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diff --git a/man-pages-posix-2017/man3p/futimens.3p b/man-pages-posix-2017/man3p/futimens.3p new file mode 100644 index 0000000..8569303 --- /dev/null +++ b/man-pages-posix-2017/man3p/futimens.3p @@ -0,0 +1,393 @@ +'\" et +.TH FUTIMENS "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual" +.\" +.SH PROLOG +This manual page is part of the POSIX Programmer's Manual. +The Linux implementation of this interface may differ (consult +the corresponding Linux manual page for details of Linux behavior), +or the interface may not be implemented on Linux. +.\" +.SH NAME +futimens, utimensat, utimes +\(em set file access and modification times +.SH SYNOPSIS +.LP +.nf +#include <sys/stat.h> +.P +int futimens(int \fIfd\fP, const struct timespec \fItimes\fP[2]); +.P +#include <fcntl.h> +.P +int utimensat(int \fIfd\fP, const char *\fIpath\fP, const struct timespec \fItimes\fP[2], + int \fIflag\fP); +.P +#include <sys/time.h> +.P +int utimes(const char *\fIpath\fP, const struct timeval \fItimes\fP[2]); +.fi +.SH DESCRIPTION +The +\fIfutimens\fR() +and +\fIutimensat\fR() +functions shall set the access and modification times of a file +to the values of the +.IR times +argument. The +\fIfutimens\fR() +function changes the times of the file associated with the file +descriptor +.IR fd . +The +\fIutimensat\fR() +function changes the times of the file pointed to by the +.IR path +argument, relative to the directory associated with the file +descriptor +.IR fd . +Both functions allow time specifications accurate to the nanosecond. +.P +For +\fIfutimens\fR() +and +\fIutimensat\fR(), +the +.IR times +argument is an array of two +.BR timespec +structures. The first array member represents the date and time of +last access, and the second member represents the date and time of last +modification. The times in the +.BR timespec +structure are measured in seconds and nanoseconds since the Epoch. The +file's relevant timestamp shall be set to the greatest value supported +by the file system that is not greater than the specified time. +.P +If the +.IR tv_nsec +field of a +.BR timespec +structure has the special value UTIME_NOW, the file's relevant timestamp +shall be set to the greatest value supported by the file system that is +not greater than the current time. If the +.IR tv_nsec +field has the special value UTIME_OMIT, the file's relevant timestamp +shall not be changed. In either case, the +.IR tv_sec +field shall be ignored. +.P +If the +.IR times +argument is a null pointer, both the access and modification timestamps +shall be set to the greatest value supported by the file system that is +not greater than the current time. If +\fIutimensat\fR() +is passed a relative path in the +.IR path +argument, the file to be used shall be relative to the directory +associated with the file descriptor +.IR fd +instead of the current working directory. If the access mode of +the open file description associated with the file descriptor is not +O_SEARCH, the function shall check whether directory searches +are permitted using the current permissions of the directory +underlying the file descriptor. If the access mode is O_SEARCH, +the function shall not perform the check. +.P +If +\fIutimensat\fR() +is passed the special value AT_FDCWD in the +.IR fd +parameter, the current working directory shall be used. +.P +Only a process with the effective user ID equal to the user ID of the +file, or with write access to the file, or with appropriate privileges +may use +\fIfutimens\fR() +or +\fIutimensat\fR() +with a null pointer as the +.IR times +argument or with both +.IR tv_nsec +fields set to the special value UTIME_NOW. Only a process with the +effective user ID equal to the user ID of the file or with appropriate +privileges may use +\fIfutimens\fR() +or +\fIutimensat\fR() +with a non-null +.IR times +argument that does not have both +.IR tv_nsec +fields set to UTIME_NOW and does not have both +.IR tv_nsec +fields set to UTIME_OMIT. If both +.IR tv_nsec +fields are set to UTIME_OMIT, no ownership or permissions check shall be +performed for the file, but other error conditions may still be detected +(including +.BR [EACCES] +errors related to the path prefix). +.P +Values for the +.IR flag +argument of +\fIutimensat\fR() +are constructed by a bitwise-inclusive OR of flags from the following +list, defined in +.IR <fcntl.h> : +.IP AT_SYMLINK_NOFOLLOW 6 +.br +If +.IR path +names a symbolic link, then the access and modification times +of the symbolic link are changed. +.br +.P +Upon successful completion, +\fIfutimens\fR() +and +\fIutimensat\fR() +shall mark the last file status change timestamp for update, +with the exception that if both +.IR tv_nsec +fields are set to UTIME_OMIT, the file status change timestamp +need not be marked for update. +.P +The +\fIutimes\fR() +function shall be equivalent to the +\fIutimensat\fR() +function with the special value AT_FDCWD as the +.IR fd +argument and the +.IR flag +argument set to zero, except that the +.IR times +argument is a +.BR timeval +structure rather than a +.BR timespec +structure, and accuracy is only to the microsecond, not nanosecond, +and rounding towards the nearest second may occur. +.SH "RETURN VALUE" +Upon successful completion, these functions shall return 0. +Otherwise, these functions shall return \-1 and set +.IR errno +to indicate the error. If \-1 is returned, the file times shall +not be affected. +.SH ERRORS +These functions shall fail if: +.TP +.BR EACCES +The +.IR times +argument is a null pointer, or both +.IR tv_nsec +values are UTIME_NOW, and the effective user ID of the process +does not match the