FindFirstFileEx() and Unicode
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I found at least part of the problem. A string variable cannot contain Unicode characters. So
Dim lpFileName_str As String = "\\?\UNC\" & path & "\*"will not work and comes back with, for example,"\\?\UNC\d:\?????????\*". Now I think I see why the string parameter needs to be changed to a pointer to the path, rather than a string representing the path. Also, when I put the path into memory, and then retrieve it, everything is correct except the"\*"at the end...It gets interpreted as"[foreign character]*". So I think I'm finally on to at least part of the solution. I'll take a look at how to handle backslashes in Unicode strings and see what happens. That also explains why the return value from the function was "-1", file not found.treddie wrote:
string variable cannot contain Unicode characters
Considering every single string in .NET is stored as Unicode, that statement is not true. The encoding is UTF-16.
treddie wrote:
for example,
"\\?\UNC\d:\?????????\*The problem with what your looking at is that not every font has glyphs for every Unicode character, so you get boxes for those. In addition, if the string is being displayed by a control or other rendering device that doesn't support the encoding, characters that are not recognized are replaced with question marks. Read this[^].
treddie wrote:
Now I think I see why the string parameter needs to be changed to a pointer to the path, rather than a string representing the path
Hehe. You never pass a "string". Strings are always passed by pointer. You can only put one value, per parameter, on the stack when function call is made. In the case of strings, or other object that is not an intrinsic type, it's always a pointer.
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Dave Kreskowiak -
this might not do all you want - but Uwe Keim from here on CP & 'Zeta' did some work on this Zeta Long Paths[^] http://zetalongpaths.codeplex.com/[^] hth 'g'
Bummer...It's in some form of C. I'm not a C guy. I can struggle through it and eventually figure it out, but the hardest part is converting to vb and getting the function declarations correct. One oddity in his code, is I did not see any references to FindFirstFileEx()...Only FindFirstFile() which cannot deal with wide path names.
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treddie wrote:
string variable cannot contain Unicode characters
Considering every single string in .NET is stored as Unicode, that statement is not true. The encoding is UTF-16.
treddie wrote:
for example,
"\\?\UNC\d:\?????????\*The problem with what your looking at is that not every font has glyphs for every Unicode character, so you get boxes for those. In addition, if the string is being displayed by a control or other rendering device that doesn't support the encoding, characters that are not recognized are replaced with question marks. Read this[^].
treddie wrote:
Now I think I see why the string parameter needs to be changed to a pointer to the path, rather than a string representing the path
Hehe. You never pass a "string". Strings are always passed by pointer. You can only put one value, per parameter, on the stack when function call is made. In the case of strings, or other object that is not an intrinsic type, it's always a pointer.
A guide to posting questions on CodeProject[^]
Dave KreskowiakDave Kreskowiak wrote:
string variable cannot contain Unicode characters
Yah, that was sloppy reasoning on my part. Although, I also can't explain why I was getting inconsistent behavior in what was being reported in the string. Sometimes, when I would pass the pathname to the string, it would come back with ?'s. So without having a stable situation that I can depend on, I can't come to any conclusion on what that was all about. Especially since I can't duplicate the problem. But now, what I have found is that the string holds the foreign characters just fine, but something odd happens when I send the string to an RTB and a plain TextBox. The RTB displays "\*" as "*", but the TextBox had no problem at all and correctly shows, "\*". But if I hover my mouse over the "rtb1.text =" statement in the code, it reads fine! Weird.
Dave Kreskowiak wrote:
You never pass a "string".
But why do they declare strings in any function that accepts them? I've used ANSI strings before with no problem, just as MSDN suggests. The headaches happen when I get to Unicode strings.
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treddie wrote:
I also found through tests that the TRUE limit for Windows, is 240 characters max.
Not quite. A fully qualifed filePATH to a file (including filename) is 248 characters max. A fileNAME (with no path information at all) is 260 characters max. Think of setting the "current directory" first before trying to access a file with a name like that. That's one way to get a filepath longer than the 248 character limit.
treddie wrote:
This may be a bug in Windows
Considering that code has been around for, literally, decades, its not a bug. These are hardcoded limits in NTFS.
