The C RTL provides an extensive list of feature switches that
can be set using DECC$ logical names. These switches affect the
behavior of a C application at run time.
The feature switches introduce new behaviors and also preserve
old behaviors that have been deprecated.
You enable most features by setting a logical name to ENABLE and
disable a feature by setting the logical name to DISABLE:
$ DEFINE DECC$feature ENABLE
$ DEFINE DECC$feature DISABLE
Some feature logical names can be set to a numeric value. For
example:
$ DEFINE DECC$PIPE_BUFFER_SIZE 32768
NOTES
o Do not set C RTL feature logical names for the system.
Set them only for the applications that need them,
because other applications including OpenVMS components
depend on the default behavior of these logical names.
o Older feature logicals from earlier releases of the
C Run-Time Library were documented as supplying "any
equivalence string" to enable a feature. While this was
true at one time, we now strongly recommend that you use
ENABLE for setting these feature logicals and DISABLE for
disabling them. Failure to do so may produce unexpected
results.
The reason for this is twofold:
- In previous versions of the C RTL, any equivalence
string, even DISABLE, may have enabled a feature
logical.
- In subsequent and current versions of the C RTL, the
following equivalence strings will disable a feature
logical. Do not use them to enable a feature logical.
DISABLE
0 (zero)
F
FALSE
N
NO
Any other string not on this list will enable a
feature logical. The unintentionally misspelled string
"DSABLE", for example, will enable a feature logical.
The C RTL also provides several functions to manage feature
logicals within your applications:
decc$feature_get
decc$feature_get_value
decc$feature_get_index
decc$feature_get_name
decc$feature_set
decc$feature_set_value
decc$feature_show
decc$feature_show_all
See the reference section for more information on these
functions.
The C RTL feature logical names are listed below, grouped by the
type of features they control:
Feature Logical Name Default
------- ------- ---- -------
Performance Optimizations:
DECC$ENABLE_GETENV_CACHE DISABLE
DECC$LOCALE_CACHE_SIZE 0
DECC$TZ_CACHE_SIZE 2
Legacy Behaviors:
DECC$ALLOW_UNPRIVILEGED_NICE DISABLE
DECC$NO_ROOTED_SEARCH_LISTS DISABLE
DECC$PRINTF_USES_VAX_ROUND DISABLE
DECC$THREAD_DATA_AST_SAFE DISABLE
DECC$V62_RECORD_GENERATION DISABLE
DECC$WRITE_SHORT_RECORDS DISABLE
DECC$XPG4_STRPTIME DISABLE
File Attributes:
DECC$DEFAULT_LRL 32767
DECC$DEFAULT_UDF_RECORD DISABLE
DECC$FIXED_LENGTH_SEEK_TO_EOF DISABLE
DECC$ACL_ACCESS_CHECK DISABLE
Mailboxes:
DECC$MAILBOX_CTX_STM DISABLE
Changes for UNIX Conformance:
DECC$SELECT_IGNORES_INVALID_FD DISABLE
DECC$STRTOL_ERANGE DISABLE
DECC$VALIDATE_SIGNAL_IN_KILL DISABLE
General UNIX Enhancements:
DECC$UNIX_LEVEL DISABLE
DECC$ARGV_PARSE_STYLE DISABLE
DECC$PIPE_BUFFER_SIZE 512
DECC$PIPE_BUFFER_QUOTA 512
DECC$STREAM_PIPE DISABLE
DECC$POPEN_NO_CRLF_REC_ATTR DISABLE
DECC$STDIO_CTX_EOL DISABLE
DECC$USE_RAB64 DISABLE
DECC$GLOB_UNIX_STYLE DISABLE
Enhancements for UNIX Style Filenames:
DECC$DISABLE_TO_VMS_LOGNAME_TRANSLATION DISABLE
DECC$EFS_CHARSET DISABLE
DECC$ENABLE_TO_VMS_LOGNAME_CACHE ENABLE
DECC$FILENAME_ENCODING_UTF8 DISABLE
DECC$FILENAME_UNIX_NO_VERSION DISABLE
DECC$FILENAME_UNIX_REPORT DISABLE
DECC$READDIR_DROPDOTNOTYPE DISABLE
DECC$RENAME_NO_INHERIT DISABLE
DECC$RENAME_ALLOW_DIR DISABLE
Enhancements for UNIX Style File Attributes:
DECC$EFS_FILE_TIMESTAMPS DISABLE
DECC$EXEC_FILEATTR_INHERITANCE DISABLE
DECC$FILE_OWNER_UNIX DISABLE
DECC$FILE_PERMISSION_UNIX DISABLE
DECC$FILE_SHARING DISABLE
UNIX Compliance Mode:
DECC$DETACHED_CHILD_PROCESS DISABLE
DECC$FILENAME_UNIX_ONLY DISABLE
DECC$POSIX_STYLE_UID DISABLE
DECC$USE_JPI$_CREATOR DISABLE
New Behaviors for POSIX Conformance:
DECC$ALLOW_REMOVE_OPEN_FILES DISABLE
DECC$POSIX_SEEK_STREAM_FILE DISABLE
DECC$UMASK RMS default
Filename Handling:
DECC$POSIX_COMPLIANT_PATHNAMES DISABLE
DECC$DISABLE_POSIX_ROOT ENABLE
DECC$EFS_CASE_PRESERVE DISABLE
DECC$EFS_CASE_SPECIAL DISABLE
DECC$EFS_NO_DOTS_IN_DIRNAME DISABLE
DECC$READDIR_KEEPDOTDIR DISABLE
DECC$UNIX_PATH_BEFORE_LOGNAME DISABLE
1 – DECC$ACL_ACCESS_CHECK
The DECC$ACL_ACCESS_CHECK feature logical controls the behavior
of the access function.
