tests: qgraph API for the qtest driver framework

Add qgraph API that allows to add/remove nodes and edges from the graph,
implementation of Depth First Search to discover the paths and basic unit
test to check correctness of the API.
Included also a main executable that takes care of starting the framework,
create the nodes, set the available drivers/machines, discover the path and
run tests.

graph.h provides the public API to manage the graph nodes/edges
graph_extra.h provides a more private API used successively by the gtest integration part
qos-test.c provides the main executable
Signed-off-by: NEmanuele Giuseppe Esposito <e.emanuelegiuseppe@gmail.com>
[Paolo's changes compared to the Google Summer of Code submission:
 * added subprocess to test options
 * refactored object creation to support live migration tests
 * removed driver .before callback (unused)
 * removed test .after callbacks (replaced by GTest destruction queue)]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

configure

@@ -7647,7 +7647,7 @@ fi
 # tests might fail. Prefer to keep the relevant files in their own
 # directory and symlink the directory instead.
 DIRS="tests tests/tcg tests/tcg/cris tests/tcg/lm32 tests/libqos tests/qapi-schema tests/tcg/xtensa tests/qemu-iotests tests/vm"
-DIRS="$DIRS tests/fp"
+DIRS="$DIRS tests/fp tests/qgraph"
 DIRS="$DIRS docs docs/interop fsdev scsi"
 DIRS="$DIRS pc-bios/optionrom pc-bios/spapr-rtas pc-bios/s390-ccw"
 DIRS="$DIRS roms/seabios roms/vgabios"

include/qemu/module.h

@@ -45,6 +45,7 @@ typedef enum {
     MODULE_INIT_QOM,
     MODULE_INIT_TRACE,
     MODULE_INIT_XEN_BACKEND,
+    MODULE_INIT_LIBQOS,
     MODULE_INIT_MAX
 } module_init_type;
 
@@ -54,6 +55,7 @@ typedef enum {
 #define trace_init(function) module_init(function, MODULE_INIT_TRACE)
 #define xen_backend_init(function) module_init(function, \
                                                MODULE_INIT_XEN_BACKEND)
+#define libqos_init(function) module_init(function, MODULE_INIT_LIBQOS)
 
 #define block_module_load_one(lib) module_load_one("block-", lib)
 #define ui_module_load_one(lib) module_load_one("ui-", lib)

tests/Makefile.include

@@ -732,7 +732,10 @@ tests/test-crypto-ivgen$(EXESUF): tests/test-crypto-ivgen.o $(test-crypto-obj-y)
 tests/test-crypto-afsplit$(EXESUF): tests/test-crypto-afsplit.o $(test-crypto-obj-y)
 tests/test-crypto-block$(EXESUF): tests/test-crypto-block.o $(test-crypto-obj-y)
 
-libqos-obj-y = tests/libqos/pci.o tests/libqos/fw_cfg.o tests/libqos/malloc.o
+libqgraph-obj-y = tests/libqos/qgraph.o
+
+libqos-obj-y = $(libqgraph-obj-y) tests/libqos/pci.o tests/libqos/fw_cfg.o
+libqos-obj-y += tests/libqos/malloc.o tests/libqos/malloc-generic.o
 libqos-obj-y += tests/libqos/i2c.o tests/libqos/libqos.o
 libqos-spapr-obj-y = $(libqos-obj-y) tests/libqos/malloc-spapr.o
 libqos-spapr-obj-y += tests/libqos/libqos-spapr.o
@@ -744,7 +747,13 @@ libqos-pc-obj-y += tests/libqos/ahci.o
 libqos-omap-obj-y = $(libqos-obj-y) tests/libqos/i2c-omap.o
 libqos-imx-obj-y = $(libqos-obj-y) tests/libqos/i2c-imx.o
 libqos-usb-obj-y = $(libqos-spapr-obj-y) $(libqos-pc-obj-y) tests/libqos/usb.o
-libqos-virtio-obj-y = $(libqos-spapr-obj-y) $(libqos-pc-obj-y) tests/libqos/virtio.o tests/libqos/virtio-pci.o tests/libqos/virtio-mmio.o tests/libqos/malloc-generic.o
+libqos-virtio-obj-y = $(libqos-spapr-obj-y) $(libqos-pc-obj-y) tests/libqos/virtio.o tests/libqos/virtio-pci.o tests/libqos/virtio-mmio.o
+
+check-unit-y += tests/test-qgraph$(EXESUF)
+tests/test-qgraph$(EXESUF): tests/test-qgraph.o $(libqgraph-obj-y)
+
+check-qtest-generic-y += tests/qos-test$(EXESUF)
+tests/qos-test$(EXESUF): tests/qos-test.o $(libqgraph-obj-y)
 
