use Win32API::Registry 0.21 qw( :ALL );
RegOpenKeyEx( HKEY_LOCAL_MACHINE, "SYSTEM\\Disk", 0, KEY_READ, $key );
or die "Can't open HKEY_LOCAL_MACHINE\\SYSTEM\\Disk: ",
regLastError(),"\n";
RegQueryValueEx( $key, "Information", [], $type, $data, [] );
or die "Can't read HKEY_L*MACHINE\\SYSTEM\\Disk\\Information: ",
regLastError(),"\n";
[...]
RegCloseKey( $key )
or die "Can't close HKEY_LOCAL_MACHINE\\SYSTEM\\Disk: ",
regLastError(),"\n";
For a description of the logical structure of the Registry, see the documentation for the "Win32::TieRegistry" module.
To pass in "NULL" as the pointer to an optional buffer, pass in an empty list reference, "[]".
Beyond raw access to the API calls and related constants, this module handles smart buffer allocation and translation of return codes.
All calls return a true value for success and a false value for failure. After any failure, $^E should automatically be set to indicate the reason. However, current versions of Perl often overwrite $^E too quickly, so you can use "regLastError()" instead, which is only set by Win32API::Registry routines. "regLastError()" is also good if you have a really old version of Perl that does not connect $^E to "GetLastError()" on Win32.
Note that $! is not set by these routines except by "Win32API::Registry::constant()" when a constant is not defined.
[Note that much of the following documentation refers to the behavior of the underlying API calls which may vary in current and future versions of the Win32 API without any changes to this module. Therefore you should check the Win32 API documentation directly when needed.]
$sPrivname is a Win32 privilege name [see ``:SE_'']. For example, "SeBackupPrivilege" [a.k.a. "SE_BACKUP_NAME"] controls whether you can use "RegSaveKey()" and "SeRestorePrivilege" [a.k.a. "SE_RESTORE_NAME"] controls whether you can use "RegLoadKey()".
If $bEnable is true, then "AllowPriv()" tries to enable the privilege. Otherwise it tries to disable the privilege.
$sComputer is the name [or address] of the computer to be shutdown or rebooted. You can use "[]" [for "NULL"] or "" to indicate the local computer.
$sMessage is the message to be displayed in a pop-up window on the desktop of the computer to be shutdown or rebooted until the timeout expires or the shutdown is aborted via "AbortSystemShutdown()". With "$iTimeoutSecs == 0", the message will never be visible.
$iTimeoutSecs is the number of seconds to wait before starting the shutdown.
If $bForce is false, then any applications running on the remote computer get a chance to prompt the remote user whether they want to save changes. Also, for any applications that do not exit quickly enough, the operating system will prompt the user whether they wish to wait longer for the application to exit or force it to exit now. At any of these prompts the user can press CANCEL to abort the shutdown but if no applications have unsaved data, they will likely all exit quickly and the shutdown will progress with the remote user having no option to cancel the shutdown.
If $bForce is true, all applications are told to exit immediately and so will not prompt the user even if there is unsaved data. Any applications that take too long to exit will be forcibly killed after a short time. The only way to abort the shutdown is to call "AbortSystemShutdown()" before the timeout expires and there is no way to abort the shutdown once it has begun.
If $bReboot is true, the computer will automatically reboot once the shutdown is complete. If $bReboot is false, then when the shutdown is complete the computer will halt at a screen indicating that the shutdown is complete and offering a way for the user to start to boot the computer.
You must have the "SeRemoteShutdownPrivilege" privilege on the remote computer for this call to succeed. If shutting down the local computer, then the calling process must have the "SeShutdownPrivilege" privilege and have it enabled.
$sComputer is the name [or address] of a remote computer whose Registry you wish to access.
$hKey must be either "HKEY_LOCAL_MACHINE" or "HKEY_USERS" and specifies which root Registry key on the remote computer you wish to have access to.
$phKey will be set to the handle to be used to access the remote Registry key if the call succeeds.
