Cleanup/refactoring pass on hwclock.

Inline open_wall_clock_rtc() into rtc_open(), factor out xtzset(),
inline set_sysclock_from_hwclock(), set_hwclock_from_sysclock(),
and set_sysclock_timezone().

/etc/adjtime is short enough we don't need to bother with a break.

The final "else" case in main() should always trigger because >0 in optstr
says "at most zero arguments", so the || at the end is always true, so
take the test off.

3 files changed, 87 insertions, 103 deletions

diff --git a/lib/lib.h b/lib/lib.h
index 621ed276..a659b696 100644
--- a/lib/lib.h
+++ b/lib/lib.h
@@ -128,6 +128,7 @@ char *xreadlink(char *name);
 long xparsetime(char *arg, long units, long *fraction);
 void xpidfile(char *name);
 void xregcomp(regex_t *preg, char *rexec, int cflags);
+char *xtzset(char *new);
 
 // lib.c
 void verror_msg(char *msg, int err, va_list va);
diff --git a/lib/xwrap.c b/lib/xwrap.c
index cd3c6845..0a2b38ff 100644
--- a/lib/xwrap.c
+++ b/lib/xwrap.c
@@ -627,3 +627,14 @@ void xregcomp(regex_t *preg, char *regex, int cflags)
     error_exit("xregcomp: %s", libbuf);
   }
 }
+
+char *xtzset(char *new)
+{
+  char *tz = getenv("TZ");
+
+  if (tz) tz = xstrdup(tz);
+  if (setenv("TZ", new, 1)) perror_exit("setenv");
+  tzset();
+
+  return tz;
+}
diff --git a/toys/pending/hwclock.c b/toys/pending/hwclock.c
index 003174f7..5ca035aa 100644
--- a/toys/pending/hwclock.c
+++ b/toys/pending/hwclock.c
@@ -2,9 +2,9 @@
  *
  * Copyright 2014 Bilal Qureshi <bilal.jmi@gmail.com>
  *
- * No Standard.
+ * No standard, but see Documentation/rtc.txt in the linux kernel source..
  *
-USE_HWCLOCK(NEWTOY(hwclock, ">0(fast)f(rtc):u(utc)l(localtime)t(systz)w(systohc)s(hctosys)r(show)[!ul][!rsw]", TOYFLAG_USR|TOYFLAG_BIN))
+USE_HWCLOCK(NEWTOY(hwclock, ">0(fast)f(rtc):u(utc)l(localtime)t(systz)w(systohc)s(hctosys)r(show)[-ul][!rtsw]", TOYFLAG_USR|TOYFLAG_BIN))
 
 config HWCLOCK
   bool "hwclock"
@@ -12,7 +12,7 @@ config HWCLOCK
   help
     usage: hwclock [-rswtluf]
 
-    -f FILE Use specified device file instead of /dev/rtc (--show)
+    -f FILE Use specified device file instead of /dev/rtc (--rtc)
     -l      Hardware clock uses localtime (--localtime)
     -r      Show hardware clock time (--show)
     -s      Set system time from hardware clock (--hctosys)
@@ -20,6 +20,7 @@ config HWCLOCK
     -u      Hardware clock uses UTC (--utc)
     -w      Set hardware clock from system time (--systohc)
 */
+
 #define FOR_hwclock
 #include "toys.h"
 #include <linux/rtc.h>
@@ -30,7 +31,7 @@ GLOBALS(
   int utc;
 )
 
-static int check_hctosys(struct dirtree* node)
+static int rtc_find(struct dirtree* node)
 {
   FILE *fp;
 
@@ -39,147 +40,118 @@ static int check_hctosys(struct dirtree* node)
   snprintf(toybuf, sizeof(toybuf), "/sys/class/rtc/%s/hctosys", node->name);
   fp = fopen(toybuf, "r");
   if (fp) {
-    int hctosys = 0;
-    int items = fscanf(fp, "%d", &hctosys);
+    int hctosys = 0, items = fscanf(fp, "%d", &hctosys);
+
     fclose(fp);
     if (items == 1 && hctosys == 1) {
       snprintf(toybuf, sizeof(toybuf), "/dev/%s", node->name);
       TT.fname = toybuf;
+
       return DIRTREE_ABORT;
     }
   }
-  return 0;
-}
 