 tests/qmp-test$(EXESUF): tests/qmp-test.o
 tests/qmp-cmd-test$(EXESUF): tests/qmp-cmd-test.o

tests/libqos/qgraph.c

+/*
+ * libqos driver framework
+ *
+ * Copyright (c) 2018 Emanuele Giuseppe Esposito <e.emanuelegiuseppe@gmail.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2 as published by the Free Software Foundation.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>
+ */
+
+#include "qemu/osdep.h"
+#include "libqtest.h"
+#include "qemu/queue.h"
+#include "libqos/qgraph_internal.h"
+#include "libqos/qgraph.h"
+
+#define QGRAPH_PRINT_DEBUG 0
+#define QOS_ROOT ""
+typedef struct QOSStackElement QOSStackElement;
+
+/* Graph Edge.*/
+struct QOSGraphEdge {
+    QOSEdgeType type;
+    char *dest;
+    void *arg;                /* just for QEDGE_CONTAINS
+                               * and QEDGE_CONSUMED_BY */
+    char *extra_device_opts;  /* added to -device option, "," is
+                               * automatically added
+                               */
+    char *before_cmd_line;    /* added before node cmd_line */
+    char *after_cmd_line;     /* added after -device options */
+    char *edge_name;          /* used by QEDGE_CONTAINS */
+    QSLIST_ENTRY(QOSGraphEdge) edge_list;
+};
+
+typedef QSLIST_HEAD(, QOSGraphEdge) QOSGraphEdgeList;
+
+/**
+ * Stack used to keep track of the discovered path when using
+ * the DFS algorithm
+ */
+struct QOSStackElement {
+    QOSGraphNode *node;
+    QOSStackElement *parent;
+    QOSGraphEdge *parent_edge;
+    int length;
+};
+
+/* Each enty in these hash table will consist of <string, node/edge> pair. */
+static GHashTable *edge_table;
+static GHashTable *node_table;
+
+/* stack used by the DFS algorithm to store the path from machine to test */
+static QOSStackElement qos_node_stack[QOS_PATH_MAX_ELEMENT_SIZE];
+static int qos_node_tos;
+
+/**
+ * add_edge(): creates an edge of type @type
+ * from @source to @dest node, and inserts it in the
+ * edges hash table
+ *
+ * Nodes @source and @dest do not necessarily need to exist.
+ * Possibility to add also options (see #QOSGraphEdgeOptions)
+ * edge->edge_name is used as identifier for get_device relationships,
+ * so by default is equal to @dest.
+ */
+static void add_edge(const char *source, const char *dest,
+                     QOSEdgeType type, QOSGraphEdgeOptions *opts)
+{
+    char *key;
+    QOSGraphEdgeList *list = g_hash_table_lookup(edge_table, source);
+
+    if (!list) {
+        list = g_new0(QOSGraphEdgeList, 1);
+        key = g_strdup(source);
+        g_hash_table_insert(edge_table, key, list);
+    }
+
+    if (!opts) {
+        opts = &(QOSGraphEdgeOptions) { };
+    }
+
+    QOSGraphEdge *edge = g_new0(QOSGraphEdge, 1);
+    edge->type = type;
+    edge->dest = g_strdup(dest);
+    edge->edge_name = g_strdup(opts->edge_name ?: dest);
+    edge->arg = g_memdup(opts->arg, opts->size_arg);
+
+    edge->before_cmd_line =
+        opts->before_cmd_line ? g_strconcat(" ", opts->before_cmd_line, NULL) : NULL;
+    edge->extra_device_opts =
+        opts->extra_device_opts ? g_strconcat(",", opts->extra_device_opts, NULL) : NULL;
+    edge->after_cmd_line =
+        opts->after_cmd_line ? g_strconcat(" ", opts->after_cmd_line, NULL) : NULL;
+
+    QSLIST_INSERT_HEAD(list, edge, edge_list);
+}
+
+/* destroy_edges(): frees all edges inside a given @list */
+static void destroy_edges(void *list)
+{
+    QOSGraphEdge *temp;
+    QOSGraphEdgeList *elist = list;
+
+    while (!QSLIST_EMPTY(elist)) {
+        temp = QSLIST_FIRST(elist);
+        QSLIST_REMOVE_HEAD(elist, edge_list);
+        g_free(temp->dest);
+        g_free(temp->before_cmd_line);
