The MsiEnumComponentsEx function enumerates installed components. The function retrieves the component code for one component each time it is called. The component code is the string GUID unique to the component, version, and language.
Windows Installer 4.5 or earlier: Not supported. This function is available beginning with Windows Installer 5.0.
UINT MsiEnumComponentsExA( LPCSTR szUserSid, DWORD dwContext, DWORD dwIndex, CHAR  szInstalledComponentCode, MSIINSTALLCONTEXT *pdwInstalledContext, LPSTR szSid, LPDWORD pcchSid );
A null-terminated string that contains a security identifier (SID.) The enumeration of installed components extends to users identified by this SID. The special SID string s-1-1-0 (Everyone) specifies an enumeration of all installed components across all products of all users in the system. A SID value other than s-1-1-0 specifies a user SID for a particular user and restricts the enumeration to instances of applications installed by the specified user.
||Specifies the currently logged-on user.|
||An enumeration for a specific user in the system. An example of an user SID is "S-1-3-64-2415071341-1358098788-3127455600-2561".|
||Specifies all users in the system.|
The special SID string s-1-5-18 (System) cannot be used to enumerate applications installed in the per-machine installation context. Setting the SID value to s-1-5-18 returns ERROR_INVALID_PARAMETER. When dwContext is set to MSIINSTALLCONTEXT_MACHINE only, szUserSid must be NULL.
A flag that restricts the enumeration of installed component to instances of products installed in the specified installation context. The enumeration includes only product instances installed by the users specified by szUserSid.
Specifies the index of the component to retrieve. This parameter must be zero (0) for the first call to MsiEnumComponentsEx function. For each subsequent call, the index must be incremented by 1. The index should only be incremented if the previous call to the function returns ERROR_SUCCESS. Components are not ordered and can be returned by the function in any order.
An output buffer that receives the component code GUID for the installed component. The length of the buffer should be large enough to hold a null-terminated string value containing the component code. The first 38 TCHAR characters receives the GUID for the component, and the 39th character receives a terminating NULL character.
A flag that gives the installation context the application that installed the component.
Receives the security identifier (SID) that identifies the user that installed the application that owns the component. The location receives an empty string if this instance of the application is installed in a per-machine installation context.
The length of the buffer at this location should be large enough to hold a null-terminated string value containing the SID. If the buffer is too small, the function returns ERROR_MORE_DATA and the location pointed to by pcchSid receives the number of TCHAR in the SID, not including the terminating NULL character.
If szSid is set to NULL and pcchSid is a valid pointer to a location in memory, the function returns ERROR_SUCCESS and the location receives the number of TCHAR in the SID, not including the terminating null character. The function can then be called again to retrieve the value, with the szSid buffer resized large enough to contain *pcchSid + 1 characters.
||The application is installed in a per-machine installation context.|
||The SID for the user in the system that installed the application.|
Receives the number of TCHAR in the SID, not including the terminating null character. When the function returns, this variable is set to the size of the requested SID whether or not the function can successfully copy the SID and terminating null character into the buffer location pointed to by szSid. The size is returned as the number of TCHAR in the requested value, not including the terminating null character.
This parameter can be set to NULL only if szSid is also NULL, otherwise the function returns ERROR_INVALID_PARAMETER. If szSid and pcchSid are both set to NULL, the function returns ERROR_SUCCESS if the SID exists, without retrieving the SID value.
The MsiEnumProductsEx function returns one of the following values.
||Administrator privileges are required to enumerate components of applications installed by users other than the current user.|
||The configuration data is corrupt.|
||An invalid parameter is passed to the function.|
||There are no more components to enumerate.|
||The function succeeded.|
||The provided buffer was too small to hold the entire value.|
||The function failed.|
|Minimum supported client||Windows Installer 5.0 on Windows Server 2012, Windows 8, Windows Server 2008 R2 or Windows 7. See the Windows Installer Run-Time Requirements for information about the minimum Windows service pack that is required by a Windows Installer version.|