[Libguestfs] [PATCH v3 3/6] lib: qemu: Run QMP ‘query-qmp-schema’ against the qemu binary.
Richard W.M. Jones
rjones at redhat.com
Tue Sep 12 17:04:21 UTC 2017
This adds an extra test using QMP (the QEMU Monitor Protocol). This
allows us to get extra information about the qemu binary beyond what
is available from the version number or ‘qemu -help’.
---
lib/qemu.c | 151 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 149 insertions(+), 2 deletions(-)
diff --git a/lib/qemu.c b/lib/qemu.c
index f7536ec76..097d56929 100644
--- a/lib/qemu.c
+++ b/lib/qemu.c
@@ -37,6 +37,8 @@
#include <libxml/uri.h>
+#include <yajl/yajl_tree.h>
+
#include "full-write.h"
#include "ignore-value.h"
@@ -51,9 +53,11 @@ struct qemu_data {
char *qemu_help; /* Output of qemu -help. */
char *qemu_devices; /* Output of qemu -device ? */
+ char *qmp_schema; /* Output of QMP query-qmp-schema. */
/* The following fields are derived from the fields above. */
struct version qemu_version; /* Parsed qemu version number. */
+ yajl_val qmp_schema_tree; /* qmp_schema parsed into a JSON tree */
};
static int test_qemu_help (guestfs_h *g, struct qemu_data *data);
@@ -62,12 +66,17 @@ static int write_cache_qemu_help (guestfs_h *g, const struct qemu_data *data, co
static int test_qemu_devices (guestfs_h *g, struct qemu_data *data);
static int read_cache_qemu_devices (guestfs_h *g, struct qemu_data *data, const char *filename);
static int write_cache_qemu_devices (guestfs_h *g, const struct qemu_data *data, const char *filename);
+static int test_qmp_schema (guestfs_h *g, struct qemu_data *data);
+static int read_cache_qmp_schema (guestfs_h *g, struct qemu_data *data, const char *filename);
+static int write_cache_qmp_schema (guestfs_h *g, const struct qemu_data *data, const char *filename);
static int read_cache_qemu_stat (guestfs_h *g, struct qemu_data *data, const char *filename);
static int write_cache_qemu_stat (guestfs_h *g, const struct qemu_data *data, const char *filename);
static void parse_qemu_version (guestfs_h *g, const char *, struct version *qemu_version);
+static void parse_json (guestfs_h *g, const char *, yajl_val *);
static void read_all (guestfs_h *g, void *retv, const char *buf, size_t len);
static int generic_read_cache (guestfs_h *g, const char *filename, char **strp);
static int generic_write_cache (guestfs_h *g, const char *filename, const char *str);
+static int generic_qmp_test (guestfs_h *g, struct qemu_data *data, const char *qmp_command, char **outp);
/* This structure abstracts the data we are reading from qemu and how
* we get it.
@@ -93,6 +102,8 @@ static const struct qemu_fields {
test_qemu_help, read_cache_qemu_help, write_cache_qemu_help },
{ "devices",
test_qemu_devices, read_cache_qemu_devices, write_cache_qemu_devices },
+ { "qmp-schema",
+ test_qmp_schema, read_cache_qmp_schema, write_cache_qmp_schema },
};
#define NR_FIELDS (sizeof qemu_fields / sizeof qemu_fields[0])
@@ -101,7 +112,7 @@ static const struct qemu_fields {
* this to discard any memoized data cached by previous versions of
* libguestfs.
*/
-#define MEMO_GENERATION 1
+#define MEMO_GENERATION 2
/**
* Test that the qemu binary (or wrapper) runs, and do C<qemu -help>
@@ -156,8 +167,16 @@ guestfs_int_test_qemu (guestfs_h *g)
r = qemu_fields[i].read_cache (g, data, filename);
if (r == -1)
goto error;
- if (r == 0) /* cache gone, maybe deleted by the tmp cleaner */
+ if (r == 0) {
+ /* Cache gone, maybe deleted by the tmp cleaner, so we must run
+ * the full tests. We will have a partially filled qemu_data
+ * structure. The safest way to deal with that is to free
+ * it and start again.
+ */
+ guestfs_int_free_qemu_data (data);
+ data = safe_calloc (g, 1, sizeof *data);
goto do_test;
+ }
}
goto out;
@@ -190,6 +209,7 @@ guestfs_int_test_qemu (guestfs_h *g)
out:
/* Derived fields. */
parse_qemu_version (g, data->qemu_help, &data->qemu_version);
+ parse_json (g, data->qmp_schema, &data->qmp_schema_tree);
return data;
@@ -280,6 +300,26 @@ write_cache_qemu_devices (guestfs_h *g, const struct qemu_data *data,
}
static int
+test_qmp_schema (guestfs_h *g, struct qemu_data *data)
+{
+ return generic_qmp_test (g, data, "query-qmp-schema", &data->qmp_schema);
+}
+
+static int
+read_cache_qmp_schema (guestfs_h *g, struct qemu_data *data,
+ const char *filename)
+{
+ return generic_read_cache (g, filename, &data->qmp_schema);
+}
+
+static int
+write_cache_qmp_schema (guestfs_h *g, const struct qemu_data *data,
+ const char *filename)
+{
+ return generic_write_cache (g, filename, data->qmp_schema);
+}
+
+static int
read_cache_qemu_stat (guestfs_h *g, struct qemu_data *data,
const char *filename)
{
@@ -342,6 +382,27 @@ parse_qemu_version (guestfs_h *g, const char *qemu_help,
}
/**
+ * Parse the json output from QMP. But don't fail if parsing
+ * is not possible.
