Fix tzalloc(nullptr) and add a test.
This works (by reading /etc/localtime) on NetBSD, but not on Android
since we have no such file. Fix that by using our equivalent system
property instead.
Also s/time zone/timezone/ in documentation and comments. We've always
been inconsistent about this (as is upstream in code comments and
documentation) but it seems especially odd now we expose a _type_ that
spells it "timezone" to talk of "time zone" even as we're describing
that type and its associated functions.
Bug: https://github.com/chronotope/chrono/issues/499
Test: treehugger
Change-Id: I142995a3ab4deff1073a0aa9e63ce8eac850b93d
diff --git a/libc/Android.bp b/libc/Android.bp
index ffa8222..dc3c73f 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -269,7 +269,7 @@
"-DTHREAD_SAFE=1",
// The name of the tm_gmtoff field in our struct tm.
"-DTM_GMTOFF=tm_gmtoff",
- // TZDEFAULT is not applicable to Android as there is no one file per time zone mapping
+ // Android uses a system property instead of /etc/localtime, so make callers crash.
"-DTZDEFAULT=NULL",
// Where we store our tzdata.
"-DTZDIR=\"/system/usr/share/zoneinfo\"",
diff --git a/libc/include/time.h b/libc/include/time.h
index 5b76288..08f30ef 100644
--- a/libc/include/time.h
+++ b/libc/include/time.h
@@ -42,22 +42,22 @@
/* If we just use void* in the typedef, the compiler exposes that in error messages. */
struct __timezone_t;
-/** The `timezone_t` type that represents a time zone. */
+/** The `timezone_t` type that represents a timezone. */
typedef struct __timezone_t* timezone_t;
/** Divisor to compute seconds from the result of a call to clock(). */
#define CLOCKS_PER_SEC 1000000
/**
- * The name of the current time zone's non-daylight savings (`tzname[0]`) and
+ * The name of the current timezone's non-daylight savings (`tzname[0]`) and
* daylight savings (`tzname[1]`) variants. See tzset().
*/
extern char* _Nonnull tzname[];
-/** Whether the current time zone ever uses daylight savings time. See tzset(). */
+/** Whether the current timezone ever uses daylight savings time. See tzset(). */
extern int daylight;
-/** The difference in seconds between UTC and the current time zone. See tzset(). */
+/** The difference in seconds between UTC and the current timezone. See tzset(). */
extern long int timezone;
struct sigevent;
@@ -86,7 +86,7 @@
int tm_isdst;
/** Offset from UTC (GMT) in seconds for this time. */
long int tm_gmtoff;
- /** Name of the time zone for this time. */
+ /** Name of the timezone for this time. */
const char* _Nullable tm_zone;
};
@@ -145,7 +145,7 @@
* [mktime(3)](http://man7.org/linux/man-pages/man3/mktime.3p.html) converts
* broken-down time `tm` into the number of seconds since the Unix epoch.
*
- * See tzset() for details of how the time zone is set, and mktime_rz()
+ * See tzset() for details of how the timezone is set, and mktime_rz()
* for an alternative.
*
* Returns the time in seconds on success, and returns -1 and sets `errno` on failure.
@@ -154,7 +154,7 @@
/**
* mktime_z(3) converts broken-down time `tm` into the number of seconds
- * since the Unix epoch, assuming the given time zone.
+ * since the Unix epoch, assuming the given timezone.
*
* Returns the time in seconds on success, and returns -1 and sets `errno` on failure.
*
@@ -178,7 +178,7 @@
* the number of seconds since the Unix epoch in `t` to a broken-down time.
* That broken-down time will be written to the given struct `tm`.
*
- * See tzset() for details of how the time zone is set, and localtime_rz()
+ * See tzset() for details of how the timezone is set, and localtime_rz()
* for an alternative.
*
* Returns a pointer to a broken-down time on success, and returns null and sets `errno` on failure.
@@ -187,7 +187,7 @@
/**
* localtime_rz(3) converts the number of seconds since the Unix epoch in
- * `t` to a broken-down time, assuming the given time zone. That broken-down
+ * `t` to a broken-down time, assuming the given timezone. That broken-down
* time will be written to the given struct `tm`.
*
* Returns a pointer to a broken-down time on success, and returns null and sets `errno` on failure.
@@ -278,29 +278,36 @@
/**
* [tzset(3)](http://man7.org/linux/man-pages/man3/tzset.3.html) tells
- * libc that the time zone has changed.
+ * libc that the timezone has changed.
