Improve compression format recognition

[chaz/tar] / src / buffer.c

diff --git a/src/buffer.c b/src/buffer.c
index 95e8a26de1e42a5b2b922300c57dbd3e22db25f0..1a96595d9a982168d1da56f53863fdd6ee069f11 100644 (file)
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -391,7 +391,10 @@ check_compressed_archive (bool *pshort)
   /* Restore global values */
   read_full_records = sfr;
 
-  if (tar_checksum (record_start, true) == HEADER_SUCCESS)
+  if ((strcmp (record_start->header.magic, TMAGIC) == 0 ||
+       strcmp (record_start->buffer + offsetof (struct posix_header, magic),
+              OLDGNU_MAGIC) == 0) &&
+      tar_checksum (record_start, true) == HEADER_SUCCESS)
     /* Probably a valid header */
     return ct_tar;
 
@@ -668,6 +671,22 @@ init_buffer (void)
   record_end = record_start + blocking_factor;
 }
 
+static void
+check_tty (enum access_mode mode)
+{
+  /* Refuse to read archive from and write it to a tty. */
+  if (strcmp (archive_name_array[0], "-") == 0
+      && isatty (mode == ACCESS_READ ? STDIN_FILENO : STDOUT_FILENO))
+    {
+      FATAL_ERROR ((0, 0,
+                   mode == ACCESS_READ
+                   ? _("Refusing to read archive contents from terminal "
+                       "(missing -f option?)")
+                   : _("Refusing to write archive contents to terminal "
+                       "(missing -f option?)")));
+    }
+}
+
 /* Open an archive file.  The argument specifies whether we are
    reading or writing, or both.  */
 static void
@@ -688,6 +707,7 @@ _open_archive (enum access_mode wanted_access)
 
   /* When updating the archive, we start with reading.  */
   access_mode = wanted_access == ACCESS_UPDATE ? ACCESS_READ : wanted_access;
+  check_tty (access_mode);
 
   read_full_records = read_full_records_option;
 
@@ -731,7 +751,6 @@ _open_archive (enum access_mode wanted_access)
             enum compress_type type;
 
             archive = STDIN_FILENO;
-
             type = check_compressed_archive (&shortfile);
             if (type != ct_tar && type != ct_none)
               FATAL_ERROR ((0, 0,