+        g_free(temp->after_cmd_line);
+        g_free(temp->extra_device_opts);
+        g_free(temp->edge_name);
+        g_free(temp->arg);
+        g_free(temp);
+    }
+    g_free(elist);
+}
+
+/**
+ * create_node(): creates a node @name of type @type
+ * and inserts it to the nodes hash table.
+ * By default, node is not available.
+ */
+static QOSGraphNode *create_node(const char *name, QOSNodeType type)
+{
+    if (g_hash_table_lookup(node_table, name)) {
+        g_printerr("Node %s already created\n", name);
+        abort();
+    }
+
+    QOSGraphNode *node = g_new0(QOSGraphNode, 1);
+    node->type = type;
+    node->available = false;
+    node->name = g_strdup(name);
+    g_hash_table_insert(node_table, node->name, node);
+    return node;
+}
+
+/**
+ * destroy_node(): frees a node @val from the nodes hash table.
+ * Note that node->name is not free'd since it will represent the
+ * hash table key
+ */
+static void destroy_node(void *val)
+{
+    QOSGraphNode *node = val;
+    g_free(node->command_line);
+    g_free(node);
+}
+
+/**
+ * destroy_string(): frees @key from the nodes hash table.
+ * Actually frees the node->name
+ */
+static void destroy_string(void *key)
+{
+    g_free(key);
+}
+
+/**
+ * search_node(): search for a node @key in the nodes hash table
+ * Returns the QOSGraphNode if found, #NULL otherwise
+ */
+static QOSGraphNode *search_node(const char *key)
+{
+    return g_hash_table_lookup(node_table, key);
+}
+
+/**
+ * get_edgelist(): returns the edge list (value) assigned to
+ * the @key in the edge hash table.
+ * This list will contain all edges with source equal to @key
+ *
+ * Returns: on success: the %QOSGraphEdgeList
+ *          otherwise: abort()
+ */
+static QOSGraphEdgeList *get_edgelist(const char *key)
+{
+    return g_hash_table_lookup(edge_table, key);
+}
+
+/**
+ * search_list_edges(): search for an edge with destination @dest
+ * in the given @edgelist.
+ *
+ * Returns: on success: the %QOSGraphEdge
+ *          otherwise: #NULL
+ */
+static QOSGraphEdge *search_list_edges(QOSGraphEdgeList *edgelist,
+                                       const char *dest)
+{
+    QOSGraphEdge *tmp, *next;
+    if (!edgelist) {
+        return NULL;
+    }
+    QSLIST_FOREACH_SAFE(tmp, edgelist, edge_list, next) {
+        if (g_strcmp0(tmp->dest, dest) == 0) {
+            break;
+        }
+    }
+    return tmp;
+}
+
+/**
+ * search_machine(): search for a machine @name in the node hash
+ * table. A machine is the child of the root node.
+ * This function forces the research in the childs of the root,
+ * to check the node is a proper machine
+ *
+ * Returns: on success: the %QOSGraphNode
+ *          otherwise: #NULL
+ */
+static QOSGraphNode *search_machine(const char *name)
+{
+    QOSGraphNode *n;
+    QOSGraphEdgeList *root_list = get_edgelist(QOS_ROOT);
+    QOSGraphEdge *e = search_list_edges(root_list, name);
+    if (!e) {
+        return NULL;
+    }
+    n = search_node(e->dest);
+    if (n->type == QNODE_MACHINE) {
+        return n;
+    }
+    return NULL;
+}
+
+/**
+ * create_interface(): checks if there is already
+ * a node @node in the node hash table, if not
+ * creates a node @node of type #QNODE_INTERFACE
+ * and inserts it. If there is one, check it's
+ * a #QNODE_INTERFACE and abort() if it's not.
+ */
+static void create_interface(const char *node)
+{
+    QOSGraphNode *interface;
+    interface = search_node(node);
+    if (!interface) {
+        create_node(node, QNODE_INTERFACE);
+    } else if (interface->type != QNODE_INTERFACE) {
