmp = NULL;
-			while (tmp) {
-				bb_error_msg("%s not created: cannot resolve hardlink", tmp->name);
-				oldtmp = tmp;
-				tmp = tmp->next;
-				free(oldtmp->name);
-				free(oldtmp);
-			}
-			saved_hardlinks = NULL;
-			pending_hardlinks = 0;
-		}
-		return EXIT_FAILURE;
+		/* Always round up. ">> 9" divides by 512 */
+		printf("%"OFF_FMT"u blocks\n", (archive_handle->offset + 511) >> 9);
+		goto create_hardlinks;
 	}
 
 	if (S_ISLNK(file_header->mode)) {
@@ -130,25 +78,33 @@ char get_header_cpio(archive_handle_t *archive_handle)
 	} else {
 		file_header->link_target = NULL;
 	}
-	if (nlink > 1 && !S_ISDIR(file_header->mode)) {
-		if (file_header->size == 0) { /* Put file on a linked list for later */
-			hardlinks_t *new = xmalloc(sizeof(hardlinks_t));
+
+// TODO: data_extract_all can't deal with hardlinks to non-files...
+// (should be !S_ISDIR instead of S_ISREG here)
+
+	if (nlink > 1 && S_ISREG(file_header->mode)) {
+		hardlinks_t *new = xmalloc(sizeof(*new) + namesize);
+		new->inode = inode;
+		new->mode  = mode ;
+		new->mtime = mtime;
+		new->uid   = uid  ;
+		new->gid   = gid  ;
+		strcpy(new->name, file_header->name);
+		/* Put file on a linked list for later */
+		if (size == 0) {
 			new->next = saved_hardlinks;
-			new->inode = inode;
-			/* name current allocated, freed later */
-			new->name = file_header->name;
-			file_header->name = NULL;
 			saved_hardlinks = new;
 			return EXIT_SUCCESS; /* Skip this one */
+			/* TODO: this breaks cpio -t (it does not show hardlinks) */
 		}
-		/* Found the file with data in */
-		pending_hardlinks = nlink;
+		new->next = saved_hardlinks_created;
+		saved_hardlinks_created = new;
 	}
 	file_header->device = makedev(major, minor);
 
 	if (archive_handle->filter(archive_handle) == EXIT_SUCCESS) {
 		archive_handle->action_data(archive_handle);
-		archive_handle->action_header(archive_handle->file_header);
+		archive_handle->action_header(file_header);
 	} else {
 		data_skip(archive_handle);
 	}
@@ -156,6 +112,57 @@ char get_header_cpio(archive_handle_t *archive_handle)
 	archive_handle->offset += file_header->size;
 
 	free(file_header->link_target);
+	free(file_header->name);
+	file_header->link_target = NULL;
+	file_header->name = NULL;
 
 	return EXIT_SUCCESS;
+
+ create_hardlinks:
+	free(file_header->link_target);
+	free(file_header->name);
+
+	while (saved_hardlinks) {
+		hardlinks_t *cur;
+		hardlinks_t *make_me = saved_hardlinks;
+		saved_hardlinks = make_me->next;
+
+		memset(file_header, 0, sizeof(*file_header));
+		file_header->name = make_me->name;
+		file_header->mode = make_me->mode;
+		/*file_header->size = 0;*/
+
+		/* Try to find a file we are hardlinked to */
+		cur = saved_hardlinks_created;
+		while (cur) {
+			/* TODO: must match maj/min too! */
+			if (cur->inode == make_me->inode) {
+				file_header->link_target = cur->name;
+				 /* link_target != NULL, size = 0: "I am a hardlink" */
+				if (archive_handle->filter(archive_handle) == EXIT_SUCCESS)
+					archive_handle->action_data(archive_handle);
+				free(make_me);
+				goto next_link;
+			}
+		}
+		/* Oops... no file with such inode was created... do it now
+		 * (happens when hardlinked files are empty (zero length)) */
+		file_header->mtime = make_me->mtime;
+		file_header->uid   = make_me->uid  ;
+		file_header->gid   = make_me->gid  ;
+		if (archive_handle->filter(archive_handle) == EXIT_SUCCESS)
+			archive_handle->action_data(archive_handle);
+		/* Move to the list of created hardlinked files */
+		make_me->next = saved_hardlinks_created;
+		saved_hardlinks_created = make_me;
+ next_link: ;
+	}
+
+	while (saved_hardlinks_created) {
+		hardlinks_t *p = saved_hardlinks_created;
+		saved_hardlinks_created = p->next;
+		free(p);
+	}
+
+	return EXIT_FAILURE; /* "No more files to process" */
 }
diff --git a/archival/libunarchive/seek_by_jump.c b/archival/libunarchive/seek_by_jump.c
index 8b5f3e887..5288c1d73 100644
--- a/archival/libunarchive/seek_by_jump.c
+++ b/archival/libunarchive/seek_by_jump.c
@@ -9,11 +9,9 @@
 void seek_by_jump(const archive_handle_t *archive_handle, unsigned amount)
 {
 	if (lseek(archive_handle->src_fd, (off_t) amount, SEEK_CUR) == (off_t) -1) {
-#if ENABLE_FEATURE_UNARCHIVE_TAPE
-		if (errno == ESPIPE) {
+		if (errno == ESPIPE)
 			seek_by_read(archive_handle, amount);
-		} else
-#endif
+		else
 			bb_perror_msg_and_die("seek failure");
 	}
 }