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Dave KreskowiakDave Kreskowiak wrote:
I also found through tests that the TRUE limit for Windows, is 240 characters
max.I'm not so sure about that, Dave. I ran some extensive tests many months ago when working on this program and found that there are 4 Windows limits. Their numbers are as follows, according to MS: Folder name = 260 characters File name (w/ extension) = 260 characters Folder path w/o file name = 260 characters Full path w/ filename = 260 characters Obviously you can't have 260 in all categories so it's a matter of whatever the actual amounts are for each category, that they don't exceed any of the 4 limits. At any rate, I tested all 4 cases and found that when you subtract out the twelve 8.3-filename chars, the 3 root characters, and the null character at the end of any path (all the characters the user has no control over), you are left with at that point only 244 characters, including backslashes, that you can play with. But, you have to actually limit yourself to 240 maximum, user-controlled characters to prevent the Windows crash on folder/file name right-click -> properties. I think that last case classifies as a bug in that your Windows session gets trashed if you go over 240 characters when getting a file's properties. This was true in my tests for both WinXP (latest SP), and Win7 (6.1.7600 Build 7600), although the manner of the crash was different for each system. The WinXP crash was really bad and would hang the computer.
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Dave Kreskowiak wrote:
string variable cannot contain Unicode characters
Yah, that was sloppy reasoning on my part. Although, I also can't explain why I was getting inconsistent behavior in what was being reported in the string. Sometimes, when I would pass the pathname to the string, it would come back with ?'s. So without having a stable situation that I can depend on, I can't come to any conclusion on what that was all about. Especially since I can't duplicate the problem. But now, what I have found is that the string holds the foreign characters just fine, but something odd happens when I send the string to an RTB and a plain TextBox. The RTB displays "\*" as "*", but the TextBox had no problem at all and correctly shows, "\*". But if I hover my mouse over the "rtb1.text =" statement in the code, it reads fine! Weird.
Dave Kreskowiak wrote:
You never pass a "string".
But why do they declare strings in any function that accepts them? I've used ANSI strings before with no problem, just as MSDN suggests. The headaches happen when I get to Unicode strings.
treddie wrote:
But why do they declare strings in any function that accepts them?
Because you're definfing the TYPE of the pointer. What kind of object does it point to? What are the rules for incrementing that pointer if needed?? If you go back to C, a "string" in it's most basic form is just a pointer to an array of type char (character). Under Windows, you can have ASCII strings and wide-character strings. Incrementing the pointer for an ASCII character just adding 1 to the pointer, but, for multi-byte characters, such as Unicode, you increment the pointer by 2 or more.
A guide to posting questions on CodeProject[^]
Dave Kreskowiak -
treddie wrote:
But why do they declare strings in any function that accepts them?
Because you're definfing the TYPE of the pointer. What kind of object does it point to? What are the rules for incrementing that pointer if needed?? If you go back to C, a "string" in it's most basic form is just a pointer to an array of type char (character). Under Windows, you can have ASCII strings and wide-character strings. Incrementing the pointer for an ASCII character just adding 1 to the pointer, but, for multi-byte characters, such as Unicode, you increment the pointer by 2 or more.
A guide to posting questions on CodeProject[^]
Dave Kreskowiak -
treddie wrote:
I also found through tests that the TRUE limit for Windows, is 240 characters max.
Not quite. A fully qualifed filePATH to a file (including filename) is 248 characters max. A fileNAME (with no path information at all) is 260 characters max. Think of setting the "current directory" first before trying to access a file with a name like that. That's one way to get a filepath longer than the 248 character limit.
treddie wrote:
This may be a bug in Windows
Considering that code has been around for, literally, decades, its not a bug. These are hardcoded limits in NTFS.
A guide to posting questions on CodeProject[^]
Dave KreskowiakActually, NTFS is not at all that limited. It's just that the kernel32.dll API interface is limited to those path limits. From MSDN, CreateFile page: In the ANSI version of this function, the name is limited to MAX_PATH characters. To extend this limit to 32,767 wide characters, call the Unicode version of the function and prepend "\\?\" to the path. For more information, see Naming Files, Paths, and Namespaces. By adding \\?\ you tell the kernel32 API to NOT do any parsing or processing on the path, and instead pass it directly on to the filesystem driver. From MSDN page on Naming Files, Paths, and Namespaces (Windows): For file I/O, the "\\?\" prefix to a path string tells the Windows APIs to disable all string parsing and to send the string that follows it straight to the file system. But not all functions can work with the extended paths, because some functions inherently need to do processing on the path.
