Use android::base::Readlink in init.

Bug: http://b/30988271
Change-Id: Ia0000e9dd7883c31ccbd54fc01bf585c3f8b3fa7

3 files changed, 32 insertions, 49 deletions

diff --git a/init/devices.cpp b/init/devices.cpp
index 830b74cb2..bad04aec1 100644
--- a/init/devices.cpp
+++ b/init/devices.cpp
@@ -14,21 +14,23 @@
  * limitations under the License.
  */
 
+#include <dirent.h>
 #include <errno.h>
+#include <fcntl.h>
 #include <fnmatch.h>
+#include <libgen.h>
 #include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
 #include <sys/stat.h>
+#include <sys/time.h>
 #include <sys/types.h>
-
-#include <fcntl.h>
-#include <dirent.h>
+#include <sys/un.h>
+#include <sys/wait.h>
 #include <unistd.h>
-#include <string.h>
 
-#include <sys/socket.h>
-#include <sys/un.h>
 #include <linux/netlink.h>
 
 #include <memory>
@@ -39,8 +41,6 @@
 #include <selinux/avc.h>
 
 #include <private/android_filesystem_config.h>
-#include <sys/time.h>
-#include <sys/wait.h>
 
 #include <android-base/file.h>
 #include <android-base/stringprintf.h>
@@ -541,30 +541,49 @@ static char **get_block_device_symlinks(struct uevent *uevent)
     return links;
 }
 
+static void make_link_init(const char* oldpath, const char* newpath) {
+  const char* slash = strrchr(newpath, '/');
+  if (!slash) return;
+
+  if (mkdir_recursive(dirname(newpath), 0755)) {
+    PLOG(ERROR) << "Failed to create directory " << dirname(newpath);
+  }
+
+  if (symlink(oldpath, newpath) && errno != EEXIST) {
+    PLOG(ERROR) << "Failed to symlink " << oldpath << " to " << newpath;
+  }
+}
+
+static void remove_link(const char* oldpath, const char* newpath) {
+  std::string path;
+  if (android::base::Readlink(newpath, &path) && path == oldpath) unlink(newpath);
+}
+
 static void handle_device(const char *action, const char *devpath,
         const char *path, int block, int major, int minor, char **links)
 {
-    int i;
-
     if(!strcmp(action, "add")) {
         make_device(devpath, path, block, major, minor, (const char **)links);
         if (links) {
-            for (i = 0; links[i]; i++)
+            for (int i = 0; links[i]; i++) {
                 make_link_init(devpath, links[i]);
+            }
         }
     }
 
     if(!strcmp(action, "remove")) {
         if (links) {
-            for (i = 0; links[i]; i++)
+            for (int i = 0; links[i]; i++) {
                 remove_link(devpath, links[i]);
+            }
         }
         unlink(devpath);
     }
 
     if (links) {
-        for (i = 0; links[i]; i++)
+        for (int i = 0; links[i]; i++) {
             free(links[i]);
+        }
         free(links);
     }
 }
diff --git a/init/util.cpp b/init/util.cpp
index 10ab1c73c..e451edd72 100644
--- a/init/util.cpp
+++ b/init/util.cpp
@@ -270,40 +270,6 @@ void sanitize(char *s)
     }
 }
 
-void make_link_init(const char *oldpath, const char *newpath)
-{
-    int ret;
-    char buf[256];
-    const char *slash;
-    int width;
-
-    slash = strrchr(newpath, '/');
-    if (!slash)
-        return;
-    width = slash - newpath;
-    if (width <= 0 || width > (int)sizeof(buf) - 1)
-        return;
-    memcpy(buf, newpath, width);
-    buf[width] = 0;
-    ret = mkdir_recursive(buf, 0755);
-    if (ret) PLOG(ERROR) << "Failed to create directory " << buf;
-
-    ret = symlink(oldpath, newpath);
-    if (ret && errno != EEXIST) PLOG(ERROR) << "Failed to symlink " << oldpath << " to " << newpath;
-}
-
-void remove_link(const char *oldpath, const char *newpath)
-{
-    char path[256];
-    ssize_t ret;
-    ret = readlink(newpath, path, sizeof(path) - 1);
-    if (ret <= 0)
-        return;
-    path[ret] = 0;
-    if (!strcmp(path, oldpath))
-        unlink(newpath);
-}
-
 int wait_for_file(const char *filename, int timeout)
 {
     struct stat info;
diff --git a/init/util.h b/init/util.h
index f020da8c1..5fcbdf070 100644
--- a/init/util.h
+++ b/init/util.h
@@ -51,8 +51,6 @@ unsigned int decode_uid(const char *s);
 
 int mkdir_recursive(const char *pathname, mode_t mode);
 void sanitize(char *p);
-void make_link_init(const char *oldpath, const char *newpath);
-void remove_link(const char *oldpath, const char *newpath);
 int wait_for_file(const char *filename, int timeout);
 void import_kernel_cmdline(bool in_qemu,
                            const std::function<void(const std::string&, const std::string&, bool)>&);