+ */
+static void
+parse_json (guestfs_h *g, const char *json, yajl_val *treep)
+{
+ char parse_error[256] = "";
+
+ if (!json)
+ return;
+
+ *treep = yajl_tree_parse (json, parse_error, sizeof parse_error);
+ if (*treep == NULL) {
+ if (strlen (parse_error) > 0)
+ debug (g, "QMP parse error: %s (ignored)", parse_error);
+ else
+ debug (g, "QMP unknown parse error (ignored)");
+ }
+}
+
+/**
* Generic functions for reading and writing the cache files, used
* where we are just reading and writing plain text strings.
*/
@@ -376,6 +437,90 @@ generic_write_cache (guestfs_h *g, const char *filename, const char *str)
return 0;
}
+/**
+ * Run a generic QMP test on the QEMU binary.
+ */
+static int
+generic_qmp_test (guestfs_h *g, struct qemu_data *data,
+ const char *qmp_command,
+ char **outp)
+{
+ CLEANUP_CMD_CLOSE struct command *cmd = guestfs_int_new_command (g);
+ int r, fd;
+ CLEANUP_FCLOSE FILE *fp = NULL;
+ CLEANUP_FREE char *line = NULL;
+ size_t allocsize = 0;
+ ssize_t len;
+
+ guestfs_int_cmd_add_string_unquoted (cmd, "echo ");
+ /* QMP is modal. You have to send the qmp_capabilities command first. */
+ guestfs_int_cmd_add_string_unquoted (cmd, "'{ \"execute\": \"qmp_capabilities\" }' ");
+ guestfs_int_cmd_add_string_unquoted (cmd, "'{ \"execute\": \"");
+ guestfs_int_cmd_add_string_unquoted (cmd, qmp_command);
+ guestfs_int_cmd_add_string_unquoted (cmd, "\" }' ");
+ /* Exit QEMU after sending the commands. */
+ guestfs_int_cmd_add_string_unquoted (cmd, "'{ \"execute\": \"quit\" }' ");
+ guestfs_int_cmd_add_string_unquoted (cmd, " | ");
+ guestfs_int_cmd_add_string_quoted (cmd, g->hv);
+ guestfs_int_cmd_add_string_unquoted (cmd, " -display none");
+ guestfs_int_cmd_add_string_unquoted (cmd, " -machine ");
+ guestfs_int_cmd_add_string_quoted (cmd,
+#ifdef MACHINE_TYPE
+ MACHINE_TYPE ","
+#endif
+ "accel=kvm:tcg");
+ guestfs_int_cmd_add_string_unquoted (cmd, " -qmp stdio");
+ guestfs_int_cmd_clear_capture_errors (cmd);
+
+ fd = guestfs_int_cmd_pipe_run (cmd, "r");
+ if (fd == -1)
+ return -1;
+
+ /* Read the output line by line. We expect to see:
+ * line 1: {"QMP": {"version": ... } } # greeting from QMP
+ * line 2: {"return": {}} # output from qmp_capabilities
+ * line 3: {"return": ... } # the data from our qmp_command
+ * line 4: {"return": {}} # output from quit
+ * line 5: {"timestamp": ...} # shutdown event
+ */
+ fp = fdopen (fd, "r"); /* this will close (fd) at end of scope */
+ if (fp == NULL) {
+ perrorf (g, "fdopen");
+ return -1;
+ }
+ len = getline (&line, &allocsize, fp); /* line 1 */
+ if (len == -1 || strstr (line, "\"QMP\"") == NULL) {
+ parse_failure:
+ debug (g, "did not understand QMP monitor output from %s (ignored)",
+ g->hv);
+ /* QMP tests are optional, don't fail if we cannot parse the
+ * output. However we MUST return an empty string on non-error
+ * paths.
+ */
+ *outp = safe_strdup (g, "");
+ return 0;
+ }
+ len = getline (&line, &allocsize, fp); /* line 2 */
+ if (len == -1 || strstr (line, "\"return\"") == NULL)
+ goto parse_failure;
+ len = getline (&line, &allocsize, fp); /* line 3 */
+ if (len == -1 || strstr (line, "\"return\"") == NULL)
+ goto parse_failure;
+ *outp = safe_strdup (g, line);
+ /* The other lines we don't care about, so finish parsing here. */
+ ignore_value (getline (&line, &allocsize, fp)); /* line 4 */
+ ignore_value (getline (&line, &allocsize, fp)); /* line 5 */
+
+ r = guestfs_int_cmd_pipe_wait (cmd);
+ /* QMP tests are optional, don't fail if the tests fail. */
+ if (r == -1 || !WIFEXITED (r) || WEXITSTATUS (r) != 0) {
+ debug (g, "%s wait failed or unexpected exit status (ignored)", g->hv);
+ return 0;
+ }
+
+ return 0;
+}
+
static void
read_all (guestfs_h *g, void *retv, const char *buf, size_t len)
{
@@ -762,6 +907,8 @@ guestfs_int_free_qemu_data (struct qemu_data *data)
if (data) {
free (data->qemu_help);
free (data->qemu_devices);
+ free (data->qmp_schema);
+ yajl_tree_free (data->qmp_schema_tree);
free (data);
}
}
--
2.13.2
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