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Actually, NTFS is not at all that limited. It's just that the kernel32.dll API interface is limited to those path limits. From MSDN, CreateFile page: In the ANSI version of this function, the name is limited to MAX_PATH characters. To extend this limit to 32,767 wide characters, call the Unicode version of the function and prepend "\\?\" to the path. For more information, see Naming Files, Paths, and Namespaces. By adding \\?\ you tell the kernel32 API to NOT do any parsing or processing on the path, and instead pass it directly on to the filesystem driver. From MSDN page on Naming Files, Paths, and Namespaces (Windows): For file I/O, the "\\?\" prefix to a path string tells the Windows APIs to disable all string parsing and to send the string that follows it straight to the file system. But not all functions can work with the extended paths, because some functions inherently need to do processing on the path.
Yeah, I knew that. Slip of the brain when I typed it.
A guide to posting questions on CodeProject[^]
Dave Kreskowiak -
Yeah, I knew that. Slip of the brain when I typed it.
A guide to posting questions on CodeProject[^]
Dave KreskowiakOK, I'm finally getting this to work. I took the suggestion more seriously that GetLastError() might provide some insight into the problem. It wasn't anything that explicitly told me what was wrong, but it did cause me to take a much closer look at all of my declarations, and realizing that using "\\?\UNC\" was not correct...It needs to be just "\\?\". But also took to heart your comments on strings and pointers. In that regard, I found some typing problems here and there, and missed some lines that were still not rewritten for pointers. I'll post the resulting code here, shortly, after I copy my test code over to my final demo program and fix some remaining issues.
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Howdie. I am researching how to use the Unicode version of FindFirstFileEx() in vb.Net and am having a heck of a time getting this to work. I had downloaded an example and it used the standard version, FindFirstFile(). I then modified the code to work with FindFirstFileEx(), instead, and got that to work, too, but only for ANSI characters (Alias "FindFirstFileExA"). But when I attempted to use the Unicode version (Alias "FindFirstFileExW"), it fails miserably. The best I have been able to do is get a non-zero return value from the function (which means it found the folder), but all the returned WFD structure contains are null strings for the folder name and alternate folder name. I have googled the problem (MSDN is of no help in this regard) and did find one reference on how to alter the function parameters to provide pointers instead of a string and the WFD structure, themselves. At any rate, here is my code for just the top half that looks for folders. The bottom half deals with searching for files, but it is just a repeat of this example, essentially. If I can get this top half to work with your help, I can certainly get the bottom half to work. I would have liked to attach a zip containing the project and the test folder I used, but it does not look like attachments are possible, here. Thanks for any help!
Option Strict Off
Option Explicit On
'Option Infer OffImports VB = Microsoft.VisualBasic
Imports System.Runtime.InteropServicesFriend Class Form1
Inherits System.Windows.Forms.Form'Private Declare Function FindFirstFileExW Lib "kernel32.dll" Alias "FindFirstFileExW" (ByVal lpFileName As String, ByVal fInfoLevelId As FINDEX_INFO_LEVELS, ByVal lpFindFileData As WIN32_FIND_DATA, ByVal fSearchOp As FINDEX_SEARCH_OPS, ByRef lpSearchFilter As Int32, ByVal dwAdditionalFlags As Integer) As Long
Private Declare Function FindFirstFileExW Lib "kernel32.dll" Alias "FindFirstFileExW" (ByVal lpFileName_IntPtr As IntPtr, ByVal fInfoLevelId As FINDEX_INFO_LEVELS, ByRef lpFindFileData_IntPtr As IntPtr, ByVal fSearchOp As FINDEX_SEARCH_OPS, ByRef lpSearchFilter As Int32, ByVal dwAdditionalFlags As Integer) As LongPrivate Declare Function FindNextFileW Lib "kernel32" Alias "FindNextFileW" (ByVal hFindFile As Long, ByRef lpFindFileData As WIN32_FIND_DATA) As Integer
Private Declare Function GetFileAttributesW Lib "kernel32" Alias "GetFileAttributesW" (ByVal lpFileName As String) As Integer
Private Declare Function FindClose Lib "kernel32" (ByVal hFindFile A
Hi treddie, Based on my understanding of your code, I see no reason to use FindFirstFileEx versus FindFirstFile. Also, the directory filter flag option can fail silently if it is not supported and you need to check the attributes anyways if it was your intent to just recover directories. But it appears as your code is also doing these checks. Just a word of caution about interop examples you find on the web; many of these were originally done in VB6 and may not have been properly modified for DotNet types. Here are links to a reference and a tool that you may find useful in working with interop. Miscellaneous Marshaling (look at the links under "See Also") Samples[^] PInvoke Interop Assistant[^] I was bored so I tried putting together a simple TreeView file explorer that bypasses the 260 character limit. It may serve as an example for what you are trying to do. Just place a TreeView control on new WinForm project and paste this code. I used the command prompt "Subst" command to create a drive reference to a path that reached the 260 character barier and then added some more directories under that substituted drive to get to a file that had 400+ characters in it's path to test this. It appears to work. Edit: There appears to be a length limit on codeblock code.
