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Add parsing for TZif v2+ (tzdata2 APEX) on Android #5235

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Add parsing for TZif v2+ (tzdata2 APEX) on Android #5235

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103 changes: 88 additions & 15 deletions Sources/CoreFoundation/CFTimeZone.c
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Original file line number Diff line number Diff line change
Expand Up @@ -61,14 +61,15 @@

#if TARGET_OS_LINUX || TARGET_OS_BSD || TARGET_OS_WIN32 || TARGET_OS_WASI
struct tzhead {
char tzh_magic[4]; /* TZ_MAGIC */
char tzh_reserved[16]; /* reserved for future use */
char tzh_ttisgmtcnt[4]; /* coded number of trans. time flags */
char tzh_ttisstdcnt[4]; /* coded number of trans. time flags */
char tzh_leapcnt[4]; /* coded number of leap seconds */
char tzh_timecnt[4]; /* coded number of transition times */
char tzh_typecnt[4]; /* coded number of local time types */
char tzh_charcnt[4]; /* coded number of abbr. chars */
char tzh_magic[4]; /* TZ_MAGIC */
char version[1]; /* version */
char tzh_reserved[15]; /* reserved for future use */
char tzh_ttisgmtcnt[4]; /* coded number of trans. time flags */
char tzh_ttisstdcnt[4]; /* coded number of trans. time flags */
char tzh_leapcnt[4]; /* coded number of leap seconds */
char tzh_timecnt[4]; /* coded number of transition times */
char tzh_typecnt[4]; /* coded number of local time types */
char tzh_charcnt[4]; /* coded number of abbr. chars */
};
#endif

Expand Down Expand Up @@ -297,15 +298,17 @@ static void __CFAndroidTimeZoneParse(FILE *fp, __CFAndroidTimeZoneListEnumerateC
static void __CFAndroidTimeZoneListEnumerate(__CFAndroidTimeZoneListEnumerateCallback callback, void *context1, void *context2) {
// The best reference should be Android Bionic's libc/tzcode/bionic.cpp
static const char *tzDataFiles[] = {
"/data/misc/zoneinfo/current/tzdata",
"/system/usr/share/zoneinfo/tzdata"
"/apex/com.android.tzdata/etc/tz/tzdata" /* Android 10 + Mainline module */
"/data/misc/zoneinfo/current/tzdata", /* Andorid 8-9 APK time-zone update */
"/system/usr/share/zoneinfo/tzdata", /* System fallback – always exists */
};

for (int idx = 0; idx < COUNT_OF(tzDataFiles); idx++) {
FILE *fp = fopen(tzDataFiles[idx], "rb");
__CFAndroidTimeZoneParse(fp, callback, context1, context2);
if (fp) {
__CFAndroidTimeZoneParse(fp, callback, context1, context2);
fclose(fp);
return;
}
}
}
Expand Down Expand Up @@ -491,6 +494,20 @@ CF_INLINE int32_t __CFDetzcode(const unsigned char *bufp) {
return (int32_t)result;
}

CF_INLINE int64_t __CFDetzcode64(const unsigned char *bufp) {
// `result` is uint64_t to avoid undefined behaviour of shifting left negative values
uint64_t result = (bufp[0] & 0x80) ? ~0L : 0L;
result = (result << 8) | (bufp[0] & 0xff);
result = (result << 8) | (bufp[1] & 0xff);
result = (result << 8) | (bufp[2] & 0xff);
result = (result << 8) | (bufp[3] & 0xff);
result = (result << 8) | (bufp[4] & 0xff);
result = (result << 8) | (bufp[5] & 0xff);
result = (result << 8) | (bufp[6] & 0xff);
result = (result << 8) | (bufp[7] & 0xff);
return (int64_t)result;
}

CF_INLINE void __CFEntzcode(int32_t value, unsigned char *bufp) {
bufp[0] = (value >> 24) & 0xff;
bufp[1] = (value >> 16) & 0xff;
Expand All @@ -499,20 +516,34 @@ CF_INLINE void __CFEntzcode(int32_t value, unsigned char *bufp) {
}

static Boolean __CFParseTimeZoneData(CFAllocatorRef allocator, CFDataRef data, CFTZPeriod **tzpp, CFIndex *cntp) {
int32_t len, timecnt, typecnt, charcnt, idx, cnt;
int32_t len, timecnt, typecnt, charcnt, leapcnt, ttisgmtcnt, ttisstdcnt, idx, cnt, version;
const uint8_t *p, *timep, *typep, *ttisp, *charp;
CFStringRef *abbrs;
Boolean result = true;
int32_t trans_size = 4;

p = CFDataGetBytePtr(data);
len = CFDataGetLength(data);
if (len < (int32_t)sizeof(struct tzhead)) {
return false;
}

