a45fcce631
sizeof(time_t) was previously switched from 4 to 8, ROM functions that use time_t or dependent types (such as "struct stat") are no longer called due as they still treat sizeof(time_t) as 4 (see commit 24c20d18). However, there is a ROM callpath that was left out. If putchar is the first stdio print related call, the call path will result in cantwrite() -> __swsetup_r() -> __smakebuf_r() -> __swhatbuf_r() using the ROM "struct stat" (where sizeof(time_t)==4). Instead of removing all printf related ROM newlib functions (which will result in increased binary size), this commit adds a workaround to setup the stdio files before any print related calls occur. This results in cantwrite() always returning false, thus the callpath described above never being reached. Closes https://github.com/espressif/esp-idf/issues/9269
System Notes
Timekeeping
The following are the timekeeping mechanisms available and their differences:
- System time (
esp_system_get_time)
Time with the origin at g_startup_time. The implementation is not handled by esp_system,
but it does provide a default implementation using RTC timer. Currently, esp_timer
provides system time, since the hardware timers are under the control of that
component. However, no matter the underlying timer, the system time provider
should maintain the definition of having the origin point at g_startup_time.
esp_timertime (esp_timer_get_time)
This is the time read from an underlying hardware timer, controlled through config. Origin is at the point where the underlying timer starts counting.
newlibtime (gettimeofday)
Timekeeping function in standard library. Can be set (settimeofday) or moved forward/backward (adjtime);
with the possibility of the changes being made persistent through config.
Currently implemented in terms of system time, as the point of origin is fixed.
If persistence is enabled, RTC time is also used in conjuction with system time.
- RTC time (
esp_rtc_get_time_us)
Time read from RTC timer.