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Diffstat (limited to 'man/man3/attr_list.3')
| -rw-r--r-- | man/man3/attr_list.3 | 269 |
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diff --git a/man/man3/attr_list.3 b/man/man3/attr_list.3 new file mode 100644 index 0000000..71408a4 --- /dev/null +++ b/man/man3/attr_list.3 @@ -0,0 +1,269 @@ +.TH ATTR_LIST 3 +.SH NAME +attr_list, attr_listf \- list the names of the user attributes of a filesystem object +.SH C SYNOPSIS +.PP +.sp +.nf +.B #include <sys/attributes.h> +.sp +.B "int attr_list (const char \(**path, char \(**buffer, " +.B " const int buffersize, int flags," +.B " attrlist_cursor_t \(**cursor);" +.PP +.B "int attr_listf (int fd, char \(**buffer, " +.B " const int buffersize, int flags," +.B " attrlist_cursor_t \(**cursor);" +.Op +.SH DESCRIPTION +The +.I attr_list +and +.I attr_listf +functions provide a way to list the existing attributes of a +filesystem object. +.P +.I Path\^ +points to a path name for a filesystem object, and +.I fd\^ +refers to the file descriptor associated with a file. +The +.I buffer +will be filled with a structure describing at least a portion of the +attributes associated with the given filesystem object. +.I Buffer +will be overwritten with an \f4attrlist_t\fP structure +containing a list of the attributes associated with +that filesystem object, up to a maximum of +.I buffersize +bytes. +The +.I buffer +must be sufficiently large to hold the appropriate data structures +plus at least one maximally sized attribute name, +but cannot be more than ATTR_MAX_VALUELEN (currently 64KB) bytes in length. +.PP +.Op c p a +The contents of an \f4attrlist_t\fP structure include the following members: +.P +.RS 3 +.nf +.ft 4 +.ta 9n 22n +__int32_t al_count; /\(** number of entries in attrlist \(**/ +__int32_t al_more; /\(** T/F: more attrs (do syscall again) \(**/ +__int32_t al_offset[1]; /\(** byte offsets of attrs [var-sized] \(**/ +.ft 1 +.fi +.RE +.PP +The +.I al_count +field shows the number of attributes represented in this buffer, +which is also the number of elements in the +.I al_offset +array. +The +.I al_more +field will be non-zero if another +.I attr_list +call would result in more attributes. +The +.I al_offset +array contains the byte offset within the +.I buffer +of the structure describing each of the attributes, +an \f4attrlist_ent_t\fP structure. +The \f4ATTR_ENTRY(buffer, index)\fP macro will help with decoding the list. +It takes a pointer to the +.I buffer +and an +.I index +into the +.I al_offset +array and returns a pointer to the corresponding +\f4attrlist_ent_t\fP structure. +.PP +The contents of an \f4attrlist_ent_t\fP structure +include the following members: +.P +.RS 3 +.nf +.ft 4 +.ta 9n 22n +u_int32_t a_valuelen; /\(** number bytes in value of attr \(**/ +char a_name[]; /\(** attr name (NULL terminated) \(**/ +.ft 1 +.fi +.Op +.RE +.PP +The +.I a_valuelen +field shows the size in bytes of the value +associated with the attribute whose name is stored in the +.I a_name +field. +The name is a NULL terminated string. +.PP +Note that the value of the attribute cannot be obtained through +this interface, the +.I attr_get +call should be used to get the value. +The +.I attr_list +interface tells the calling process how large of a buffer +it must have in order to get the attribute\'s value. +.PP +The +.I flags +argument can contain the following symbols bitwise OR\'ed together: +.TP +.SM +\%ATTR_ROOT +List the attributes that are in the +.B root +address space, not in the +.B user +address space. +(limited to use by super-user only) +.TP +.SM +\%ATTR_DONTFOLLOW +Do not follow symbolic links when resolving a +.I path +on an +.I attr_list +function call. +The default is to follow symbolic links. +.PP +The +.I cursor +argument is a pointer to an opaque data structure that the kernel uses +to track the calling process\'s position in the attribute list. +The only valid operations on a +.I cursor +are to pass it into an +.I attr_list +function call or to zero it out. +It should be zero\'ed out before the first +.I attr_list +call. +Note that multi-threaded applications may keep more than one +.I cursor +in order to serve multiple contexts, ie: the +.I attr_list +call is "thread-safe". +.PP +.I attr_list +will fail if one or more of the following are true: +.TP 17 +.SM +\%[ENOENT] +The named file does not exist. +.TP +.SM +\%[EPERM] +The effective user +.SM ID +does not match the owner of the file +and the effective user +.SM ID +is not super-user. +.TP +.SM +\%[ENOTDIR] +A component of the +path prefix +is not a directory. +.TP +.SM +\%[EACCES] +Search permission is denied on a +component of the +path prefix. +.TP +.SM +\%[EINVAL] +A bit was set in the +.I flag +argument that is not defined for this system call, +or the buffer was too small or too large. +.TP +.SM +\%[EFAULT] +Either +.I Path +or +.I buffer +points outside the allocated address space of the process, or +.I buffer +or +.I bufsize +are not 32bit aligned. +.TP +.SM +\%[ELOOP] +A path name lookup involved too many symbolic links. +.TP +.SM +\%[ENAMETOOLONG] +The length of +.I path +exceeds +.SM +.RI { MAXPATHLEN }, +or a pathname component is longer than +.SM +.RI { MAXNAMELEN }. +.TP +.SM +\%[ENOATTR] +.I attribute\^ +does not exist for this file. +.PP +.I attr_listf\^ +will fail if: +.TP 15 +.SM +\%[EINVAL] +A bit was set in the +.I flag +argument that is not defined for this system call, or +.I fd\^ +refers to a socket, not a file, +or the buffer was too small or too large. +.TP +.SM +\%[EFAULT] +Either +.I Path +or +.I buffer +points outside the allocated address space of the process, or +.I buffer +or +.I bufsize +are not 32bit aligned. +.TP +.SM +\%[EBADF] +.I Fd\^ +does not refer to a valid descriptor. +.SH "SEE ALSO" +attr(1), +.br +attrctl(2), +.br +attr_get(3), attr_getf(3), +.br +attr_multi(3), attr_multif(3) +.br +attr_remove(3), attr_removef(3), +.br +attr_set(3), attr_set(3) +.SH "DIAGNOSTICS" +Upon successful completion, a value of 0 is returned. +Otherwise, a value of \-1 is returned and +.I errno\^ +is set to indicate the error. |