+        fprintf(stderr, "Error: Node %s is not an interface\n", node);
+        abort();
+    }
+}
+
+/**
+ * build_machine_cmd_line(): builds the command line for the machine
+ * @node. The node name must be a valid qemu identifier, since it
+ * will be used to build the command line.
+ *
+ * It is also possible to pass an optional @args that will be
+ * concatenated to the command line.
+ *
+ * For machines, prepend -M to the machine name. ", @rgs" is added
+ * after the -M <machine> command.
+ */
+static void build_machine_cmd_line(QOSGraphNode *node, const char *args)
+{
+    char *machine = qos_get_machine_type(node->name);
+    if (args) {
+        node->command_line = g_strconcat("-M ", machine, ",", args, NULL);
+    } else {
+        node->command_line = g_strconcat("-M ", machine, " ", NULL);
+    }
+}
+
+/**
+ * build_driver_cmd_line(): builds the command line for the driver
+ * @node. The node name must be a valid qemu identifier, since it
+ * will be used to build the command line.
+ *
+ * Driver do not need additional command line, since it will be
+ * provided by the edge options.
+ *
+ * For drivers, prepend -device to the node name.
+ */
+static void build_driver_cmd_line(QOSGraphNode *node)
+{
+    node->command_line = g_strconcat(" -device ", node->name, NULL);
+}
+
+/* qos_print_cb(): callback prints all path found by the DFS algorithm. */
+static void qos_print_cb(QOSGraphNode *path, int length)
+{
+    #if QGRAPH_PRINT_DEBUG
+        printf("%d elements\n", length);
+
+        if (!path) {
+            return;
+        }
+
+        while (path->path_edge) {
+            printf("%s ", path->name);
+            switch (path->path_edge->type) {
+            case QEDGE_PRODUCES:
+                printf("--PRODUCES--> ");
+                break;
+            case QEDGE_CONSUMED_BY:
+                printf("--CONSUMED_BY--> ");
+                break;
+            case QEDGE_CONTAINS:
+                printf("--CONTAINS--> ");
+                break;
+            }
+            path = search_node(path->path_edge->dest);
+        }
+
+        printf("%s\n\n", path->name);
+    #endif
+}
+
+/* qos_push(): push a node @el and edge @e in the qos_node_stack */
+static void qos_push(QOSGraphNode *el, QOSStackElement *parent,
+                     QOSGraphEdge *e)
+{
+    int len = 0; /* root is not counted */
+    if (qos_node_tos == QOS_PATH_MAX_ELEMENT_SIZE) {
+        g_printerr("QOSStack: full stack, cannot push");
+        abort();
+    }
+
+    if (parent) {
+        len = parent->length + 1;
+    }
+    qos_node_stack[qos_node_tos++] = (QOSStackElement) {
+        .node = el,
+        .parent = parent,
+        .parent_edge = e,
+        .length = len,
+    };
+}
+
+/* qos_tos(): returns the top of stack, without popping */
+static QOSStackElement *qos_tos(void)
+{
+    return &qos_node_stack[qos_node_tos - 1];
+}
+
+/* qos_pop(): pops an element from the tos, setting it unvisited*/
+static QOSStackElement *qos_pop(void)
+{
+    if (qos_node_tos == 0) {
+        g_printerr("QOSStack: empty stack, cannot pop");
+        abort();
+    }
+    QOSStackElement *e = qos_tos();
+    e->node->visited = false;
+    qos_node_tos--;
+    return e;
+}
+
+/**
+ * qos_reverse_path(): reverses the found path, going from
+ * test-to-machine to machine-to-test
+ */
+static QOSGraphNode *qos_reverse_path(QOSStackElement *el)
+{
+    if (!el) {
+        return NULL;
+    }
+
+    el->node->path_edge = NULL;
+
+    while (el->parent) {
+        el->parent->node->path_edge = el->parent_edge;
+        el = el->parent;
+    }
+
+    return el->node;
+}
+
+/**
