Add dirent implementation

native/src/crt0/Android.mk

@@ -9,6 +9,7 @@ LOCAL_compiler_rt := $(shell $(TARGET_CC) -target $(LLVM_TRIPLE)$(TARGET_PLATFOR
 LOCAL_EXPORT_LDFLAGS := -static -nostartfiles -nodefaultlibs $(LOCAL_compiler_rt) -Wl,--error-limit=0
 
 LOCAL_SRC_FILES := \
+    dirent.cpp \
 	malloc.c \
 	mem.c \
 	misc.c \

native/src/crt0/dirent.cpp

@@ -0,0 +1,183 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <dirent.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <malloc.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+extern "C" int sys_getdents64(unsigned int, dirent*, unsigned int);
+
+class ErrnoRestorer {
+public:
+    explicit ErrnoRestorer() : saved_errno_(errno) {
+    }
+
+    ~ErrnoRestorer() {
+        errno = saved_errno_;
+    }
+
+    void override(int new_errno) {
+        saved_errno_ = new_errno;
+    }
+
+private:
+    int saved_errno_;
+};
+
+// Apportable decided to copy the data structure from this file
+// and use it in their own code, but they also call into readdir.
+// In order to avoid a lockup, the structure must be maintained in
+// the exact same order as in L and below. New structure members
+// need to be added to the end of this structure.
+// See b/21037208 for more details.
+struct DIR {
+  int fd_;
+  size_t available_bytes_;
+  dirent* next_;
+  dirent buff_[15];
+  long current_pos_;
+};
+
+static DIR* __allocate_DIR(int fd) {
+  DIR* d = reinterpret_cast<DIR*>(malloc(sizeof(DIR)));
+  if (d == nullptr) {
+    return nullptr;
+  }
+  d->fd_ = fd;
+  d->available_bytes_ = 0;
+  d->next_ = nullptr;
+  d->current_pos_ = 0L;
+  return d;
+}
+
+int dirfd(DIR* d) {
+  return d->fd_;
+}
+
+DIR* fdopendir(int fd) {
+  // Is 'fd' actually a directory?
+  struct stat sb;
+  if (fstat(fd, &sb) == -1) {
+    return nullptr;
+  }
+  if (!S_ISDIR(sb.st_mode)) {
+    errno = ENOTDIR;
+    return nullptr;
+  }
+
+  return __allocate_DIR(fd);
+}
+
+DIR* opendir(const char* path) {
+  int fd = open(path, O_CLOEXEC | O_DIRECTORY | O_RDONLY);
+  return (fd != -1) ? __allocate_DIR(fd) : nullptr;
+}
+
+static bool __fill_DIR(DIR* d) {
+  int rc = TEMP_FAILURE_RETRY(sys_getdents64(d->fd_, d->buff_, sizeof(d->buff_)));
+  if (rc <= 0) {
+    return false;
+  }
+  d->available_bytes_ = rc;
+  d->next_ = d->buff_;
+  return true;
+}
+
+static dirent* __readdir_locked(DIR* d) {
+  if (d->available_bytes_ == 0 && !__fill_DIR(d)) {
+    return nullptr;
+  }
+
+  dirent* entry = d->next_;
+  d->next_ = reinterpret_cast<dirent*>(reinterpret_cast<char*>(entry) + entry->d_reclen);
+  d->available_bytes_ -= entry->d_reclen;
+  // The directory entry offset uses 0, 1, 2 instead of real file offset,
+  // so the value range of long type is enough.
+  d->current_pos_ = static_cast<long>(entry->d_off);
+  return entry;
+}
+
+dirent* readdir(DIR* d) {
+  return __readdir_locked(d);
+}
+__strong_alias(readdir64, readdir);
+
+int readdir_r(DIR* d, dirent* entry, dirent** result) {
+  ErrnoRestorer errno_restorer;
+
+  *result = nullptr;
+  errno = 0;
+
+  dirent* next = __readdir_locked(d);
+  if (errno != 0 && next == nullptr) {
+    return errno;
+  }
+
+  if (next != nullptr) {
+    memcpy(entry, next, next->d_reclen);
+    *result = entry;
+  }
+  return 0;
+}
+__strong_alias(readdir64_r, readdir_r);
+
+int closedir(DIR* d) {
+  if (d == nullptr) {
+    errno = EINVAL;
+    return -1;
+  }
+
+  int fd = d->fd_;
+  int rc = close(fd);
+  free(d);
+  return rc;
+}
+
+void rewinddir(DIR* d) {
+  lseek(d->fd_, 0, SEEK_SET);
+  d->available_bytes_ = 0;
+  d->current_pos_ = 0L;
+}
+
+void seekdir(DIR* d, long offset) {
+  off_t ret = lseek(d->fd_, offset, SEEK_SET);
+  if (ret != -1L) {
+    d->available_bytes_ = 0;
+    d->current_pos_ = ret;
+  }
+}
+
+long telldir(DIR* d) {
+  return d->current_pos_;
+}

native/src/crt0/syscall.c

@@ -66,6 +66,7 @@ EXPORT_SYMBOL(fchownat);
 EXPORT_SYMBOL(readv);
 EXPORT_SYMBOL(lseek);
 EXPORT_SYMBOL(execve);
+EXPORT_SYMBOL(getdents64);
 
 SYMBOL_ALIAS(exit, _exit);