TimeZoneIanaAbbrevMap.c

 
#include "TimeZoneIanaAbbrevMap.h"
 
#include <stdlib.h>
#include <dirent.h>
#include <time.h>
#include <sys/stat.h>
#include <unistd.h>
 
#include <winpr/string.h>
 
typedef struct
{
  char* Iana;
  char* Abbrev;
} TimeZoneInanaAbbrevMapEntry;
 
const static char* zonepath = "/usr/share/zoneinfo";
 
static TimeZoneInanaAbbrevMapEntry* TimeZoneIanaAbbrevMap = NULL;
static size_t TimeZoneIanaAbbrevMapSize = 0;
 
static void append(const char* iana, const char* sname)
{
  const size_t size = TimeZoneIanaAbbrevMapSize + 1;
 
  TimeZoneInanaAbbrevMapEntry* tmp =
      realloc(TimeZoneIanaAbbrevMap, size * sizeof(TimeZoneInanaAbbrevMapEntry));
  if (!tmp)
    return;
  TimeZoneIanaAbbrevMap = tmp;
  TimeZoneIanaAbbrevMapSize = size;
 
  TimeZoneInanaAbbrevMapEntry* cur = &TimeZoneIanaAbbrevMap[size - 1];
  cur->Abbrev = _strdup(sname);
  cur->Iana = _strdup(iana);
}
 
static void append_timezone(const char* dir, const char* name)
{
  char* tz = NULL;
  if (!dir && !name)
    return;
  if (!dir)
  {
    size_t len = 0;
    winpr_asprintf(&tz, &len, "%s", name);
  }
  else
  {
    size_t len = 0;
    winpr_asprintf(&tz, &len, "%s/%s", dir, name);
  }
  if (!tz)
    return;
 
  const char* otz = getenv("TZ");
  char* oldtz = NULL;
  if (otz)
    oldtz = _strdup(otz);
  setenv("TZ", tz, 1);
  tzset();
  const time_t t = time(NULL);
  struct tm lt = { 0 };
  (void)localtime_r(&t, &lt);
  append(tz, lt.tm_zone);
  if (oldtz)
  {
    setenv("TZ", oldtz, 1);
    free(oldtz);
  }
  else
    unsetenv("TZ");
  free(tz);
}
 
static void handle_link(const char* base, const char* dir, const char* name);
 
static char* topath(const char* base, const char* bname, const char* name)
{
  size_t plen = 0;
  char* path = NULL;
 
  if (!base && !bname && !name)
    return NULL;
 
  if (!base && !name)
    return _strdup(bname);
 
  if (!bname && !name)
    return _strdup(base);
 
  if (!base && !bname)
    return _strdup(name);
 
  if (!base)
    winpr_asprintf(&path, &plen, "%s/%s", bname, name);
  else if (!bname)
    winpr_asprintf(&path, &plen, "%s/%s", base, name);
  else if (!name)
    winpr_asprintf(&path, &plen, "%s/%s", base, bname);
  else
    winpr_asprintf(&path, &plen, "%s/%s/%s", base, bname, name);
  return path;
}
 
static void iterate_subdir_recursive(const char* base, const char* bname, const char* name)
{
  char* path = topath(base, bname, name);
  if (!path)
    return;
 
  DIR* d = opendir(path);
  if (d)
  {
    struct dirent* dp = NULL;
    while ((dp = readdir(d)) != NULL)
    {
      switch (dp->d_type)
      {
        case DT_DIR:
        {
          if (strcmp(dp->d_name, ".") == 0)
            continue;
          if (strcmp(dp->d_name, "..") == 0)
            continue;
          iterate_subdir_recursive(path, dp->d_name, NULL);
        }
        break;
        case DT_LNK:
          handle_link(base, bname, dp->d_name);
          break;
        case DT_REG:
          append_timezone(bname, dp->d_name);
          break;
        default:
          break;
      }
    }
    closedir(d);
  }
  free(path);
}
 
static char* get_link_target(const char* base, const char* dir, const char* name)
{
  char* apath = NULL;
  char* path = topath(base, dir, name);
  if (!path)
    return NULL;
 
  SSIZE_T rc = -1;
  size_t size = 0;
  char* target = NULL;
  do
  {
    size += 64;
    char* tmp = realloc(target, size + 1);
    if (!tmp)
      goto fail;
 
    target = tmp;
 
    memset(target, 0, size + 1);
    rc = readlink(path, target, size);
    if (rc < 0)
      goto fail;
  } while ((size_t)rc >= size);
 
  apath = topath(base, dir, target);
fail:
  free(target);
  free(path);
  return apath;
}
 
void handle_link(const char* base, const char* dir, const char* name)
{
  int isDir = -1;
 
  char* target = get_link_target(base, dir, name);
  if (target)
  {
    struct stat s = { 0 };
    const int rc3 = stat(target, &s);
    if (rc3 == 0)
      isDir = S_ISDIR(s.st_mode);
 
    free(target);
  }
 
  switch (isDir)
  {
    case 1:
      iterate_subdir_recursive(base, dir, name);
      break;
    case 0:
      append_timezone(dir, name);
      break;
    default:
      break;
  }
}
 
static void TimeZoneIanaAbbrevCleanup(void)
{
  if (!TimeZoneIanaAbbrevMap)
    return;
 
  for (size_t x = 0; x < TimeZoneIanaAbbrevMapSize; x++)
  {
    TimeZoneInanaAbbrevMapEntry* entry = &TimeZoneIanaAbbrevMap[x];
    free(entry->Iana);
    free(entry->Abbrev);
  }
  free(TimeZoneIanaAbbrevMap);
  TimeZoneIanaAbbrevMap = NULL;
  TimeZoneIanaAbbrevMapSize = 0;
}
 
static void TimeZoneIanaAbbrevInitialize(void)
{
  static BOOL initialized = FALSE;
  if (initialized)
    return;
 
  iterate_subdir_recursive(zonepath, NULL, NULL);
  (void)atexit(TimeZoneIanaAbbrevCleanup);
  initialized = TRUE;
}
 
size_t TimeZoneIanaAbbrevGet(const char* abbrev, const char** list, size_t listsize)
{
  TimeZoneIanaAbbrevInitialize();
 
  size_t rc = 0;
  for (size_t x = 0; x < TimeZoneIanaAbbrevMapSize; x++)
  {
    const TimeZoneInanaAbbrevMapEntry* entry = &TimeZoneIanaAbbrevMap[x];
    if (strcmp(abbrev, entry->Abbrev) == 0)
    {
      if (listsize > rc)
        list[rc] = entry->Iana;
      rc++;
    }
  }
 
  return rc;
}