diff mbox series

[v5,06/14] migration/qemu-file: Add qemu_file_get_to_fd()

Message ID 20221229110345.12480-7-avihaih@nvidia.com
State New
Headers show
Series vfio/migration: Implement VFIO migration protocol v2 | expand

Commit Message

Avihai Horon Dec. 29, 2022, 11:03 a.m. UTC 
Add new function qemu_file_get_to_fd() that allows reading data from
QEMUFile and writing it straight into a given fd.

This will be used later in VFIO migration code.

Signed-off-by: Avihai Horon <avihaih@nvidia.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
---
 migration/qemu-file.h |  1 +
 migration/qemu-file.c | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

Comments

Cédric Le Goater Jan. 9, 2023, 11:20 a.m. UTC | #1 
On 12/29/22 12:03, Avihai Horon wrote:
> Add new function qemu_file_get_to_fd() that allows reading data from
> QEMUFile and writing it straight into a given fd.
> 
> This will be used later in VFIO migration code.
> 
> Signed-off-by: Avihai Horon <avihaih@nvidia.com>
> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
> ---
>   migration/qemu-file.h |  1 +
>   migration/qemu-file.c | 34 ++++++++++++++++++++++++++++++++++
>   2 files changed, 35 insertions(+)
> 
> diff --git a/migration/qemu-file.h b/migration/qemu-file.h
> index fa13d04d78..9d0155a2a1 100644
> --- a/migration/qemu-file.h
> +++ b/migration/qemu-file.h
> @@ -148,6 +148,7 @@ int qemu_file_shutdown(QEMUFile *f);
>   QEMUFile *qemu_file_get_return_path(QEMUFile *f);
>   void qemu_fflush(QEMUFile *f);
>   void qemu_file_set_blocking(QEMUFile *f, bool block);
> +int qemu_file_get_to_fd(QEMUFile *f, int fd, size_t size);
>   
>   void ram_control_before_iterate(QEMUFile *f, uint64_t flags);
>   void ram_control_after_iterate(QEMUFile *f, uint64_t flags);
> diff --git a/migration/qemu-file.c b/migration/qemu-file.c
> index 2d5f74ffc2..79303c9d34 100644
> --- a/migration/qemu-file.c
> +++ b/migration/qemu-file.c
> @@ -940,3 +940,37 @@ QIOChannel *qemu_file_get_ioc(QEMUFile *file)
>   {
>       return file->ioc;
>   }
> +
> +/*
> + * Read size bytes from QEMUFile f and write them to fd.
> + */
> +int qemu_file_get_to_fd(QEMUFile *f, int fd, size_t size)
> +{
> +    while (size) {
> +        size_t pending = f->buf_size - f->buf_index;
> +        ssize_t rc;
> +
> +        if (!pending) {
> +            rc = qemu_fill_buffer(f);
> +            if (rc < 0) {
> +                return rc;
> +            }
> +            if (rc == 0) {
> +                return -1;

Given the call stack, -1 would be interpreted  as EPERM. May be EIO instead ?

C.

