diff --git a/.clang-format b/.clang-format
new file mode 100644
index 0000000..2b83a1f
--- /dev/null
+++ b/.clang-format
@@ -0,0 +1,11 @@
+BasedOnStyle: Google
+AllowShortBlocksOnASingleLine: false
+AllowShortFunctionsOnASingleLine: false
+
+CommentPragmas: NOLINT:.*
+DerivePointerAlignment: false
+IndentWidth: 2
+PointerAlignment: Left
+TabWidth: 2
+UseTab: Never
+PenaltyExcessCharacter: 32
diff --git a/libc/Android.mk b/libc/Android.mk
index 74ac33b..ca20d3d 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -79,6 +79,8 @@
     bionic/__poll_chk.cpp \
     bionic/__pread64_chk.cpp \
     bionic/__pread_chk.cpp \
+    bionic/__pwrite64_chk.cpp \
+    bionic/__pwrite_chk.cpp \
     bionic/__read_chk.cpp \
     bionic/__readlink_chk.cpp \
     bionic/__readlinkat_chk.cpp \
@@ -95,6 +97,7 @@
     bionic/__umask_chk.cpp \
     bionic/__vsnprintf_chk.cpp \
     bionic/__vsprintf_chk.cpp \
+    bionic/__write_chk.cpp
 
 libc_bionic_ndk_src_files := \
     bionic/abort.cpp \
diff --git a/libc/bionic/__pwrite64_chk.cpp b/libc/bionic/__pwrite64_chk.cpp
new file mode 100644
index 0000000..e488ca1
--- /dev/null
+++ b/libc/bionic/__pwrite64_chk.cpp
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+#undef _FORTIFY_SOURCE
+#include <unistd.h>
+#include "private/libc_logging.h"
+
+extern "C" ssize_t __pwrite64_chk(int fd, const void* buf, size_t count, off64_t offset,
+                                  size_t buf_size) {
+  if (__predict_false(count > buf_size)) {
+    __fortify_chk_fail("pwrite64: prevented read past end of buffer", 0);
+  }
+
+  if (__predict_false(count > SSIZE_MAX)) {
+    __fortify_chk_fail("pwrite64: count > SSIZE_MAX", 0);
+  }
+
+  return pwrite64(fd, buf, count, offset);
+}
diff --git a/libc/bionic/__pwrite_chk.cpp b/libc/bionic/__pwrite_chk.cpp
new file mode 100644
index 0000000..a889ef6
--- /dev/null
+++ b/libc/bionic/__pwrite_chk.cpp
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+#undef _FORTIFY_SOURCE
+#include <unistd.h>
+#include "private/libc_logging.h"
+
+extern "C" ssize_t __pwrite_chk(int fd, const void* buf, size_t count, off_t offset,
+                                size_t buf_size) {
+  if (__predict_false(count > buf_size)) {
+    __fortify_chk_fail("pwrite: prevented read past end of buffer", 0);
+  }
+
+  if (__predict_false(count > SSIZE_MAX)) {
+    __fortify_chk_fail("pwrite: count > SSIZE_MAX", 0);
+  }
+
+  return pwrite(fd, buf, count, offset);
+}
diff --git a/libc/bionic/__write_chk.cpp b/libc/bionic/__write_chk.cpp
new file mode 100644
index 0000000..cbd247a
--- /dev/null
+++ b/libc/bionic/__write_chk.cpp
@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+#undef _FORTIFY_SOURCE
+#include <unistd.h>
+#include "private/libc_logging.h"
+
+extern "C" ssize_t __write_chk(int fd, const void* buf, size_t count, size_t buf_size) {
+  if (__predict_false(count > buf_size)) {
+    __fortify_chk_fail("write: prevented read past end of buffer", 0);
+  }
+
+  if (__predict_false(count > SSIZE_MAX)) {
+    __fortify_chk_fail("write: count > SSIZE_MAX", 0);
+  }
+
+  return write(fd, buf, count);
+}
diff --git a/libc/include/unistd.h b/libc/include/unistd.h
index 904447c..91ae89e 100644
--- a/libc/include/unistd.h
+++ b/libc/include/unistd.h
@@ -238,11 +238,26 @@
 __errordecl(__pread64_count_toobig_error, "pread64 called with count > SSIZE_MAX");
 extern ssize_t __pread64_real(int, void*, size_t, off64_t) __RENAME(pread64);
 
