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@linux.ibm.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
This commit is contained in:
Stefan Berger 2019-07-25 14:22:06 -04:00 committed by Daniel P. Berrangé
parent 1f46dd4cba
commit 149eda402f
3 changed files with 100 additions and 0 deletions

View File

@ -1725,6 +1725,7 @@ virCommandSetOutputFD;
virCommandSetPidFile; virCommandSetPidFile;
virCommandSetPreExecHook; virCommandSetPreExecHook;
virCommandSetSELinuxLabel; virCommandSetSELinuxLabel;
virCommandSetSendBuffer;
virCommandSetUID; virCommandSetUID;
virCommandSetUmask; virCommandSetUmask;
virCommandSetWorkingDirectory; virCommandSetWorkingDirectory;

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@ -76,6 +76,16 @@ struct _virCommandFD {
unsigned int flags; 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 { struct _virCommand {
int has_error; /* ENOMEM on allocation failure, -1 for anything else. */ int has_error; /* ENOMEM on allocation failure, -1 for anything else. */
@ -135,6 +145,9 @@ struct _virCommand {
char *appArmorProfile; char *appArmorProfile;
#endif #endif
int mask; int mask;
virCommandSendBufferPtr sendBuffers;
size_t numSendBuffers;
}; };
/* See virCommandSetDryRun for description for this variable */ /* See virCommandSetDryRun for description for this variable */
@ -1728,6 +1741,85 @@ 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.
*/
#if defined(F_SETFL)
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;
}
if (VIR_REALLOC_N(cmd->sendBuffers, i + 1) < 0) {
cmd->has_error = ENOMEM;
return -1;
}
cmd->sendBuffers[i].fd = fd;
cmd->sendBuffers[i].buffer = buffer;
cmd->sendBuffers[i].buflen = buflen;
cmd->sendBuffers[i].offset = 0;
cmd->numSendBuffers++;
return 0;
}
#else /* !defined(F_SETFL) */
int
virCommandSetSendBuffer(virCommandPtr cmd,
int fd ATTRIBUTE_UNUSED,
unsigned char *buffer ATTRIBUTE_UNUSED,
size_t buflen ATTRIBUTE_UNUSED)
{
if (!cmd || cmd->has_error)
return -1;
cmd->has_error = ENOTSUP;
return -1;
}
#endif
/** /**
* virCommandSetInputBuffer: * virCommandSetInputBuffer:
* @cmd: the command to modify * @cmd: the command to modify
@ -2867,6 +2959,8 @@ virCommandFree(virCommandPtr cmd)
VIR_FREE(cmd->appArmorProfile); VIR_FREE(cmd->appArmorProfile);
#endif #endif
virCommandFreeSendBuffers(cmd);
VIR_FREE(cmd); VIR_FREE(cmd);
} }

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@ -146,6 +146,11 @@ void virCommandAddArgList(virCommandPtr cmd,
void virCommandSetWorkingDirectory(virCommandPtr cmd, void virCommandSetWorkingDirectory(virCommandPtr cmd,
const char *pwd) ATTRIBUTE_NONNULL(2); const char *pwd) ATTRIBUTE_NONNULL(2);
int virCommandSetSendBuffer(virCommandPtr cmd,
int fd,
unsigned char *buffer, size_t buflen)
ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(3);
void virCommandSetInputBuffer(virCommandPtr cmd, void virCommandSetInputBuffer(virCommandPtr cmd,
const char *inbuf) ATTRIBUTE_NONNULL(2); const char *inbuf) ATTRIBUTE_NONNULL(2);