`localtime()` may set ENOENT in some docker environment

[iphydf]

https://github.com/fuhsnn/slimcc/commit/7b7c98604ab3eb85e68d7b3ae7f884d5537638c8 the assert added here triggers.

Input file:

#include <assert.h>

Another option:

#include ""

[fuhsnn]

It looks like localtime() set errno when the compiled executable is executed with docker RUN Probably specific to Ubuntu docker, changed base to debian:latest or debian:buster-slim and the errno is gone.

localtime_errno.c

#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <errno.h>

int main(void) {
  time_t now = time(NULL);
  if (errno)
    fprintf(stderr, "time() set errno to %d", errno), exit(1);

  struct tm *tmp = localtime(&now);
  if (!tmp)
    fprintf(stderr, "localtime() return null"), exit(1);
  if (errno)
    fprintf(stderr, "localtime() set errno to %d", errno), exit(1);
}

dockerfile

...
WORKDIR /work/localtime_errno_test
COPY localtime_errno.c /work/localtime_errno_test/
RUN gcc localtime_errno.c -o out
RUN ./out #bad

[fuhsnn]

Tried a few more dockerhub images localtime() set ENOENT: alpine:latest, ubuntu:20.04 localtime() doesn't set ENOENT fedora:40 debian:latest gcc:latest

Anyway, I removed the assert and main should be good now.