+extern ssize_t __pwrite_chk(int, const void*, size_t, off_t, size_t);
+__errordecl(__pwrite_dest_size_error, "pwrite called with size bigger than destination");
+__errordecl(__pwrite_count_toobig_error, "pwrite called with count > SSIZE_MAX");
+extern ssize_t __pwrite_real(int, const void*, size_t, off_t) __RENAME(pwrite);
+
+extern ssize_t __pwrite64_chk(int, const void*, size_t, off64_t, size_t);
+__errordecl(__pwrite64_dest_size_error, "pwrite64 called with size bigger than destination");
+__errordecl(__pwrite64_count_toobig_error, "pwrite64 called with count > SSIZE_MAX");
+extern ssize_t __pwrite64_real(int, const void*, size_t, off64_t) __RENAME(pwrite64);
+
 extern ssize_t __read_chk(int, void*, size_t, size_t);
 __errordecl(__read_dest_size_error, "read called with size bigger than destination");
 __errordecl(__read_count_toobig_error, "read called with count > SSIZE_MAX");
 extern ssize_t __read_real(int, void*, size_t) __RENAME(read);
 
+extern ssize_t __write_chk(int, const void*, size_t, size_t);
+__errordecl(__write_dest_size_error, "write called with size bigger than destination");
+__errordecl(__write_count_toobig_error, "write called with count > SSIZE_MAX");
+extern ssize_t __write_real(int, const void*, size_t) __RENAME(write);
+
 extern ssize_t __readlink_chk(const char*, char*, size_t, size_t);
 __errordecl(__readlink_dest_size_error, "readlink called with size bigger than destination");
 __errordecl(__readlink_size_toobig_error, "readlink called with size > SSIZE_MAX");
@@ -342,6 +357,62 @@
     return __pread64_chk(fd, buf, count, offset, bos);
 }
 
+#if defined(__USE_FILE_OFFSET64)
+#define __PWRITE_PREFIX(x) __pwrite64_ ## x
+#else
+#define __PWRITE_PREFIX(x) __pwrite_ ## x
+#endif
+
+__BIONIC_FORTIFY_INLINE
+ssize_t pwrite(int fd, const void* buf, size_t count, off_t offset) {
+    size_t bos = __bos0(buf);
+
+#if !defined(__clang__)
+    if (__builtin_constant_p(count) && (count > SSIZE_MAX)) {
+        __PWRITE_PREFIX(count_toobig_error)();
+    }
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __PWRITE_PREFIX(real)(fd, buf, count, offset);
+    }
+
+    if (__builtin_constant_p(count) && (count > bos)) {
+        __PWRITE_PREFIX(dest_size_error)();
+    }
+
+    if (__builtin_constant_p(count) && (count <= bos)) {
+        return __PWRITE_PREFIX(real)(fd, buf, count, offset);
+    }
+#endif
+
+    return __PWRITE_PREFIX(chk)(fd, buf, count, offset, bos);
+}
+
+__BIONIC_FORTIFY_INLINE
+ssize_t pwrite64(int fd, const void* buf, size_t count, off64_t offset) {
+    size_t bos = __bos0(buf);
+
+#if !defined(__clang__)
+    if (__builtin_constant_p(count) && (count > SSIZE_MAX)) {
+        __pwrite64_count_toobig_error();
+    }
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __pwrite64_real(fd, buf, count, offset);
+    }
+
+    if (__builtin_constant_p(count) && (count > bos)) {
+        __pwrite64_dest_size_error();
+    }
+
+    if (__builtin_constant_p(count) && (count <= bos)) {
+        return __pwrite64_real(fd, buf, count, offset);
+    }
+#endif
+
+    return __pwrite64_chk(fd, buf, count, offset, bos);
+}
+
 __BIONIC_FORTIFY_INLINE
 ssize_t read(int fd, void* buf, size_t count) {
     size_t bos = __bos0(buf);
@@ -368,6 +439,33 @@
 }
 
 __BIONIC_FORTIFY_INLINE
+ssize_t write(int fd, const void* buf, size_t count) {
+    size_t bos = __bos0(buf);
+
+#if !defined(__clang__)
+#if 0 /* work around a false positive due to a missed optimization */
+    if (__builtin_constant_p(count) && (count > SSIZE_MAX)) {
+        __write_count_toobig_error();
+    }
+#endif
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __write_real(fd, buf, count);
+    }
+
+    if (__builtin_constant_p(count) && (count > bos)) {
+        __write_dest_size_error();
+    }
+
+    if (__builtin_constant_p(count) && (count <= bos)) {
+        return __write_real(fd, buf, count);
+    }
+#endif
+
+    return __write_chk(fd, buf, count, bos);
+}
+
+__BIONIC_FORTIFY_INLINE
 ssize_t readlink(const char* path, char* buf, size_t size) {
     size_t bos = __bos(buf);
 
diff --git a/libc/libc.map b/libc/libc.map
index 6117d53..4670079 100644
--- a/libc/libc.map
+++ b/libc/libc.map
@@ -1337,6 +1337,9 @@
     __fread_chk;
     __fwrite_chk;
     __getcwd_chk;
+    __pwrite_chk;
+    __pwrite64_chk;
+    __write_chk;
     getgrgid_r;
     getgrnam_r;
 } LIBC;
diff --git a/linker/linker_phdr.cpp b/linker/linker_phdr.cpp
index cf012f4..30bc6fa 100644
--- a/linker/linker_phdr.cpp
+++ b/linker/linker_phdr.cpp
@@ -382,7 +382,7 @@
       return false;
     }
 
