<table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Issue</th>
<td>
<a href=https://github.com/llvm/llvm-project/issues/121715>121715</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>
[lldb] Interactive command line interface nonfunctional on Windows with cross-platform libedit
</td>
</tr>
<tr>
<th>Labels</th>
<td>
new issue
</td>
</tr>
<tr>
<th>Assignees</th>
<td>
</td>
</tr>
<tr>
<th>Reporter</th>
<td>
lulle2007200
</td>
</tr>
</table>
<pre>
I have built LLDB 19.1.6 on windows with libedit support using this cross-platform libedit port: [https://github.com/michaeljclark/libedit](https://github.com/michaeljclark/libedit).
Here is the cmake command used:
```
cmake -S llvm -B build -G Ninja `
-DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_INSTALL_PREFIX="install" `
-DCMAKE_CXX_COMPILER=cl -DCMAKE_C_COMPILER=cl `
-DLLDB_EMBED_PYTHON_HOME=0 `
-DLLVM_ENABLE_PROJECTS="lldb;clang" `
-DLLDB_INCLUDE_TESTS=Off `
-DLLDB_ENABLE_LIBEDIT=On `
-DLLDB_ENABLE_CURSES=Off `
-DLLDB_ENABLE_LZMA=Off `
-DLLDB_ENABLE_LIBXML2=Off `
-DLLDB_ENABLE_PYTHON=Off `
-DLLDB_ENABLE_LUA=Off `
-DLibEdit_LIBRARIES="C:\Program Files (x86)\Windows Kits\10\Lib\10.0.22621.0\um\x64\Crypt32.Lib;C:\Program Files (x86)\Windows Kits\10\Lib\10.0.22621.0\um\x64\Winmm.Lib;C:\Program Files (x86)\Windows Kits\10\Lib\10.0.22621.0\um\x64\UserEnv.Lib;C:\Program Files (x86)\Windows Kits\10\Lib\10.0.22621.0\um\x64\Secur32.Lib;C:\Users\Christoph\Dev\libedit\install\lib\edit.lib;C:\libedit\install\lib\compat.lib;C:\libedit\install\lib\regex.lib;C:\libedit\install\lib\terminfo.lib;C:\libedit\install\lib\edit.lib;C:\libedit\install\lib\pdcurses.lib" `
-DLibEdit_INCLUDE_DIRS="C:\libedit\libedit"
```
The `getline` function libedit provides in `libedit\compat\win32` is incomplete and doesn't return -1 on errors or when no characters were read and doesn't handle memory allocations. I have replaced it with the following:
```
ssize_t getline(char **lineptr, size_t *n, FILE *stream)
{
size_t lim = *n;
size_t size = *n;
char *s = *lineptr;
if(s && !lim){
abort();
}
if(!s){
size = 0;
lim = 0;
}
int c, i = 0;
while (--lim > 0 && (c=fgetc(stream)) != EOF && c != '\n'){
if(i >= size){
size += 80;
char *ptr = (char*)realloc(s, size);
if(!ptr){
goto error;
}
s = ptr;
}
s[i++] = c;
}
if (c == '\n'){
if(i >= size){
size += 80;
char *ptr = (char*)realloc(s, size);
if(!ptr){
goto error;
}
s = ptr;
}
s[i++] = c;
}
if(i >= size){
size += 80;
char *ptr = (char*)realloc(s, size);
if(!ptr){
goto error;
}
s = ptr;
}
s[i] = '\0';
*lineptr = s;
*n = size;
if(i){
return i;
}
return -1;
error:
free(s);
*lineptr = NULL;
*n = 0;
return -1;
}
```
Pretty ugly, but works.
The resulting lldb executable is not functional.
Launching and attaching to a process by pid (e.g. lldb --attach-pid xxxx) etc. works fine, but the interactive command line is non-functional and does not accept any user keyboard input (command line stays blank).
Here is a call stack when suspending lldb:
```
SelectHelper.cpp Line 228 C++ liblldb.dll!SelectHelper::Select()
ConnectionFileDescriptorPosix.cpp Line 477 C++ liblldb.dll!lldb_private::ConnectionFileDescriptor::BytesAvailable(const lldb_private::Timeout<std::ratio<1,1000000>> & timeout, lldb_private::Status * error_ptr)
ConnectionFileDescriptorPosix.cpp Line 272 C++ liblldb.dll!lldb_private::ConnectionFileDescriptor::Read(void * dst, unsigned __int64 dst_len, const lldb_private::Timeout<std::ratio<1,1000000>> & timeout, lldb::ConnectionStatus & status, lldb_private::Status * error_ptr)
Editline.cpp Line 576 C++ liblldb.dll!lldb_private::Editline::GetCharacter(wchar_t * c)
read.c Line 401 C liblldb.dll!el_wgetc(editline * el, wchar_t * cp)
read.c Line 225 C liblldb.dll!read_getcmd(editline * el, unsigned char * cmdnum, wchar_t * ch)
read.c Line 514 C liblldb.dll!el_wgets(editline * el, int * nread)
eln.c Line 72 C liblldb.dll!el_gets(editline * el, int * nread)
Editline.cpp Line 1497 C++ liblldb.dll!lldb_private::Editline::GetLine(std::string & line, bool & interrupted)
IOHandler.cpp Line 354 C++ liblldb.dll!lldb_private::IOHandlerEditline::GetLine(std::string & line, bool & interrupted)
IOHandler.cpp Line 596 C++ liblldb.dll!lldb_private::IOHandlerEditline::Run()
Debugger.cpp Line 1107 C++ liblldb.dll!lldb_private::Debugger::RunIOHandlers()
CommandInterpreter.cpp Line 3404 C++ liblldb.dll!lldb_private::CommandInterpreter::RunCommandInterpreter(lldb_private::CommandInterpreterRunOptions & options)
Line 1253 C++ liblldb.dll!lldb::SBDebugger::RunCommandInterpreter(bool auto_handle_events, bool spawn_thread) SBDebugger.cpp
Driver.cpp Line 621 C++ lldb.exe!Driver::MainLoop()
Driver.cpp Line 807 C++ lldb.exe!main(int argc, const char * * argv)
```
In particular, the call
```
const int num_set_fds = ::select(nfds, read_fdset_ptr, write_fdset_ptr, error_fdset_ptr, tv_ptr);
```
in SelectHelper.cpp line 214 always fails and the loop
```
while (handle == m_io_sp->GetWaitableHandle()) { ... }`
```
in ConnectionFileDescriptorPosix.cpp line 473 is never left.
I'm not too familiar with the inner workings of lldb.
</pre>
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