Improve hacky XLib code

xdg/get-x-slave-devnodes/Makefile

@@ -1,5 +1,5 @@
 get-x-slave-devnodes: get-x-slave-devnodes.c
-	$(CC) -O2 --std=c99 -pedantic -Wall get-x-slave-devnodes.c -o get-x-slave-devnodes -lX11 -lXi
+	$(CC) -O2 --std=gnu99 -pedantic -Wall get-x-slave-devnodes.c -o get-x-slave-devnodes -lX11 -lXi
 clean:
 	rm -f get-x-slave-devnodes
 

xdg/get-x-slave-devnodes/get-x-slave-devnodes.c

@@ -6,6 +6,8 @@
  *     https://github.com/anko/xkbcat
 */
 
+#define _GNU_SOURCE
+
 #include <string.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -28,7 +30,7 @@ char* get_property_xi2(Display* dpy, int deviceid, Atom property, const char* pr
     char* ret = NULL;
 
     name = XGetAtomName(dpy, property);
-    int interested_in_property = (strcmp(name, property_name) == 0);
+    bool interested_in_property = (strcmp(name, property_name) == 0);
     XFree(name);
     if (!interested_in_property)
         return ret;
@@ -51,22 +53,18 @@ char* get_property_xi2(Display* dpy, int deviceid, Atom property, const char* pr
                     }
 
                     int len = strlen((char*)ptr);
-                    ret = (char*)malloc(len+1);
+                    ret = strdup((const char*)ptr);
-                    strcpy(ret, (const char*)ptr);
 
-                    j += len; /* The loop's j++ jumps over the
+                    j += len;   // The loop's j++ jumps over the terminating 0
-                                                terminating 0 */
+                    ptr += len; // ptr += size below jumps over the terminating 0
-                    ptr += len; /* ptr += size below jumps over
-                                            the terminating 0 */
                     break;
+
                 default:
                     // Unknown type
                     done = True;
                     break;
             }
-
             ptr += act_format/8;
-
             if (done == True)
                 break;
         }
@@ -75,65 +73,145 @@ char* get_property_xi2(Display* dpy, int deviceid, Atom property, const char* pr
     return ret;
 }
 
-
+int is_xinput2_available(Display* disp)
-void assert_xinput2(Display* disp)
 {
     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");
+        fprintf(stderr, "XInput extension not available\n");
-            exit(2);
+        return -1;
     }
-    }
+
-    { // 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);
+        fprintf(stderr, "XInput 2.0 support required (got %d.%d)\n", major, minor);
-            exit(3);
+        return -2;
     }
     else if (queryResult != Success)
     {
-            fprintf(stderr, "XIQueryVersion failed!\n");
+        fprintf(stderr, "XIQueryVersion failed\n");
-            exit(4);
+        return -3;
     }
+
+    return 0;
+}
+
+typedef struct SlaveInfo
+{
+    char* slave_names;
+    char* dev_nodes;
+} SlaveInfo;
+
+SlaveInfo new_slave_info()
+{
+    SlaveInfo si;
+    si.slave_names = NULL;
+    si.dev_nodes = NULL;
+    return si;
+}
+
+void free_slave_info(SlaveInfo si)
+{
+    free(si.slave_names);
+    free(si.dev_nodes);
+    si.slave_names = NULL;
+    si.dev_nodes = NULL;
+}
+
+bool is_empty_slave_info(SlaveInfo si)
+{
+    return (si.slave_names == NULL || si.dev_nodes == NULL);
+}
+
+void replace(char* str, char old, char new)
+{
+    int i = 0;
+    while (str[i] != '\0')
+    {
+        if (str[i] == old)
+            str[i] = new;
+        i++;
     }
 }
 
