man2/fchmodat.2

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  26 .TH FCHMODAT 2 2006-05-05 "Linux 2.6.16" "Linux Programmer's Manual"
  27 .SH NAME
  28 fchmodat \- change permissions of a file relative to a directory \
  29 file descriptor
  30 .SH SYNOPSIS
  31 .nf
  32 .B #define _ATFILE_SOURCE
  33 .B #include <sys/stat.h>
  34 .sp
  35 .BI "int fchmodat(int " dirfd ", const char *" pathname ", mode_t " \
  36 mode ", int " flags );
  37 .fi
  38 .SH DESCRIPTION
  39 The
  40 .BR fchmodat ()
  41 system call operates in exactly the same way as
  42 .BR chmod (2),
  43 except for the differences described in this manual page.
  44
  45 If the pathname given in
  46 .I pathname
  47 is relative, then it is interpreted relative to the directory
  48 referred to by the file descriptor
  49 .IR dirfd
  50 (rather than relative to the current working directory of
  51 the calling process, as is done by
  52 .BR chmod (2)
  53 for a relative pathname).
  54
  55 If
  56 .I pathname
  57 is relative and
  58 .I dirfd
  59 is the special value
  60 .BR AT_FDCWD ,
  61 then
  62 .I pathname
  63 is interpreted relative to the current working
  64 directory of the calling process (like
  65 .BR chmod (2)).
  66
  67 If
  68 .IR pathname
  69 is absolute, then
  70 .I dirfd
  71 is ignored.
  72
  73 .I flags
  74 can either be 0, or include the following flag:
  75 .TP
  76 .B AT_SYMLINK_NOFOLLOW
  77 If
  78 .I pathname
  79 is a symbolic link, do not dereference it:
  80 instead operate on the link itself.
  81 This flag is not currently implemented.
  82 .SH "RETURN VALUE"
  83 On success,
  84 .BR fchmodat ()
  85 returns 0.
  86 On error, \-1 is returned and
  87 .I errno
  88 is set to indicate the error.
  89 .SH ERRORS
  90 The same errors that occur for
  91 .BR chmod (2)
  92 can also occur for
  93 .BR fchmodat ().
  94 The following additional errors can occur for
  95 .BR fchmodat ():
  96 .TP
  97 .B EBADF
  98 .I dirfd
  99 is not a valid file descriptor.
 100 .TP
 101 .B EINVAL
 102 Invalid flag specified in
 103 .IR flags .
 104 .TP
 105 .B ENOTDIR
 106 .I pathname
 107 is relative and
 108 .I dirfd
 109 is a file descriptor referring to a file other than a directory.
 110 .TP
 111 .B ENOTSUP
 112 .IR flags
 113 specified
 114 .BR AT_SYMLINK_NOFOLLOW ,
 115 which is not supported.
 116 .SH NOTES
 117 See
 118 .BR openat (2)
 119 for an explanation of the need for
 120 .BR fchmodat ().
 121 .SH "CONFORMING TO"
 122 This system call is non-standard but is proposed
 123 for inclusion in a future revision of POSIX.1.
 124 .SH VERSIONS
 125 .BR fchmodat ()
 126 was added to Linux in kernel 2.6.16.
 127 .SH "SEE ALSO"
 128 .BR chmod (2),
 129 .BR openat (2),
 130 .BR path_resolution (2)