first commit

binder_alloc/Android.bp

@@ -0,0 +1,7 @@
+cc_binary {
+    name: "binder_alloc",
+    srcs: ["main.cpp"],
+    cflags: ["-Wall", "-Werror"],
+    vendor: true,
+}
+

binder_alloc/main.cpp

@@ -0,0 +1,73 @@
+#include <errno.h>
+#include <fcntl.h>
+#include <libgen.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#define BINDERFS_MAX_NAME 255
+struct binderfs_device {
+    char name[BINDERFS_MAX_NAME + 1];
+    __u32 major;
+    __u32 minor;
+};
+#define BINDER_CTL_ADD _IOWR('b', 1, struct binderfs_device)
+
+void usage(char *bin) {
+    printf("USAGE: %s BINDER-CONTROL-PATH DEVICE1 [DEVICE2 ...]\n", bin);
+    printf("EXAMPLE: binder_alloc /dev/binderfs/binder-control binder hwbinder vndbinder\n");
+}
+
+int main(int argc, char *argv[])
+{
+    int fd, ret;
+    size_t len;
+    struct binderfs_device device{};
+
+    if (argc < 3) {
+        usage(basename(argv[0]));
+        exit(EXIT_FAILURE);
+    }
+
+    fd = open(argv[1], O_RDONLY | O_CLOEXEC);
+    if (fd < 0) {
+        printf("%s - Failed to open binder-control device\n", strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+
+    char *dir = dirname(argv[1]); // "/dev/binderfs"
+    char *pathname = (char *) malloc(strlen(dir) + BINDERFS_MAX_NAME + 2); // "/dev/binderfs/binder"
+
+    for (int i = 2; i < argc; ++i) {
+        sprintf(pathname, "%s/%s", dir, argv[i]);
+        if (access(pathname, F_OK) != -1) {
+            printf("binder device already allocated, path: %s\n", pathname);
+            chmod(pathname, 0666);
+            continue;
+        }
+        len = strlen(argv[i]);
+        if (len > BINDERFS_MAX_NAME) exit(EXIT_FAILURE);
+
+        memcpy(device.name, argv[i], len);
+        device.name[len] = '\0';
+
+        ret = ioctl(fd, BINDER_CTL_ADD, &device);
+        if (ret < 0) {
+            printf("%s - Failed to allocate new binder device\n",
+                    strerror(errno));
+            exit(EXIT_FAILURE);
+        }
+        chmod(pathname, 0666);
+        printf("Allocated new binder device with major %d, minor %d, and "
+                "name %s\n", device.major, device.minor,
+                device.name);
+    }
+    free(pathname);
+    close(fd);
+
+    exit(EXIT_SUCCESS);
+}