LDPRELOAD: Implement readv and writev

Iteratively call vcom_read for readv and vcom_write for writev
system call.

Change-Id: I1d5795165e22c84b3303dde3273ce0cfa76abb4a
Signed-off-by: Steven <sluong@cisco.com>

3 files changed, 106 insertions, 8 deletions

diff --git a/vcl-ldpreload/src/libvcl-ldpreload/vcom.c b/vcl-ldpreload/src/libvcl-ldpreload/vcom.c
index 37cf936..564df1a 100644
--- a/vcl-ldpreload/src/libvcl-ldpreload/vcom.c
+++ b/vcl-ldpreload/src/libvcl-ldpreload/vcom.c
@@ -18,7 +18,10 @@
 #include <dlfcn.h>
 #include <pthread.h>
 #include <time.h>
-
+#include <sys/uio.h>
+#include <limits.h>
+#define __need_IOV_MAX
+#include <bits/stdio_lim.h>
 #include <stdarg.h>
 
 #include <libvcl-ldpreload/vcom_socket_wrapper.h>
@@ -28,8 +31,6 @@
 #include <uri/vppcom.h>
 #include <libvcl-ldpreload/vcom_socket.h>
 
-
-
 /* GCC have printf type attribute check. */
 #ifdef HAVE_FUNCTION_ATTRIBUTE_FORMAT
 #define PRINTF_ATTRIBUTE(a,b)                       \
@@ -62,11 +63,6 @@
 #define DO_NOT_SANITIZE_ADDRESS_ATTRIBUTE
 #endif
 
-
-
-
-
-
 #define VCOM_SOCKET_FD_MAX  0x10000
 
 static char vcom_app_name[MAX_VCOM_APP_NAME];
@@ -260,6 +256,47 @@ read (int __fd, void *__buf, size_t __nbytes)
   return libc_read (__fd, __buf, __nbytes);
 }
 
+ssize_t
+readv (int __fd, const struct iovec * __iov, int __iovcnt)
+{
+  size_t len = 0;
+  ssize_t total = 0;
+
+  if (is_vcom_socket_fd (__fd))
+    {
+      if (__iov == 0 || __iovcnt == 0 || __iovcnt > IOV_MAX)
+	return -EINVAL;
+
+      /* Sanity check */
+      for (int i = 0; i < __iovcnt; ++i)
+	{
+	  if (SSIZE_MAX - len < __iov[i].iov_len)
+	    return -EINVAL;
+	  len += __iov[i].iov_len;
+	}
+
+      for (int i = 0; i < __iovcnt; ++i)
+	{
+	  len = vcom_read (__fd, __iov[i].iov_base, __iov[i].iov_len);
+	  if (len < 0)
+	    {
+	      if (total > 0)
+		return total;
+	      else
+		{
+		  errno = len;;
+		  return -1;
+		}
+	    }
+	  else
+	    total += len;
+	}
+      return (total);
+    }
+  else
+    return libc_readv (__fd, __iov, __iovcnt);
+}
+
 /* Write N bytes of BUF to FD.  Return the number written, or -1.
 
    This function is a cancellation point and therefore
@@ -307,6 +344,47 @@ write (int __fd, const void *__buf, size_t __n)
   return libc_write (__fd, __buf, __n);
 }
 
+ssize_t
+writev (int __fd, const struct iovec * __iov, int __iovcnt)
+{
+  size_t len = 0;
+  ssize_t total = 0;
+
+  if (is_vcom_socket_fd (__fd))
+    {
+      if (__iov == 0 || __iovcnt == 0 || __iovcnt > IOV_MAX)
+	return -EINVAL;
+
+      /* Sanity check */
+      for (int i = 0; i < __iovcnt; ++i)
+	{
+	  if (SSIZE_MAX - len < __iov[i].iov_len)
+	    return -EINVAL;
+	  len += __iov[i].iov_len;
+	}
+
+      for (int i = 0; i < __iovcnt; ++i)
+	{
+	  len = vcom_write (__fd, __iov[i].iov_base, __iov[i].iov_len);
+	  if (len < 0)
+	    {
+	      if (total > 0)
+		return total;
+	      else
+		{
+		  errno = len;;
+		  return -1;
+		}
+	    }
+	  else
+	    total += len;
+	}
+      return (total);
+    }
+  else
+    return libc_writev (__fd, __iov, __iovcnt);
+}
+
 /* Do the file control operation described by CMD on FD.
    The remaining arguments are interpreted depending on CMD.
 
diff --git a/vcl-ldpreload/src/libvcl-ldpreload/vcom_socket_wrapper.c b/vcl-ldpreload/src/libvcl-ldpreload/vcom_socket_wrapper.c
index 8fe7e1d..c8b7ee6 100644
--- a/vcl-ldpreload/src/libvcl-ldpreload/vcom_socket_wrapper.c
+++ b/vcl-ldpreload/src/libvcl-ldpreload/vcom_socket_wrapper.c
@@ -578,6 +578,14 @@ libc_read (int fd, void *buf, size_t count)
   return swrap.libc.symbols._libc_read.f (fd, buf, count);
 }
 
+ssize_t
+libc_readv (int fd, const struct iovec *iov, int iovcnt)
+{
+  swrap_bind_symbol_libc (readv);
+
+  return swrap.libc.symbols._libc_readv.f (fd, iov, iovcnt);
+}
+
 int
 libc_recv (int sockfd, void *buf, size_t len, int flags)
 {
@@ -671,6 +679,14 @@ libc_write (int fd, const void *buf, size_t count)
   return swrap.libc.symbols._libc_write.f (fd, buf, count);
 }
 
+ssize_t
+libc_writev (int fd, const struct iovec *iov, int iovcnt)
+{
+  swrap_bind_symbol_libc (writev);
+
+  return swrap.libc.symbols._libc_writev.f (fd, iov, iovcnt);
+}
+
 int
 libc_shutdown (int fd, int how)
 {
diff --git a/vcl-ldpreload/src/libvcl-ldpreload/vcom_socket_wrapper.h b/vcl-ldpreload/src/libvcl-ldpreload/vcom_socket_wrapper.h
index e3590d6..25aa609 100644
--- a/vcl-ldpreload/src/libvcl-ldpreload/vcom_socket_wrapper.h
+++ b/vcl-ldpreload/src/libvcl-ldpreload/vcom_socket_wrapper.h
@@ -142,6 +142,8 @@ int libc_listen (int sockfd, int backlog);
 
 int libc_read (int fd, void *buf, size_t count);
 
+ssize_t libc_readv (int fd, const struct iovec *iov, int iovcnt);
+
 int libc_recv (int sockfd, void *buf, size_t len, int flags);
 
 int
@@ -173,6 +175,8 @@ int libc_socketpair (int domain, int type, int protocol, int sv[2]);
 
 ssize_t libc_write (int fd, const void *buf, size_t count);
 
+ssize_t libc_writev (int fd, const struct iovec *iov, int iovcnt);
+
 int libc_shutdown (int fd, int how);
 
 int