This function is rarely used since you will usually get the value of a constant by having that constant imported into your package by listing the constant name in the "use Win32API::Registry" statement and then simply using the constant name in your code [perhaps followed by "()"]. This function is useful for verifying constant names not in Perl code, for example, after prompting a user to type in a constant name.
$hKey is the handle to a Registry key [either "HKEY_*" or from a previous call].
$sSubKey is the name of the new subkey to be created.
$iZero is reserved for future use and should always be specified as 0.
$sClass is a string to be used as the class for the new subkey. We are not aware of any current use for Registry key class information so the empty string, "", should usually be used here.
$iOpts is a numeric value containing bits that control options used while creating the new subkey. "REG_OPTION_NON_VOLATILE" is the default. "REG_OPTION_VOLATILE" [which is ignored on Windows 95] means the data stored under this key is not kept in a file and will not be preserved when the system reboots. "REG_OPTION_BACKUP_RESTORE" [also ignored on Windows 95] means ignore the $iAccess parameter and try to open the new key with the access required to backup or restore the key.
$iAccess is a numeric mask of bits specifying what type of access is desired when opening the new subkey. See "RegOpenKeyEx()".
$pSecAttr is a "SECURITY_ATTRIBUTES" structure packed into a Perl string which controls whether the returned handle can be inherited by child processes. Normally you would pass "[]" for this parameter to have "NULL" passed to the underlying API indicating that the handle cannot be inherited. If not under Windows95, then $pSecAttr also allows you to specify "SECURITY_DESCRIPTOR" that controls which users will have what type of access to the new key --- otherwise the new key inherits its security from its parent key.
$phKey will be set to the handle to be used to access the new subkey if the call succeeds.
$piDisp will be set to either "REG_CREATED_NEW_KEY" or "REG_OPENED_EXISTING_KEY" to indicate for which reason the call succeeded. Can be specified as "[]" if you don't care.
If $phKey and $piDisp start out as integers, then they will probably remain unchanged if the call fails.
$hKey is the handle to a Registry key [either "HKEY_*" or from a previous call].
$sSubKey is the name of the subkey to be deleted.
$hKey is the handle to a Registry key [either "HKEY_*" or from a previous call].
$sValueKey is the name of the value to be deleted.
$hKey is the handle to a Registry key [either "HKEY_*" or from a previous call].
$iIndex is the sequence number of the immediate subkey that you want information on. Start with this value as 0 then repeat the call incrementing this value each time until the call fails with $^E/"regLastError()" numerically equal to "ERROR_NO_MORE_ITEMS".
$sName will be set to the name of the subkey. Can be "[]" if you don't care about the name.
$plName initially specifies the [minimum] buffer size to be allocated for $sName. Will be set to the length of the subkey name if the requested subkey exists even if $sName isn't successfully set to the subkey name. See ``Buffer sizes'' for more information.
$pNull is reserved for future used and should be passed as "[]".
$sClass will be set to the class name for the subkey. Can be "[]" if you don't care about the class.
$plClass initially specifies the [minimum] buffer size to be allocated for $sClass and will be set to the length of the subkey class name if the requested subkey exists. See ``Buffer sizes'' for more information.
$pftLastWrite will be set to a "FILETIME" structure packed into a Perl string and indicating when the subkey was last changed. Can be "[]".
You may omit both $plName and $plClass to get the same effect as passing in "[]" for each of them.
$hKey is the handle to a Registry key [either "HKEY_*" or from a previous call].
$iIndex is the sequence number of the value that you want information on. Start with this value as 0 then repeat the call incrementing this value each time until the call fails with "ERROR_NO_MORE_ITEMS".
$sValName will be set to the name of the value. Can be "[]" if you don't care about the name.
$plValName initially specifies the [minimum] buffer size to be allocated for $sValName. Will be set to the length of the value name if the requested value exists even if $sValName isn't successfully set to the value name. See ``Buffer sizes'' for more information.
$pNull is reserved for future used and should be passed as "[]".
$piType will be set to the type of data stored in the value data. If the call succeeds, it will be set to a "REG_*" value unless passed in as "[]".