*
- * Android looks at both the system property `persist.sys.timezone` and the
- * environment variable `TZ`. The former is the device's current time zone
- * as shown in Settings, while the latter is usually unset but can be used
- * to override the global setting. This is a bad idea outside of unit tests
- * or single-threaded programs because it's inherently thread-unsafe.
- * See tzalloc(), localtime_rz(), mktime_z(), and tzfree() for an
- * alternative.
+ * tzset() on Android looks at both the system property
+ * `persist.sys.timezone` and the environment variable `TZ`. The former is
+ * the device's current timezone as shown in Settings, while the latter is
+ * usually unset but can be used to override the global setting. This is a
+ * bad idea outside of unit tests or single-threaded programs because it's
+ * inherently thread-unsafe. See tzalloc(), localtime_rz(), mktime_z(),
+ * and tzfree() for an alternative.
*/
void tzset(void);
/**
- * tzalloc(3) allocates a time zone corresponding to the given Olson id.
+ * tzalloc(3) allocates a timezone corresponding to the given Olson ID.
*
- * Returns a time zone object on success, and returns NULL and sets `errno` on failure.
+ * A null `id` returns the system timezone (as seen in Settings) from
+ * the system property `persist.sys.timezone`, ignoring `$TZ`. Although
+ * tzset() honors `$TZ`, callers of tzalloc() can use `$TZ` themselves if
+ * that's the (thread-unsafe) behavior they want, but by ignoring `$TZ`
+ * tzalloc() is thread safe (though obviously the system timezone can
+ * change, especially if your mobile device is actually mobile!).
+ *
+ * Returns a timezone object on success, and returns NULL and sets `errno` on failure.
*
* Available since API level 35.
*/
timezone_t _Nullable tzalloc(const char* _Nullable __id) __INTRODUCED_IN(35);
/**
- * tzfree(3) frees a time zone object returned by tzalloc().
+ * tzfree(3) frees a timezone object returned by tzalloc().
*
* Available since API level 35.
*/
@@ -320,7 +327,7 @@
/**
* [clock_getcpuclockid(3)](http://man7.org/linux/man-pages/man3/clock_getcpuclockid.3.html)
- * gets the clock id of the cpu-time clock for the given `pid`.
+ * gets the clock ID of the cpu-time clock for the given `pid`.
*
* Returns 0 on success, and returns -1 and returns an error number on failure.
*/
diff --git a/libc/system_properties/context_lookup_benchmark_data.h b/libc/system_properties/context_lookup_benchmark_data.h
index b928875..1d7250c 100644
--- a/libc/system_properties/context_lookup_benchmark_data.h
+++ b/libc/system_properties/context_lookup_benchmark_data.h
@@ -321,7 +321,7 @@
persist.vendor. u:object_r:vendor_default_prop:s0
vendor. u:object_r:vendor_default_prop:s0
-# Properties that relate to time / time zone detection behavior.
+# Properties that relate to time / timezone detection behavior.
persist.time. u:object_r:time_prop:s0
# Properties that relate to server configurable flags
diff --git a/libc/tzcode/bionic.cpp b/libc/tzcode/bionic.cpp
index d2b5d80..7091707 100644
--- a/libc/tzcode/bionic.cpp
+++ b/libc/tzcode/bionic.cpp
@@ -36,10 +36,45 @@
#include "private/CachedProperty.h"
extern "C" void tzset_unlocked(void);
+extern "C" void __bionic_get_system_tz(char* buf, size_t n);
extern "C" int __bionic_open_tzdata(const char*, int32_t*);
extern "C" void tzsetlcl(char const*);
+void __bionic_get_system_tz(char* buf, size_t n) {
+ static CachedProperty persist_sys_timezone("persist.sys.timezone");
+ const char* name = persist_sys_timezone.Get();
+
+ // If the system property is not set, perhaps because this is called
+ // before the default value has been set (the recovery image being a
+ // classic example), fall back to GMT.
+ if (name == nullptr) name = "GMT";
+
+ strlcpy(buf, name, n);
+
+ if (!strcmp(buf, "GMT")) {
+ // Typically we'll set the system property to an Olson ID, but
+ // java.util.TimeZone also supports the "GMT+xxxx" style, and at
+ // least historically (see http://b/25463955) some Android-based set
+ // top boxes would get the timezone from the TV network in this format
+ // and use it directly in the system property. This caused trouble
+ // for native code because POSIX and Java disagree about the sign in
+ // a timezone string. For POSIX, "GMT+3" means "3 hours west/behind",
+ // but for Java it means "3 hours east/ahead". Since (a) Java is the
+ // one that matches human expectations and (b) this system property is
+ // used directly by Java, we flip the sign here to translate from Java
+ // to POSIX. We only need to worry about the "GMT+xxxx" case because
+ // the expectation is that these are valid java.util.TimeZone ids,
+ // not general POSIX custom timezone specifications (which is why this
+ // code only applies to the system property, and not to the environment
+ // variable).