-    if (file_end >= static_cast<size_t>(file_size_)) {
+    if (file_end > static_cast<size_t>(file_size_)) {
       DL_ERR("invalid ELF file \"%s\" load segment[%zd]:"
           " p_offset (%p) + p_filesz (%p) ( = %p) past end of file (0x%" PRIx64 ")",
           name_, i, reinterpret_cast<void*>(phdr->p_offset),
diff --git a/tests/fortify_compilation_test.cpp b/tests/fortify_compilation_test.cpp
index 072006e..1326597 100644
--- a/tests/fortify_compilation_test.cpp
+++ b/tests/fortify_compilation_test.cpp
@@ -21,6 +21,7 @@
 #include <poll.h>
 #include <stdarg.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <sys/socket.h>
 #include <sys/stat.h>
@@ -248,7 +249,7 @@
 }
 
 void test_fwrite_overflow() {
-  char buf[4];
+  char buf[4] = {0};
   // NOLINTNEXTLINE(whitespace/line_length)
   // GCC: error: call to '__fwrite_overflow' declared with attribute error: fwrite called with overflowing size * count
   // clang should emit a warning, but doesn't
@@ -270,3 +271,27 @@
   // clang should emit a warning, but doesn't
   getcwd(buf, 5);
 }
+
+void test_pwrite64_size() {
+  char buf[4] = {0};
+  // NOLINTNEXTLINE(whitespace/line_length)
+  // GCC: error: call to '__pwrite64_dest_size_error' declared with attribute error: pwrite64 called with size bigger than destination
+  // clang should emit a warning, but doesn't
+  pwrite64(STDOUT_FILENO, buf, 5, 0);
+}
+
+void test_pwrite64_too_big() {
+  void *buf = calloc(atoi("5"), 1);
+  // NOLINTNEXTLINE(whitespace/line_length)
+  // GCC: error: call to '__pwrite64_count_toobig_error' declared with attribute error: pwrite64 called with count > SSIZE_MAX
+  // clang should emit a warning, but doesn't
+  pwrite64(STDOUT_FILENO, buf, SIZE_MAX, 0);
+}
+
+void test_write_size() {
+  char buf[4] = {0};
+  // NOLINTNEXTLINE(whitespace/line_length)
+  // GCC: error: call to '__write_dest_size_error' declared with attribute error: write called with size bigger than destination
+  // clang should emit a warning, but doesn't
+  write(STDOUT_FILENO, buf, 5);
+}
diff --git a/tests/fortify_test.cpp b/tests/fortify_test.cpp
index 8f66cc8..a349da9 100644
--- a/tests/fortify_test.cpp
+++ b/tests/fortify_test.cpp
@@ -645,6 +645,22 @@
   close(fd);
 }
 
+TEST_F(DEATHTEST, pwrite_fortified) {
+  char buf[1] = {0};
+  size_t ct = atoi("2"); // prevent optimizations
+  int fd = open("/dev/null", O_WRONLY);
+  ASSERT_FORTIFY(pwrite(fd, buf, ct, 0));
+  close(fd);
+}
+
+TEST_F(DEATHTEST, pwrite64_fortified) {
+  char buf[1] = {0};
+  size_t ct = atoi("2"); // prevent optimizations
+  int fd = open("/dev/null", O_WRONLY);
+  ASSERT_FORTIFY(pwrite64(fd, buf, ct, 0));
+  close(fd);
+}
+
 TEST_F(DEATHTEST, read_fortified) {
   char buf[1];
   size_t ct = atoi("2"); // prevent optimizations
@@ -653,6 +669,14 @@
   close(fd);
 }
 
+TEST_F(DEATHTEST, write_fortified) {
+  char buf[1] = {0};
+  size_t ct = atoi("2"); // prevent optimizations
+  int fd = open("/dev/null", O_WRONLY);
+  ASSERT_EXIT(write(fd, buf, ct), testing::KilledBySignal(SIGABRT), "");
+  close(fd);
+}
+
 TEST_F(DEATHTEST, fread_fortified) {
   char buf[1];
   size_t ct = atoi("2"); // prevent optimizations