(from_header): Handle 32-bit two's complement negative time stamps

even if the leading octal digit is 2 or 3.

diff --git a/src/list.c b/src/list.c
index ad0aba0d711b93b323e0e15718898abc5bc50a03..6b69bc6c19ea745fcba2bd6cdc7a3ec0779d4511 100644 (file)
--- a/src/list.c
+++ b/src/list.c
@@ -565,16 +565,25 @@ from_header (char const *where0, size_t digs, char const *type,
        }
 
       /* Parse the output of older, unportable tars, which generate
-        negative values in two's complement octal.  */
-      if ((overflow || maxval < value) && '4' <= *where1)
+         negative values in two's complement octal.  If the leading
+         nonzero digit is 1, we can't recover the original value
+         reliably; so do this only if the digit is 2 or more.  This
+         catches the common case of 32-bit negative time stamps.  */
+      if ((overflow || maxval < value) && '2' <= *where1)
        {
          /* Compute the negative of the input value, assuming two's
             complement.  */
-         for (value = 0, where = where1, overflow = 0; ; )
+         int digit = (*where1 - '0') | 4;
+         overflow = 0;
+         value = 0;
+         where = where1;
+         for (;;)
            {
-             value += 7 - (*where++ - '0');
+             value += 7 - digit;
+             where++;
              if (where == lim || ! ISODIGIT (*where))
                break;
+             digit = *where - '0';
              overflow |= value ^ (value << LG_8 >> LG_8);
              value <<= LG_8;
            }