Paul Eggert wrote:
> > On NetBSD, tzalloc() is in libc, and tzalloc("\\") returns NULL.
> > On other platforms, tzalloc() comes from Gnulib, and tzalloc("\\") returns
> > non-NULL.
> >
> > Which behaviour is correct?
>
> Both. The set of supported TZ values is system-dependent.
OK, then we need to
- conditionally disable the respective parts of the parse-datetime test
(done through patch 1 below),
- update the documentation of tzalloc to clarify that it may return NULL
for arguments that the implementation considers as invalid.
(done through patch 2 below).
I also took the opportunity to move the documentation of the 'time_rz'
module from the module description to the .h file. Why?
- Because the usual places where people look for reference documentation are
the manual and the .h files. They don't look in the module description.
- Because the reference documentation refers to arguments of these functions,
by name. One cannot understand the documentation if the function
declarations are far away.
Another thing: The module summary reads
Reentrant time zone functions: localtime_rz, mktime_z, etc.
What does the word "reentrant" mean here? Since the functions localtime_rz,
mktime_z don't invoke themselves recursively with a different time zone
argument, nor do they take function pointer parameters (callback), I think
"reentrant" means nothing here.
A close term is "multithread-safe". The API could be implemented in a
multithread-safe way, but time_rz.c is not multithread-safe, due to the
function 'change_env'.
It is planned to provide a multithread-safe implementation at some point?
Bruno
>From 35f8ff2e1162bf3ee60d99b6812f2ae10f3f2898 Mon Sep 17 00:00:00 2001
From: Bruno Haible <[email protected]>
Date: Sun, 14 Mar 2021 19:19:07 +0100
Subject: [PATCH 1/2] parse-datetime tests: Avoid a test failure on NetBSD.
Reported by Thomas Klausner <[email protected]> in
<https://lists.gnu.org/archive/html/bug-gnulib/2021-03/msg00069.html>.
* tests/test-parse-datetime.c (main): Skip two tests on NetBSD.
---
ChangeLog | 7 +++++++
tests/test-parse-datetime.c | 4 ++++
2 files changed, 11 insertions(+)
diff --git a/ChangeLog b/ChangeLog
index a5ba848..63aaa7b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2021-03-14 Bruno Haible <[email protected]>
+
+ parse-datetime tests: Avoid a test failure on NetBSD.
+ Reported by Thomas Klausner <[email protected]> in
+ <https://lists.gnu.org/archive/html/bug-gnulib/2021-03/msg00069.html>.
+ * tests/test-parse-datetime.c (main): Skip two tests on NetBSD.
+
2021-03-10 Paul Eggert <[email protected]>
libc-config: port to DragonFlyBSD 5.9
diff --git a/tests/test-parse-datetime.c b/tests/test-parse-datetime.c
index acca47c..b972e96 100644
--- a/tests/test-parse-datetime.c
+++ b/tests/test-parse-datetime.c
@@ -431,8 +431,12 @@ main (int argc _GL_UNUSED, char **argv)
ASSERT ( parse_datetime (&result, "TZ=\"\"", &now));
ASSERT ( parse_datetime (&result, "TZ=\"\" ", &now));
ASSERT ( parse_datetime (&result, " TZ=\"\"", &now));
+ /* Exercise patterns which may be valid or invalid, depending on the
+ platform. */
+#if !defined __NetBSD__
ASSERT ( parse_datetime (&result, "TZ=\"\\\\\"", &now));
ASSERT ( parse_datetime (&result, "TZ=\"\\\"\"", &now));
+#endif
/* Outlandishly-long time zone abbreviations should not cause problems. */
{
--
2.7.4
>From 02a474ef457f470776031b3cc38ee6e891dbff17 Mon Sep 17 00:00:00 2001
From: Bruno Haible <[email protected]>
Date: Sun, 14 Mar 2021 19:22:07 +0100
Subject: [PATCH 2/2] time_rz: Put reference documentation into the .h file.
* lib/time.in.h (timezone_t, tzalloc, tzfree, localtime_rz, mktime_z):
Add comments, based on modules/time_rz.
* modules/time_rz (Comment): Remove section.
---
ChangeLog | 7 +++++++
lib/time.in.h | 42 ++++++++++++++++++++++++++++++++++++++++--
modules/time_rz | 11 -----------
3 files changed, 47 insertions(+), 13 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 63aaa7b..b71c327 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
2021-03-14 Bruno Haible <[email protected]>
+ time_rz: Put reference documentation into the .h file.
+ * lib/time.in.h (timezone_t, tzalloc, tzfree, localtime_rz, mktime_z):
+ Add comments, based on modules/time_rz.
