Merge pull request #12335 from taosdata/fix/ZhiqiangWang/fix-15436-Ubuntu-timezone-error

fix(os): Ubuntu timezone error.

source/os/src/osTimezone.c

@@ -125,7 +125,7 @@ void taosGetSystemTimezone(char *outTimezoneStr, enum TdTimezone *tsTimezone) {
     strcpy(outTimezoneStr, tz);
   }
 
-#else
+#elif defined(_TD_DARWIN_64)
   char  buf[4096] = {0};
   char *tz = NULL;
   {
@@ -170,5 +170,108 @@ void taosGetSystemTimezone(char *outTimezoneStr, enum TdTimezone *tsTimezone) {
    */
   snprintf(outTimezoneStr, TD_TIMEZONE_LEN, "%s (%s, %+03ld00)", tz, tm1.tm_isdst ? tzname[daylight] : tzname[0],
            -timezone / 3600);
+#else
+
+  if (taosCheckExistFile("/etc/timezone")) {
+    /*
+    * NOTE: do not remove it.
+    * Enforce set the correct daylight saving time(DST) flag according
+    * to current time
+    */
+    time_t    tx1 = taosGetTimestampSec();
+    struct tm tm1;
+    taosLocalTime(&tx1, &tm1);
+    /* load time zone string from /etc/timezone */
+    // FILE *f = fopen("/etc/timezone", "r");
+    errno = 0;
+    TdFilePtr pFile = taosOpenFile("/etc/timezone", TD_FILE_READ);
+    char  buf[68] = {0};
+    if (pFile != NULL) {
+      int len = taosReadFile(pFile, buf, 64);
+      if (len < 64 && taosGetErrorFile(pFile)) {
+        taosCloseFile(&pFile);
+        printf("read /etc/timezone error, reason:%s", strerror(errno));
+        return;
+      }
+
+      taosCloseFile(&pFile);
+
+      buf[sizeof(buf) - 1] = 0;
+      char *lineEnd = strstr(buf, "\n");
+      if (lineEnd != NULL) {
+        *lineEnd = 0;
+      }
+
+      // for CentOS system, /etc/timezone does not exist. Ignore the TZ environment variables
+      if (strlen(buf) > 0) {
+        setenv("TZ", buf, 1);
+      }
+    }
+    // get and set default timezone
+    tzset();
+    /*
+    * get CURRENT time zone.
+    * system current time zone is affected by daylight saving time(DST)
+    *
+    * e.g., the local time zone of London in DST is GMT+01:00,
+    * otherwise is GMT+00:00
+    */
+    int32_t tz = (-timezone * MILLISECOND_PER_SECOND) / MILLISECOND_PER_HOUR;
+    *tsTimezone = tz;
+    tz += daylight;
+
+    /*
+    * format example:
+    *
+    * Asia/Shanghai   (CST, +0800)
+    * Europe/London   (BST, +0100)
+    */
+    snprintf(outTimezoneStr, TD_TIMEZONE_LEN, "%s (%s, %s%02d00)", buf, tzname[daylight], tz >= 0 ? "+" : "-", abs(tz));
+  } else {
+    char  buf[4096] = {0};
+    char *tz = NULL;
+    {
+      int n = readlink("/etc/localtime", buf, sizeof(buf));
+      if (n < 0) {
+        printf("read /etc/localtime error, reason:%s", strerror(errno));
+        return;
+      }
+      buf[n] = '\0';
+      for (int i = n - 1; i >= 0; --i) {
+        if (buf[i] == '/') {
+          if (tz) {
+            tz = buf + i + 1;
+            break;
+          }
+          tz = buf + i + 1;
+        }
+      }
+      if (!tz || 0 == strchr(tz, '/')) {
+        printf("parsing /etc/localtime failed");
+        return;
+      }
+
+      setenv("TZ", tz, 1);
+      tzset();
+    }
+
+    /*
+    * NOTE: do not remove it.
+    * Enforce set the correct daylight saving time(DST) flag according
+    * to current time
+    */
+    time_t    tx1 = taosGetTimestampSec();
+    struct tm tm1;
+    taosLocalTime(&tx1, &tm1);
+
+    /*
+    * format example:
+    *
+    * Asia/Shanghai   (CST, +0800)
+    * Europe/London   (BST, +0100)
+    */
+    snprintf(outTimezoneStr, TD_TIMEZONE_LEN, "%s (%s, %+03ld00)", tz, tm1.tm_isdst ? tzname[daylight] : tzname[0],
+            -timezone / 3600);
+  }
 #endif
 }