$pValData will be set to the data [packed into a Perl string] that is stored in the requested value. Can be "[]" if you don't care about the value data.
$plValData initially specifies the [minimum] buffer size to be allocated for $sValData and will be set to the length of the value data if the requested value exists. See ``Buffer sizes'' for more information.
You may omit both $plValName and $plValData to get the same effect as passing in "[]" for each of them.
$hKey is the handle to a Registry key [either "HKEY_*" or from a previous call].
$hKey is the handle to a Registry key [either "HKEY_*" or from a previous call].
$iSecInfo is a numeric "SECURITY_INFORMATION" value that specifies which parts of the "SECURITY_DESCRIPTOR" structure to retrieve. Should be "OWNER_SECURITY_INFORMATION", "GROUP_SECURITY_INFORMATION", "DACL_SECURITY_INFORMATION", or or "SACL_SECURITY_INFORMATION" or two or more of these bits combined using "|".
$pSecDesc will be set to the requested "SECURITY_DESCRIPTOR" structure [packed into a Perl string].
$plSecDesc initially specifies the [minimum] buffer size to be allocated for $sSecDesc and will be set to the length of the security descriptor. See ``Buffer sizes'' for more information. You may omit this parameter to get the same effect as passing in "[]" for it.
Just like $^E, in a numeric context "regLastError()" returns the numeric error value while in a string context it returns a text description of the error [actually it returns a Perl scalar that contains both values so "$x= regLastError()" causes $x to give different values in string vs. numeric contexts]. On old versions of Perl where $^E isn't tied to "GetLastError()", "regLastError" simply returns the number of the error and you'll need to use <Win32::FormatMessage> to get the error string.
The last form sets the error returned by future calls to "regLastError()" and should not be used often. $uError must be a numeric error code. Also returns the dual-valued version of $uError.
$hKey is the handle to a Registry key that can have hives loaded to it. This must be "HKEY_LOCAL_MACHINE", "HKEY_USERS", or a remote version of one of these from a call to "RegConnectRegistry()".
$sSubKey is the name of the new subkey to created and associated with the hive file.
$sFileName is the name of the hive file to be loaded. This file name is interpretted relative to the "%SystemRoot%/System32/config" directory on the computer where the $hKey key resides. If $sFileName is on a FAT file system, then its name must not have an extension.
You must have the "SE_RESTORE_NAME" privilege to use this routine.
WARNING: Loading of hive files via a network share may silently corrupt the hive and so should not be attempted [this is a problem in at least some versions of the underlying API which this module does not try to fix or avoid]. To access a hive file located on a remote computer, connect to the remote computer's Registry and load the hive via that.
$hKey is the handle to a Registry key [either "HKEY_*" or from a previous call] for which you wish to be notified when any changes are made to it.
If $bWatchSubtree is true, then changes to any subkey or descendant of $hKey are also reported.
$iNotifyFilter controllers what types of changes are reported. It is a numeric value containing one or more of the following bit masks:
$hEvent is ignored unless $bAsync is true. Otherwise, $hEvent is a handle to a Win32 event that will be signaled when changes are to be reported.
If $bAsync is true, then "RegNotifyChangeKeyValue()" returns immediately and uses $hEvent to notify your process of changes. If $bAsync is false, then "RegNotifyChangeKeyValue()" does not return until there is a change to be notified of.
This routine does not work with Registry keys on remote computers.
$hKey is the handle to a Registry key [either "HKEY_*" or from a previous call].
$sSubKey is the name of an existing subkey to be opened. Can be "" or "[]" to open an additional handle to the key specified by $hKey.
$iOptions is a numeric value containing bits that control options used while opening the subkey. There are currently no supported options so this parameter should be specified as 0.
