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[Emacs-diffs] /srv/bzr/emacs/trunk r103643: Improve quality of tests for
From: |
Paul Eggert |
Subject: |
[Emacs-diffs] /srv/bzr/emacs/trunk r103643: Improve quality of tests for time stamp overflow. |
Date: |
Sat, 12 Mar 2011 22:43:00 -0800 |
User-agent: |
Bazaar (2.0.3) |
------------------------------------------------------------
revno: 103643 [merge]
committer: Paul Eggert <address@hidden>
branch nick: trunk
timestamp: Sat 2011-03-12 22:43:00 -0800
message:
Improve quality of tests for time stamp overflow.
modified:
src/ChangeLog
src/deps.mk
src/dired.c
src/editfns.c
src/systime.h
=== modified file 'src/ChangeLog'
--- a/src/ChangeLog 2011-03-12 19:19:47 +0000
+++ b/src/ChangeLog 2011-03-13 06:43:00 +0000
@@ -1,3 +1,35 @@
+2011-03-13 Paul Eggert <address@hidden>
+
+ Improve quality of tests for time stamp overflow.
+ For example, without this patch (encode-time 0 0 0 1 1
+ 1152921504606846976) returns the obviously-bogus value (-948597
+ 62170) on my RHEL 5.5 x86-64 host. With the patch, it correctly
+ reports time overflow. See
+ <http://lists.gnu.org/archive/html/emacs-devel/2011-03/msg00470.html>.
+ * deps.mk (editfns.o): Depend on ../lib/intprops.h.
+ * editfns.c: Include limits.h and intprops.h.
+ (TIME_T_MIN, TIME_T_MAX): New macros.
+ (time_overflow): Move earlier, to before first use.
+ (hi_time, lo_time): New functions, for an accurate test for
+ out-of-range times.
+ (Fcurrent_time, Fget_internal_run_time, make_time): Use them.
+ (Fget_internal_run_time): Don't assume time_t fits in int.
+ (make_time): Use list2 instead of Fcons twice.
+ (Fdecode_time): More accurate test for out-of-range times.
+ (check_tm_member): New function.
+ (Fencode_time): Use it, to test for out-of-range times.
+ (lisp_time_argument): Don't rely on undefined left-shift and
+ right-shift behavior when checking for time stamp overflow.
+
+ * editfns.c (time_overflow): New function, refactoring common code.
+ (Fformat_time_string, Fdecode_time, Fencode_time):
+ (Fcurrent_time_string): Use it.
+
+ Move 'make_time' to be next to its inverse 'lisp_time_argument'.
+ * dired.c (make_time): Move to ...
+ * editfns.c (make_time): ... here.
+ * systime.h: Note the move.
+
2011-03-12 YAMAMOTO Mitsuharu <address@hidden>
* fringe.c (update_window_fringes): Remove unused variables.
=== modified file 'src/deps.mk'
--- a/src/deps.mk 2011-03-12 12:03:24 +0000
+++ b/src/deps.mk 2011-03-13 06:43:00 +0000
@@ -87,7 +87,8 @@
msdos.h dosfns.h dispextern.h charset.h coding.h atimer.h systime.h \
lisp.h $(config_h)
editfns.o: editfns.c window.h buffer.h systime.h $(INTERVALS_H) character.h \
- coding.h frame.h blockinput.h atimer.h ../lib/unistd.h ../lib/strftime.h \
+ coding.h frame.h blockinput.h atimer.h \
+ ../lib/intprops.h ../lib/strftime.h ../lib/unistd.h \
lisp.h globals.h $(config_h)
emacs.o: emacs.c commands.h systty.h syssignal.h blockinput.h process.h \
termhooks.h buffer.h atimer.h systime.h $(INTERVALS_H) lisp.h $(config_h) \
=== modified file 'src/dired.c'
--- a/src/dired.c 2011-02-25 19:08:18 +0000
+++ b/src/dired.c 2011-03-11 20:24:09 +0000
@@ -848,13 +848,6 @@
return value;
}
-Lisp_Object