Imports System.Runtime.InteropServices
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
TreeView1.Nodes.Add(DriveToTreeNode("c"c))
End SubPrivate Sub TreeView1_AfterCollapse(ByVal sender As Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles TreeView1.AfterCollapse
e.Node.Nodes.Clear()
e.Node.Nodes.Add(New TreeNode With {.Tag = New NodeData With {.IsDirectory = True}}) ' add dummy node
End SubPrivate Sub TreeView1_BeforeExpand(ByVal sender As Object, ByVal e As System.Windows.Forms.TreeViewCancelEventArgs) Handles TreeView1.BeforeExpand
' only directories can have nodes
e.Node.Nodes.Clear()
EnumerateDirectory(e.Node)
End SubPrivate Sub TreeView1_MouseDoubleClick(ByVal sender As Obje
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Hi treddie, Based on my understanding of your code, I see no reason to use FindFirstFileEx versus FindFirstFile. Also, the directory filter flag option can fail silently if it is not supported and you need to check the attributes anyways if it was your intent to just recover directories. But it appears as your code is also doing these checks. Just a word of caution about interop examples you find on the web; many of these were originally done in VB6 and may not have been properly modified for DotNet types. Here are links to a reference and a tool that you may find useful in working with interop. Miscellaneous Marshaling (look at the links under "See Also") Samples[^] PInvoke Interop Assistant[^] I was bored so I tried putting together a simple TreeView file explorer that bypasses the 260 character limit. It may serve as an example for what you are trying to do. Just place a TreeView control on new WinForm project and paste this code. I used the command prompt "Subst" command to create a drive reference to a path that reached the 260 character barier and then added some more directories under that substituted drive to get to a file that had 400+ characters in it's path to test this. It appears to work. Edit: There appears to be a length limit on codeblock code.
Imports System.Runtime.InteropServices
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
TreeView1.Nodes.Add(DriveToTreeNode("c"c))
End SubPrivate Sub TreeView1_AfterCollapse(ByVal sender As Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles TreeView1.AfterCollapse
e.Node.Nodes.Clear()
e.Node.Nodes.Add(New TreeNode With {.Tag = New NodeData With {.IsDirectory = True}}) ' add dummy node
End SubPrivate Sub TreeView1_BeforeExpand(ByVal sender As Object, ByVal e As System.Windows.Forms.TreeViewCancelEventArgs) Handles TreeView1.BeforeExpand
' only directories can have nodes
e.Node.Nodes.Clear()
EnumerateDirectory(e.Node)
End SubPrivate Sub TreeView1_MouseDoubleClick(ByVal sender As Obje
Here is the remainder of the code.