/* read version 1 header */
if (!(p[0] == 'T' && p[1] == 'Z' && p[2] == 'i' && p[3] == 'f')) return false; /* Don't parse without TZif at head of file */

p += 20 + 4 + 4 + 4; /* skip reserved, ttisgmtcnt, ttisstdcnt, leapcnt */
p += 4;
version = __CFDetzcode(p);
if (version > 1) {
trans_size = 8;
}
p += 1;
p += 15; /* skip reserved */
ttisgmtcnt = __CFDetzcode(p);
p += 4;
ttisstdcnt = __CFDetzcode(p);
p += 4;
leapcnt = __CFDetzcode(p);
p += 4;
timecnt = __CFDetzcode(p);
p += 4;
typecnt = __CFDetzcode(p);
Expand All @@ -530,8 +561,46 @@ static Boolean __CFParseTimeZoneData(CFAllocatorRef allocator, CFDataRef data, C
if (len - (int32_t)sizeof(struct tzhead) < (4 + 1) * timecnt + (4 + 1 + 1) * typecnt + charcnt) {
return false;
}

if (trans_size == 8) {
int32_t skip = timecnt * 5 + typecnt * 6 + charcnt + leapcnt * 8 + ttisstdcnt + ttisgmtcnt;
p += skip; /* skip version 1 data block */

/* read version 2+ header */
if (!(p[0] == 'T' && p[1] == 'Z' && p[2] == 'i' && p[3] == 'f')) return false; /* Don't parse without TZif at head of file */
p += 4;
version = __CFDetzcode(p);
p += 1;

p += 15; /* skip reserved */
ttisgmtcnt = __CFDetzcode(p);
p += 4;
ttisstdcnt = __CFDetzcode(p);
p += 4;
leapcnt = __CFDetzcode(p);
p += 4;
timecnt = __CFDetzcode(p);
p += 4;
typecnt = __CFDetzcode(p);
p += 4;
charcnt = __CFDetzcode(p);
p += 4;

if (typecnt <= 0 || timecnt < 0 || charcnt < 0) {
return false;
}
if (1024 < timecnt || 32 < typecnt || 128 < charcnt) {
// reject excessive timezones to avoid arithmetic overflows for
// security reasons and to reject potentially corrupt files
return false;
}
if (len - (((int32_t)sizeof(struct tzhead)) * 2) - skip < (trans_size + 1) * timecnt + (4 + 1 + 1) * typecnt + charcnt) {
return false;
}
}

timep = p;
typep = timep + 4 * timecnt;
typep = timep + trans_size * timecnt;
ttisp = typep + timecnt;
charp = ttisp + (4 + 1 + 1) * typecnt;
cnt = (0 < timecnt) ? timecnt : 1;
Expand All @@ -548,12 +617,16 @@ static Boolean __CFParseTimeZoneData(CFAllocatorRef allocator, CFDataRef data, C
int32_t itime, offset;
uint8_t type, dst, abbridx;

if (trans_size == 8) {
at = (CFAbsoluteTime)(__CFDetzcode64(timep) + 0.0) - kCFAbsoluteTimeIntervalSince1970;
} else {
at = (CFAbsoluteTime)(__CFDetzcode(timep) + 0.0) - kCFAbsoluteTimeIntervalSince1970;
}
if (0 == timecnt) itime = INT_MIN;
else if (at < (CFAbsoluteTime)INT_MIN) itime = INT_MIN;
else if ((CFAbsoluteTime)INT_MAX < at) itime = INT_MAX;
else itime = (int32_t)at;
timep += 4; /* harmless if 0 == timecnt */
timep += trans_size; /* harmless if 0 == timecnt */
type = (0 < timecnt) ? (uint8_t)*typep++ : 0;
if (typecnt <= type) {
result = false;
Expand Down