Open System Services Library Calls Reference Manual (G06.27+, H06.04+)

OSS Library Calls (n - r) opendir(3)
Use on Guardian Objects
A call to opendir() on /G, followed by calls to readdir(), 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.
Guardian process names can be directories. However, a Guardian process cannot be opened
using opendir( ). Attempts to do so fail. If the named process is a subtype 30 process, errno is
set to [EPERM]. If the named process is not a subtype 30 process, errno is set to [ENOENT].
Use From the Guardian Environment
The opendir( ) function is one of a set of functions that have the following effects when the first
of them is called from the Guardian environment:
• Two Guardian file system file numbers (not necessarily the next two available) are allo-
cated for the root directory and the current working directory. These file numbers cannot
be closed by calling the Guardian FILE_CLOSE_ procedure.
• The current working directory is assigned from the VOLUME attribute of the Guardian
environment =_DEFAULTS DEFINE.
• The use of static memory by the process increases slightly.
These effects occur only when the first of the set of functions is called. The effects are not cumu-
lative.
EXAMPLES
The following example shows how to open and search a directory for the entry name:
len = strlen(name);
dir_pointer = opendir(".");
for (dp = readdir(dir_pointer); dp != NULL;
dp = readdir(dir_pointer))
if (strlen(dp->d_name) == len && !strcmp(dp->d_name, name)) {
closedir(dir_pointer);
return FOUND;
}
closedir(dir_pointer);
return NOT_FOUND;
RETURN VALUES
Upon successful completion, the opendir() function returns a pointer to an object of type DIR.
Otherwise, null is returned and errno is set to indicate the error.
ERRORS
If any of the following conditions occurs, the opendir( ) function sets errno to the corresponding
value:
[EACCES] Search permission is denied for any component of the directory named by the
dir_name parameter, or read permission is denied for this name.
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