tar: add support for PAX-encoded path=LONGFILENAME

function                                             old     new   delta
get_header_tar                                      1478    1759    +281

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

4 files changed, 46 insertions, 44 deletions

diff --git a/archival/libarchive/data_extract_all.c b/archival/libarchive/data_extract_all.c
index f565e5471..3f67b835f 100644
--- a/archival/libarchive/data_extract_all.c
+++ b/archival/libarchive/data_extract_all.c
@@ -13,13 +13,13 @@ void FAST_FUNC data_extract_all(archive_handle_t *archive_handle)
         int res;
 
 #if ENABLE_FEATURE_TAR_SELINUX
-        char *sctx = archive_handle->tar__next_file_sctx;
+        char *sctx = archive_handle->tar__sctx[PAX_NEXT_FILE];
         if (!sctx)
-                sctx = archive_handle->tar__global_sctx;
+                sctx = archive_handle->tar__sctx[PAX_GLOBAL];
         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;
+                free(archive_handle->tar__sctx[PAX_NEXT_FILE]);
+                archive_handle->tar__sctx[PAX_NEXT_FILE] = NULL;
         }
 #endif
 
diff --git a/archival/libarchive/data_extract_to_command.c b/archival/libarchive/data_extract_to_command.c
index cc2ff7798..a2ce33b51 100644
--- a/archival/libarchive/data_extract_to_command.c
+++ b/archival/libarchive/data_extract_to_command.c
@@ -64,13 +64,13 @@ void FAST_FUNC data_extract_to_command(archive_handle_t *archive_handle)
         file_header_t *file_header = archive_handle->file_header;
 
 #if 0 /* do we need this? ENABLE_FEATURE_TAR_SELINUX */
-        char *sctx = archive_handle->tar__next_file_sctx;
+        char *sctx = archive_handle->tar__sctx[PAX_NEXT_FILE];
         if (!sctx)
-                sctx = archive_handle->tar__global_sctx;
+                sctx = archive_handle->tar__sctx[PAX_GLOBAL];
         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;
+                free(archive_handle->tar__sctx[PAX_NEXT_FILE]);
+                archive_handle->tar__sctx[PAX_NEXT_FILE] = NULL;
         }
 #endif
 
diff --git a/archival/libarchive/get_header_tar.c b/archival/libarchive/get_header_tar.c
index a63c0fb01..8c699754b 100644
--- a/archival/libarchive/get_header_tar.c
+++ b/archival/libarchive/get_header_tar.c
@@ -90,23 +90,20 @@ static unsigned long long getOctal(char *str, int len)
 }
 #define GET_OCTAL(a) getOctal((a), sizeof(a))
 
-#if ENABLE_FEATURE_TAR_SELINUX
-/* Scan a PAX header for SELinux contexts, via "RHT.security.selinux" keyword.
- * This is what Red Hat's patched version of tar uses.
- */
-# define SELINUX_CONTEXT_KEYWORD "RHT.security.selinux"
-static char *get_selinux_sctx_from_pax_hdr(archive_handle_t *archive_handle, unsigned sz)
+/* "global" is 0 or 1 */
+static void process_pax_hdr(archive_handle_t *archive_handle, unsigned sz, int global)
 {
         char *buf, *p;
-        char *result;
+        unsigned blk_sz;
+
+        blk_sz = (sz + 511) & (~511);
+        p = buf = xmalloc(blk_sz + 1);
+        xread(archive_handle->src_fd, buf, blk_sz);
+        archive_handle->offset += blk_sz;
 
-        p = buf = xmalloc(sz + 1);
         /* prevent bb_strtou from running off the buffer */
         buf[sz] = '\0';
-        xread(archive_handle->src_fd, buf, sz);
-        archive_handle->offset += sz;
 