With DECC$ACL_ACCESS_CHECK enabled, the access function checks
both UIC protection and OpenVMS Access Control Lists (ACLs).
With DECC$ACL_ACCESS_CHECK disabled, the access function checks
only UIC protection.
2 – DECC$ALLOW_REMOVE_OPEN_FILES
The DECC$ALLOW_REMOVE_OPEN_FILES feature logical controls the
behavior of the remove function on open files. Ordinarily, the
operation fails. However, POSIX conformance dictates that the
operation succeed.
With DECC$ALLOW_REMOVE_OPEN_FILES enabled, this POSIX conformant
behavior is achieved.
3 – DECC$ALLOW_UNPRIVILEGED_NICE
With DECC$ALLOW_UNPRIVILEGED_NICE enabled, the nice function
exhibits its legacy behavior of not checking the privilege of
the calling process (that is, any user may lower the nice value
to increase process priorities). Also, when the caller sets a
priority above MAX_PRIORITY, the nice value is set to the base
priority.
With DECC$ALLOW_UNPRIVILEGED_NICE disabled, the nice function
conforms to the X/Open standard of checking the privilege of the
calling process (only users with ALTPRI privilege can lower the
nice value to increase process priorities), and when the caller
sets a priority above MAX_PRIORITY, the nice value is set to MAX_
PRIORITY.
4 – DECC$ARGV_PARSE_STYLE
With DECC$ARGV_PARSE_STYLE enabled, case is preserved in command-
line arguments when the process has been set up for extended DCL
parsing using SET PROCESS/PARSE_STYLE=EXTENDED.
DECC$ARGV_PARSE_STYLE must be defined externally as a logical
name or set in a function called using the LIB$INITIALIZE
mechanism because it is evaluated before function main is
called.
5 – DECC$DEFAULT_LRL
DECC$DEFAULT_LRL specifies the default value for the RMS
attribute for the longest record length. The default value 32767
is the largest record size supported by RMS.
Default: 32767
Maximum: 32767
6 – DECC$DEFAULT_UDF_RECORD
With DECC$DEFAULT_UDF_RECORD enabled, file access mode defaults
to RECORD instead of STREAM mode for all files except STREAMLF.
7 – DECC$DETACHED_CHILD_PROCESS
With DECC$DETACHED_CHILD_PROCESS enabled, child processes created
using vfork and exec are created as detached processes instead of
subprocesses.
This feature has only limited support. In some cases the console
cannot be shared between the parent process and the detached
process, which can cause exec to fail.
8 – DECC$DISABLE_POSIX_ROOT
With DECC$DISABLE_POSIX_ROOT enabled, support for the POSIX root
directory defined by SYS$POSIX_ROOT is disabled.
With DECC$DISABLE_POSIX_ROOT disabled, the SYS$POSIX_ROOT logical
name is interpreted as the equivalent of the file path "/". If
a UNIX path starting with a slash (/) is given and the value
after the leading slash cannot be translated as a logical name,
SYS$POSIX_ROOT is used as the parent directory for the specified
UNIX file path.
The C RTL supports a UNIX style root that behaves like a real
directory. This allows such actions as:
% cd /
% mkdir /dirname
% tar -xvf tarfile.tar /dirname
% ls /
Previously, the C RTL did not recognize "/" as a directory name.
The normal processing for a file path starting with "/" was to
interpret the first element as a logical name or device name. If
this failed, there was special processing for the name /dev/null
and names starting with /bin and /tmp:
/dev/null NLA0:
/bin SYS$SYSTEM:
/tmp SYS$SCRATCH:
These behaviors are retained for compatibility purposes. In
addition, support has been added to the C RTL for the logical
name SYS$POSIX_ROOT as an equivalent to "/".
To enable this feature for use by the C RTL, define SYS$POSIX_
ROOT as a concealed logical name. For example:
$ DEFINE/TRANSLATION=(CONCEALED,TERMINAL) SYS$POSIX_ROOT -
"$1$DKA0:[SYS0.abc.]"
To disable this feature:
$ DEFINE DECC$DISABLE_POSIX_ROOT DISABLE
Enabling SYS$POSIX_ROOT results in the following behavior:
o If the existing translation of a UNIX path starting with "/"
fails and SYS$POSIX_ROOT is defined, the name is interpreted
as if it starts with /sys$posix_root.
o When converting from an OpenVMS to a UNIX style filename,
and the OpenVMS name starts with "SYS$POSIX_ROOT:", then
the "SYS$POSIX_ROOT:" is removed. For example, SYS$POSIX_
ROOT:[dirname] becomes /dirname. If the resulting name
could be interpreted as a logical name or one of the special
cases previously listed, the result is /./dirname instead of
/dirname.
9 – DECC$DISABLE_TO_VMS_LOGNAME_TRANSLATION
With DECC$DISABLE_TO_VMS_LOGNAME_TRANSLATION enabled, the
conversion routine decc$to_vms will only treat the first element
of a UNIX style name as a logical name if there is a leading
slash (/).