-// Search /sys/class/rtc for the RTC that the system clock is set from.
-// See the kernel's Documentation/rtc.txt.
-static int open_wall_clock_rtc(int flag)
-{
-  TT.fname = NULL;
-  dirtree_read("/sys/class/rtc", check_hctosys);
-  return TT.fname ? xopen(TT.fname, flag) : -1;
+  return 0;
 }
 
+// Your system should have a /dev/rtc symlink. If your system is misconfigured,
+// search /sys/class/rtc for RTC system clock set from, then try /dev/misc/rtc.
 static int rtc_open(int flag)
 {
   if (!TT.fname) {
     int fd; 
 
     if ((fd = open((TT.fname = "/dev/rtc"), flag)) != -1) return fd;
-    else if ((fd = open_wall_clock_rtc(flag)) != -1) return fd;
-    else TT.fname = "/dev/misc/rtc";
+    TT.fname = 0;
+    dirtree_read("/sys/class/rtc", rtc_find);
+    if (TT.fname) return xopen(TT.fname, flag);
+    TT.fname = "/dev/misc/rtc";
   }
+
   return xopen(TT.fname, flag);
 }
 
-static time_t get_rtc()
+// Get current time in seconds from rtc device. We could get subsecond time by
+// waiting for next time change, but haven't implemented that yet.
+static time_t get_rtc_seconds()
 {
   struct tm time;
   time_t tm;
-  char *ptz_old = 0;
+  char *ptz_old = ptz_old;
   int fd = rtc_open(O_RDONLY);
 
   xioctl(fd, RTC_RD_TIME, &time);
   close(fd);
-  if (TT.utc) {
-    ptz_old = getenv("TZ");
-    if (putenv((char*)"TZ=UTC0")) perror_exit("putenv");
-    tzset();
-  }
+
+  if (TT.utc) ptz_old = xtzset("UTC0");
   if ((tm = mktime(&time)) < 0) error_exit("mktime failed");
   if (TT.utc) {
-    if (unsetenv("TZ") < 0) perror_exit("unsetenv");
-    if (ptz_old && putenv(ptz_old - 3)) perror_exit("putenv");
-    tzset();
+    free(xtzset(ptz_old));
+    free(ptz_old);
   }
-  return tm;
-}
 
-static void set_sysclock_from_hwclock()
-{
-  struct timezone tmzone;
-  struct timeval tmval;
-
-  tmzone.tz_minuteswest = timezone / 60 - 60 * daylight;
-  tmzone.tz_dsttime = 0;
-  tmval.tv_sec = get_rtc();
-  tmval.tv_usec = 0;
-  if (settimeofday(&tmval, &tmzone) < 0) perror_exit("settimeofday");
-}
-
-static void set_hwclock_from_sysclock()
-{
-  struct timeval tmval;
-  struct tm time;
-  int fd = rtc_open(O_WRONLY);
-
-  if (gettimeofday(&tmval, NULL) < 0) perror_exit("gettimeofday");
-  // converting a time value to broken-down UTC time
-  if (TT.utc && !gmtime_r((time_t*)&tmval.tv_sec, &time)) 
-    error_exit("gmtime_r failed");
-  // converting a time value to a broken-down localtime
-  else if (!(localtime_r((time_t*)&tmval.tv_sec, &time)))
-    error_exit("localtime_r failed");
-
-  /* The value of tm_isdst will positive if daylight saving time is in effect,
-   * zero if it is not and negative if the information is not available. 
-   * */
-  time.tm_isdst = 0;
-  xioctl(fd, RTC_SET_TIME, &time);
-  close(fd);
-}
-
-static void set_sysclock_timezone()
-{
-  struct timezone tmzone;
-  struct timeval tmval;
-  struct tm *pb;
-
-  if (gettimeofday(&tmval, NULL) < 0) perror_exit("gettimeofday");
-  if (!(pb = localtime(&tmval.tv_sec))) error_exit("localtime failed");
-  // extern long timezone => defined in header sys/time.h
-  tmzone.tz_minuteswest = timezone / 60;
-  if (pb->tm_isdst) tmzone.tz_minuteswest -= 60;
-  tmzone.tz_dsttime = 0; // daylight saving time is not in effect
-  if (gettimeofday(&tmval, NULL) < 0) perror_exit("gettimeofday");
-  if (!TT.utc) tmval.tv_sec += tmzone.tz_minuteswest * 60;
-  if (settimeofday(&tmval, &tmzone) < 0) perror_exit("settimeofday");
+  return tm;
 }
 