-
+int append_as_line(char** dst, char* line)
-void print_device_nodes(Display* disp)
 {
-	XIDeviceInfo* all_slaves;
+    uint len_newstr = strlen(line) + 2;
-	XIDeviceInfo* current_slave;
+    if (*dst != NULL)
-	int num_slaves;
+        len_newstr += strlen(*dst);
+
+    char* newstr = (char*)malloc(len_newstr);
+    if (newstr == NULL)
+        return -1;
+
+    newstr[0] = '\0';
+    replace(line, '\n', ' ');
+    if (*dst != NULL)
+        strcat(newstr, *dst);
+    strcat(newstr, line);
+    strcat(newstr, "\n");
+
+    free(*dst);
+    *dst = newstr;
+    return 0;
+}
+
+SlaveInfo get_slave_info(Display* disp)
+{
+	int num_slaves;
+	XIDeviceInfo* all_slaves = XIQueryDevice(disp, XIAllDevices, &num_slaves);
+    SlaveInfo slaveinfo = new_slave_info();
+    bool fail = false;
 
-	all_slaves = XIQueryDevice(disp, XIAllDevices, &num_slaves);
 	for (int i = 0; i < num_slaves; i++)
 	{
-		current_slave = &all_slaves[i];
+		XIDeviceInfo* current_slave = &all_slaves[i];
-
         int nprops;
-        Atom* props;
+        Atom* props = XIListProperties(disp, current_slave->deviceid, &nprops);
-        props = XIListProperties(disp, current_slave->deviceid, &nprops);
-        if (!nprops)
-            printf("Device '%s' does not report any properties.\n", current_slave->name);
 
-        while(nprops--)
+        while(nprops-- && !fail)
         {
-            char* property = get_property_xi2(disp, current_slave->deviceid, props[nprops], "Device Node");
+            char* devnode = get_property_xi2(disp, current_slave->deviceid, props[nprops], "Device Node");
-            if (property != NULL)
+            if (current_slave->name != NULL && devnode != NULL)
             {
-                printf("%s=%s\n", current_slave->name, property);
+                int append_slave_success = append_as_line(&slaveinfo.slave_names, current_slave->name);
-                free(property);
+                int append_devnode_success = append_as_line(&slaveinfo.dev_nodes, devnode);
+                if (append_slave_success != 0 || append_devnode_success != 0)
+                    fail = true;
             }
+            free(devnode);
         }
         XFree(props);
+        if (fail)
+        {
+            free_slave_info(slaveinfo);
+            break;
         }
 
+	}
 	XIFreeDeviceInfo(all_slaves);
+    return slaveinfo;
+}
+
+Display* connect_to_x(const char* xDisplayName)
+{
+    Display* disp = XOpenDisplay(xDisplayName);
+    if (NULL == disp)
+    {
+        fprintf(stderr, "Cannot open X display '%s'\n", xDisplayName);
+        return NULL;
+    }
+
+    if (is_xinput2_available(disp) != 0)
+    {
+        XCloseDisplay(disp);
+        return NULL;
+    }
+
+    return disp;
 }
 
 
@@ -142,19 +220,22 @@ int main(int argc, char * argv[])
     char* xDisplayName = getenv("DISPLAY");
     if (xDisplayName == NULL)
     {
-        printf("DISPLAY environment variable not found\n");
+        fprintf(stderr, "DISPLAY environment variable not found\n");
         exit(1);
     }
 
-    // Connect to X display
+    Display* disp = connect_to_x(xDisplayName);
-    Display* disp = XOpenDisplay(xDisplayName);
+    if (disp == NULL)
-    if (NULL == disp)
+        exit(1);
+
+    SlaveInfo si = get_slave_info(disp);
+    if (!is_empty_slave_info(si))
     {
-        fprintf(stderr, "Cannot open X display '%s'\n", xDisplayName);
+        printf("%s", si.slave_names);
-        exit(1);
+        printf("%s", si.dev_nodes);
     }
-    assert_xinput2(disp);
 
-    print_device_nodes(disp);
+    free_slave_info(si);
+    XCloseDisplay(disp);
     exit(0);
 }