10 – DECC$EFS_CASE_PRESERVE
With DECC$EFS_CASE_PRESERVE enabled, case is preserved for
filenames on ODS-5 disks.
With DECC$EFS_CASE_PRESERVE disabled, UNIX style filenames are
always reported in lowercase.
However, note that enabling DECC$EFS_CASE_SPECIAL overrides the
setting for DECC$EFS_CASE_PRESERVE.
11 – DECC$EFS_CASE_SPECIAL
With DECC$EFS_CASE_SPECIAL enabled, case is preserved only for
filenames containing lowercase. If an element of a filename
contains all uppercase letters, it is reported in all lowercase
in UNIX style.
When enabled, DECC$EFS_CASE_SPECIAL overrides the value of
DECC$EFS_CASE_PRESERVE.
12 – DECC$EFS_CHARSET
With DECC$EFS_CHARSET enabled, UNIX names can contain ODS-5
extended characters. Support includes multiple dots and all ASCII
characters in the range 0 to 255, except the following:
<NUL>
/ *
" ?
Unless DECC$FILENAME_UNIX_ONLY is enabled, some characters can be
interpreted as OpenVMS characters depending on context. They are:
: ^
[ ;
<
DECC$EFS_CHARSET might be necessary for existing applications
that make assumptions about filenames based on the presence
of certain characters, because the following nonstandard and
undocumented C RTL extensions do not work when EFS extended
character-set support is enabled:
o $HOME is interpreted as the user's login directory
With DECC$EFS_CHARSET enabled, $HOME is treated literally and
may be in an OpenVMS or UNIX style filename.
o ~name is interpreted as the login directory for user name
With DECC$EFS_CHARSET enabled, ~name is treated literally and
can be in an OpenVMS or UNIX style filename.
o Wild card regular expressions in the form [a-z]
With DECC$EFS_CHARSET enabled, square brackets are acceptable
in OpenVMS and UNIX style filenames. For instance, in a
function such as open, abc[a-z]ef.txt is interpreted as a
UNIX style name equivalent to the OpenVMS style name abc^[a-
z^]ef.txt, and [a-z]bc is interpreted as an OpenVMS style name
equivalent to the UNIX style name /sys$disk/a-z/bc.
With DECC$EFS_CHARSET enabled, the following encoding for EFS
extended characters is supported when converting from an OpenVMS
style filename to a UNIX style filename:
o All ODS-2 compatible names
o All encoding for 8-bit characters, either as single byte or
using two-digit hexadecimal form ^ab. In a UNIX path these are
always represented as a single byte.
o Encoding for DEL (^7F)
o The following characters when preceded by a caret:
space ! , _ & ' ( ) + @ { } ; # [ ] % ^ = $ - ~ .
o The following characters when not preceded by a caret:
$ - ~ .
o The implementation supports the conversion from OpenVMS to
UNIX needed for functions readdir, ftw, getname, fgetname,
getcwd, and others.
NOTE
There are some special cases in C RTL filename processing.
For example:
o Pathnames ending in ^.dir are treated as directories, and
when translated, these characters are truncated from the
string.
o Pathnames begining with ^/ treat the next token as a
logical name or a directory from the root.
The following sample program shows these nuances:
#include <stdio.h>
#include <dirent.h>
#include <unixlib.h>
#include <string.h>
main()
{
char adir[80];
DIR *dir;
struct dirent *dp;
int decc_feature_efs_charset_index = 0;
int decc_feature_efs_charset_default_val = 0;
if (
( (decc_feature_efs_charset_index =
decc$feature_get_index("DECC$EFS_CHARSET")) == -1 )
||
( (decc_feature_efs_charset_default_val =
decc$feature_get_value(decc_feature_efs_charset_index, 0)) == -1 )
||
( (decc$feature_set_value(decc_feature_efs_charset_index, 1, TRUE) == -1))
)
{
printf("Error setting up DECC$EFS_CHARSET macro\n");
}
strcpy(adir, "SYS$SYSDEVICE:[SSHTEST.TEST.a^,test^.dir^;22]");
printf("\n\nFor %s\n", adir);
mrb: dir = opendir(adir);
if(dir)
{
do
{
dp = readdir(dir);
if(dp->d_name) printf("%s\n", dp->d_name);
} while (dp);
}
closedir(dir);
strcpy(adir, "SYS$SYSDEVICE:[SSHTEST.TEST.a^,test^.dir]");
printf("\n\nFor %s\n", adir);
dir = opendir(adir);
if(dir)
{
do
{
dp = readdir(dir);
if(dp->d_name) printf("%s\n", dp->d_name);
} while (dp);
}
closedir(dir);
strcpy(adir, "SYS$SYSDEVICE:[SSHTEST.TEST.a^\\test]");
printf("\n\nFor %s\n", adir);
dir = opendir(adir);
if(dir)
{
do
{
dp = readdir(dir);
if(dp->d_name) printf("%s\n", dp->d_name);
} while (dp);
}
strcpy(adir, "SYS$SYSDEVICE:[SSHTEST.TEST.copies]");
printf("\n\nFor %s\n", adir);
dir = opendir(adir);
if(dir)
{
do
{
dp = readdir(dir);
if(dp->d_name) printf("%s\n", dp->d_name);
} while (dp);
}
closedir(dir);
strcpy(adir, "/SYS$SYSDEVICE/SSHTEST/TEST/copies");
printf("\n\nFor %s\n", adir);
dir = opendir(adir);
if(dir)
{
do
{
dp = readdir(dir);
if(dp->d_name) printf("%s\n", dp->d_name);
} while (dp);
}
closedir(dir);
}
13 – DECC$EFS_FILE_TIMESTAMPS
With DECC$EFS_FILE_TIMESTAMPS enabled, stat and fstat report
new ODS-5 access time (st_atime), attribute revision time
(st_ctime) and modification time (st_mtime) for files on ODS-5
volumes that have the extended file times enabled using SET
VOLUME/VOLUME=ACCESS_DATES.
