diff mbox series

[v18,08/20] io: add qio_channel_readv_full_all_eof & qio_channel_readv_full_all helpers

Message ID 68865004c4ecce557214bac5b3c527cfe3681b77.1610570756.git.jag.raman@oracle.com (mailing list archive)
State New, archived
Headers show
Series Initial support for multi-process Qemu | expand

Commit Message

Jag Raman Jan. 13, 2021, 8:53 p.m. UTC
From: Elena Ufimtseva <elena.ufimtseva@oracle.com>

Adds qio_channel_readv_full_all_eof() and qio_channel_readv_full_all()
to read both data and FDs. Refactors existing code to use these helpers.

Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
---
 include/io/channel.h | 51 +++++++++++++++++++++++++++++++++
 io/channel.c         | 80 +++++++++++++++++++++++++++++++++++++++++++---------
 2 files changed, 117 insertions(+), 14 deletions(-)

Comments

Stefan Hajnoczi Jan. 14, 2021, 1:49 p.m. UTC | #1
On Wed, Jan 13, 2021 at 03:53:27PM -0500, Jagannathan Raman wrote:
>      while (nlocal_iov > 0) {
>          ssize_t len;
> -        len = qio_channel_readv(ioc, local_iov, nlocal_iov, errp);
> +        len = qio_channel_readv_full(ioc, local_iov, nlocal_iov, local_fds,
> +                                     local_nfds, errp);
>          if (len == QIO_CHANNEL_ERR_BLOCK) {
>              if (qemu_in_coroutine()) {
>                  qio_channel_yield(ioc, G_IO_IN);
> @@ -112,20 +140,41 @@ int qio_channel_readv_all_eof(QIOChannel *ioc,
>                  qio_channel_wait(ioc, G_IO_IN);
>              }
>              continue;
> -        } else if (len < 0) {
> -            goto cleanup;
> -        } else if (len == 0) {
> -            if (partial) {
> +        }
> +
> +        if (len <= 0) {
> +            if ((len == 0) && partial) {
> +                size_t fd_idx = 0;
> +
>                  error_setg(errp,
>                             "Unexpected end-of-file before all bytes were read");
> -            } else {
> +
> +                if (nfds) {
> +                    fd_idx = *nfds;
> +                    *nfds = 0;
> +                }
> +
> +                while (fds && fd_idx) {
> +                    close((*fds)[fd_idx - 1]);
> +                    fd_idx--;
> +                }
> +
> +                if (fds) {
> +                    g_free(*fds);
> +                    *fds = NULL;
> +                }
> +            } else if (len == 0) {
>                  ret = 0;
>              }

The len < 0 case is missing. This function will return -1 and errp has
been set by qio_channel_readv_full(). However, we may have received fds
in a previous loop iteration (partial == true), so it is necessary to
close, free, and reset fds/nfds before returning.
Jag Raman Jan. 14, 2021, 3:41 p.m. UTC | #2
> On Jan 14, 2021, at 8:49 AM, Stefan Hajnoczi <stefanha@redhat.com> wrote:
> 
> On Wed, Jan 13, 2021 at 03:53:27PM -0500, Jagannathan Raman wrote:
>>     while (nlocal_iov > 0) {
>>         ssize_t len;
>> -        len = qio_channel_readv(ioc, local_iov, nlocal_iov, errp);
>> +        len = qio_channel_readv_full(ioc, local_iov, nlocal_iov, local_fds,
>> +                                     local_nfds, errp);
>>         if (len == QIO_CHANNEL_ERR_BLOCK) {
>>             if (qemu_in_coroutine()) {
>>                 qio_channel_yield(ioc, G_IO_IN);
>> @@ -112,20 +140,41 @@ int qio_channel_readv_all_eof(QIOChannel *ioc,
>>                 qio_channel_wait(ioc, G_IO_IN);
>>             }
>>             continue;
>> -        } else if (len < 0) {
>> -            goto cleanup;
>> -        } else if (len == 0) {
>> -            if (partial) {
>> +        }
>> +
>> +        if (len <= 0) {
>> +            if ((len == 0) && partial) {
>> +                size_t fd_idx = 0;
>> +
>>                 error_setg(errp,
>>                            "Unexpected end-of-file before all bytes were read");
>> -            } else {
>> +
>> +                if (nfds) {
>> +                    fd_idx = *nfds;
>> +                    *nfds = 0;
>> +                }
>> +
>> +                while (fds && fd_idx) {
>> +                    close((*fds)[fd_idx - 1]);
>> +                    fd_idx--;
>> +                }
>> +
>> +                if (fds) {
>> +                    g_free(*fds);
>> +                    *fds = NULL;
>> +                }
>> +            } else if (len == 0) {
>>                 ret = 0;
>>             }
> 
> The len < 0 case is missing. This function will return -1 and errp has
> been set by qio_channel_readv_full(). However, we may have received fds
> in a previous loop iteration (partial == true), so it is necessary to
> close, free, and reset fds/nfds before returning.