-        result = NULL;
         while (sz != 0) {
                 char *end, *value;
                 unsigned len;
@@ -133,19 +130,33 @@ static char *get_selinux_sctx_from_pax_hdr(archive_handle_t *archive_handle, uns
                  * (we do not bother to check that it *was* a newline)
                  */
                 p[-1] = '\0';
-                /* Is it selinux security context? */
                 value = end + 1;
+
+#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
+                if (!global && strncmp(value, "path=", sizeof("path=") - 1) == 0) {
+                        value += sizeof("path=") - 1;
+                        free(archive_handle->tar__longname);
+                        archive_handle->tar__longname = xstrdup(value);
+                        continue;
+                }
+#endif
+
+#if ENABLE_FEATURE_TAR_SELINUX
+                /* Scan for SELinux contexts, via "RHT.security.selinux" keyword.
+                 * This is what Red Hat's patched version of tar uses.
+                 */
+# define SELINUX_CONTEXT_KEYWORD "RHT.security.selinux"
                 if (strncmp(value, SELINUX_CONTEXT_KEYWORD"=", sizeof(SELINUX_CONTEXT_KEYWORD"=") - 1) == 0) {
                         value += sizeof(SELINUX_CONTEXT_KEYWORD"=") - 1;
-                        result = xstrdup(value);
-                        break;
+                        free(archive_handle->tar__sctx[global]);
+                        archive_handle->tar__sctx[global] = xstrdup(value);
+                        continue;
                 }
+#endif
         }
 
         free(buf);
-        return result;
 }
-#endif
 
 char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
 {
@@ -418,12 +429,14 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
         case 'S':       /* Sparse file */
         case 'V':       /* Volume header */
 #endif
-#if !ENABLE_FEATURE_TAR_SELINUX
         case 'g':       /* pax global header */
-        case 'x':       /* pax extended header */
-#else
+        case 'x': {     /* pax extended header */
+                if ((uoff_t)file_header->size > 0xfffff) /* paranoia */
+                        goto skip_ext_hdr;
+                process_pax_hdr(archive_handle, file_header->size, (tar.typeflag == 'g'));
+                goto again_after_align;
+        }
  skip_ext_hdr:
-#endif
         {
                 off_t sz;
                 bb_error_msg("warning: skipping header '%c'", tar.typeflag);
@@ -435,18 +448,6 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
                 /* return get_header_tar(archive_handle); */
                 goto again_after_align;
         }
-#if ENABLE_FEATURE_TAR_SELINUX
-        case 'g':       /* pax global header */
-        case 'x': {     /* pax extended header */
-                char **pp;
-                if ((uoff_t)file_header->size > 0xfffff) /* paranoia */
-                        goto skip_ext_hdr;
-                pp = (tar.typeflag == 'g') ? &archive_handle->tar__global_sctx : &archive_handle->tar__next_file_sctx;
-                free(*pp);
-                *pp = get_selinux_sctx_from_pax_hdr(archive_handle, file_header->size);
-                goto again;
-        }
-#endif
         default:
                 bb_error_msg_and_die("unknown typeflag: 0x%x", tar.typeflag);
         }
diff --git a/include/bb_archive.h b/include/bb_archive.h
index d1a9a34ec..4987de6cf 100644
--- a/include/bb_archive.h
+++ b/include/bb_archive.h
@@ -77,19 +77,20 @@ typedef struct archive_handle_t {
         off_t offset;
 
         /* Archiver specific. Can make it a union if it ever gets big */
+#define PAX_NEXT_FILE 0
+#define PAX_GLOBAL    1
 #if ENABLE_TAR || ENABLE_DPKG || ENABLE_DPKG_DEB
         smallint tar__end;
 # if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
         char* tar__longname;
         char* tar__linkname;
 # endif
-#if ENABLE_FEATURE_TAR_TO_COMMAND
+# if ENABLE_FEATURE_TAR_TO_COMMAND
         char* tar__to_command;
         const char* tar__to_command_shell;
-#endif
+# endif
 # if ENABLE_FEATURE_TAR_SELINUX
-        char* tar__global_sctx;
-        char* tar__next_file_sctx;
+        char* tar__sctx[2];
 # endif
 #endif
 #if ENABLE_CPIO || ENABLE_RPM2CPIO || ENABLE_RPM