If DECC$EFS_FILE_TIMESTAMPS is disabled, or the volume is not
ODS-5, or the volume does not have support for these additional
times enabled, st_ctime continues to be the file creation time
and st_atime the same as the st_mtime.
The utime and utimes functions support these ODS-5 times in the
same way as stat.
14 – DECC$EFS_NO_DOTS_IN_DIRNAME
With support for extended characters in filenames for ODS-5,
a name such as NAME.EXT can be interpreted as NAME.EXT.DIR.
Determining if directory [.name^.ext] exists adds overhead to
UNIX name translation when support for extended character support
in UNIX filenames is enabled.
Enabling the DECC$EFS_NO_DOTS_IN_DIRNAME feature logical
suppresses the interpretation of a filename containing dots as
a directory name. With this logical enabled, NAME.EXT is assumed
to be a filename; no check is made for directory [.name^.ext].
15 – DECC$ENABLE_GETENV_CACHE
The C RTL supplements the list of environment variables in the
environ table with all logical names and DCL symbols available to
the process.
By default, whenever getenv is called for a name not in the
environ table, an attempt is made to resolve this as a logical
name and, if this fails, as a DCL symbol.
With DECC$ENABLE_GETENV_CACHE enabled, once a logical name or
DCL name has been successfully translated, its value is stored
in a cache. When the same name is requested in a future call
to getenv, the value is returned from the cache instead of
reevaluating the logical name or DCL symbol.
16 – DECC$ENABLE_TO_VMS_LOGNAME_CACHE
Use the DECC$ENABLE_TO_VMS_LOGNAME_CACHE to improve the
performance of UNIX name translation. The value is the life of
each cache entry in seconds. The equivalence string ENABLE is
evaluated as 1 second.
Define DECC$ENABLE_TO_VMS_LOGNAME_CACHE to 1 to enable the cache
with a 1-second life for each entry.
Define DECC$ENABLE_TO_VMS_LOGNAME_CACHE to 2 to enable the cache
with a 2-second life for each entry.
Define DECC$ENABLE_TO_VMS_LOGNAME_CACHE to -1 to enable the cache
without a cache entry expiration.
17 – DECC$EXEC_FILEATTR_INHERITANCE
The DECC$EXEC_FILEATTR_INHERITANCE feature logical affects child
processes that are C programs.
For versions of OpenVMS before Version 7.3-2, DECC$EXEC_FILEATTR_
INHERITANCE is either enabled or disabled:
o With DECC$EXEC_FILEATTR_INHERITANCE enabled, the current file
pointer and the file open mode is passed to the child process
in exec calls.
o With this logical name disabled, the child process does not
inherit append mode or the file position.
For OpenVMS Version 7.3-2 and higher, DECC$EXEC_FILEATTR_
INHERITANCE can be defined to 1 or 2, or be disabled:
o With DECC$EXEC_FILEATTR_INHERITANCE defined to 1, a child
process inherits file positioning for all file access modes
except append.
o With DECC$EXEC_FILEATTR_INHERITANCE defined to 2, a child
process inherits file positioning for all file access modes
including append.
o With DECC$EXEC_FILEATTR_INHERITANCE disabled, a child process
does not inherit the file position for any access modes.
18 – DECC$FILENAME_ENCODING_UTF8
C RTL routines that deal with filenames now support filenames in
UTF-8 encoding when given in UNIX style.
For example, on an ODS-5 disk the OpenVMS DIRECTORY command
supports a filename with the following characters:
disk:[mydir]^U65E5^U672C^U8A9E.txt
This filename contains three UCS-2 characters (call them xxx,
yyy, and zzz for typographical purposes) meaning "day", "origin",
and "language", respectively.
With UTF-8 support enabled, a C program can now read the filename
from the VMS directory and use that filename as an UTF-8 encoded
string.
For example, opendir("/disk/mydir") followed by a readdir will
place the following into the d_name field of the supplied dirent
structure:
"\xE6\x97\xA5\xE6\x9C\xAC\xE8\xAA\x9E.txt"
One of the following calls can then open this file:
open("/disk/mydir/\xE6\x97\xA5\xE6\x9C\xAC\xE8\xAA\x9E.txt",O_RDWR,0)
open("/disk/mydir/xxxyyyzzz.txt", O_RDWR,0)
The "\xE6\x97\xA5" above is the byte stream E697A5, which
represents the xxx character in UTF-8 encoding.
This feature enhances the UNIX portability of international
software that uses UTF-8 encoded filenames.
The DECC$FILENAME_ENCODING_UTF8 feature logical controls whether
or not the C RTL allows and correctly interprets Unicode UTF-8
encoding for filenames given in UNIX style.
This logical is undefined by default, and the C RTL behavior is
to accept filenames as ASCII and Latin-1 format.
