add pwritevNoInt and preadvNoInt to FileUtil

Summary: Adds `pwritevNoInt()` and `preadvNoInt()` to FileUtil.

Reviewed By: yfeldblum

Differential Revision: D18213230

fbshipit-source-id: 0dfcd19ecf4500aa2bba279800d65821309371c6

folly/FileUtil.cpp

@@ -111,6 +111,10 @@ ssize_t readvNoInt(int fd, const iovec* iov, int count) {
   return wrapNoInt(readv, fd, iov, count);
 }
 
+ssize_t preadvNoInt(int fd, const iovec* iov, int count, off_t offset) {
+  return wrapNoInt(preadv, fd, iov, count, offset);
+}
+
 ssize_t writeNoInt(int fd, const void* buf, size_t count) {
   return wrapNoInt(write, fd, buf, count);
 }
@@ -123,6 +127,10 @@ ssize_t writevNoInt(int fd, const iovec* iov, int count) {
   return wrapNoInt(writev, fd, iov, count);
 }
 
+ssize_t pwritevNoInt(int fd, const iovec* iov, int count, off_t offset) {
+  return wrapNoInt(pwritev, fd, iov, count, offset);
+}
+
 ssize_t readFull(int fd, void* buf, size_t count) {
   return wrapFull(read, fd, buf, count);
 }

folly/FileUtil.h

@@ -54,10 +54,12 @@ int shutdownNoInt(NetworkSocket fd, int how);
 ssize_t readNoInt(int fd, void* buf, size_t n);
 ssize_t preadNoInt(int fd, void* buf, size_t n, off_t offset);
 ssize_t readvNoInt(int fd, const iovec* iov, int count);
+ssize_t preadvNoInt(int fd, const iovec* iov, int count, off_t offset);
 
 ssize_t writeNoInt(int fd, const void* buf, size_t n);
 ssize_t pwriteNoInt(int fd, const void* buf, size_t n, off_t offset);
 ssize_t writevNoInt(int fd, const iovec* iov, int count);
+ssize_t pwritevNoInt(int fd, const iovec* iov, int count, off_t offset);
 
 /**
  * Wrapper around read() (and pread()) that, in addition to retrying on