 void hwclock_main()
 {
-  // check for UTC
-  if (!(toys.optflags & FLAG_u)) {
+  struct timezone tzone;
+  struct timeval timeval;
+
+  // check for Grenich Mean Time
+  if (toys.optflags & FLAG_u) TT.utc = 1;
+  else {
     FILE *fp = fopen("/etc/adjtime", "r");
 
     if (fp) {
-      char *line = NULL;
-      size_t st;
-
-      while (0 < getline(&line, &st, fp)) {
-        if (!strncmp(line, "UTC", 3)) {
-          TT.utc = 1;
-          break;
-        }
+      for (;;) {
+        char *line = 0;
+
+        if (getline(&line, (void *)toybuf, fp) <= 0) break;
+        TT.utc += !strncmp(line, "UTC", 3);
         free(line);
       }
       fclose(fp);
     }
-  } else TT.utc = 1;
-
-  if (toys.optflags & FLAG_w) set_hwclock_from_sysclock();
-  else if (toys.optflags & FLAG_s) set_sysclock_from_hwclock(); 
-  else if (toys.optflags & FLAG_t) set_sysclock_timezone();
-  else if ((toys.optflags & FLAG_r) || (toys.optflags & FLAG_l) 
-      || !*toys.optargs)
-  {
-    time_t tm = get_rtc();
-    char *s, *pctm = ctime(&tm);
-
-    // ctime() is defined as equivalent to asctime(localtime(t)),
-    // which is defined to overflow its buffer rather than return NULL.
-    // if (!pctm) error_exit("can't happen");
-    if ((s = strrchr(pctm, '\n'))) *s = '\0';
+  }
+
+  if (toys.optflags & FLAG_w) {
+    struct tm tm;
+    int fd = rtc_open(O_WRONLY);
+
+    if (gettimeofday(&timeval, 0)) perror_exit("gettimeofday");
+    if ((TT.utc ? gmtime_r : localtime_r)(&timeval.tv_sec, &tm))
+      error_exit("timeval");
+
+    /* The value of tm_isdst will positive if daylight saving time is in effect,
+     * zero if it is not and negative if the information is not available. 
+     * */
+    tm.tm_isdst = 0;
+    xioctl(fd, RTC_SET_TIME, &time);
+    close(fd);
+  } else if (toys.optflags & FLAG_s) {
+    tzone.tz_minuteswest = timezone / 60 - 60 * daylight;
+    tzone.tz_dsttime = 0;
+    timeval.tv_sec = get_rtc_seconds();
+    timeval.tv_usec = 0;
+    if (settimeofday(&timeval, &tzone) < 0) perror_exit("settimeofday");
+  } else if (toys.optflags & FLAG_t) {
+    struct tm *pb;
+
+    if (gettimeofday(&timeval, NULL) < 0) perror_exit("gettimeofday");
+    if (!(pb = localtime(&timeval.tv_sec))) error_exit("localtime failed");
+    // extern long timezone is defined in header sys/time.h
+    tzone.tz_minuteswest = timezone / 60;
+    if (pb->tm_isdst) tzone.tz_minuteswest -= 60;
+    tzone.tz_dsttime = 0; // daylight saving time is not in effect
+    if (gettimeofday(&timeval, NULL) < 0) perror_exit("gettimeofday");
+    if (!TT.utc) timeval.tv_sec += tzone.tz_minuteswest * 60;
+    if (settimeofday(&timeval, &tzone) < 0) perror_exit("settimeofday");
+  } else {
+    time_t tm = get_rtc_seconds();
+    char *pctm = ctime(&tm), *s = strrchr(pctm, '\n');
+
+    if (s) *s = '\0';
     // TODO: implement this.
     xprintf("%s  0.000000 seconds\n", pctm);
   }