This feature works only on ODS-5 disks. Therefore, to enable
Unicode UTF-8 encoding, you must define both the DECC$FILENAME_
ENCODING_UTF8 and DECC$EFS_CHARSET logicals to ENABLE.
19 – DECC$FILENAME_UNIX_ONLY
With DECC$FILENAME_UNIX_ONLY enabled, filenames are never
interpreted as OpenVMS style names. This prevents any
interpretation of the following as OpenVMS special characters:
: [ ^
20 – DECC$FILENAME_UNIX_NO_VERSION
With DECC$FILENAME_UNIX_NO_VERSION enabled, OpenVMS version
numbers are not supported in UNIX style filenames.
With DECC$FILENAME_UNIX_NO_VERSION disabled, in UNIX style names,
version numbers are reported preceded by a period (.).
21 – DECC$FILENAME_UNIX_REPORT
With DECC$FILENAME_UNIX_REPORT enabled, all filenames are
reported in UNIX style unless the caller specifically selects
OpenVMS style. This applies to getpwnam, getpwuid, argv[0],
getname, fgetname, and tempnam.
With DECC$FILENAME_UNIX_REPORT disabled, unless specified in the
function call, filenames are reported in OpenVMS style.
22 – DECC$FILE_PERMISSION_UNIX
With DECC$FILE_PERMISSION_UNIX enabled, the file permissions
for new files and directories are set according to the file
creation mode and umask. This includes mode 0777. When an earlier
version of the file exists, the file permissions for the new file
are inherited from the earlier version. This mode sets DELETE
permission for a new directory when WRITE permission is enabled.
With DECC$FILE_PERMISSION_UNIX disabled, modes 0 and 0777
indicate using RMS default protection or protection from the
previous version of the file. Permissions for new directories
also follow OpenVMS rules, including disabling DELETE
permissions.
23 – DECC$FILE_SHARING
With DECC$FILE_SHARING enabled, all files are opened with full
sharing enabled (FAB$M_DEL | FAB$M_GET | FAB$M_PUT | FAB$M_UPD).
This is set as a logical OR with any sharing mode specified by
the caller.
24 – DECC$FIXED_LENGTH_SEEK_TO_EOF
With DECC$FIXED_LENGTH_SEEK_TO_EOF enabled, lseek, fseeko, and
fseek with the direction parameter set to SEEK_END will position
relative to the last byte in the file for files with fixed-length
records.
With DECC$FIXED_LENGTH_SEEK_TO_EOF disabled, lseek, fseek, and
fseeko when called with SEEK_EOF on files with fixed-length
records, will position relative to the end of the last record
in the file.
25 – DECC$GLOB_UNIX_STYLE
Enabling DECC$GLOB_UNIX_STYLE selects the UNIX mode of the glob
function, which uses UNIX style filenames and wildcards instead
of OpenVMS style filenames and wildcards.
26 – DECC$LOCALE_CACHE_SIZE
DECC$LOCALE_CACHE_SIZE defines how much memory, in bytes, to
allocate for caching locale data. The default value is 0, which
disables the locale cache.
Default: 0
Maximum: 2147483647
27 – DECC$MAILBOX_CTX_STM
By default, an open on a local mailbox that is not a pipe treats
mailbox records as having a record attribute of FAB$M_CR.
With DECC$MAILBOX_CTX_STM enabled, the record attribute FAB$M_CR
is not set.
28 – DECC$NO_ROOTED_SEARCH_LISTS
When the decc$to_vms function evaluates a UNIX style path string,
if it determines the first element to be a logical name, then:
o For rooted logicals or devices, it appends ":[000000]" to the
logical name.
For example, if log1 is a rooted logical ($DEFINE LOG1
[DIR_NAME.]) then /log1/filename.ext translates to
LOG1:[000000]FILENAME.EXT.
o For nonrooted logicals, it appends just a colon (:) to the
logical name.
For example, if log2 is a nonrooted logical ($ DEFINE
LOG2 [DIR_NAME]), then /log2/filename.ext translates to
LOG2:FILENAME.EXT.
o If the first element is a search-list logical, the translation
proceeds by evaluating the first element in the search list,
and translating the path as previously described.
The preceding three cases lead to predictable, expected results.
In the case where the first element is a search list that
consists of a mixture of rooted and nonrooted logicals,
translating paths as described previously can lead to different
behavior from that of older versions of OpenVMS (before OpenVMS
Version 7.3-1):
o Before OpenVMS Version 7.3-1, regardless of the contents of
the logical, the decc$to_vms function appended only a colon
(:). For search lists that consisted of a mixture of rooted
and nonrooted logicals, this resulted in certain expected
behaviors.
o For OpenVMS Version 7.3-1 and later, if the first element
of the mixed search list is a rooted logical, then decc$to_
vms appends ":[000000]" to the logical name, resulting in
different behavior from that of OpenVMS releases prior to
Version 7.3-1.
DECC$NO_ROOTED_SEARCH_LISTS controls how the decc$to_vms function
resolves search-list logicals and provides a means to restore the
OpenVMS behavior prior to Version 7.3-1.
With DECC$NO_ROOTED_SEARCH_LISTS enabled:
o If a logical is detected in a file specification, and it is
a search list, then a colon (:) is appended when forming the
OpenVMS file specification.
o If it is not a search list, the behavior is the same as with
DECC$NO_ROOTED_SEARCH_LISTS disabled.
Enabling this feature logical provides the pre-Version 7.3-1
behavior for search list logicals.
