time: fix incorrect DST offset when using POSIX timezones without DST

[musl] / src / time / __tz.c

diff --git a/src/time/__tz.c b/src/time/__tz.c
index fbe3d49..814edcd 100644 (file)
--- a/src/time/__tz.c
+++ b/src/time/__tz.c
@@ -15,7 +15,7 @@ weak_alias(__tzname, tzname);
 
 static char std_name[TZNAME_MAX+1];
 static char dst_name[TZNAME_MAX+1];
-const char __gmt[] = "GMT";
+const char __utc[] = "UTC";
 
 static int dst_off;
 static int r0[5], r1[5];
@@ -27,7 +27,7 @@ static char old_tz_buf[32];
 static char *old_tz = old_tz_buf;
 static size_t old_tz_size = sizeof old_tz_buf;
 
-static int lock[2];
+static volatile int lock[1];
 
 static int getint(const char **p)
 {
@@ -36,19 +36,16 @@ static int getint(const char **p)
        return x;
 }
 
-static int getsigned(const char **p)
+static int getoff(const char **p)
 {
+       int neg = 0;
        if (**p == '-') {
                ++*p;
-               return -getint(p);
+               neg = 1;
+       } else if (**p == '+') {
+               ++*p;
        }
-       if (**p == '+') ++*p;
-       return getint(p);
-}
-
-static int getoff(const char **p)
-{
-       int off = 3600*getsigned(p);
+       int off = 3600*getint(p);
        if (**p == ':') {
                ++*p;
                off += 60*getint(p);
@@ -57,7 +54,7 @@ static int getoff(const char **p)
                        off += getint(p);
                }
        }
-       return off;
+       return neg ? -off : off;
 }
 
 static void getrule(const char **p, int rule[5])
@@ -87,7 +84,7 @@ static void getname(char *d, const char **p)
        int i;
        if (**p == '<') {
                ++*p;
-               for (i=0; **p!='>' && i<TZNAME_MAX; i++)
+               for (i=0; (*p)[i]!='>' && i<TZNAME_MAX; i++)
                        d[i] = (*p)[i];
                ++*p;
        } else {
@@ -128,7 +125,8 @@ static void do_tzset()
                "/usr/share/zoneinfo/\0/share/zoneinfo/\0/etc/zoneinfo/\0";
 
        s = getenv("TZ");
-       if (!s || !*s) s = __gmt;
+       if (!s) s = "/etc/localtime";
+       if (!*s) s = __utc;
 
        if (old_tz && !strcmp(s, old_tz)) return;
 
@@ -138,7 +136,7 @@ static void do_tzset()
         * free so as not to pull it into static programs. Growth
         * strategy makes it so free would have minimal benefit anyway. */
        i = strlen(s);
-       if (i > PATH_MAX+1) s = __gmt, i = 3;
+       if (i > PATH_MAX+1) s = __utc, i = 3;
        if (i >= old_tz_size) {
                old_tz_size *= 2;
                if (i >= old_tz_size) old_tz_size = i+1;
@@ -153,7 +151,8 @@ static void do_tzset()
        if (*s == ':' || ((p=strchr(s, '/')) && !memchr(s, ',', p-s))) {
                if (*s == ':') s++;
                if (*s == '/' || *s == '.') {
-                       if (!libc.secure) map = __map_file(s, &map_size);
+                       if (!libc.secure || !strcmp(s, "/etc/localtime"))
+                               map = __map_file(s, &map_size);
                } else {
                        size_t l = strlen(s);
                        if (l <= NAME_MAX && !strchr(s, '.')) {
@@ -166,6 +165,12 @@ static void do_tzset()
                                }
                        }
                }
+               if (!map) s = __utc;
+       }
+       if (map && (map_size < 44 || memcmp(map, "TZif", 4))) {
+               __munmap((void *)map, map_size);
+               map = 0;
+               s = __utc;
        }
 
        zi = map;
@@ -202,7 +207,7 @@ static void do_tzset()
                                }
                        }
                        if (!__tzname[0]) __tzname[0] = __tzname[1];
-                       if (!__tzname[0]) __tzname[0] = (char *)__gmt;
+                       if (!__tzname[0]) __tzname[0] = (char *)__utc;
                        if (!__daylight) {
                                __tzname[1] = __tzname[0];
                                dst_off = __timezone;
@@ -211,7 +216,7 @@ static void do_tzset()
                }
        }
 
-       if (!s) s = __gmt;
+       if (!s) s = __utc;
        getname(std_name, &s);
        __tzname[0] = std_name;
        __timezone = getoff(&s);
@@ -225,7 +230,7 @@ static void do_tzset()
                        dst_off = __timezone - 3600;
        } else {
                __daylight = 0;
-               dst_off = 0;
+               dst_off = __timezone;
        }
 
        if (*s == ',') s++, getrule(&s, r0);
@@ -349,9 +354,9 @@ void __secs_to_zone(long long t, int local, int *isdst, long *offset, long *oppo
                size_t alt, i = scan_trans(t, local, &alt);
                if (i != -1) {
                        *isdst = types[6*i+4];
-                       *offset = -(int32_t)zi_read32(types+6*i);
+                       *offset = (int32_t)zi_read32(types+6*i);
                        *zonename = (const char *)abbrevs + types[6*i+5];
-                       if (oppoff) *oppoff = -(int32_t)zi_read32(types+6*alt);
+                       if (oppoff) *oppoff = (int32_t)zi_read32(types+6*alt);
                        UNLOCK(lock);
                        return;
                }
@@ -368,32 +373,28 @@ void __secs_to_zone(long long t, int local, int *isdst, long *offset, long *oppo
        long long t0 = rule_to_secs(r0, y);
        long long t1 = rule_to_secs(r1, y);
 
+       if (!local) {
+               t0 += __timezone;
+               t1 += dst_off;
+       }
        if (t0 < t1) {
-               if (!local) {
-                       t0 += __timezone;
-                       t1 += dst_off;
-               }
                if (t >= t0 && t < t1) goto dst;
                goto std;
        } else {
-               if (!local) {
-                       t1 += __timezone;
-                       t0 += dst_off;
-               }
                if (t >= t1 && t < t0) goto std;
                goto dst;
        }
 std:
        *isdst = 0;
-       *offset = __timezone;
-       if (oppoff) *oppoff = dst_off;
+       *offset = -__timezone;
+       if (oppoff) *oppoff = -dst_off;
        *zonename = __tzname[0];
        UNLOCK(lock);
        return;
 dst:
        *isdst = 1;
-       *offset = dst_off;
-       if (oppoff) *oppoff = __timezone;
+       *offset = -dst_off;
+       if (oppoff) *oppoff = -__timezone;
        *zonename = __tzname[1];
        UNLOCK(lock);
 }
@@ -412,7 +413,7 @@ const char *__tm_to_tzname(const struct tm *tm)
        const void *p = tm->__tm_zone;
        LOCK(lock);
        do_tzset();
-       if (p != __gmt && p != __tzname[0] && p != __tzname[1] &&
+       if (p != __utc && p != __tzname[0] && p != __tzname[1] &&
            (!zi || (uintptr_t)p-(uintptr_t)abbrevs >= abbrevs_end - abbrevs))
                p = "";
        UNLOCK(lock);