From b8d9bd41b7daaa35de8335b20af145a808ae9b07 Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Fri, 11 Mar 2011 22:49:53 -0800 Subject: [PATCH] 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 it, it reports time overflow. * 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. --- src/ChangeLog | 19 ++++++++++ src/deps.mk | 3 +- src/editfns.c | 99 ++++++++++++++++++++++++++++++++++++--------------- 3 files changed, 92 insertions(+), 29 deletions(-) diff --git a/src/ChangeLog b/src/ChangeLog index a0c4941ec1..b3362b9fbc 100644 --- a/src/ChangeLog +++ b/src/ChangeLog @@ -1,3 +1,22 @@ +2011-03-12 Paul Eggert + + 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 it, it reports time overflow. + * 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. + 2011-03-11 Paul Eggert * editfns.c (time_overflow): New function, refactoring common code. diff --git a/src/deps.mk b/src/deps.mk index 2b162b07bb..fba856c1be 100644 --- a/src/deps.mk +++ b/src/deps.mk @@ -87,7 +87,8 @@ dosfns.o: buffer.h termchar.h termhooks.h frame.h blockinput.h window.h \ 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) \ diff --git a/src/editfns.c b/src/editfns.c index fe8541f718..4e8ac316a8 100644 --- a/src/editfns.c +++ b/src/editfns.c @@ -45,6 +45,8 @@ along with GNU Emacs. If not, see . */ #endif #include +#include +#include #include #include "intervals.h" @@ -1415,6 +1417,44 @@ DEFUN ("emacs-pid", Femacs_pid, Semacs_pid, 0, 0, 0, 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; + if (((TYPE_SIGNED (time_t) + && TIME_T_MIN >> 16 < MOST_NEGATIVE_FIXNUM + && hi < MOST_NEGATIVE_FIXNUM) + || (MOST_POSITIVE_FIXNUM < TIME_T_MAX >> 16 + && MOST_POSITIVE_FIXNUM < hi))) + 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 @@ -1429,8 +1469,8 @@ resolution finer than a second. */) 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))); } @@ -1449,7 +1489,8 @@ on systems that do not provide resolution finer than a second. */) { #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? */ @@ -1464,8 +1505,8 @@ on systems that do not provide resolution finer than a second. */) 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 @@ -1477,19 +1518,12 @@ on systems that do not provide resolution finer than a second. */) } -/* Report a time value that is out of range for Emacs. */ -static void -time_overflow (void) -{ - error ("Specified time is not representable"); -} - /* Make a Lisp list that represents the time T. */ Lisp_Object make_time (time_t t) { - return Fcons (make_number (t >> 16), - Fcons (make_number (t & 0177777), Qnil)); + return list2 (make_number (hi_time (t)), + make_number (lo_time (t))); } /* Decode a Lisp list SPECIFIED_TIME that represents a time. @@ -1753,7 +1787,9 @@ DOW and ZONE.) */) BLOCK_INPUT; decoded_time = localtime (&time_spec); UNBLOCK_INPUT; - if (! decoded_time) + 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); @@ -1778,6 +1814,20 @@ DOW and ZONE.) */) 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. @@ -1806,19 +1856,12 @@ usage: (encode-time SECOND MINUTE HOUR DAY MONTH YEAR &optional ZONE) */) 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)) -- 2.20.1