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Diffstat (limited to 'upstream/opensuse-tumbleweed/man3/adjtime.3')
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diff --git a/upstream/opensuse-tumbleweed/man3/adjtime.3 b/upstream/opensuse-tumbleweed/man3/adjtime.3 new file mode 100644 index 00000000..1d9da6e4 --- /dev/null +++ b/upstream/opensuse-tumbleweed/man3/adjtime.3 @@ -0,0 +1,153 @@ +'\" t +.\" Copyright (c) 2006 by Michael Kerrisk <mtk.manpages@gmail.com> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH adjtime 3 2023-07-20 "Linux man-pages 6.05.01" +.SH NAME +adjtime \- correct the time to synchronize the system clock +.SH LIBRARY +Standard C library +.RI ( libc ", " \-lc ) +.SH SYNOPSIS +.nf +.B #include <sys/time.h> +.PP +.BI "int adjtime(const struct timeval *" delta ", struct timeval *" olddelta ); +.fi +.PP +.RS -4 +Feature Test Macro Requirements for glibc (see +.BR feature_test_macros (7)): +.RE +.PP +.BR adjtime (): +.nf + Since glibc 2.19: + _DEFAULT_SOURCE + glibc 2.19 and earlier: + _BSD_SOURCE +.fi +.SH DESCRIPTION +The +.BR adjtime () +function gradually adjusts the system clock (as returned by +.BR gettimeofday (2)). +The amount of time by which the clock is to be adjusted is specified +in the structure pointed to by +.IR delta . +This structure has the following form: +.PP +.in +4n +.EX +struct timeval { + time_t tv_sec; /* seconds */ + suseconds_t tv_usec; /* microseconds */ +}; +.EE +.in +.PP +If the adjustment in +.I delta +is positive, then the system clock is speeded up by some +small percentage (i.e., by adding a small +amount of time to the clock value in each second) until the adjustment +has been completed. +If the adjustment in +.I delta +is negative, then the clock is slowed down in a similar fashion. +.PP +If a clock adjustment from an earlier +.BR adjtime () +call is already in progress +at the time of a later +.BR adjtime () +call, and +.I delta +is not NULL for the later call, then the earlier adjustment is stopped, +but any already completed part of that adjustment is not undone. +.PP +If +.I olddelta +is not NULL, then the buffer that it points to is used to return +the amount of time remaining from any previous adjustment that +has not yet been completed. +.SH RETURN VALUE +On success, +.BR adjtime () +returns 0. +On failure, \-1 is returned, and +.I errno +is set to indicate the error. +.SH ERRORS +.TP +.B EINVAL +The adjustment in +.I delta +is outside the permitted range. +.TP +.B EPERM +The caller does not have sufficient privilege to adjust the time. +Under Linux, the +.B CAP_SYS_TIME +capability is required. +.SH ATTRIBUTES +For an explanation of the terms used in this section, see +.BR attributes (7). +.TS +allbox; +lbx lb lb +l l l. +Interface Attribute Value +T{ +.na +.nh +.BR adjtime () +T} Thread safety MT-Safe +.TE +.sp 1 +.SH STANDARDS +None. +.SH HISTORY +4.3BSD, System V. +.SH NOTES +The adjustment that +.BR adjtime () +makes to the clock is carried out in such a manner that the clock +is always monotonically increasing. +Using +.BR adjtime () +to adjust the time prevents the problems that can be caused for certain +applications (e.g., +.BR make (1)) +by abrupt positive or negative jumps in the system time. +.PP +.BR adjtime () +is intended to be used to make small adjustments to the system time. +Most systems impose a limit on the adjustment that can be specified in +.IR delta . +In the glibc implementation, +.I delta +must be less than or equal to (INT_MAX / 1000000 \- 2) +and greater than or equal to (INT_MIN / 1000000 + 2) +(respectively 2145 and \-2145 seconds on i386). +.SH BUGS +A longstanding bug +.\" http://sourceware.org/bugzilla/show_bug?id=2449 +.\" http://bugzilla.kernel.org/show_bug.cgi?id=6761 +meant that if +.I delta +was specified as NULL, +no valid information about the outstanding clock adjustment was returned in +.IR olddelta . +(In this circumstance, +.BR adjtime () +should return the outstanding clock adjustment, without changing it.) +This bug is fixed +.\" Thanks to the new adjtimex() ADJ_OFFSET_SS_READ flag +on systems with glibc 2.8 or later and +Linux kernel 2.6.26 or later. +.SH SEE ALSO +.BR adjtimex (2), +.BR gettimeofday (2), +.BR time (7) |