$iAccess is a numeric mask of bits specifying what type of access is desired when opening the new subkey. Should be a combination of one or more of the following bit masks:
KEY_READ | KEY_WRITE | KEY_CREATE_LINK
KEY_QUERY_VALUE | KEY_ENUMERATE_SUBKEYS | KEY_NOTIFY | STANDARD_RIGHTS_READ
KEY_SET_VALUE | KEY_CREATE_SUB_KEY | STANDARD_RIGHTS_WRITE
$phKey will be set to the handle to be used to access the new subkey if the call succeeds.
$hKey is the handle to a Registry key [either "HKEY_*" or from a previous call].
$sClass will be set to the class name for the key. Can be "[]" if you don't care about the class.
$plClass initially specifies the [minimum] buffer size to be allocated for $sClass and will be set to the length of the key's class name. See ``Buffer sizes'' for more information. You may omit this parameter to get the same effect as passing in "[]" for it.
$pNull is reserved for future use and should be passed as "[]".
$pcSubKeys will be set to the count of the number of subkeys directly under this key. Can be "[]".
$plSubKey will be set to the length of the longest subkey name. Can be "[]".
$plSubClass will be set to the length of the longest class name used with an immediate subkey of this key. Can be "[]".
$pcValues will be set to the count of the number of values in this key. Can be "[]".
$plValName will be set to the length of the longest value name in this key. Can be "[]".
$plValData will be set to the length of the longest value data in this key. Can be "[]".
$plSecDesc will be set to the length of this key's full security descriptor.
$pftTime will be set to a "FILETIME" structure packed into a Perl string and indicating when this key was last changed. Can be "[]".
$hKey is the handle to a Registry key [either "HKEY_*" or from a previous call].
$pValueEnts should contain a list of "VALENT" structures packed into a single Perl string. Each "VALENT" structure should have the "ve_valuename" entry [the first 4 bytes] pointing to a string containing the name of a value stored in this key. The remaining fields are set if the function succeeds.
$cValueEnts should contain the count of the number of "VALENT" structures contained in $pValueEnts.
$pBuffer will be set to the data from all of the requested values concatenated into a single Perl string.
$plBuffer initially specifies the [minimum] buffer size to be allocated for $sBuffer and will be set to the total length of the data to be written to $sBuffer. See ``Buffer sizes'' for more information. You may omit this parameter to get the same effect as passing in "[]" for it.
Here is sample code to populate $pValueEnts:
# @ValueNames= ...list of value name strings...;
$cValueEnts= @ValueNames;
$pValueEnts= pack( " p x4 x4 x4 " x $cValueEnts, @ValueNames );
Here is sample code to retrieve the data type and data length returned in $pValueEnts:
@Lengths= unpack( " x4 L x4 x4 " x $cValueEnts, $pValueEnts );
@Types= unpack( " x4 x4 x4 L " x $cValueEnts, $pValueEnts );
Given the above, and assuming you haven't modified $sBuffer since the call, you can also extract the value data strings from $sBuffer by using the pointers returned in $pValueEnts:
@Data= unpack( join( "", map {" x4 x4 P$_ x4 "} @Lengths ),
$pValueEnts );
Much better is to use the lengths and extract directly from $sBuffer using "unpack()" [or "substr()"]:
@Data= unpack( join("",map("P$_",@Lengths)), $sBuffer );
$hKey is the handle to a Registry key [either "HKEY_*" or from a previous call].
$sValueName is the name of the value whose data you wish to retrieve.
$pNull this parameter is reserved for future use and should be specified as "[]".
$piType will be set to indicate what type of data is stored in the named value. Will be set to a "REG_*" value if the function succeeds.
$pValueData will be set to the value data [packed into a Perl string] that is stored in the named value. Can be "[]" if you don't care about the value data.
$plValueData initially specifies the [minimum] buffer size to be allocated for $sValueData and will be set to the size [always in bytes] of the data to be written to $sValueData, even if $sValueData is not successfully written to. See ``Buffer sizes'' for more information.
$hKey is the handle to a Registry key that has hive(s) loaded in it. This must be "HKEY_LOCAL_MACHINE", "HKEY_USERS", or a remote version of one of these from a call to "RegConnectRegistry()".
