kit

kit
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02_errno_touch.c (503B)

      1 /* Tier 2: touch errno. We deliberately call a function that fails
      2  * (close(-1) → EBADF) and read errno after. errno's lowering varies
      3  * by libc — in musl it's `__thread int errno;` (exercises
      4  * R_AARCH64_TLSLE_* and PT_TLS emission); in glibc it's
      5  * `(*__errno_location())` (a per-thread function call, no TLS reloc
      6  * on the caller side). Either way the test asserts the value. */
      7 
      8 #include <errno.h>
      9 #include <unistd.h>
     10 
     11 int main(void) {
     12   (void)close(-1);
     13   return errno == EBADF ? 0 : 1;
     14 }