diff options
Diffstat (limited to 'man3p/chown.3p')
| -rw-r--r-- | man3p/chown.3p | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/man3p/chown.3p b/man3p/chown.3p new file mode 100644 index 000000000..6244a76ed --- /dev/null +++ b/man3p/chown.3p @@ -0,0 +1,174 @@ +.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved +.TH "CHOWN" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual" +.\" chown +.SH NAME +chown \- change owner and group of a file +.SH SYNOPSIS +.LP +\fB#include <unistd.h> +.br +.sp +int chown(const char *\fP\fIpath\fP\fB, uid_t\fP \fIowner\fP\fB, gid_t\fP +\fIgroup\fP\fB); +.br +\fP +.SH DESCRIPTION +.LP +The \fIchown\fP() function shall change the user and group ownership +of a file. +.LP +The \fIpath\fP argument points to a pathname naming a file. The user +ID and group ID of the named file shall be set to the +numeric values contained in \fIowner\fP and \fIgroup\fP, respectively. +.LP +Only processes with an effective user ID equal to the user ID of the +file or with appropriate privileges may change the +ownership of a file. If _POSIX_CHOWN_RESTRICTED is in effect for \fIpath\fP: +.IP " *" 3 +Changing the user ID is restricted to processes with appropriate privileges. +.LP +.IP " *" 3 +Changing the group ID is permitted to a process with an effective +user ID equal to the user ID of the file, but without +appropriate privileges, if and only if \fIowner\fP is equal to the +file's user ID or ( \fBuid_t\fP)-1 and \fIgroup\fP is equal +either to the calling process' effective group ID or to one of its +supplementary group IDs. +.LP +.LP +If the specified file is a regular file, one or more of the S_IXUSR, +S_IXGRP, or S_IXOTH bits of the file mode are set, and the +process does not have appropriate privileges, the set-user-ID (S_ISUID) +and set-group-ID (S_ISGID) bits of the file mode shall be +cleared upon successful return from \fIchown\fP(). If the specified +file is a regular file, one or more of the S_IXUSR, S_IXGRP, +or S_IXOTH bits of the file mode are set, and the process has appropriate +privileges, it is implementation-defined whether the +set-user-ID and set-group-ID bits are altered. If the \fIchown\fP() +function is successfully invoked on a file that is not a +regular file and one or more of the S_IXUSR, S_IXGRP, or S_IXOTH bits +of the file mode are set, the set-user-ID and set-group-ID +bits may be cleared. +.LP +If \fIowner\fP or \fIgroup\fP is specified as ( \fBuid_t\fP)-1 or +( \fBgid_t\fP)-1, respectively, the corresponding ID of +the file shall not be changed. If both owner and group are -1, the +times need not be updated. +.LP +Upon successful completion, \fIchown\fP() shall mark for update the +\fIst_ctime\fP field of the file. +.SH RETURN VALUE +.LP +Upon successful completion, 0 shall be returned; otherwise, -1 shall +be returned and \fIerrno\fP set to indicate the error. If +-1 is returned, no changes are made in the user ID and group ID of +the file. +.SH ERRORS +.LP +The \fIchown\fP() function shall fail if: +.TP 7 +.B EACCES +Search permission is denied on a component of the path prefix. +.TP 7 +.B ELOOP +A loop exists in symbolic links encountered during resolution of the +\fIpath\fP argument. +.TP 7 +.B ENAMETOOLONG +The length of the \fIpath\fP argument exceeds {PATH_MAX} or a pathname +component is longer than {NAME_MAX}. +.TP 7 +.B ENOTDIR +A component of the path prefix is not a directory. +.TP 7 +.B ENOENT +A component of \fIpath\fP does not name an existing file or \fIpath\fP +is an empty string. +.TP 7 +.B EPERM +The effective user ID does not match the owner of the file, or the +calling process does not have appropriate privileges and +_POSIX_CHOWN_RESTRICTED indicates that such privilege is required. +.TP 7 +.B EROFS +The named file resides on a read-only file system. +.sp +.LP +The \fIchown\fP() function may fail if: +.TP 7 +.B EIO +An I/O error occurred while reading or writing to the file system. +.TP 7 +.B EINTR +The \fIchown\fP() function was interrupted by a signal which was caught. +.TP 7 +.B EINVAL +The owner or group ID supplied is not a value supported by the implementation. +.TP 7 +.B ELOOP +More than {SYMLOOP_MAX} symbolic links were encountered during resolution +of the \fIpath\fP argument. +.TP 7 +.B ENAMETOOLONG +As a result of encountering a symbolic link in resolution of the \fIpath\fP +argument, the length of the substituted pathname +string exceeded {PATH_MAX}. +.sp +.LP +\fIThe following sections are informative.\fP +.SH EXAMPLES +.LP +None. +.SH APPLICATION USAGE +.LP +Although \fIchown\fP() can be used on some implementations by the +file owner to change the owner and group to any desired +values, the only portable use of this function is to change the group +of a file to the effective GID of the calling process or to a +member of its group set. +.SH RATIONALE +.LP +System III and System V allow a user to give away files; that is, +the owner of a file may change its user ID to anything. This +is a serious problem for implementations that are intended to meet +government security regulations. Version 7 and 4.3 BSD permit +only the superuser to change the user ID of a file. Some government +agencies (usually not ones concerned directly with security) +find this limitation too confining. This volume of IEEE\ Std\ 1003.1-2001 +uses \fImay\fP to permit secure implementations +while not disallowing System V. +.LP +System III and System V allow the owner of a file to change the group +ID to anything. Version 7 permits only the superuser to +change the group ID of a file. 4.3 BSD permits the owner to change +the group ID of a file to its effective group ID or to any of +the groups in the list of supplementary group IDs, but to no others. +.LP +The POSIX.1-1990 standard requires that the \fIchown\fP() function +invoked by a non-appropriate privileged process clear the +S_ISGID and the S_ISUID bits for regular files, and permits them to +be cleared for other types of files. This is so that changes in +accessibility do not accidentally cause files to become security holes. +Unfortunately, requiring these bits to be cleared on +non-executable data files also clears the mandatory file locking bit +(shared with S_ISGID), which is an extension on many +implementations (it first appeared in System V). These bits should +only be required to be cleared on regular files that have one or +more of their execute bits set. +.SH FUTURE DIRECTIONS +.LP +None. +.SH SEE ALSO +.LP +\fIchmod\fP() , \fIpathconf\fP() , the Base Definitions volume of +IEEE\ Std\ 1003.1-2001, \fI<sys/types.h>\fP, \fI<unistd.h>\fP +.SH COPYRIGHT +Portions of this text are reprinted and reproduced in electronic form +from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology +-- Portable Operating System Interface (POSIX), The Open Group Base +Specifications Issue 6, Copyright (C) 2001-2003 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 . |