Thanks for the feedback, Stefan! We have addressed this and sent the next version out for review.
diff mbox series

Patch

diff --git a/include/io/channel.h b/include/io/channel.h
index 19e76fc..f725665 100644
--- a/include/io/channel.h
+++ b/include/io/channel.h
@@ -778,6 +778,57 @@  void qio_channel_set_aio_fd_handler(QIOChannel *ioc,
                                     void *opaque);
 
 /**
+ * qio_channel_readv_full_all_eof:
+ * @ioc: the channel object
+ * @iov: the array of memory regions to read data to
+ * @niov: the length of the @iov array
+ * @fds: an array of file handles to read
+ * @nfds: number of file handles in @fds
+ * @errp: pointer to a NULL-initialized error object
+ *
+ *
+ * Performs same function as qio_channel_readv_all_eof.
+ * Additionally, attempts to read file descriptors shared
+ * over the channel. The function will wait for all
+ * requested data to be read, yielding from the current
+ * coroutine if required.
+ *
+ * Returns: 1 if all bytes were read, 0 if end-of-file
+ *          occurs without data, or -1 on error
+ */
+
+int qio_channel_readv_full_all_eof(QIOChannel *ioc,
+                                   const struct iovec *iov,
+                                   size_t niov,
+                                   int **fds, size_t *nfds,
+                                   Error **errp);
+
+/**
+ * qio_channel_readv_full_all:
+ * @ioc: the channel object
+ * @iov: the array of memory regions to read data to
+ * @niov: the length of the @iov array
+ * @fds: an array of file handles to read
+ * @nfds: number of file handles in @fds
+ * @errp: pointer to a NULL-initialized error object
+ *
+ *
+ * Performs same function as qio_channel_readv_all_eof.
+ * Additionally, attempts to read file descriptors shared
+ * over the channel. The function will wait for all
+ * requested data to be read, yielding from the current
+ * coroutine if required.
+ *
+ * Returns: 0 if all bytes were read, or -1 on error
+ */
+
+int qio_channel_readv_full_all(QIOChannel *ioc,
+                               const struct iovec *iov,
+                               size_t niov,
+                               int **fds, size_t *nfds,
+                               Error **errp);
+
+/**
  * qio_channel_writev_full_all:
  * @ioc: the channel object
  * @iov: the array of memory regions to write data from
diff --git a/io/channel.c b/io/channel.c
index 0d4b8b5..a7c19ad 100644
--- a/io/channel.c
+++ b/io/channel.c
@@ -92,19 +92,47 @@  int qio_channel_readv_all_eof(QIOChannel *ioc,
                               size_t niov,
                               Error **errp)
 {
+    return qio_channel_readv_full_all_eof(ioc, iov, niov, NULL, NULL, errp);
+}
+
+int qio_channel_readv_all(QIOChannel *ioc,
+                          const struct iovec *iov,
+                          size_t niov,
+                          Error **errp)
+{
+    return qio_channel_readv_full_all(ioc, iov, niov, NULL, NULL, errp);
+}
+
+int qio_channel_readv_full_all_eof(QIOChannel *ioc,
+                                   const struct iovec *iov,
+                                   size_t niov,
+                                   int **fds, size_t *nfds,
+                                   Error **errp)
+{
     int ret = -1;
     struct iovec *local_iov = g_new(struct iovec, niov);
     struct iovec *local_iov_head = local_iov;
     unsigned int nlocal_iov = niov;
+    int **local_fds = fds;
+    size_t *local_nfds = nfds;
     bool partial = false;
 
+    if (nfds) {
+        *nfds = 0;
+    }
+
+    if (fds) {
+        *fds = NULL;
+    }
+
     nlocal_iov = iov_copy(local_iov, nlocal_iov,
                           iov, niov,
                           0, iov_size(iov, niov));
 
     while (nlocal_iov > 0) {
         ssize_t len;
-        len = qio_channel_readv(ioc, local_iov, nlocal_iov, errp);
+        len = qio_channel_readv_full(ioc, local_iov, nlocal_iov, local_fds,
+                                     local_nfds, errp);
         if (len == QIO_CHANNEL_ERR_BLOCK) {
             if (qemu_in_coroutine()) {
                 qio_channel_yield(ioc, G_IO_IN);
@@ -112,20 +140,41 @@  int qio_channel_readv_all_eof(QIOChannel *ioc,
                 qio_channel_wait(ioc, G_IO_IN);
             }
             continue;
-        } else if (len < 0) {
-            goto cleanup;
-        } else if (len == 0) {
-            if (partial) {
+        }
+
+        if (len <= 0) {
+            if ((len == 0) && partial) {
+                size_t fd_idx = 0;
+
                 error_setg(errp,
                            "Unexpected end-of-file before all bytes were read");
-            } else {
+
+                if (nfds) {
+                    fd_idx = *nfds;
+                    *nfds = 0;
+                }
+
+                while (fds && fd_idx) {
+                    close((*fds)[fd_idx - 1]);
+                    fd_idx--;
+                }
+
+                if (fds) {
+                    g_free(*fds);
+                    *fds = NULL;
+                }
+            } else if (len == 0) {
                 ret = 0;
             }
+
             goto cleanup;
         }
 
         partial = true;
         iov_discard_front(&local_iov, &nlocal_iov, len);
+
+        local_fds = NULL;
+        local_nfds = 0;
     }
 
     ret = 1;
@@ -135,20 +184,23 @@  int qio_channel_readv_all_eof(QIOChannel *ioc,
     return ret;
 }
 
-int qio_channel_readv_all(QIOChannel *ioc,
-                          const struct iovec *iov,
-                          size_t niov,
-                          Error **errp)
+int qio_channel_readv_full_all(QIOChannel *ioc,
+                               const struct iovec *iov,
+                               size_t niov,
+                               int **fds, size_t *nfds,
+                               Error **errp)
 {
-    int ret = qio_channel_readv_all_eof(ioc, iov, niov, errp);
+    int ret = qio_channel_readv_full_all_eof(ioc, iov, niov, fds, nfds, errp);
 
     if (ret == 0) {
-        ret = -1;
         error_setg(errp,
                    "Unexpected end-of-file before all bytes were read");
-    } else if (ret == 1) {
-        ret = 0;
+        return -1;
     }
+    if (ret == 1) {
+        return 0;
+    }
+
     return ret;
 }