With DECC$NO_ROOTED_SEARCH_LISTS disabled:
o If a logical is detected in a file specification, and it is
a rooted logical (or a search list whose first element is a
rooted logical), then ":[000000]" is appended when forming the
OpenVMS file specification.
o If it is a nonrooted logical (or a search list whose first
element is a nonrooted logical), then just a colon (:) is
appended.
Disabling this feature logical provides the behavior for OpenVMS
Version 7.3-1 and later.
29 – DECC$PIPE_BUFFER_QUOTA
OpenVMS Version 7.3-2 adds an optional fourth argument of type
int to the pipe function to specify the buffer quota of the
pipe's mailbox. In previous OpenVMS versions, the buffer quota
was equal to the buffer size.
DECC$PIPE_BUFFER_QUOTA lets you specify a buffer quota to use
for the pipe function if the optional fourth argument of that
function is omitted.
If the optional pipe fourth argument is omitted and DECC$PIPE_
BUFFER_QUOTA is not defined, then the buffer quota defaults to
the buffer size, as before.
Default: 512
Minimum: 512
Maximum: 2147483647
30 – DECC$PIPE_BUFFER_SIZE
The system default buffer size of 512 bytes for pipe write
operations can limit performance and generate extra line feeds
when handling messages longer than 512 bytes.
DECC$PIPE_BUFFER_SIZE allows a larger buffer size to be used for
pipe functions such as pipe and popen. A value of 512 to 65535
bytes can be specified.
If DECC$PIPE_BUFFER_SIZE is not specified, the default buffer
size 512 is used.
Default: 512
Minimum: 512
Maximum: 65535
31 – DECC$POPEN_NO_CRLF_REC_ATTR
With DECC$POPEN_NO_CRLF_REC_ATTR disabled, a pipe opened with the
popen function has its record attributes set to CR/LF carriage
control (fab$b_rat |= FAB$M_CR). This is the default behavior.
With DECC$POPEN_NO_CRLF_REC_ATTR enabled, CR/LF carriage control
is prevented from being added to the pipe records. This is
compatible with UNIX behavior, but be aware that enabling this
feature might result in undesired behavior from other functions,
such as gets, that rely on the carriage-return character.
32 – DECC$POSIX_COMPLIANT_PATHNAMES
With DECC$POSIX_COMPLIANT_PATHNAMES enabled, an application
is allowed to present POSIX-compliant pathnames to any C RTL
function that accepts a pathname.
By default DECC$POSIX_COMPLIANT_PATHNAMES is disabled, and the
usual C RTL behavior prevails. This disabled mode includes
interpretation of pathnames as UNIX style specifications and
uses rules that are different and unrelated to POSIX-compliant
pathname processing.
To enable DECC$POSIX_COMPLIANT_PATHNAMES, set it to one of the
following values:
1 All pathnames are designated as POSIX style.
2 Pathnames that end in ":" or contain any of the bracket
characters "[]<>", and that can be successfully parsed by
the SYS$FILESCAN service, are designated as OpenVMS style.
Otherwise, they are designated as POSIX style.
3 The pathnames "." and "..", or pathnames that contain "/" are
designated as POSIX style. Otherwise, they are designated as
OpenVMS style.
4 All pathnames are designated as OpenVMS style.
See Chapter 12 of the VSI C Run-Time Library Reference Manual
for OpenVMS Systems for more information on POSIX-compliant
pathnames and symbolic links.
33 – DECC$POSIX_SEEK_STREAM_FILE
With DECC$POSIX_SEEK_STREAM_FILE enabled, positioning beyond
end-of-file on STREAM files does not write to the file until the
next write. If the write is beyond the current end-of-file, this
positions beyond the old end-of-file, and the start position for
the write is filled with zeros.
With DECC$POSIX_SEEK_STREAM_FILE disabled, positioning beyond
end-of-file will immediately write zeros to the file from the
current end-of-file to the new position.
34 – DECC$POSIX_STYLE_UID
With DECC$POSIX_STYLE_UID enabled, 32-bit UIDs and GIDs are
interpreted as POSIX style identifiers.
With this logical name disabled, UIDs and GIDs are derived from
the process UIC.
This feature is only available on OpenVMS systems providing POSIX
style UID and GID support.
35 – DECC$PRINTF_USES_VAX_ROUND
With DECC$PRINTF_USES_VAX_ROUND enabled, the F and E format
specifiers of printf use VAX rounding rules for programs compiled
with IEEE float.
36 – DECC$READDIR_DROPDOTNOTYPE
With DECC$READDIR_DROPDOTNOTYPE enabled, readdir when reporting
files in UNIX style only reports the trailing period (.) for
files with no file type when the filename contains a period.
With this logical name disabled, all files without a file type
are reported with a trailing period.
37 – DECC$READDIR_KEEPDOTDIR
The default behavior when reporting files in UNIX style from
readdir is to report directories without a file type.
With DECC$READDIR_KEEPDOTDIR enabled, directories are reported in
UNIX style with a file type of ".DIR".
