[Qemu-devel] Re: [PATCH v7 3/6] char: Let writers know how much data was written in case of errors

[Anthony Liguori]

On 05/04/2010 04:39 PM, Amit Shah wrote:
On writing errors, we just returned -1 even if some bytes were already
written out. Ensure we return the number of bytes written before we
return the error (on a subsequent call to qemu_chr_write()).
Signed-off-by: Amit Shah<amit.s...@redhat.com>
---
  qemu-char.c |   12 +++++++++++-
  1 files changed, 11 insertions(+), 1 deletions(-)

diff --git a/qemu-char.c b/qemu-char.c
index 76ad12c..decf687 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -507,6 +507,9 @@ int send_all(int fd, const void *buf, int len1)
      while (len>  0) {
          ret = send(fd, buf, len, 0);
          if (ret<  0) {
+            if (len1 - len) {
+                return len1 - len;
+            }
              errno = WSAGetLastError();
              if (errno != WSAEWOULDBLOCK) {
                  return -1;
@@ -531,8 +534,15 @@ static int unix_write(int fd, const uint8_t *buf, int len1)
      while (len>  0) {
          ret = write(fd, buf, len);
          if (ret<  0) {
-            if (errno != EINTR&&  errno != EAGAIN)
+            if (errno == EINTR) {
+                continue;
+            }
+            if (len1 - len) {
+                return len1 - len;
+            }
+            if (errno != EAGAIN) {
                  return -1;
+            }
          } else if (ret == 0) {
              break;
          } else {
   

This will break lots of things.  The contract for send_all and 
unix_write is that the transmit all data.

Regards,

Anthony Liguori