GetPrivateProfileSection results are truncated

[ryannewington]

Describe the bug
GetPrivateProfileSection is used to return a section from an INI file.

Consider the following example

[Unicode]
Unicode=yes
[Version]
signature="$CHICAGO$"
Revision=1

I can call the GetPrivateProfileSection function to return the contents of say the Version section. The API returns the results in the following format

signature="$CHICAGO$"\0Revision=1\0\0

When the StringBuilder used in the PInvoke declaration encounters the first null character, it stops building the string, and the rest of the result is discarded.

What code is involved

string inf = "C:\temp\my.ini"
StringBuilder sectionData = new StringBuilder(32000);

var bytesFilled = Kernel32.GetPrivateProfileSection("Version", sectionData, 32000, inf);

// sectionData will now hold only the first element

Expected behavior
All items should be available. Perhaps an array of strings is more appopriate.

[dahall]

The values are there, but you have to know a little trick to extract them: sectionData.ToString().Split('\0', StringSplitOptions.RemoveEmptyEntries) will return the list of strings. However, this may not be obvious to all developers so I'll add an overload that takes a byte array.

[ryannewington]

I gave that a go, but I still only get the first result. There are 4 entries in this section.

[dahall]

I just added overloads to those methods that take an IntPtr instead of StringBuilder. This should allow you to allocate memory and pass it to the methods. You can then do the following:

string inf = @"C:\temp\my.ini";
var chars = 32,767;
using var mem = new SafeCoTaskMemHandle(chars * StringHelper.GetCharSize());
var bytesFilled = Kernel32.GetPrivateProfileSection("Version", mem, chars, inf);
return mem.ToStringEnum();

If you'd like to try this before the next release, you can check the project home page for info on the AppVeyor prerelease NuGet feed.

[ryannewington]

Brilliant. That is working great, thanks David.

Was I doing something wrong with the StringBuilder?

[dahall]

No. It appears that different versions of .NET handle StringBuilder internals differently. I'm actually working on some better wrappers so you can simply call : return Kernel32.GetPrivateProfileSection("Version", inf) and get a string[] with the values. I'll let you know when those are done.

[dahall]

Would a wrapper class be a valuable addition to do something like the following?

var ini = new InitializationFile(@"C:\temp\my.ini");
var versionSettings = ini.Sections["Version"];
foreach (var keyValuePair in versionSettings)
   Console.WriteLine($"{keyValuePair.Key}={keyValuePair.Value}");
versionSettings["MyNewKey"] = "some value";

[dahall]

I just added one to the AppVeyor build. Look for Vanara.Configuration.InitializationFile. I also just pushed a bunch of changes to make the native API functions behave. I removed many of the StringBuilder based functions. Please give me your thoughts.

[ryannewington]

Yeah thats an awesome idea. I turned to the API because most other parsers are regex or similarly based and I didn't feel comfortable with that. I'll convert my code over to use this and let you know how it goes

[ryannewington]

Is it in the Vanara.PInvoke.Kernel32 package? I'm not seeing an updated version on AppVeyor.

[dahall]

Yes. I got confirmation of the build a few minutes ago.

[dahall]

Sometimes VS has a hard time updating packages whose version didn't change. You may need to flush your NuGet caches.

[dahall]

Released!

[ryannewington]

Sorry - late on the feedback, but I have used it and it is working well. Great idea. Thanks again David.

[dahall]

Glad it is useful. I laid in bed stewing on the idea and it came together quickly the next morning.