Open System Services Library Calls Reference Manual (G06.29+, H06.08+, J06.03+)

readdir64(3) OSS Library Calls Reference Manual
• The caller might receive a SIGSEGV or SIGILL signal in the OSS environment.
• The caller might cause a trap condition in the Guardian environment.
• User memory might be corrupted.
General Considerations for Directory Operations
Directory entries represent files. Files can be removed from a directory or added to a directory
asynchronously to the operation of the readdir64() function.
If files are removed from a directory after the most recent call to the opendir( ) or rewinddir( )
function but before the first call to the readdir64( ) function, the readdir64( ) function does not
return entries for these files. If files are added to a directory after the most recent call to the
opendir( ) or rewinddir( ) function but before the first call to the readdir64() function, the read-
dir64( ) function returns entries for these files.
The readdir64() function retrieves a block of directory entries with each actual read operation
and stores them in a system buffer. The readdir64() function marks for update the st_atime
field of the directory each time the directory is actually read.
The first call to the readdir64( ) function after a call to the opendir( ) or rewinddir( ) function
retrieves a block of directory entries. The first two entries of the block are for . (dot) and ..(dot-
dot). Therefore, the first entry returned is for . (dot). Each subsequent call to readdir64( ) fetches
another entry from the buffer until the buffer is empty, at which time another block of entries is
automatically retrieved.
If files are added to a directory after a block of entries has been fetched for a readdir64( ) call, no
entries are returned for those files. If files are deleted after a block of entries has been fetched,
entries are returned for those files.
Directory Operations After fork Operations
If, after a call to the fork( ) or tdm_fork( ) function, both the parent and child processes call the
readdir64( ) function to access an OSS directory, the results of the calls are undefined.
If, after a call to the fork( ) or tdm_fork( ) function, both the parent and child processes call the
rewinddir( ) function and the readdir64( ) function to access an OSS directory, the results are
undefined.
Use on Guardian Objects
Only disks appear as entries in the /G directory.
A call to opendir( ) on /G, followed by calls to readdir64( ), returns all of the Guardian volumes
on the system.
The same sequence performed on /G/vol returns all of the subvolumes and temporary files on that
particular volume.
The same sequence performed on /G/vol/subvol returns
all
of the files on that particular subvo-
lume, including files that are inaccessible to the OSS interface such as Enscribe structured files
and SQL objects.
The OSS pathnames (relative to /G) returned for Guardian files are in lowercase. The read-
dir64( ) function also returns the . (dot) and ..(dot-dot) entries for each directory that has been
successfully opened.
Use on Objects in /E
For objects in /E that reside on remote HP NonStop server nodes, the d_ino field of the dirent64
structure contains the Expand node number of the remote HP NonStop server node containing the
object. The d_ino value for objects in /E that reside on the local node is the pseudo Expand node
number 255.
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