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

7 files changed, 99 insertions, 105 deletions

diff --git a/TODO_config_nommu b/TODO_config_nommu
index 42d17314a..7fdec69bd 100644
--- a/TODO_config_nommu
+++ b/TODO_config_nommu
@@ -130,7 +130,6 @@ CONFIG_UNZIP=y
 #
 # Common options for cpio and tar
 #
-CONFIG_FEATURE_UNARCHIVE_TAPE=y
 
 #
 # Common options for dpkg and dpkg_deb
diff --git a/archival/Config.in b/archival/Config.in
index 28450612e..35ac40bb7 100644
--- a/archival/Config.in
+++ b/archival/Config.in
@@ -307,13 +307,6 @@ config UNZIP
 comment "Common options for cpio and tar"
         depends on CPIO || TAR
 
-config FEATURE_UNARCHIVE_TAPE
-        bool "Enable tape drive support"
-        default n
-        depends on CPIO || TAR
-        help
-          I don't think this is needed anymore.
-
 comment "Common options for dpkg and dpkg_deb"
         depends on DPKG || DPKG_DEB
 
diff --git a/archival/cpio.c b/archival/cpio.c
index dd9ed756c..2919ff8de 100644
--- a/archival/cpio.c
+++ b/archival/cpio.c
@@ -171,9 +171,7 @@ static int cpio_o(void)
                                 int fd = xopen(name, O_RDONLY);
                                 fflush(stdout);
                                 /* We must abort if file got shorter too! */
-                                if (bb_copyfd_size(fd, STDOUT_FILENO, st.st_size) != st.st_size) {
-                                        bb_error_msg_and_die("I/O error or file '%s' was truncated", name);
-                                }
+                                bb_copyfd_exact_size(fd, STDOUT_FILENO, st.st_size);
                                 bytes += st.st_size;
                                 close(fd);
                         }
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");
         }
 }
diff --git a/scripts/defconfig b/scripts/defconfig
index c24d85242..26cc8d25d 100644
--- a/scripts/defconfig
+++ b/scripts/defconfig
@@ -130,7 +130,6 @@ CONFIG_UNZIP=y
 #
 # Common options for cpio and tar
 #
-CONFIG_FEATURE_UNARCHIVE_TAPE=y
 # CONFIG_FEATURE_DEB_TAR_GZ is not set
 # CONFIG_FEATURE_DEB_TAR_BZ2 is not set
 # CONFIG_FEATURE_DEB_TAR_LZMA is not set