[libvirt] [PATCH] Make QEMU text monitor parsing more robust
Daniel P. Berrange
berrange at redhat.com
Tue Dec 8 18:08:04 UTC 2009
The QEMU 0.10.0 release (and possibly other 0.10.x) has a bug where
it sometimes/often forgets to display the initial monitor greeting
line, soley printing a (qemu). This in turn confuses the text
console parsing because it has a '(qemu)' it is not expecting. The
confusion results in a negative malloc. Bad things follow.
This re-writes the text console handling to be more robust. The key
idea is that it should only look for a (qemu), once it has seen the
original command echo'd back. This ensures it'll skip the bogus stray
(qemu) with broken QEMUs.
* src/qemu/qemu_monitor.c: Add some (disabled) debug code
* src/qemu/qemu_monitor_text.c: Re-write way command replies
are detected
---
src/qemu/qemu_monitor.c | 28 +++++++++++
src/qemu/qemu_monitor_text.c | 102 +++++++++++++++++++++++++++--------------
2 files changed, 95 insertions(+), 35 deletions(-)
diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
index abb763c..103cf28 100644
--- a/src/qemu/qemu_monitor.c
+++ b/src/qemu/qemu_monitor.c
@@ -39,6 +39,8 @@
#define VIR_FROM_THIS VIR_FROM_QEMU
+#define QEMU_DEBUG_RAW_IO 0
+
struct _qemuMonitor {
virMutex lock;
virCond notify;
@@ -163,6 +165,24 @@ char *qemuMonitorEscapeShell(const char *in)
}
+#if QEMU_DEBUG_RAW_IO
+#include <c-ctype.h>
+static char * qemuMonitorEscapeNonPrintable(const char *text)
+{
+ int i;
+ virBuffer buf = VIR_BUFFER_INITIALIZER;
+ for (i = 0 ; text[i] != '\0' ; i++) {
+ if (c_isprint(text[i]) ||
+ text[i] == '\n' ||
+ (text[i] == '\r' && text[i+1] == '\n'))
+ virBufferVSprintf(&buf,"%c", text[i]);
+ else
+ virBufferVSprintf(&buf, "0x%02x", text[i]);
+ }
+ return virBufferContentAndReset(&buf);
+}
+#endif
+
void qemuMonitorLock(qemuMonitorPtr mon)
{
virMutexLock(&mon->lock);
@@ -282,7 +302,15 @@ qemuMonitorIOProcess(qemuMonitorPtr mon)
if (mon->msg && mon->msg->txOffset == mon->msg->txLength)
msg = mon->msg;
+#if QEMU_DEBUG_RAW_IO
+ char *str1 = qemuMonitorEscapeNonPrintable(msg ? msg->txBuffer : "");
+ char *str2 = qemuMonitorEscapeNonPrintable(mon->buffer);
+ VIR_ERROR("Process %d %p %p [[[[%s]]][[[%s]]]", (int)mon->bufferOffset, mon->msg, msg, str1, str2);
+ VIR_FREE(str1);
+ VIR_FREE(str2);
+#else
VIR_DEBUG("Process %d", (int)mon->bufferOffset);
+#endif
if (mon->json)
len = qemuMonitorJSONIOProcess(mon,
mon->buffer, mon->bufferOffset,
diff --git a/src/qemu/qemu_monitor_text.c b/src/qemu/qemu_monitor_text.c
index 0d5ad79..72cb2bb 100644
--- a/src/qemu/qemu_monitor_text.c
+++ b/src/qemu/qemu_monitor_text.c
@@ -94,46 +94,78 @@ int qemuMonitorTextIOProcess(qemuMonitorPtr mon ATTRIBUTE_UNUSED,
/* Look for a non-zero reply followed by prompt */
if (msg && !msg->finished) {
- const char *end;
-
- /* We might get a prompt for a password */
- end = strstr(data + used, PASSWORD_PROMPT);
- if (end) {
- VIR_DEBUG("Woooo passwowrd [%s]", data + used);
- if (msg->passwordHandler) {
- size_t consumed;
- /* Try and handle the prompt */
- if (msg->passwordHandler(mon, msg,
- data + used,
- len - used,
- msg->passwordOpaque) < 0)
- return -1;
+ char *start = NULL;
+ char *end = NULL;
+ char *skip;
- /* Skip over prompt now */
- consumed = (end + strlen(PASSWORD_PROMPT))
- - (data + used);
- used += consumed;
- } else {
- errno = EACCES;
- return -1;
+ /* If we're here, we've already sent the command. We now
+ * strip the trailing '\r' because it makes the matching
+ * code that follows a little easier ie we can just strstr()
+ * for the original command
+ */
+ if (msg->txLength > 0) {
+ char *tmp;
+ if ((tmp = strchr(msg->txBuffer, '\r'))) {
+ *tmp = '\0';
}
}
- /* We use the arrival of BASIC_PROMPT to detect when we've got a
- * complete reply available from a command */
- end = strstr(data + used, BASIC_PROMPT);
- if (end) {
- /* QEMU echos the command back to us, full of control
- * character junk that we don't want. Fortunately this
- * is all terminated by LINE_ENDING, so we can easily
- * skip over the control character junk */
- const char *start = strstr(data + used, LINE_ENDING);
- if (!start)
- start = data + used;
- else
- start += strlen(LINE_ENDING);
- int want = end - start;
+ /* QEMU echos the command back to us, full of control
+ * character junk that we don't want. We have to skip
+ * over this junk by looking for the first complete
+ * repetition of our command. Then we can look for
+ * the prompt that is supposed to follow
+ *
+ * NB, we can't optimize by immediately looking for
+ * LINE_ENDING, because QEMU 0.10 has bad problems
+ * when initially connecting where it might write a
+ * prompt in the wrong place. So we must not look
+ * for LINE_ENDING, or BASIC_PROMPT until we've
+ * seen our original command echod.
+ */
+ skip = strstr(data + used, msg->txBuffer);
+
+ /* After the junk we should have a line ending... */
+ if (skip) {
+ start = strstr(skip + strlen(msg->txBuffer), LINE_ENDING);
+ }
+
+ /* ... then our command reply data, following by a (qemu) prompt */
+ if (start) {
+ char *passwd;
+ start += strlen(LINE_ENDING);
+
+ /* We might get a prompt for a password before the (qemu) prompt */
+ passwd = strstr(start, PASSWORD_PROMPT);
+ if (passwd) {
+ VIR_DEBUG("Seen a passwowrd prompt [%s]", data + used);
+ if (msg->passwordHandler) {
+ int i;
+ /* Try and handle the prompt */
+ if (msg->passwordHandler(mon, msg,
+ start,
+ passwd - start + strlen(PASSWORD_PROMPT),
+ msg->passwordOpaque) < 0)
+ return -1;
+
+ /* Blank out the password prompt so we don't re-trigger
+ * if we have to go back to sleep for more I/O */
+ for (i = 0 ; i < strlen(PASSWORD_PROMPT) ; i++)
+ start[i] = ' ';
+
+ /* Handled, so skip forward over password prompt */
+ start = passwd;
+ } else {
+ errno = EACCES;
+ return -1;
+ }
+ }
+ end = strstr(start, BASIC_PROMPT);
+ }
+
+ if (start && end) {
+ int want = end - start;
/* Annoyingly some commands may not have any reply data
* at all upon success, but since we've detected the
* BASIC_PROMPT we can reasonably reliably cope */
--
1.6.5.2
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