Tidy: Better comments, scope tempvars, better errs

Maintenance.  No functionality changes.

1 files changed, 32 insertions, 29 deletions

diff --git a/xkbcat.c b/xkbcat.c
index 0092317..1512307 100644
--- a/xkbcat.c
+++ b/xkbcat.c
@@ -22,54 +22,56 @@ USAGE: xkbcat [-display <display>] [-up]\n\
 
 int main(int argc, char * argv[]) {
 
-    const char * hostname    = DEFAULT_DISPLAY;
-    bool         printKeyUps = DEFAULT_PRINT_UP;
+    const char * xDisplayName = DEFAULT_DISPLAY;
+    bool         printKeyUps  = DEFAULT_PRINT_UP;
 
     // Get arguments
     for (int i = 1; i < argc; i++) {
         if      (!strcmp(argv[i], "-help"))     printUsage();
-        else if (!strcmp(argv[i], "-display"))  hostname    = argv[++i];
+        else if (!strcmp(argv[i], "-display"))  xDisplayName = argv[++i];
         else if (!strcmp(argv[i], "-up"))       printKeyUps = true;
         else { printf("Unexpected argument `%s`\n", argv[i]); printUsage(); }
     }
 
-    // Set up X
-    Display * disp = XOpenDisplay(hostname);
+    // Connect to X display
+    Display * disp = XOpenDisplay(xDisplayName);
     if (NULL == disp) {
-        fprintf(stderr, "Cannot open X display: %s\n", hostname);
+        fprintf(stderr, "Cannot open X display: %s\n", xDisplayName);
         exit(1);
     }
 
-    // Test for XInput 2 extension
-    int xiOpcode, queryEvent, queryError;
-    if (! XQueryExtension(disp, "XInputExtension", &xiOpcode,
-                &queryEvent, &queryError)) {
-        fprintf(stderr, "X Input extension not available\n");
-        exit(2);
+    int xiOpcode;
+    { // Test for XInput 2 extension
+        int queryEvent, queryError;
+        if (! XQueryExtension(disp, "XInputExtension", &xiOpcode,
+                    &queryEvent, &queryError)) {
+            fprintf(stderr, "X Input extension not available\n");
+            exit(2);
+        }
     }
-    { // Request XInput 2.0, guarding against changes in future versions
+    { // Request XInput 2.0, to guard against changes in future versions
         int major = 2, minor = 0;
         int queryResult = XIQueryVersion(disp, &major, &minor);
         if (queryResult == BadRequest) {
             fprintf(stderr, "Need XI 2.0 support (got %d.%d)\n", major, minor);
             exit(3);
         } else if (queryResult != Success) {
-            fprintf(stderr, "Internal error\n");
+            fprintf(stderr, "XIQueryVersion failed!\n");
             exit(4);
         }
     }
-
-    // Register events
-    Window root = DefaultRootWindow(disp);
-    XIEventMask m;
-    m.deviceid = XIAllMasterDevices;
-    m.mask_len = XIMaskLen(XI_LASTEVENT);
-    m.mask = calloc(m.mask_len, sizeof(char));
-    XISetMask(m.mask, XI_RawKeyPress);
-    if (printKeyUps) XISetMask(m.mask, XI_RawKeyRelease);
-    XISelectEvents(disp, root, &m, 1);
-    XSync(disp, false);
-    free(m.mask);
+    { // Register to receive XInput events
+        Window root = DefaultRootWindow(disp);
+        XIEventMask m;
+        m.deviceid = XIAllMasterDevices;
+        m.mask_len = XIMaskLen(XI_LASTEVENT);
+        m.mask = calloc(m.mask_len, sizeof(char));
+        XISetMask(m.mask, XI_RawKeyPress);
+        if (printKeyUps) XISetMask(m.mask, XI_RawKeyRelease);
+        XISelectEvents(disp, root, &m, 1 /*number of masks*/);
+        XSync(disp, false);
+        free(m.mask);
+    }
 
     while ("forever") {
         XEvent event;
@@ -84,13 +86,14 @@ int main(int argc, char * argv[]) {
                 case XI_RawKeyPress: {
                     XIRawEvent *ev = cookie->data;
 
-                    // Ask X what it calls that key
-                    KeySym s = XkbKeycodeToKeysym(disp, ev->detail, 0, 0);
+                    // Ask X what it calls that key; skip if it doesn't know
+                    KeySym s = XkbKeycodeToKeysym(disp, ev->detail,
+                            0 /*group*/, 0 /*shift level*/);
                     if (NoSymbol == s) continue;
                     char *str = XKeysymToString(s);
                     if (NULL == str) continue;
 
-
+                    // Output line
                     if (printKeyUps) printf("%s",
                             cookie->evtype == XI_RawKeyPress ? "+" : "-");
                     printf("%s\n", str);