owner of the file and write access is denied. +.TP +.BR EINVAL +Either of the +.IR times +argument structures specified a +.IR tv_nsec +value that was neither UTIME_NOW nor UTIME_OMIT, and was a value less +than zero or greater than or equal to 1\|000 million. +.TP +.BR EINVAL +A new file timestamp would be a value whose +.IR tv_sec +component is not a value supported by the file system. +.TP +.BR EPERM +The +.IR times +argument is not a null pointer, does not have both +.IR tv_nsec +fields set to UTIME_NOW, does not have both +.IR tv_nsec +fields set to UTIME_OMIT, the calling process' effective user ID does +not match the owner of the file, and the calling process does not have +appropriate privileges. +.TP +.BR EROFS +The file system containing the file is read-only. +.P +The +\fIfutimens\fR() +function shall fail if: +.TP +.BR EBADF +The +.IR fd +argument is not a valid file descriptor. +.P +The +\fIutimensat\fR() +function shall fail if: +.TP +.BR EACCES +The access mode of the open file description associated with +.IR fd +is not O_SEARCH and the permissions of the directory underlying +.IR fd +do not permit directory searches. +.TP +.BR EBADF +The +.IR path +argument does not specify an absolute path and the +.IR fd +argument is neither AT_FDCWD nor a valid file descriptor open +for reading or searching. +.TP +.BR ENOTDIR +The +.IR path +argument is not an absolute path and +.IR fd +is a file descriptor associated with a non-directory file. +.P +The +\fIutimensat\fR() +and +\fIutimes\fR() +functions shall fail if: +.TP +.BR EACCES +Search permission is denied by a component of the path prefix. +.TP +.BR ELOOP +A loop exists in symbolic links encountered during resolution of the +.IR path +argument. +.TP +.BR ENAMETOOLONG +.br +The length of a component of a pathname is longer than +{NAME_MAX}. +.TP +.BR ENOENT +A component of +.IR path +does not name an existing file or +.IR path +is an empty string. +.TP +.BR ENOTDIR +A component of the path prefix names an existing file that is neither +a directory nor a symbolic link to a directory, or the +.IR path +argument contains at least one non-\c +<slash> +character and ends with one or more trailing +<slash> +characters and the last pathname component names an existing file +that is neither a directory nor a symbolic link to a directory. +.P +The +\fIutimensat\fR() +and +\fIutimes\fR() +functions may fail if: +.TP +.BR ELOOP +More than +{SYMLOOP_MAX} +symbolic links were encountered during resolution of the +.IR path +argument. +.TP +.BR ENAMETOOLONG +.br +The length of a pathname exceeds +{PATH_MAX}, +or pathname resolution of a symbolic link produced an intermediate +result with a length that exceeds +{PATH_MAX}. +.P +The +\fIutimensat\fR() +function may fail if: +.TP +.BR EINVAL +The value of the +.IR flag +argument is not valid. +.LP +.IR "The following sections are informative." +.SH EXAMPLES +None. +.SH "APPLICATION USAGE" +None. +.SH RATIONALE +The purpose of the +\fIutimensat\fR() +function is to set the access and modification time of files in +directories other than the current working directory without exposure +to race conditions. Any part of the path of a file could be changed in +parallel to a call to +\fIutimes\fR(), +resulting in unspecified behavior. By opening a file descriptor for +the target directory and using the +\fIutimensat\fR() +function it can be guaranteed that the changed file is located relative +to the desired directory. +.P +The standard developers considered including a special case for the +permissions required by +\fIutimensat\fR() +when one +.IR tv_nsec +field is UTIME_NOW and the other is UTIME_OMIT. One possibility would +be to include this case in with the cases where +.IR times +is a null pointer or both fields are UTIME_NOW, where the call is allowed +if the process has write permission for the file. However, associating +write permission with an update to just the last data access timestamp +(which is normally updated by +\fIread\fR()) +did not seem appropriate. The other possibility would be to specify that +this one case is allowed if the process has read permission, but this +was felt to be too great a departure from the +\fIutime\fR() +and +\fIutimes\fR() +functions on which +\fIutimensat\fR() +is based. If an application needs to set the last data access timestamp +to the current time for a file on which it has read permission but is not +the owner, it can do so by opening the file, reading one or more bytes +(or reading a directory entry, if the file is a directory), and then +closing it. +.SH "FUTURE DIRECTIONS" +None. +.SH "SEE ALSO" +.IR "\fIread\fR\^(\|)", +.IR "\fIutime\fR\^(\|)" +.P +The Base Definitions volume of POSIX.1\(hy2017, +.IR "\fB<fcntl.h>\fP", +.IR "\fB<sys_stat.h>\fP", +.IR "\fB<sys_time.h>\fP" +.\" +.SH COPYRIGHT +Portions of this text are reprinted and reproduced in electronic form +from IEEE Std 1003.1-2017, Standard for Information Technology +-- Portable Operating System Interface (POSIX), The Open Group Base +Specifications Issue 7, 2018 Edition, +Copyright (C) 2018 by the Institute of +Electrical and Electronics Engineers, Inc and The Open Group. +In the event of any discrepancy between this version and the original IEEE and +The Open Group Standard, the original IEEE and The Open Group Standard +is the referee document. The original Standard can be obtained online at +http://www.opengroup.org/unix/online.html . +.PP +Any typographical or formatting errors that appear +in this page are most likely +to have been introduced during the conversion of the source files to +man page format. To report such errors, see +https://www.kernel.org/doc/man-pages/reporting_bugs.html . |