From patchwork Thu Dec 31 01:33:11 2009
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Subject: [01/14] Introduce qemu_write_full()
From: "Kirill A. Shutemov" <kirill@shutemov.name>
X-Patchwork-Id: 41946
Message-Id: <1262223199-19062-1-git-send-email-kirill@shutemov.name>
To: qemu-devel@nongnu.org
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Date: Thu, 31 Dec 2009 03:33:11 +0200

A variant of write(2) which handles partial write.

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
---
 osdep.c       |   27 +++++++++++++++++++++++++++
 qemu-common.h |    1 +
 2 files changed, 28 insertions(+), 0 deletions(-)

diff --git a/osdep.c b/osdep.c
index e4836e7..d2406f2 100644
--- a/osdep.c
+++ b/osdep.c
@@ -243,6 +243,33 @@ int qemu_open(const char *name, int flags, ...)
     return ret;
 }
 
+/*
+ * A variant of write(2) which handles partial write.
+ *
+ * Return the number of bytes transferred.
+ * Set errno if fewer than `count' bytes are written.
+ */
+ssize_t qemu_write_full(int fd, const void *buf, size_t count)
+{
+    ssize_t ret = 0;
+    ssize_t total = 0;
+
+    while (count) {
+        ret = write(fd, buf, count);
+        if (ret < 0) {
+            if (errno == EINTR)
+                continue;
+            break;
+        }
+
+        count -= ret;
+        buf += ret;
+	total += ret;
+    }
+
+    return total;
+}
+
 #ifndef _WIN32
 /*
  * Creates a pipe with FD_CLOEXEC set on both file descriptors
diff --git a/qemu-common.h b/qemu-common.h
index 8630f8c..a8144cb 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -160,6 +160,7 @@ void qemu_mutex_lock_iothread(void);
 void qemu_mutex_unlock_iothread(void);
 
 int qemu_open(const char *name, int flags, ...);
+ssize_t qemu_write_full(int fd, const void *buf, size_t count);
 void qemu_set_cloexec(int fd);
 
 #ifndef _WIN32