-make_time (time_t time)
-{
- return Fcons (make_number (time >> 16),
- Fcons (make_number (time & 0177777), Qnil));
-}
-
static char *
stat_uname (struct stat *st)
{
=== modified file 'src/editfns.c'
--- a/src/editfns.c 2011-02-28 01:07:29 +0000
+++ b/src/editfns.c 2011-03-13 06:27:18 +0000
@@ -45,6 +45,8 @@
#endif
#include <ctype.h>
+#include <limits.h>
+#include <intprops.h>
#include <strftime.h>
#include "intervals.h"
@@ -87,6 +89,7 @@
extern Lisp_Object w32_get_internal_run_time (void);
#endif
+static void time_overflow (void) NO_RETURN;
static int tm_diff (struct tm *, struct tm *);
static void find_field (Lisp_Object, Lisp_Object, Lisp_Object,
EMACS_INT *, Lisp_Object, EMACS_INT *);
@@ -1414,6 +1417,49 @@
return make_number (getpid ());
}
+
+
+#ifndef TIME_T_MIN
+# define TIME_T_MIN TYPE_MINIMUM (time_t)
+#endif
+#ifndef TIME_T_MAX
+# define TIME_T_MAX TYPE_MAXIMUM (time_t)
+#endif
+
+/* Report that a time value is out of range for Emacs. */
+static void
+time_overflow (void)
+{
+ error ("Specified time is not representable");
+}
+
+/* Return the upper part of the time T (everything but the bottom 16 bits),
+ making sure that it is representable. */
+static EMACS_INT
+hi_time (time_t t)
+{
+ time_t hi = t >> 16;
+
+ /* Check for overflow, helping the compiler for common cases where
+ no runtime check is needed, and taking care not to convert
+ negative numbers to unsigned before comparing them. */
+ if (! ((! TYPE_SIGNED (time_t)
+ || MOST_NEGATIVE_FIXNUM <= TIME_T_MIN >> 16
+ || MOST_NEGATIVE_FIXNUM <= hi)
+ && (TIME_T_MAX >> 16 <= MOST_POSITIVE_FIXNUM
+ || hi <= MOST_POSITIVE_FIXNUM)))
+ time_overflow ();
+
+ return hi;
+}
+
+/* Return the bottom 16 bits of the time T. */
+static EMACS_INT
+lo_time (time_t t)
+{
+ return t & ((1 << 16) - 1);
+}
+
DEFUN ("current-time", Fcurrent_time, Scurrent_time, 0, 0, 0,
doc: /* Return the current time, as the number of seconds since
1970-01-01 00:00:00.
The time is returned as a list of three integers. The first has the
@@ -1428,8 +1474,8 @@
EMACS_TIME t;
EMACS_GET_TIME (t);
- return list3 (make_number ((EMACS_SECS (t) >> 16) & 0xffff),
- make_number ((EMACS_SECS (t) >> 0) & 0xffff),
+ return list3 (make_number (hi_time (EMACS_SECS (t))),
+ make_number (lo_time (EMACS_SECS (t))),
make_number (EMACS_USECS (t)));
}
@@ -1448,7 +1494,8 @@
{
#ifdef HAVE_GETRUSAGE
struct rusage usage;
- int secs, usecs;
+ time_t secs;
+ int usecs;
if (getrusage (RUSAGE_SELF, &usage) < 0)
/* This shouldn't happen. What action is appropriate? */
@@ -1463,8 +1510,8 @@
secs++;
}
- return list3 (make_number ((secs >> 16) & 0xffff),
- make_number ((secs >> 0) & 0xffff),
+ return list3 (make_number (hi_time (secs)),
+ make_number (lo_time (secs)),
make_number (usecs));
#else /* ! HAVE_GETRUSAGE */
#ifdef WINDOWSNT
@@ -1476,6 +1523,19 @@
}
+/* Make a Lisp list that represents the time T. */
+Lisp_Object
+make_time (time_t t)
+{
+ return list2 (make_number (hi_time (t)),
+ make_number (lo_time (t)));
+}
+
+/* Decode a Lisp list SPECIFIED_TIME that represents a time.
+ If SPECIFIED_TIME is nil, use the current time.
+ Set *RESULT to seconds since the Epoch.
+ If USEC is not null, set *USEC to the microseconds component.