+ * qos_traverse_graph(): graph-walking algorithm, using Depth First Search it
+ * starts from the root @machine and walks all possible path until it
+ * reaches a test node.
+ * At that point, it reverses the path found and invokes the @callback.
+ *
+ * Being Depth First Search, time complexity is O(|V| + |E|), while
+ * space is O(|V|). In this case, the maximum stack size is set by
+ * QOS_PATH_MAX_ELEMENT_SIZE.
+ */
+static void qos_traverse_graph(QOSGraphNode *root, QOSTestCallback callback)
+{
+    QOSGraphNode *v, *dest_node, *path;
+    QOSStackElement *s_el;
+    QOSGraphEdge *e, *next;
+    QOSGraphEdgeList *list;
+
+    qos_push(root, NULL, NULL);
+
+    while (qos_node_tos > 0) {
+        s_el = qos_tos();
+        v = s_el->node;
+        if (v->visited) {
+            qos_pop();
+            continue;
+        }
+        v->visited = true;
+        list = get_edgelist(v->name);
+        if (!list) {
+            qos_pop();
+            if (v->type == QNODE_TEST) {
+                v->visited = false;
+                path = qos_reverse_path(s_el);
+                callback(path, s_el->length);
+            }
+        } else {
+            QSLIST_FOREACH_SAFE(e, list, edge_list, next) {
+                dest_node = search_node(e->dest);
+
+                if (!dest_node) {
+                    fprintf(stderr, "node %s in %s -> %s does not exist\n",
+                            e->dest, v->name, e->dest);
+                    abort();
+                }
+
+                if (!dest_node->visited && dest_node->available) {
+                    qos_push(dest_node, s_el, e);
+                }
+            }
+        }
+    }
+}
+
+/* QGRAPH API*/
+
+QOSGraphNode *qos_graph_get_node(const char *key)
+{
+    return search_node(key);
+}
+
+bool qos_graph_has_node(const char *node)
+{
+    QOSGraphNode *n = search_node(node);
+    return n != NULL;
+}
+
+QOSNodeType qos_graph_get_node_type(const char *node)
+{
+    QOSGraphNode *n = search_node(node);
+    if (n) {
+        return n->type;
+    }
+    return -1;
+}
+
+bool qos_graph_get_node_availability(const char *node)
+{
+    QOSGraphNode *n = search_node(node);
+    if (n) {
+        return n->available;
+    }
+    return false;
+}
+
+QOSGraphEdge *qos_graph_get_edge(const char *node, const char *dest)
+{
+    QOSGraphEdgeList *list = get_edgelist(node);
+    return search_list_edges(list, dest);
+}
+
+QOSEdgeType qos_graph_edge_get_type(QOSGraphEdge *edge)
+{
+    if (!edge) {
+        return -1;
+    }
+    return edge->type;;
+}
+
+char *qos_graph_edge_get_dest(QOSGraphEdge *edge)
+{
+    if (!edge) {
+        return NULL;
+    }
+    return edge->dest;
+}
+
+void *qos_graph_edge_get_arg(QOSGraphEdge *edge)
+{
+    if (!edge) {
+        return NULL;
+    }
+    return edge->arg;
+}
+
+char *qos_graph_edge_get_after_cmd_line(QOSGraphEdge *edge)
+{
+    if (!edge) {
+        return NULL;
+    }
+    return edge->after_cmd_line;
+}
+
+char *qos_graph_edge_get_before_cmd_line(QOSGraphEdge *edge)
+{
+    if (!edge) {
+        return NULL;
+    }
+    return edge->before_cmd_line;
+}
+
+char *qos_graph_edge_get_extra_device_opts(QOSGraphEdge *edge)
+{
+    if (!edge) {
+        return NULL;
+    }
+    return edge->extra_device_opts;
+}
+
+char *qos_graph_edge_get_name(QOSGraphEdge *edge)
+{
+    if (!edge) {
+        return NULL;
+    }
+    return edge->edge_name;
+}
+
+bool qos_graph_has_edge(const char *start, const char *dest)
+{
+    QOSGraphEdgeList *list = get_edgelist(start);
+    QOSGraphEdge *e = search_list_edges(list, dest);
+    return e != NULL;
+}
+
+QOSGraphNode *qos_graph_get_machine(const char *node)