$sSubKey is the name of the subkey of $hKey whose hive you wish to have replaced on the next reboot.
$sNewFile is the name of a file that will replace the existing hive file when the system reboots.
$sOldFile is the file name to save the current hive file to when the system reboots.
$sNewFile and $sOldFile are interpretted relative to the "%SystemRoot%/System32/config" directory on the computer where the $hKey key resides [I think]. If either file is [would be] on a FAT file system, then its name must not have an extension.
You must have the "SE_RESTORE_NAME" privilege to use this routine.
$hKey is the handle to a Registry key [either "HKEY_*" or from a previous call].
$sFileName is the name of the hive file to be read. For each value and subkey in this file, a value or subkey will be added or replaced in $hKey.
$uFlags is usally 0. It can also be "REG_WHOLE_HIVE_VOLATILE" which, rather than copying the hive over the existing key, replaces the existing key with a temporary, memory-only Registry key and then copies the hive contents into it. This option only works if $hKey is "HKEY_LOCAL_MACHINE", "HKEY_USERS", or a remote version of one of these from a call to "RegConnectRegistry()".
"RegRestoreKey" does not delete values nor keys from the existing Registry tree when there is no corresponding value/key in the hive file.
$hKey is the handle to a Registry key [either "HKEY_*" or from a previous call].
$sFileName is the name of the file that the Registry tree should be saved to. It is interpretted relative to the "%SystemRoot%/System32/config" directory on the computer where the $hKey key resides. If $sFileName is on a FAT file system, then it must not have an extension.
$pSecAttr contains a "SECURITY_ATTRIBUTES" structure that specifies the permissions to be set on the new file that is created. This can be "[]".
You must have the "SE_RESTORE_NAME" privilege to use this routine.
$hKey is the handle to a Registry key [either "HKEY_*" or from a previous call].
$uSecInfo is a numeric "SECURITY_INFORMATION" value that specifies which "SECURITY_DESCRIPTOR" structure to set. Should be "OWNER_SECURITY_INFORMATION", "GROUP_SECURITY_INFORMATION", "DACL_SECURITY_INFORMATION", or "SACL_SECURITY_INFORMATION" or two or more of these bits combined using "|".
$pSecDesc contains the new "SECURITY_DESCRIPTOR" structure packed into a Perl string.
$hKey is the handle to a Registry key [either "HKEY_*" or from a previous call].
$sName is the name of the value to be set.
$uZero is reserved for future use and should be specified as 0.
$uType is the type of data stored in $pData. It should be a "REG_*" value.
$pData is the value data packed into a Perl string.
$lData is the length of the value data that is stored in $pData. You will usually omit this parameter or pass in 0 to have "length($pData)" used. In both of these cases, if $iType is "REG_SZ" or "REG_EXPAND_SZ", "RegSetValueEx()" will append a trailing '\0' to the end of $pData [unless there is already one].
$hKey is the handle to a Registry key that has hives loaded in it. This must be "HKEY_LOCAL_MACHINE", "HKEY_USERS", or a remote version of one of these from a call to "RegConnectRegistry()".
$sSubKey is the name of the subkey whose hive you wish to have unloaded.
Each of these is identical to the version listed above without the trailing ``A'':
AbortSystemShutdownA InitiateSystemShutdownA
RegConnectRegistryA RegCreateKeyA RegCreateKeyExA
RegDeleteKeyA RegDeleteValueA RegEnumKeyA
RegEnumKeyExA RegEnumValueA RegLoadKeyA
RegOpenKeyA RegOpenKeyExA RegQueryInfoKeyA
RegQueryMultipleValuesA RegQueryValueA RegQueryValueExA
RegReplaceKeyA RegRestoreKeyA RegSaveKeyA
RegSetValueA RegSetValueExA RegUnLoadKeyA
$opData is UNICODE if $piType is "REG_SZ", "REG_EXPAND_SZ", or "REG_MULTI_SZ". Note that $iolData is measured as number of bytes even in these cases.