38 – DECC$RENAME_NO_INHERIT
DECC$RENAME_NO_INHERIT provides more UNIX compliant behavior in
the rename function. With DECC$RENAME_NO_INHERIT enabled, the
following behaviors are enforced:
o If the old argument points to the pathname of a file that
is not a directory, the new argument will not point to the
pathname of a directory.
o The new argument cannot point to a directory that exists.
o If the old argument points to the pathname of a directory, the
new argument will not point to the pathname of a file that is
not a directory.
o The new name for the file does not inherit anything from
the old name. The new name must be specified completely. For
example:
Renaming "A.A" to "B" yields "B"
With this logical name disabled, you get the expected OpenVMS
behavior. For example:
Renaming "A.A" to "B" yields "B.A"
39 – DECC$RENAME_ALLOW_DIR
Enabling DECC$RENAME_ALLOW_DIR restores the prior OpenVMS
behavior of the rename function by allowing conversion to a
directory specification when the second argument is an ambiguous
file specification passed as a logical name. The ambiguity is
whether the logical name is a UNIX or OpenVMS file specification.
Consider the following example with DECC$RENAME_ALLOW_DIR
enabled:
rename("file.ext", "logical_name")
/*where logical_name = dev:[dir.subdir]*/
/* and :[dir.subdir] exists. */
This results in:
dev:[dir.subdir]file.ext
This example renames a file from one directory into another
directory, which is the same behavior as in legacy versions
of OpenVMS (versions before 7.3-1). Also in this example, if
dev:[dir.subdir] does not exist, rename returns an error.
Disabling DECC$RENAME_ALLOW_DIR provides a more UNIX compliant
conversion of the "logical_name" argument of rename. Consider the
following example with DECC$RENAME_ALLOW_DIR disabled:
rename("file.ext", "logical_name")
/* where logical_name = dev:[dir.subdir] */
This results in:
dev:[dir]subdir.ext
This example renames the file using the subdir part of the
"logical_name" argument as the new filename because on UNIX
systems, renaming a file to a directory is not allowed. So
rename internally converts the "logical_name" to a filename, and
dev:[dir]subdir is the most reasonable conversion it can perform.
This new feature switch has a side effect of causing rename to a
directory to take precedence over rename to a file. Consider this
example:
rename ( "file1.ext", "dir2" ) /* dir2 is not a logical */
With DECC$RENAME_ALLOW_DIR disabled, this example results in
dir2.ext, regardless of whether or not subdirectory [.dir2]
exists.
With DECC$RENAME_ALLOW_DIR enabled, this example results in
dir2.ext only if subdirectory [.dir2] does not exist. If
subdirectory [.dir2] does exist, the result is [.dir2]file1.ext.
NOTE
If DECC$RENAME_NO_INHERIT is enabled, UNIX compliant
behavior is expected, so DECC$RENAME_ALLOW_DIR is ignored,
and renaming a file to a directory is not allowed.
40 – DECC$SELECT_IGNORES_INVALID_FD
With DECC$SELECT_IGNORES_INVALID_FD enabled, select fails with
errno set to EBADF when an invalid file descriptor is specified
in one of the descriptor sets.
With DECC$SELECT_IGNORES_INVALID_FD disabled, select ignores
invalid file descriptors.
41 – DECC$STDIO_CTX_EOL
With DECC$STDIO_CTX_EOL enabled, writing to stdout and stderr
for stream access is deferred until a terminator is seen or the
buffer is full.
With DECC$STDIO_CTX_EOL disabled, each fwrite generates a
separate write, which for mailbox and record files generates a
separate record.
42 – DECC$STREAM_PIPE
With DECC$STREAM_PIPE enabled, the C RTL pipe function uses the
more UNIX compatible stream I/O.
With DECC$STREAM_PIPE disabled, pipe uses the OpenVMS legacy
record I/O. This is the default.
43 – DECC$STRTOL_ERANGE
With DECC$STRTOL_ERANGE enabled, the strtol behavior for an
ERANGE error is corrected to consume all remaining digits in
the string.
With DECC$STRTOL_ERANGE disabled, the legacy behavior of leaving
the pointer at the failing digit is preserved.
44 – DECC$THREAD_DATA_AST_SAFE
The C RTL has a mode that allocates storage for thread-specific
data allocated by threads at non-AST level separate for data
allocated for ASTs. In this mode, each access to thread-
specific data requires a call to LIB$AST_IN_PROG, which can add
significant overhead when accessing thread-specific data in the
C RTL.
The alternate mode protects thread-specific data only if another
function has it locked. This protects data that is in use within
the C RTL, but does not protect the caller from an AST changing
the data pointed to.
This latter mode is now the C RTL default for the strtok, ecvt,
and fcvt functions.
You can select the legacy AST safe mode by enabling DECC$THREAD_
DATA_AST_SAFE.
45 – DECC$TZ_CACHE_SIZE
DECC$TZ_CACHE_SIZE specifies the number of time zones that can be
held in memory.
Default: 2
Maximum: 2147483647
46 – DECC$UMASK
DECC$UMASK specifies the default value for the permission mask
umask. By default, a parent C program sets the umask from the RMS
default permissions for the process. A child process inherits the
parent's value for umask.
To enter the value as an octal value, add the leading zero;
otherwise, it is translated as a decimal value. For example:
$ DEFINE DECC$UMASK 026
Maximum: 0777
47 – DECC$UNIX_LEVEL
With the DECC$UNIX_LEVEL logical name, you can manage multiple
C RTL feature logical names at once. By setting a value for
DECC$UNIX_LEVEL from 1 to 100, you determine the default value
for groups of feature logical names. The value you set has a
cumulative effect: the higher the value, the more groups that
are affected. Setting a value of 20, for example, enables all the
feature logicals associated with a DECC$UNIX_LEVEL of 20, 10, and
1.
