Fix some problems with negative and out-of-range integers.

Original problem reported for HP-UX LVM v2.2 by Michael White in
<http://lists.gnu.org/archive/html/bug-tar/2012-10/msg00000.html>.
This patch fixes some other gotchas that I noticed.
* gnulib.modules: Add extern-inline.
* src/common.h: Use _GL_INLINE_HEADER_BEGIN, _GL_INLINE_HEADER_END.
(COMMON_INLINE, max, min): New macros.
(represent_uintmax, valid_timespec): New inline functions.
(SYSINT_BUFSIZE): New constant.
(sysinttostr, strtosysint, decode_timespec): New decls.
* src/create.c (start_private_header): Silently bring the time_t
value into range; it is now the caller's responsibility to deal
with any overflow error.  Use uid 0 and gid 0 rather than the
user's uid/gid, since the faked header isn't "owned" by the user
and the uid/gid could in theory be out of range.  Leave major and
minor zeroed.
(FILL): Remove.
(write_gnu_long_link): Let start_private_header zero things out.
* src/create.c (write_gnu_long_link, write_extended):
* src/xheader.c (xheader_write_global):
Use start_time, not current time; no point hammering on the clock.
* src/compare.c (diff_multivol): Check that offset, size are in range.
* src/incremen.c (read_incr_db_01, write_directory_file_entry):
Allow negative time_t, dev_t, and ino_t.
* src/list.c (max): Remove (moved to common.h).
(read_header): Check that size is in range.
(from_header): Return intmax_t, not uintmax_t, to allow negative.
All callers changed.  At compile time, check assumptions about
intmax_t and uintmax_t.  Use bool for booleans.  Avoid overflow
hassles on picky hosts.
(mode_from_header): Last arg is now bool *, not unsigned *.
All callers changed.
(simple_print_header): Do not assume UID, GID fit in 'long'.
* src/list.c (from_header):
* src/xheader.c (out_of_range_header):
Arg is now a plain minimum value, not minus minval converted to
uintmax_t.  All callers changed.
* src/misc.c (COMMON_INLINE): New macro.
(sysinttostr, strtosysint, decode_timespec): New functions.
* src/sparse.c (oldgnu_add_sparse, oldgnu_fixup_header)
(star_fixup_header):
Check for offset overflow.
(decode_num): Clear errno before calling strtoumax.
* src/tar.c (expand_pax_option): Don't discard nanoseconds.
* src/xheader.c (assign_time_option): Allow negative time_t.
(decode_record): Simplify, since out-of-range string is guaranteed
to produce a value exceeding len_max.
(xheader_read): Last arg is off_t, not size_t.
Caller should diagnose negative arg, as needed.
Check that it's in range.
(enum decode_time_status): Remove.
(_decode_time): Remove, folding into decode_time.
(decode_time): Return bool, not enum decode_time_status.
Rely on decode_timespec to do most of the work.
(code_signed_num): New function.
(code_num): Use it.
(decode_signed_num): New function.
(decode_num): Use it.
(gid_coder, gid_decoder, uid_coder, uid_decoder, sparse_map_decoder)
(sparse_map_decoder): Code and decode negative values.
(sparse_map_decoder): Improve check for out-of-range values.
* tests/time01.at: New file.
* tests/Makefile.am (TESTSUITE_AT): Add it.
* tests/testsuite.at: Include it.

src/create.c

@@ -512,12 +512,11 @@ start_private_header (const char *name, size_t size, time_t t)
   tar_name_copy_str (header->header.name, name, NAME_FIELD_SIZE);
   OFF_TO_CHARS (size, header->header.size);
 
-  TIME_TO_CHARS (t, header->header.mtime);
+  TIME_TO_CHARS (t < 0 ? 0 : min (t, MAX_OCTAL_VAL (header->header.mtime)),
+		 header->header.mtime);
   MODE_TO_CHARS (S_IFREG|S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH, header->header.mode);
-  UID_TO_CHARS (getuid (), header->header.uid);
-  GID_TO_CHARS (getgid (), header->header.gid);
-  MAJOR_TO_CHARS (0, header->header.devmajor);
-  MINOR_TO_CHARS (0, header->header.devminor);
+  UID_TO_CHARS (0, header->header.uid);
+  GID_TO_CHARS (0, header->header.gid);
   strncpy (header->header.magic, TMAGIC, TMAGLEN);
   strncpy (header->header.version, TVERSION, TVERSLEN);
   return header;
@@ -535,11 +534,6 @@ write_short_name (struct tar_stat_info *st)
   return header;
 }
 
-#define FILL(field,byte) do {            \
-  memset(field, byte, sizeof(field)-1);  \
-  (field)[sizeof(field)-1] = 0;          \
-} while (0)
-
 /* Write a GNUTYPE_LONGLINK or GNUTYPE_LONGNAME block.  */
 static void
 write_gnu_long_link (struct tar_stat_info *st, const char *p, char type)
@@ -549,13 +543,7 @@ write_gnu_long_link (struct tar_stat_info *st, const char *p, char type)
   union block *header;
   char *tmpname;
 
-  header = start_private_header ("././@LongLink", size, time (NULL));
-  FILL (header->header.mtime, '0');
-  FILL (header->header.mode, '0');
-  FILL (header->header.uid, '0');
-  FILL (header->header.gid, '0');
-  FILL (header->header.devmajor, 0);
-  FILL (header->header.devminor, 0);
+  header = start_private_header ("././@LongLink", size, start_time.tv_sec);
   uid_to_uname (0, &tmpname);
   UNAME_TO_CHARS (tmpname, header->header.uname);
   free (tmpname);
@@ -712,7 +700,7 @@ write_extended (bool global, struct tar_stat_info *st, union block *old_header)
     {
       type = XGLTYPE;
       p = xheader_ghdr_name ();
-      time (&t);
+      t = start_time.tv_sec;
     }
   else
     {