+ * modules/time_rz (Comment): Remove section.
+
+2021-03-14 Bruno Haible <[email protected]>
+
parse-datetime tests: Avoid a test failure on NetBSD.
Reported by Thomas Klausner <[email protected]> in
<https://lists.gnu.org/archive/html/bug-gnulib/2021-03/msg00069.html>.
diff --git a/lib/time.in.h b/lib/time.in.h
index 4da1172..44483d0 100644
--- a/lib/time.in.h
+++ b/lib/time.in.h
@@ -340,22 +340,60 @@ _GL_CXXALIASWARN (strftime);
# endif
# if defined _GNU_SOURCE && @GNULIB_TIME_RZ@ && ! @HAVE_TIMEZONE_T@
+/* Functions that use a first-class time zone data type, instead of
+ relying on an implicit global time zone.
+ Inspired by NetBSD. */
+
+/* Represents a time zone.
+ (timezone_t) NULL stands for UTC. */
typedef struct tm_zone *timezone_t;
+
+/* tzalloc (name)
+ Returns a time zone object for the given time zone NAME. This object
+ represents the time zone that other functions would use it the TZ
+ environment variable was set to NAME.
+ If NAME is NULL, the result represents the time zone that other functions
+ would use it the TZ environment variable was unset.
+ May return NULL if NAME is invalid (this is platform dependent) or
+ upon memory allocation failure. */
_GL_FUNCDECL_SYS (tzalloc, timezone_t, (char const *__name));
_GL_CXXALIAS_SYS (tzalloc, timezone_t, (char const *__name));
+
+/* tzfree (tz)
+ Frees a time zone object.
+ The argument must have been returned by tzalloc(). */
_GL_FUNCDECL_SYS (tzfree, void, (timezone_t __tz));
_GL_CXXALIAS_SYS (tzfree, void, (timezone_t __tz));
+
+/* localtime_rz (tz, &t, &result)
+ Converts an absolute time T to a broken-down time RESULT, assuming the
+ time zone TZ.
+ This function is like 'localtime_r', but relies on the argument TZ instead
+ of an implicit global time zone. */
_GL_FUNCDECL_SYS (localtime_rz, struct tm *,
(timezone_t __tz, time_t const *restrict __timer,
struct tm *restrict __result) _GL_ARG_NONNULL ((2, 3)));
_GL_CXXALIAS_SYS (localtime_rz, struct tm *,
(timezone_t __tz, time_t const *restrict __timer,
struct tm *restrict __result));
+
+/* mktime_z (tz, &tm)
+ Normalizes the broken-down time TM and converts it to an absolute time,
+ assuming the time zone TZ. Returns the absolute time.
+ This function is like 'mktime', but relies on the argument TZ instead
+ of an implicit global time zone. */
_GL_FUNCDECL_SYS (mktime_z, time_t,
- (timezone_t __tz, struct tm *restrict __result)
+ (timezone_t __tz, struct tm *restrict __tm)
_GL_ARG_NONNULL ((2)));
_GL_CXXALIAS_SYS (mktime_z, time_t,
- (timezone_t __tz, struct tm *restrict __result));
+ (timezone_t __tz, struct tm *restrict __tm));
+
+/* Time zone abbreviation strings (returned by 'localtime_rz' or 'mktime_z'
+ in the 'tm_zone' member of 'struct tm') are valid as long as
+ - the 'struct tm' argument is not destroyed or overwritten,
+ and
+ - the 'timezone_t' argument is not freed through tzfree(). */
+
# endif
/* Convert TM to a time_t value, assuming UTC. */
diff --git a/modules/time_rz b/modules/time_rz
index 6a2b23c..ebcef84 100644
--- a/modules/time_rz
+++ b/modules/time_rz
@@ -1,17 +1,6 @@
Description:
Reentrant time zone functions: localtime_rz, mktime_z, etc.
-Comment:
-This implements the NetBSD-inspired extensions to <time.h>, which
-defines a type timezone_t and associated allocation functions tzalloc
-and tzfree, along with two functions localtime_rz and mktime_z that
-are like localtime_r and mktime except they have a new leading
-timezone_t argument. Time zone abbreviation strings have lifetimes
-equal to the corresponding struct tm or timezone_t object (whichever
-is less). tzalloc (X) yields a time zone object equivalent to setting
-the TZ environment variable to X. tzalloc (NULL) is the same as an
-unset TZ environment variable. (timezone_t) 0 stands for UTC.
-
Files:
lib/time-internal.h
lib/time_rz.c
--
2.7.4