The principal logical names affecting UNIX like behavior are
grouped as follows:
1 General corrections
10 Enhancements
20 UNIX style filenames
30 UNIX style file attributes
90 Full UNIX behavior - No concessions to OpenVMS
Level 30 is appropriate for UNIX like programs such as BASH and
GNV.
The DECC$UNIX_LEVEL values and associated groups of affected
feature logical names are:
General Corrections (DECC$UNIX_LEVEL 1)
DECC$FIXED_LENGTH_SEEK_TO_EOF 1
DECC$POSIX_SEEK_STREAM_FILE 1
DECC$SELECT_IGNORES_INVALID_FD 1
DECC$STRTOL_ERANGE 1
DECC$VALIDATE_SIGNAL_IN_KILL 1
General Enhancements (DECC$UNIX_LEVEL 10)
DECC$ARGV_PARSE_STYLE 1
DECC$EFS_CASE_PRESERVE 1
DECC$STDIO_CTX_EOL 1
DECC$PIPE_BUFFER_SIZE 4096
DECC$USE_RAB64 1
UNIX style filenames (DECC$UNIX_LEVEL 20)
DECC$DISABLE_TO_VMS_LOGNAME_TRANSLATION 1
DECC$EFS_CHARSET 1
DECC$FILENAME_UNIX_NO_VERSION 1
DECC$FILENAME_UNIX_REPORT 1
DECC$READDIR_DROPDOTNOTYPE 1
DECC$RENAME_NO_INHERIT 1
DECC$GLOB_UNIX_STYLE
UNIX like file attributes (DECC$UNIX_LEVEL 30)
DECC$EFS_FILE_TIMESTAMPS 1
DECC$EXEC_FILEATTR_INHERITANCE 1
DECC$FILE_OWNER_UNIX 1
DECC$FILE_PERMISSION_UNIX 1
DECC$FILE_SHARING 1
UNIX compliant behavior (DECC$UNIX_LEVEL 90)
DECC$FILENAME_UNIX_ONLY 1
DECC$POSIX_STYLE_UID 1
DECC$USE_JPI$_CREATOR 1
DECC$DETACHED_CHILD_PROCESS 1
NOTES
o Defining a logical name for an individual feature logical
supersedes the default value established by DECC$UNIX_
LEVEL for that feature.
o Future revisions of the C RTL may add new feature
logicals to a given DECC$UNIX_LEVEL. For applications
that specify that UNIX level, the effect is to enable
those new feature logicals by default.
48 – DECC$UNIX_PATH_BEFORE_LOGNAME
With DECC$UNIX_PATH_BEFORE_LOGNAME enabled, when translating
a UNIX filename not starting with a leading slash (/), an
attempt is made to match this to a file or directory in the
current directory. If this is not found and the name is valid
as a logical name in an OpenVMS filename, an attempt is made to
translate the logical name and, if found, is used as part of the
resulting filename.
Enabling DECC$UNIX_PATH_BEFORE_LOGNAME overrides the setting for
DECC$DISABLE_TO_VMS_LOGNAME_TRANSLATION.
49 – DECC$USE_JPI$_CREATOR
When enabled, DECC$USE_JPI$_CREATOR determines the parent process
ID in getppid by calling $GETJPI using item JPI$_CREATOR instead
of JPI$_OWNER.
This feature is only available on systems supporting POSIX style
session identifiers.
50 – DECC$USE_RAB64
With DECC$USE_RAB64 enabled, open functions allocate a RAB64
structure instead of the traditional RAB structure.
This provides latent support for file buffers in 64-bit memory.
51 – DECC$VALIDATE_SIGNAL_IN_KILL
With DECC$VALIDATE_SIGNAL_IN_KILL enabled, a signal value that
is in the range 0 to _SIG_MAX but is not supported by the C RTL
generates an error with errno set to EINVAL, which makes the
behavior the same as for raise.
With this logical name disabled, validation of signals is
restricted to checking that the signal value is in the range 0 to
_SIG_MAX. If sys$sigprc fails, errno is set based on sys$sigprc
exit status.
52 – DECC$V62_RECORD_GENERATION
OpenVMS Versions 6.2 and higher can output record files using
different rules.
With DECC$V62_RECORD_GENERATION enabled, the output mechanism
follows the rules used for OpenVMS Version 6.2.
53 – DECC$WRITE_SHORT_RECORDS
The DECC$WRITE_SHORT_RECORDS feature logical supports a previous
change to the fwrite function (to accommodate writing records
with size less than the maximum record size), while retaining
the legacy way of writing records to a fixed-length file as the
default behavior:
With DECC$WRITE_SHORT_RECORDS enabled, short-sized records
(records with size less than the maximum record size) written at
EOF are padded with zeros to align records on record boundaries.
This is the behavior seen in OpenVMS Version 7.3-1 and some ACRTL
ECOs of that time period.
With DECC$WRITE_SHORT_RECORDS disabled, the legacy behavior
of writing records with no padding is implemented. This is the
recommended and default behavior.
54 – DECC$XPG4_STRPTIME
XPG5 support for strptime introduces pivoting year support so
that years in the range 0 to 68 are in the 21st century, and
years in the range 69-99 are in the 20th century.
With DECC$XPG4_STRPTIME enabled, XPG5 support for the pivoting
year is disabled and all years in the range 0 to 99 are in the
current century.