+ Return nonzero if successful. */
int
lisp_time_argument (Lisp_Object specified_time, time_t *result, int *usec)
{
@@ -1496,6 +1556,7 @@
else
{
Lisp_Object high, low;
+ EMACS_INT hi;
high = Fcar (specified_time);
CHECK_NUMBER (high);
low = Fcdr (specified_time);
@@ -1519,8 +1580,21 @@
else if (usec)
*usec = 0;
CHECK_NUMBER (low);
- *result = (XINT (high) << 16) + (XINT (low) & 0xffff);
- return *result >> 16 == XINT (high);
+ hi = XINT (high);
+
+ /* Check for overflow, helping the compiler for common cases
+ where no runtime check is needed, and taking care not to
+ convert negative numbers to unsigned before comparing them. */
+ if (! ((TYPE_SIGNED (time_t)
+ ? (TIME_T_MIN >> 16 <= MOST_NEGATIVE_FIXNUM
+ || TIME_T_MIN >> 16 <= hi)
+ : 0 <= hi)
+ && (MOST_POSITIVE_FIXNUM <= TIME_T_MAX >> 16
+ || hi <= TIME_T_MAX >> 16)))
+ return 0;
+
+ *result = (hi << 16) + (XINT (low) & 0xffff);
+ return 1;
}
}
@@ -1674,7 +1748,7 @@
tm = ut ? gmtime (&value) : localtime (&value);
UNBLOCK_INPUT;
if (! tm)
- error ("Specified time is not representable");
+ time_overflow ();
synchronize_system_time_locale ();
@@ -1732,8 +1806,10 @@
BLOCK_INPUT;
decoded_time = localtime (&time_spec);
UNBLOCK_INPUT;
- if (! decoded_time)
- error ("Specified time is not representable");
+ if (! (decoded_time
+ && MOST_NEGATIVE_FIXNUM - TM_YEAR_BASE <= decoded_time->tm_year
+ && decoded_time->tm_year <= MOST_POSITIVE_FIXNUM - TM_YEAR_BASE))
+ time_overflow ();
XSETFASTINT (list_args[0], decoded_time->tm_sec);
XSETFASTINT (list_args[1], decoded_time->tm_min);
XSETFASTINT (list_args[2], decoded_time->tm_hour);
@@ -1757,6 +1833,20 @@
return Flist (9, list_args);
}
+/* Return OBJ - OFFSET, checking that OBJ is a valid fixnum and that
+ the result is representable as an int. Assume OFFSET is small and
+ nonnegative. */
+static int
+check_tm_member (Lisp_Object obj, int offset)
+{
+ EMACS_INT n;
+ CHECK_NUMBER (obj);
+ n = XINT (obj);
+ if (! (INT_MIN + offset <= n && n - offset <= INT_MAX))
+ time_overflow ();
+ return n - offset;
+}
+
DEFUN ("encode-time", Fencode_time, Sencode_time, 6, MANY, 0,
doc: /* Convert SECOND, MINUTE, HOUR, DAY, MONTH, YEAR and ZONE to
internal time.
This is the reverse operation of `decode-time', which see.
@@ -1785,19 +1875,12 @@
struct tm tm;
Lisp_Object zone = (nargs > 6 ? args[nargs - 1] : Qnil);
- CHECK_NUMBER (args[0]); /* second */
- CHECK_NUMBER (args[1]); /* minute */
- CHECK_NUMBER (args[2]); /* hour */
- CHECK_NUMBER (args[3]); /* day */
- CHECK_NUMBER (args[4]); /* month */
- CHECK_NUMBER (args[5]); /* year */
-
- tm.tm_sec = XINT (args[0]);
- tm.tm_min = XINT (args[1]);
- tm.tm_hour = XINT (args[2]);
- tm.tm_mday = XINT (args[3]);
- tm.tm_mon = XINT (args[4]) - 1;
- tm.tm_year = XINT (args[5]) - TM_YEAR_BASE;
+ tm.tm_sec = check_tm_member (args[0], 0);
+ tm.tm_min = check_tm_member (args[1], 0);
+ tm.tm_hour = check_tm_member (args[2], 0);
+ tm.tm_mday = check_tm_member (args[3], 0);
+ tm.tm_mon = check_tm_member (args[4], 1);
+ tm.tm_year = check_tm_member (args[5], TM_YEAR_BASE);
tm.tm_isdst = -1;
if (CONSP (zone))
@@ -1846,7 +1929,7 @@
}
if (time == (time_t) -1)
- error ("Specified time is not representable");
+ time_overflow ();
return make_time (time);
}
@@ -1881,7 +1964,7 @@
tm = localtime (&value);
UNBLOCK_INPUT;
if (! (tm && TM_YEAR_IN_ASCTIME_RANGE (tm->tm_year) && (tem = asctime (tm))))
- error ("Specified time is not representable");
+ time_overflow ();
/* Remove the trailing newline. */
tem[strlen (tem) - 1] = '\0';
=== modified file 'src/systime.h'
--- a/src/systime.h 2011-01-25 04:08:28 +0000
+++ b/src/systime.h 2011-03-11 20:24:09 +0000
@@ -144,10 +144,8 @@
happen when this files is used outside the src directory).
Use GCPRO1 to determine if lisp.h was included. */
#ifdef GCPRO1
-/* defined in dired.c */
+/* defined in editfns.c*/
extern Lisp_Object make_time (time_t);
-
-/* defined in editfns.c*/
extern int lisp_time_argument (Lisp_Object, time_t *, int *);
#endif
@@ -172,4 +170,3 @@
#define EMACS_TIME_LE(T1, T2) (EMACS_TIME_CMP (T1, T2) <= 0)
#endif /* EMACS_SYSTIME_H */
-
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