Patchwork [V12,01/15] Implement qemu_read_full

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Submitter Mohan Kumar M
Date Sept. 5, 2011, 4:18 p.m.
Message ID <1315239516-4451-2-git-send-email-mohan@in.ibm.com>
Download mbox | patch
Permalink /patch/113411/
State New
Headers show

Comments

Mohan Kumar M - Sept. 5, 2011, 4:18 p.m.
Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com>
---
 osdep.c       |   32 ++++++++++++++++++++++++++++++++
 qemu-common.h |    2 ++
 2 files changed, 34 insertions(+), 0 deletions(-)
malc - Sept. 5, 2011, 5:57 p.m.
On Mon, 5 Sep 2011, M. Mohan Kumar wrote:

> Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com>
> ---
>  osdep.c       |   32 ++++++++++++++++++++++++++++++++
>  qemu-common.h |    2 ++
>  2 files changed, 34 insertions(+), 0 deletions(-)
> 
> diff --git a/osdep.c b/osdep.c
> index 56e6963..5a4d670 100644
> --- a/osdep.c
> +++ b/osdep.c
> @@ -126,6 +126,38 @@ ssize_t qemu_write_full(int fd, const void *buf, size_t count)
>  }
>  
>  /*
> + * A variant of read(2) which handles interrupted read.
> + * Simlar to qemu_write_full function
> + *
> + * Return the number of bytes read.
> + *
> + * This function does not work with non-blocking fd's.
> + * errno is set if fewer than `count' bytes are read because of any
> + * error
> + */
> +ssize_t qemu_read_full(int fd, void *buf, size_t count)
> +{
> +    ssize_t ret = 0;
> +    ssize_t total = 0;
> +
> +    while (count) {
> +        ret = read(fd, buf, count);
> +        if (ret <= 0) {
> +            if (errno == EINTR) {

ret == 0 is not an error so here the stale value of errno is checked,
iow this is wrong and recipe for an endless loop.

> +                continue;
> +            }
> +            break;
> +        }
> +
> +        count -= ret;
> +        buf += ret;
> +        total += ret;
> +    }
> +
> +    return total;
> +}
> +
> +/*
>   * Opens a socket with FD_CLOEXEC set
>   */
>  int qemu_socket(int domain, int type, int protocol)
> diff --git a/qemu-common.h b/qemu-common.h
> index 404c421..d6aabd2 100644
> --- a/qemu-common.h
> +++ b/qemu-common.h
> @@ -189,6 +189,8 @@ 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)
>      QEMU_WARN_UNUSED_RESULT;
> +ssize_t qemu_read_full(int fd, void *buf, size_t count)
> +    QEMU_WARN_UNUSED_RESULT;
>  void qemu_set_cloexec(int fd);
>  
>  #ifndef _WIN32
>

Patch

diff --git a/osdep.c b/osdep.c
index 56e6963..5a4d670 100644
--- a/osdep.c
+++ b/osdep.c
@@ -126,6 +126,38 @@  ssize_t qemu_write_full(int fd, const void *buf, size_t count)
 }
 
 /*
+ * A variant of read(2) which handles interrupted read.
+ * Simlar to qemu_write_full function
+ *
+ * Return the number of bytes read.
+ *
+ * This function does not work with non-blocking fd's.
+ * errno is set if fewer than `count' bytes are read because of any
+ * error
+ */
+ssize_t qemu_read_full(int fd, void *buf, size_t count)
+{
+    ssize_t ret = 0;
+    ssize_t total = 0;
+
+    while (count) {
+        ret = read(fd, buf, count);
+        if (ret <= 0) {
+            if (errno == EINTR) {
+                continue;
+            }
+            break;
+        }
+
+        count -= ret;
+        buf += ret;
+        total += ret;
+    }
+
+    return total;
+}
+
+/*
  * Opens a socket with FD_CLOEXEC set
  */
 int qemu_socket(int domain, int type, int protocol)
diff --git a/qemu-common.h b/qemu-common.h
index 404c421..d6aabd2 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -189,6 +189,8 @@  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)
     QEMU_WARN_UNUSED_RESULT;
+ssize_t qemu_read_full(int fd, void *buf, size_t count)
+    QEMU_WARN_UNUSED_RESULT;
 void qemu_set_cloexec(int fd);
 
 #ifndef _WIN32