Re: [libvirt] [PATCH v6 10/19] utils: Implement function to pass a buffer to send via a fd to virCommand

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&gt; Reviewed-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; --- 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; + }