`stime` (2) - glibc

Split from the chapter glibc: Calendar Time into the per-function layout; see the method page and the glibc ledger for coverage status.

Field	Value
Header	man2 lists `time.h` – the current host header declares it no longer
Standards	SVID; deprecated in favor of `clock_settime(2)`
Exported	compat-only `stime@GLIBC_2.2.5` (no default-version symbol; nm, host glibc 2.41)
Thread-safety	Not stated: `stime(2)` carries no ATTRIBUTES table
Ledger ID	GLIBC-stime

Declaration and gates

#include <time.h>

int stime(const time_t *t);   /* stime(2) SYNOPSIS;
                                 absent from /usr/include/time.h here */

Evidence trail on this host (glibc 2.41): grep stime /usr/include/time.h finds nothing – the declaration is gone from the header – while nm -D /lib/x86_64-linux-gnu/libc.so.6 still shows the compat symbol stime@GLIBC_2.2.5 with no @@ default version. Old binaries keep linking; new source has no way to call it portably.

Semantics

stime set the system clock to t seconds since the Epoch (1970-01-01 00:00:00 UTC). It required privilege: under Linux CAP_SYS_TIME; an unprivileged caller got EPERM (stime(2)). The man page itself opens with “NOTE: This function is deprecated; use clock_settime(2) instead” (stime(2) DESCRIPTION).

Gotchas and portability

Removed from the API surface: code that compiles today is declaring the prototype itself, which is a portability smell; use clock_settime(CLOCK_REALTIME, ...) – second-resolution stime cannot express sub-second setting anyway.
The ledger row records only the compat version GLIBC_2.2.5, matching the nm picture of a frozen, non-default symbol.
musl 1.2.5 still ships a wrapper (src/linux/stime.c, declared in include/time.h line 131) – but musl-wide it calls clock_settime, so behavior converges anyway.
Kernel-side, the stime(2)-era system clock interface is gone from modern syscall tables (set via clock_settime today).

Errors

EFAULT (bad pointer from user space), EPERM (insufficient privilege; CAP_SYS_TIME required) – per stime(2).

References

man2: stime(2); clock_settime(2) as the replacement
headers: /usr/include/time.h (negative evidence: no declaration)
symbols: nm -D libc.so.6 | grep -w stime (compat only)
musl: include/time.h, src/linux/stime.c

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