LM (Linux): try fixing LightDM version detection

src/common/processing.h

@@ -6,5 +6,6 @@
 #include "util/FFstrbuf.h"
 
 const char* ffProcessAppendStdOut(FFstrbuf* buffer, char* const argv[]);
+const char* ffProcessAppendStdErr(FFstrbuf* buffer, char* const argv[]);
 
 #endif

src/common/processing_linux.c

@@ -47,3 +47,45 @@ const char* ffProcessAppendStdOut(FFstrbuf* buffer, char* const argv[])
 
     return NULL;
 }
+
+const char* ffProcessAppendStdErr(FFstrbuf* buffer, char* const argv[])
+{
+    int pipes[2];
+
+    if(pipe(pipes) == -1)
+        return "pipe() failed";
+
+    pid_t childPid = fork();
+    if(childPid == -1)
+        return "fork() failed";
+
+    //Child
+    if(childPid == 0)
+    {
+        dup2(pipes[1], STDERR_FILENO);
+        close(pipes[0]);
+        close(pipes[1]);
+        close(STDOUT_FILENO);
+        execvp(argv[0], argv);
+        exit(901);
+    }
+
+    //Parent
+    close(pipes[1]);
+
+    int FF_AUTO_CLOSE_FD childPipeFd = pipes[0];
+    int status = -1;
+    if(waitpid(childPid, &status, 0) < 0)
+        return "waitpid(childPid, &status, 0) failed";
+
+    if (!WIFEXITED(status))
+        return "WIFEXITED(status) == false";
+
+    if(WEXITSTATUS(status) == 901)
+        return "WEXITSTATUS(status) == 901 ( execvp failed )";
+
+    if(!ffAppendFDBuffer(childPipeFd, buffer))
+        return "ffAppendFDBuffer(childPipeFd, buffer) failed";
+
+    return NULL;
+}

src/common/processing_windows.c

@@ -11,18 +11,18 @@ const char* ffProcessAppendStdOut(FFstrbuf* buffer, char* const argv[])
         .bInheritHandle = TRUE,
     };
 
-    HANDLE hChildStdoutRead, hChildStdoutWrite;
-    if (!CreatePipe(&hChildStdoutRead, &hChildStdoutWrite, &saAttr, 0))
+    HANDLE hChildPipeRead, hChildPipeWrite;
+    if (!CreatePipe(&hChildPipeRead, &hChildPipeWrite, &saAttr, 0))
         return "CreatePipe() failed";
 
-    if (!SetHandleInformation(hChildStdoutRead, HANDLE_FLAG_INHERIT, 0))
-        return "SetHandleInformation(hChildStdoutRead) failed";
+    if (!SetHandleInformation(hChildPipeRead, HANDLE_FLAG_INHERIT, 0))
+        return "SetHandleInformation(hChildPipeRead) failed";
 
     PROCESS_INFORMATION piProcInfo = {0};
     STARTUPINFOA siStartInfo = {
         .cb = sizeof(siStartInfo),
         .dwFlags = STARTF_USESTDHANDLES,
-        .hStdOutput = hChildStdoutWrite,
+        .hStdOutput = hChildPipeWrite,
     };
 
     BOOL success;
@@ -49,18 +49,80 @@ const char* ffProcessAppendStdOut(FFstrbuf* buffer, char* const argv[])
         );
     }
 
-    CloseHandle(hChildStdoutWrite);
+    CloseHandle(hChildPipeWrite);
     if(!success)
     {
-        CloseHandle(hChildStdoutRead);
+        CloseHandle(hChildPipeRead);
         return "CreateProcessA() failed";
     }
 
     char str[1024];
     DWORD nRead;
-    while(ReadFile(hChildStdoutRead, str, sizeof(str), &nRead, NULL) && nRead > 0)
+    while(ReadFile(hChildPipeRead, str, sizeof(str), &nRead, NULL) && nRead > 0)
         ffStrbufAppendNS(buffer, nRead, str);
 
-    CloseHandle(hChildStdoutRead);
+    CloseHandle(hChildPipeRead);
+    return NULL;
+}
+
+const char* ffProcessAppendStdErr(FFstrbuf* buffer, char* const argv[])
+{
+    SECURITY_ATTRIBUTES saAttr = {
+        .nLength = sizeof(SECURITY_ATTRIBUTES),
+        .lpSecurityDescriptor = NULL,
+        .bInheritHandle = TRUE,
+    };
+
+    HANDLE hChildPipeRead, hChildPipeWrite;
+    if (!CreatePipe(&hChildPipeRead, &hChildPipeWrite, &saAttr, 0))
+        return "CreatePipe() failed";
+
+    if (!SetHandleInformation(hChildPipeRead, HANDLE_FLAG_INHERIT, 0))
+        return "SetHandleInformation(hChildPipeRead) failed";
+
+    PROCESS_INFORMATION piProcInfo = {0};
+    STARTUPINFOA siStartInfo = {
+        .cb = sizeof(siStartInfo),
+        .dwFlags = STARTF_USESTDHANDLES,
+        .hStdError = hChildPipeWrite,
+    };
+
+    BOOL success;
+
+    {
+        FF_STRBUF_AUTO_DESTROY cmdline = ffStrbufCreateF("\"%s\"", argv[0]);
+        for(char* const* parg = &argv[1]; *parg; ++parg)
+        {
+            ffStrbufAppendC(&cmdline, ' ');
+            ffStrbufAppendS(&cmdline, *parg);
+        }
+
+        success = CreateProcessA(
+            NULL,          // application name
+            cmdline.chars, // command line
+            NULL,          // process security attributes
+            NULL,          // primary thread security attributes
+            TRUE,          // handles are inherited
+            0,             // creation flags
+            NULL,          // use parent's environment
+            NULL,          // use parent's current directory
+            &siStartInfo,  // STARTUPINFO pointer
+            &piProcInfo    // receives PROCESS_INFORMATION
+        );
+    }
+
+    CloseHandle(hChildPipeWrite);
+    if(!success)
+    {
+        CloseHandle(hChildPipeRead);
+        return "CreateProcessA() failed";
+    }
+
+    char str[1024];
+    DWORD nRead;
+    while(ReadFile(hChildPipeRead, str, sizeof(str), &nRead, NULL) && nRead > 0)
+        ffStrbufAppendNS(buffer, nRead, str);
+
+    CloseHandle(hChildPipeRead);
     return NULL;
 }

src/detection/lm/lm_linux.c

@@ -95,7 +95,7 @@ static const char* getXfwmVersion(FFstrbuf* version)
 
 static const char* getLightdmVersion(FFstrbuf* version)
 {
-    const char* error = ffProcessAppendStdOut(version, (char* const[]) {
+    const char* error = ffProcessAppendStdErr(version, (char* const[]) {
         "lightdm",
         "--version",
         NULL