+ char sign = buf[3];
+ if (sign == '-' || sign == '+') {
+ buf[3] = (sign == '-') ? '+' : '-';
+ }
+ }
+}
+
void tzset_unlocked() {
// The TZ environment variable is meant to override the system-wide setting.
const char* name = getenv("TZ");
@@ -47,26 +82,10 @@
// If that's not set, look at the "persist.sys.timezone" system property.
if (name == nullptr) {
- static CachedProperty persist_sys_timezone("persist.sys.timezone");
-
- if ((name = persist_sys_timezone.Get()) != nullptr && strlen(name) > 3) {
- // POSIX and Java disagree about the sign in a timezone string. For POSIX, "GMT+3" means
- // "3 hours west/behind", but for Java it means "3 hours east/ahead". Since (a) Java is
- // the one that matches human expectations and (b) this system property is used directly
- // by Java, we flip the sign here to translate from Java to POSIX. http://b/25463955.
- char sign = name[3];
- if (sign == '-' || sign == '+') {
- strlcpy(buf, name, sizeof(buf));
- buf[3] = (sign == '-') ? '+' : '-';
- name = buf;
- }
- }
+ __bionic_get_system_tz(buf, sizeof(buf));
+ name = buf;
}
- // If the system property is also not available (because you're running AOSP on a WiFi-only
- // device, say), fall back to GMT.
- if (name == nullptr) name = "GMT";
-
tzsetlcl(name);
}
@@ -192,14 +211,14 @@
close(fd);
// This file descriptor (-1) is passed to localtime.c. In invalid fd case
// upstream passes errno value around methods and having 0 there will
- // indicate that time zone was found and read successfully and localtime's
+ // indicate that timezone was found and read successfully and localtime's
// internal state was properly initialized (which wasn't as we couldn't find
- // requested time zone in the tzdata file).
+ // requested timezone in the tzdata file).
// If we reached this point errno is unlikely to be touched. It is only
// close(fd) which can do it, but that is very unlikely to happen. And
// even if it happens we can't extract any useful insights from it.
// We are overriding it to ENOENT as it matches upstream expectations -
- // time zone is absent in the tzdata file == there is no TZif file in
+ // timezone is absent in the tzdata file == there is no TZif file in
// /usr/share/zoneinfo.
errno = ENOENT;
return -1;
@@ -219,7 +238,7 @@
int fd;
// Try the two locations for the tzdata file in a strict order:
- // 1: The time zone data module which contains the main copy. This is the
+ // 1: The timezone data module which contains the main copy. This is the
// common case for current devices.
// 2: The ultimate fallback: the non-updatable copy in /system.
diff --git a/libc/tzcode/localtime.c b/libc/tzcode/localtime.c
index 5e1181f..018acad 100644
--- a/libc/tzcode/localtime.c
+++ b/libc/tzcode/localtime.c
@@ -374,8 +374,11 @@
+ 4 * TZ_MAX_TIMES];
};
-// Android-removed: There is no directory with file-per-time zone on Android.
-#ifndef __BIONIC__
+#if defined(__BIONIC__)
+// Android: there is no directory with one file per timezone on Android,
+// but we do have a system property instead.
+#include <sys/system_properties.h>
+#else
/* TZDIR with a trailing '/' rather than a trailing '\0'. */
static char const tzdirslash[sizeof TZDIR] = TZDIR "/";
#endif
@@ -415,13 +418,20 @@
#endif
register union input_buffer *up = &lsp->u.u;
register int tzheadsize = sizeof(struct tzhead);
+ char system_tz_name[PROP_VALUE_MAX];
sp->goback = sp->goahead = false;
if (! name) {
+#if defined(__BIONIC__)
+ extern void __bionic_get_system_tz(char* , size_t);
+ __bionic_get_system_tz(system_tz_name, sizeof(system_tz_name));
+ name = system_tz_name;
+#else
name = TZDEFAULT;
if (! name)
return EINVAL;
+#endif
}
#if defined(__BIONIC__)