Re: [libvirt] [PATCH v6 10/19] utils: Implement function to pass a buffer to send via a fd to virCommand
On 7/25/19 1:34 PM, Daniel P. Berrangé wrote:
On Thu, Jul 25, 2019 at 10:30:24AM -0400, Stefan Berger wrote:
> Implement virCommandSetSendBuffer() that allows the caller to pass a
> file descriptor and buffer to virCommand. virCommand will write the
> buffer into the file descriptor. That file descriptor could be the
> write end of a pipe or one of the file descriptors of a socketpair.
> The other file descriptor should be passed to the launched process to
> read the data from.
>
> Only implement the function to allocate memory for send buffers
> and to free them later on.
>
> Signed-off-by: Stefan Berger <stefanb(a)linux.ibm.com>
> Reviewed-by: Daniel P. Berrangé <berrange(a)redhat.com>
> ---
> src/libvirt_private.syms | 1 +
> src/util/vircommand.c | 76 ++++++++++++++++++++++++++++++++++++++++
> src/util/vircommand.h | 5 +++
> 3 files changed, 82 insertions(+)
>
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index cf80ea3e44..e6249caa80 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -1725,6 +1725,7 @@ virCommandSetOutputFD;
> virCommandSetPidFile;
> virCommandSetPreExecHook;
> virCommandSetSELinuxLabel;
> +virCommandSetSendBuffer;
> virCommandSetUID;
> virCommandSetUmask;
> virCommandSetWorkingDirectory;
> diff --git a/src/util/vircommand.c b/src/util/vircommand.c
> index e10ca3eb7c..5dee730826 100644
> --- a/src/util/vircommand.c
> +++ b/src/util/vircommand.c
> @@ -76,6 +76,16 @@ struct _virCommandFD {
> unsigned int flags;
> };
>
> +typedef struct _virCommandSendBuffer virCommandSendBuffer;
> +typedef virCommandSendBuffer *virCommandSendBufferPtr;
> +
> +struct _virCommandSendBuffer {
> + int fd;
> + unsigned char *buffer;
> + size_t buflen;
> + off_t offset;
> +};
> +
> struct _virCommand {
> int has_error; /* ENOMEM on allocation failure, -1 for anything else. */
>
> @@ -135,6 +145,9 @@ struct _virCommand {
> char *appArmorProfile;
> #endif
> int mask;
> +
> + virCommandSendBufferPtr sendBuffers;
> + size_t numSendBuffers;
> };
>
> /* See virCommandSetDryRun for description for this variable */
> @@ -1728,6 +1741,67 @@ virCommandSetWorkingDirectory(virCommandPtr cmd, const char
*pwd)
> }
>
>
> +static int
> +virCommandGetNumSendBuffers(virCommandPtr cmd)
> +{
> + return cmd->numSendBuffers;
> +}
> +
> +
> +static void
> +virCommandFreeSendBuffers(virCommandPtr cmd)
> +{
> + size_t i;
> +
> + for (i = 0; i < virCommandGetNumSendBuffers(cmd); i++) {
> + VIR_FORCE_CLOSE(cmd->sendBuffers[i].fd);
> + VIR_FREE(cmd->sendBuffers[i].buffer);
> + }
> + VIR_FREE(cmd->sendBuffers);
> +}
> +
> +
> +/**
> + * virCommandSetSendBuffer
> + * @cmd: the command to modify
> + *
> + * Pass a buffer to virCommand that will be written into the
> + * given file descriptor. The buffer will be freed automatically
> + * and the file descriptor closed.
> + */
> +int
> +virCommandSetSendBuffer(virCommandPtr cmd,
> + int fd,
> + unsigned char *buffer, size_t buflen)
> +{
> + size_t i = virCommandGetNumSendBuffers(cmd);
> +
> + if (!cmd || cmd->has_error)
> + return -1;
> +
> + if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0) {
> + virReportSystemError(errno, "%s",
> + _("fcntl failed to set O_NONBLOCK"));
> + cmd->has_error = errno;
> + return -1;
> + }
I hit a build failure on mingw with this change, because F_SETFL
doesn't exist.
None of the vircommand code actually runs on windows, so we just
need to stub this method out to immediately return -1 with
has_error set to ENOSUPP i guess.
Fixed them with ENOTSUP. Will post v7 assuming you will add your R-b's
then...
Stefan