$opData is UNICODE if $ouType is "REG_SZ", "REG_EXPAND_SZ", or "REG_MULTI_SZ". Note that $iolData is measured as number of bytes even in these cases.
$pData is UNICODE if $uType is "REG_SZ", "REG_EXPAND_SZ", or "REG_MULTI_SZ". Note that $lData is measured as number of bytes even in these cases.
HKEY_CLASSES_ROOT HKEY_CURRENT_CONFIG HKEY_CURRENT_USER
HKEY_DYN_DATA HKEY_LOCAL_MACHINE HKEY_PERFORMANCE_DATA
HKEY_USERS
KEY_QUERY_VALUE KEY_SET_VALUE KEY_CREATE_SUB_KEY
KEY_ENUMERATE_SUB_KEYS KEY_NOTIFY KEY_CREATE_LINK
KEY_READ KEY_WRITE KEY_EXECUTE
KEY_ALL_ACCESS
REG_CREATED_NEW_KEY REG_OPENED_EXISTING_KEY
REG_LEGAL_CHANGE_FILTER REG_NOTIFY_CHANGE_ATTRIBUTES
REG_NOTIFY_CHANGE_NAME REG_NOTIFY_CHANGE_LAST_SET
REG_NOTIFY_CHANGE_SECURITY REG_LEGAL_OPTION
REG_OPTION_BACKUP_RESTORE REG_OPTION_CREATE_LINK
REG_OPTION_NON_VOLATILE REG_OPTION_OPEN_LINK
REG_OPTION_RESERVED REG_OPTION_VOLATILE
REG_WHOLE_HIVE_VOLATILE REG_REFRESH_HIVE
REG_NO_LAZY_FLUSH
REG_NONE REG_SZ
REG_EXPAND_SZ REG_BINARY
REG_DWORD REG_DWORD_LITTLE_ENDIAN
REG_DWORD_BIG_ENDIAN REG_LINK
REG_MULTI_SZ REG_RESOURCE_LIST
REG_FULL_RESOURCE_DESCRIPTOR REG_RESOURCE_REQUIREMENTS_LIST
SE_ASSIGNPRIMARYTOKEN_NAME SE_AUDIT_NAME
SE_BACKUP_NAME SE_CHANGE_NOTIFY_NAME
SE_CREATE_PAGEFILE_NAME SE_CREATE_PERMANENT_NAME
SE_CREATE_TOKEN_NAME SE_DEBUG_NAME
SE_INCREASE_QUOTA_NAME SE_INC_BASE_PRIORITY_NAME
SE_LOAD_DRIVER_NAME SE_LOCK_MEMORY_NAME
SE_MACHINE_ACCOUNT_NAME SE_PROF_SINGLE_PROCESS_NAME
SE_REMOTE_SHUTDOWN_NAME SE_RESTORE_NAME
SE_SECURITY_NAME SE_SHUTDOWN_NAME
SE_SYSTEMTIME_NAME SE_SYSTEM_ENVIRONMENT_NAME
SE_SYSTEM_PROFILE_NAME SE_TAKE_OWNERSHIP_NAME
SE_TCB_NAME SE_UNSOLICITED_INPUT_NAME
It can be difficult to successfully build this module in a way that makes these constants available. So some builds of this module may not make them available. For such builds, trying to export any of these constants will cause a fatal error. For this reason, none of these symbols are currently included in the ":ALL" grouping.
perl -de 0
Numeric buffer sizes are used as minimum initial sizes for the buffers. The larger of this size and the size of space already allocated to the scalar will be passed to the underlying routine. If that size was insufficient, and the underlying call provides an easy method for determining the needed buffer size, then the buffer will be enlarged and the call repeated as above.
The underlying calls define buffer size parameter as unsigned, so negative buffer sizes are treated as very large positive buffer sizes which usually cause "malloc()" to fail.