Private Shared Function GetShortPathName(ByVal path As String) As String
Dim sb As New System.Text.StringBuilder(1000)
Dim len As Int32 = GetShortPathName(LongPathPrefix & path, sb, sb.Capacity)
If len > sb.Capacity Then
sb.Capacity = len
GetShortPathName(LongPathPrefix & path, sb, sb.Capacity)
End If
Return sb.ToString().Replace(LongPathPrefix, "")
End Function<StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Unicode), BestFitMapping(False)> _
Private Class WIN32_FIND_DATA
<MarshalAs(UnmanagedType.U4)> Public dwFileAttributes As IO.FileAttributes
<MarshalAs(UnmanagedType.U4)> Private ftCreationTime_dwLowDateTime As UInt32
<MarshalAs(UnmanagedType.U4)> Private ftCreationTime_dwHighDateTime As UInt32
<MarshalAs(UnmanagedType.U4)> Private ftLastAccessTime_dwLowDateTime As UInt32
<MarshalAs(UnmanagedType.U4)> Private ftLastAccessTime_dwHighDateTime As UInt32
<MarshalAs(UnmanagedType.U4)> Private ftLastWriteTime_dwLowDateTime As UInt32
<MarshalAs(UnmanagedType.U4)> Private ftLastWriteTime_dwHighDateTime As UInt32
<MarshalAs(UnmanagedType.U4)> Public nFileSizeHigh As UInt32
<MarshalAs(UnmanagedType.U4)> Public nFileSizeLow As UInt32
<MarshalAs(UnmanagedType.U4)> Public dwReserved0 As UInt32
<MarshalAs(UnmanagedType.U4)> Public dwReserved1 As UInt32' Note: by changing the cFileName size constant from 260 to 32767 to handle long ' path names, it appears that cAlternateFileName always returns blank ' if the ShortPathName is needed, then use the GetShortPathName function ' http://msdn.microsoft.com/en-us/library/windows/desktop/aa364989%28v=vs.85%29.aspx <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=32767)> Public cFileName As String <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=14)> Public cAlternateFileName As String Public Function CreationTime() As DateTime Return DateTime.FromFileTime(MergeToInt64(ftCreationTime\_dwLowDateTime, ftCreationTime\_dwHighDateTime)) End Function Public Function LastAccessTime() As DateTime Return DateTime.FromFileTime(MergeToInt64(ftLastAccessTim -
Hi treddie, Based on my understanding of your code, I see no reason to use FindFirstFileEx versus FindFirstFile. Also, the directory filter flag option can fail silently if it is not supported and you need to check the attributes anyways if it was your intent to just recover directories. But it appears as your code is also doing these checks. Just a word of caution about interop examples you find on the web; many of these were originally done in VB6 and may not have been properly modified for DotNet types. Here are links to a reference and a tool that you may find useful in working with interop. Miscellaneous Marshaling (look at the links under "See Also") Samples[^] PInvoke Interop Assistant[^] I was bored so I tried putting together a simple TreeView file explorer that bypasses the 260 character limit. It may serve as an example for what you are trying to do. Just place a TreeView control on new WinForm project and paste this code. I used the command prompt "Subst" command to create a drive reference to a path that reached the 260 character barier and then added some more directories under that substituted drive to get to a file that had 400+ characters in it's path to test this. It appears to work. Edit: There appears to be a length limit on codeblock code.
Imports System.Runtime.InteropServices
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
TreeView1.Nodes.Add(DriveToTreeNode("c"c))
End SubPrivate Sub TreeView1_AfterCollapse(ByVal sender As Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles TreeView1.AfterCollapse
e.Node.Nodes.Clear()
e.Node.Nodes.Add(New TreeNode With {.Tag = New NodeData With {.IsDirectory = True}}) ' add dummy node
End SubPrivate Sub TreeView1_BeforeExpand(ByVal sender As Object, ByVal e As System.Windows.Forms.TreeViewCancelEventArgs) Handles TreeView1.BeforeExpand
' only directories can have nodes
e.Node.Nodes.Clear()
EnumerateDirectory(e.Node)
End SubPrivate Sub TreeView1_MouseDoubleClick(ByVal sender As Obje
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OK, I'm finally getting this to work. I took the suggestion more seriously that GetLastError() might provide some insight into the problem. It wasn't anything that explicitly told me what was wrong, but it did cause me to take a much closer look at all of my declarations, and realizing that using "\\?\UNC\" was not correct...It needs to be just "\\?\". But also took to heart your comments on strings and pointers. In that regard, I found some typing problems here and there, and missed some lines that were still not rewritten for pointers. I'll post the resulting code here, shortly, after I copy my test code over to my final demo program and fix some remaining issues.
One hickup...I need to deal with a C type, LPWSTR. When I research how to get this in vb.Net, I do not find any consistent explanation of how to deal with marshaling unmanaged types. There are no real-world examples and what MSDN offers is cryptic at best. Here is my best guess that does not show any syntax errors:
Dim LPWSTR As UnmanagedType
Dim MyUnicodePointer As New MarshalAsAttribute(LPWSTR) -
Where in the documentation does it suggest that? Quite the opposite is suggested in http://msdn.microsoft.com/en-us/library/windows/desktop/aa364418%28v=vs.85%29.aspx[^]
Quote:
In the ANSI version of this function, the name is limited to MAX_PATH characters. To extend this limit to 32,767 wide characters, call the Unicode version of the function and prepend "\\?\" to the path. For more information, see Naming a File.