> +            }
> +            continue;
> +        }
> +
> +        rc = write(fd, f->buf + f->buf_index, MIN(pending, size));
> +        if (rc < 0) {
> +            return rc;
> +        }
> +        if (rc == 0) {
> +            return -1;
> +        }
> +        f->buf_index += rc;
> +        size -= rc;
> +    }
> +
> +    return 0;
> +}
Avihai Horon Jan. 9, 2023, 3:18 p.m. UTC | #2 
On 09/01/2023 13:20, Cédric Le Goater wrote:
> External email: Use caution opening links or attachments
>
>
> On 12/29/22 12:03, Avihai Horon wrote:
>> Add new function qemu_file_get_to_fd() that allows reading data from
>> QEMUFile and writing it straight into a given fd.
>>
>> This will be used later in VFIO migration code.
>>
>> Signed-off-by: Avihai Horon <avihaih@nvidia.com>
>> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
>> ---
>>   migration/qemu-file.h |  1 +
>>   migration/qemu-file.c | 34 ++++++++++++++++++++++++++++++++++
>>   2 files changed, 35 insertions(+)
>>
>> diff --git a/migration/qemu-file.h b/migration/qemu-file.h
>> index fa13d04d78..9d0155a2a1 100644
>> --- a/migration/qemu-file.h
>> +++ b/migration/qemu-file.h
>> @@ -148,6 +148,7 @@ int qemu_file_shutdown(QEMUFile *f);
>>   QEMUFile *qemu_file_get_return_path(QEMUFile *f);
>>   void qemu_fflush(QEMUFile *f);
>>   void qemu_file_set_blocking(QEMUFile *f, bool block);
>> +int qemu_file_get_to_fd(QEMUFile *f, int fd, size_t size);
>>
>>   void ram_control_before_iterate(QEMUFile *f, uint64_t flags);
>>   void ram_control_after_iterate(QEMUFile *f, uint64_t flags);
>> diff --git a/migration/qemu-file.c b/migration/qemu-file.c
>> index 2d5f74ffc2..79303c9d34 100644
>> --- a/migration/qemu-file.c
>> +++ b/migration/qemu-file.c
>> @@ -940,3 +940,37 @@ QIOChannel *qemu_file_get_ioc(QEMUFile *file)
>>   {
>>       return file->ioc;
>>   }
>> +
>> +/*
>> + * Read size bytes from QEMUFile f and write them to fd.
>> + */
>> +int qemu_file_get_to_fd(QEMUFile *f, int fd, size_t size)
>> +{
>> +    while (size) {
>> +        size_t pending = f->buf_size - f->buf_index;
>> +        ssize_t rc;
>> +
>> +        if (!pending) {
>> +            rc = qemu_fill_buffer(f);
>> +            if (rc < 0) {
>> +                return rc;
>> +            }
>> +            if (rc == 0) {
>> +                return -1;
>
> Given the call stack, -1 would be interpreted  as EPERM. May be EIO 
> instead ?
>
Sure.

I will also change write (down below) to return -errno instead of rc on 
error.

> C.
>
>> +            }
>> +            continue;
>> +        }
>> +
>> +        rc = write(fd, f->buf + f->buf_index, MIN(pending, size));
>> +        if (rc < 0) {
>> +            return rc;
>> +        }
>> +        if (rc == 0) {
>> +            return -1;
>> +        }
>> +        f->buf_index += rc;
>> +        size -= rc;
>> +    }
>> +
>> +    return 0;
>> +}
>
diff mbox series

Patch

diff --git a/migration/qemu-file.h b/migration/qemu-file.h
index fa13d04d78..9d0155a2a1 100644
--- a/migration/qemu-file.h
+++ b/migration/qemu-file.h
@@ -148,6 +148,7 @@  int qemu_file_shutdown(QEMUFile *f);
 QEMUFile *qemu_file_get_return_path(QEMUFile *f);
 void qemu_fflush(QEMUFile *f);
 void qemu_file_set_blocking(QEMUFile *f, bool block);
+int qemu_file_get_to_fd(QEMUFile *f, int fd, size_t size);
 
 void ram_control_before_iterate(QEMUFile *f, uint64_t flags);
 void ram_control_after_iterate(QEMUFile *f, uint64_t flags);
diff --git a/migration/qemu-file.c b/migration/qemu-file.c
index 2d5f74ffc2..79303c9d34 100644
--- a/migration/qemu-file.c
+++ b/migration/qemu-file.c
@@ -940,3 +940,37 @@  QIOChannel *qemu_file_get_ioc(QEMUFile *file)
 {
     return file->ioc;
 }
+
+/*
+ * Read size bytes from QEMUFile f and write them to fd.
+ */
+int qemu_file_get_to_fd(QEMUFile *f, int fd, size_t size)
+{
+    while (size) {
+        size_t pending = f->buf_size - f->buf_index;
+        ssize_t rc;
+
+        if (!pending) {
+            rc = qemu_fill_buffer(f);
+            if (rc < 0) {
+                return rc;
+            }
+            if (rc == 0) {
+                return -1;
+            }
+            continue;
+        }
+
+        rc = write(fd, f->buf + f->buf_index, MIN(pending, size));
+        if (rc < 0) {
+            return rc;
+        }
+        if (rc == 0) {
+            return -1;
+        }
+        f->buf_index += rc;
+        size -= rc;
+    }
+
+    return 0;
+}