To force the Registry.xs code to pass in a specific value for a buffer size, preceed the size with an equals sign via ""=".". Buffer sizes that are passed in as strings starting with an equals sign will have the equal sign stripped and the remainder of the string interpretted as a number [via C's "strtoul()" using only base 10] which will be passed to the underlying routine [even if the allocated buffer is actually larger]. The Registry.xs code will enlarge the buffer to the specified size, if needed, but will not enlarge the buffer based on the underlying routine requesting more space.
Some Reg*() calls may not currently set the buffer size when they return "ERROR_MORE_DATA". But some that are not documented as doing so, currently do so anyway. So the code assumes that any routine might do this and resizes any buffers and repeats the call. We hope that eventually all routines will provide this feature.
When you use "[]" for a buffer size, you can still find the length of the data returned by using "length($buffer)". Note that this length will be in bytes while a few of the buffer sizes would have been in units of wide characters.
Note that the RegQueryValueEx*() and RegEnumValue*() calls will trim the trailing '\0' [if present] from the returned data values of type "REG_SZ" or "REG_EXPAND_SZ" but only if the value data length parameter is omitted [or specified as "[]"].
The RegSetValueEx*() calls will add a trailing '\0' [if missing] to the supplied data values of type "REG_SZ" and "REG_EXPAND_SZ" but only if the value data length parameter is omitted [or specified as 0].
Probably not all of these prefix notations are used by this module. This document section may be included in any "Win32API" module and so covers some notations not used by this specific module.
$string= "This is an example string";
$unicode= pack( "S*", unpack("C*",$string), 0 );
Note how ", 0" above causes an explicit "L'\0'" to be added since Perl's implicit '\0' that it puts after each of its strings is not wide enough to terminate a UNICODE string. So UNICODE strings are different than regular strings in that the Perl version of a regular string will not include the trialing '\0' while the Perl version of a UNICODE string must include the trailing "L'\0'".
If a UNICODE string contains no non-ASCII characters, then you can convert it back into a normal string via:
$string= pack( "C*", unpack("S*",$unicode) );
$string =~ s/\0$//;
These packed arrays are also called ``vectors'' in places to avoid confusion with Perl arrays.
For strings, there is no general rule as to whether the trailing '\0' is included in such sizes. For this reason, the "Win32API" modules follow the Perl rule of always allocating one extra byte and reporting buffer sizes as being one smaller than allocated in case the '\0' is not included in the size.
For UNICODE strings, the trailing "L'\0'" may or may not be included in a length so, again, we always allocate extra room for one and don't report that extra space.
The output may be written directly into the Perl variable passed to the subroutine, the same way the buffer parameter to Perl's "sysread()". This method is often avoided in Perl because the call then lacks any visual cue that some parameters are being overwritten. But this method closely matches the C API which is what we are trying to do.
For each, a pointer is stored in a [4-byte] Perl string. You can usually use "unpack "P"" to access the real data from Perl.
For ``ppr'' [and often for ``pp''], the pointer points directly at a C "struct". For ``par'', the pointer points to the first element of a C [packed] array of "struct"s. For ``pap'', the pointer points to a C [packed] array of pointers to other things.
No routines are provided for using the data returned in the "FILETIME" buffers. Those are in the "Win32API::Time" module.
No routines are provided for dealing with UNICODE data effectively. See ``:FuncW'' above for some simple-minded UNICODE methods.
Parts of the module test will fail if used on a version of Perl that does not yet set $^E based on "GetLastError()".
On NT 4.0 [at least], the RegEnum*() calls do not set the required buffer sizes when returning "ERROR_MORE_DATA" so this module will not grow the buffers in such cases. "Win32::TieRegistry" overcomes this by using values from "RegQueryInfoKey()" for buffer sizes in RegEnum* calls.
On NT 4.0 [at least], "RegQueryInfoKey()" on "HKEY_PERFORMANCE_DATA" never succeeds. Also, "RegQueryValueEx()" on "HKEY_PERFORMANCE_DATA" never returns the required buffer size. To access "HKEY_PERFORMANCE_DATA" you will need to keep growing the data buffer until the call succeeds.
Because "goto &subroutine" seems to be buggy under Win32 Perl, it is not used in the stubs in Registry.pm.