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Where in the documentation does it suggest that? Quite the opposite is suggested in http://msdn.microsoft.com/en-us/library/windows/desktop/aa364418%28v=vs.85%29.aspx[^]
Quote:
In the ANSI version of this function, the name is limited to MAX_PATH characters. To extend this limit to 32,767 wide characters, call the Unicode version of the function and prepend "\\?\" to the path. For more information, see Naming a File.
Damn. I swear to gawd I saw it say you needed to use the Ex version to make it happen. Somewhere along the line I got messed up there. Too many questions all at once, I guess. But now that I know that, my overly-verbose usage should still work...I just have to keep track of extra arguments. Also, it is a good exercise in understanding both, since I may in the future need to use the Ex function. I haven't had a chance yet, today, to run your example.
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Damn. I swear to gawd I saw it say you needed to use the Ex version to make it happen. Somewhere along the line I got messed up there. Too many questions all at once, I guess. But now that I know that, my overly-verbose usage should still work...I just have to keep track of extra arguments. Also, it is a good exercise in understanding both, since I may in the future need to use the Ex function. I haven't had a chance yet, today, to run your example.
Quote:
Damn. I swear to gawd I saw it say you needed to use the Ex version to make it happen.
I blame it all on micro-blackhole that make one jump from one parallel universe to another just to screw with your mind when the minor differences bite you in the behind. :laugh: All I can say is that you are making an effort to learn and that is a rare and beautiful thing to see in a forum these days. :)
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Quote:
Damn. I swear to gawd I saw it say you needed to use the Ex version to make it happen.
I blame it all on micro-blackhole that make one jump from one parallel universe to another just to screw with your mind when the minor differences bite you in the behind. :laugh: All I can say is that you are making an effort to learn and that is a rare and beautiful thing to see in a forum these days. :)
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One hickup...I need to deal with a C type, LPWSTR. When I research how to get this in vb.Net, I do not find any consistent explanation of how to deal with marshaling unmanaged types. There are no real-world examples and what MSDN offers is cryptic at best. Here is my best guess that does not show any syntax errors:
Dim LPWSTR As UnmanagedType
Dim MyUnicodePointer As New MarshalAsAttribute(LPWSTR)An LPWSTR is just a Long Pointer to a Wide character String. You're just marshalling a normal string from .NET to the function your calling. Usually, you don't have to do anything special in your function Declaration other than tell it that the paramter is a
String.A guide to posting questions on CodeProject[^]
Dave Kreskowiak -
An LPWSTR is just a Long Pointer to a Wide character String. You're just marshalling a normal string from .NET to the function your calling. Usually, you don't have to do anything special in your function Declaration other than tell it that the paramter is a
String.A guide to posting questions on CodeProject[^]
Dave KreskowiakI'm confused. The function requires a pointer to a wide string, so you can't use 'As String' as a passed argument to the function FindFirstFileEx(). You have to use 'As LWPSTR' or, if I understand you correctly, 'As Long'. If that is true, then I have to wrap the string in a 'long' pointer, which for a 64bit platform would translate to Int32 (or rather, IntPtr), since a win32 function can only accept 32bits arguments and parameters. If that is true, then my existing marshal should be correct:
Dim MyStringPtr As Long = Marshal.StringToHGlobalAuto(MyString)But when I pass MyStringPtr to FindFileEx(), I only get back the first character in a Unicode folder/file name, and then, only when the first character in the string happens to be in the ANSI range.
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I'm confused. The function requires a pointer to a wide string, so you can't use 'As String' as a passed argument to the function FindFirstFileEx(). You have to use 'As LWPSTR' or, if I understand you correctly, 'As Long'. If that is true, then I have to wrap the string in a 'long' pointer, which for a 64bit platform would translate to Int32 (or rather, IntPtr), since a win32 function can only accept 32bits arguments and parameters. If that is true, then my existing marshal should be correct:
Dim MyStringPtr As Long = Marshal.StringToHGlobalAuto(MyString)But when I pass MyStringPtr to FindFileEx(), I only get back the first character in a Unicode folder/file name, and then, only when the first character in the string happens to be in the ANSI range.
I haven't read all of this thread but I don't see either the Auto or Unicode character set modifiers in your external procedure declarations, which means that the default of Ansi is being applied. This could be the root cause of your string problems as UTF16 encoded strings treated as Ansi will get truncated at the first null, i.e. after the first character. See Declare statement[^] and also Calling Windows APIs[^] for examples using both Declare and DllImport. Alan.