+{
+    return search_machine(node);
+}
+
+bool qos_graph_has_machine(const char *node)
+{
+    QOSGraphNode *m = search_machine(node);
+    return m != NULL;
+}
+
+void qos_print_graph(void)
+{
+    qos_graph_foreach_test_path(qos_print_cb);
+}
+
+void qos_graph_init(void)
+{
+    if (!node_table) {
+        node_table = g_hash_table_new_full(g_str_hash, g_str_equal,
+                                           destroy_string, destroy_node);
+        create_node(QOS_ROOT, QNODE_DRIVER);
+    }
+
+    if (!edge_table) {
+        edge_table = g_hash_table_new_full(g_str_hash, g_str_equal,
+                                           destroy_string, destroy_edges);
+    }
+}
+
+void qos_graph_destroy(void)
+{
+    if (node_table) {
+        g_hash_table_destroy(node_table);
+    }
+
+    if (edge_table) {
+        g_hash_table_destroy(edge_table);
+    }
+
+    node_table = NULL;
+    edge_table = NULL;
+}
+
+void qos_node_destroy(void *key)
+{
+    g_hash_table_remove(node_table, key);
+}
+
+void qos_edge_destroy(void *key)
+{
+    g_hash_table_remove(edge_table, key);
+}
+
+void qos_add_test(const char *name, const char *interface,
+                  QOSTestFunc test_func, QOSGraphTestOptions *opts)
+{
+    QOSGraphNode *node;
+    char *test_name = g_strdup_printf("%s-tests/%s", interface, name);;
+
+    if (!opts) {
+        opts = &(QOSGraphTestOptions) { };
+    }
+    node = create_node(test_name, QNODE_TEST);
+    node->u.test.function = test_func;
+    node->u.test.arg = opts->arg;
+    assert(!opts->edge.arg);
+    assert(!opts->edge.size_arg);
+
+    node->u.test.before = opts->before;
+    node->u.test.subprocess = opts->subprocess;
+    node->available = true;
+    add_edge(interface, test_name, QEDGE_CONSUMED_BY, &opts->edge);
+    g_free(test_name);
+}
+
+void qos_node_create_machine(const char *name, QOSCreateMachineFunc function)
+{
+    qos_node_create_machine_args(name, function, NULL);
+}
+
+void qos_node_create_machine_args(const char *name,
+                                  QOSCreateMachineFunc function,
+                                  const char *opts)
+{
+    QOSGraphNode *node = create_node(name, QNODE_MACHINE);
+    build_machine_cmd_line(node, opts);
+    node->u.machine.constructor = function;
+    add_edge(QOS_ROOT, name, QEDGE_CONTAINS, NULL);
+}
+
+void qos_node_create_driver(const char *name, QOSCreateDriverFunc function)
+{
+    QOSGraphNode *node = create_node(name, QNODE_DRIVER);
+    build_driver_cmd_line(node);
+    node->u.driver.constructor = function;
+}
+
+void qos_node_contains(const char *container, const char *contained,
+                       ...)
+{
+    va_list va;
+    va_start(va, contained);
+    QOSGraphEdgeOptions *opts;
+
+    do {
+        opts = va_arg(va, QOSGraphEdgeOptions *);
+        add_edge(container, contained, QEDGE_CONTAINS, opts);
+    } while (opts != NULL);
+
+    va_end(va);
+}
+
+void qos_node_produces(const char *producer, const char *interface)
+{
+    create_interface(interface);
+    add_edge(producer, interface, QEDGE_PRODUCES, NULL);
+}
+
+void qos_node_consumes(const char *consumer, const char *interface,
+                       QOSGraphEdgeOptions *opts)
+{
+    create_interface(interface);
+    add_edge(interface, consumer, QEDGE_CONSUMED_BY, opts);
+}
+
+void qos_graph_node_set_availability(const char *node, bool av)
+{
+    QOSGraphEdgeList *elist;
+    QOSGraphNode *n = search_node(node);
+    QOSGraphEdge *e, *next;
+    if (!n) {
+        return;
+    }
+    n->available = av;
+    elist = get_edgelist(node);
+    if (!elist) {
+        return;
+    }
+    QSLIST_FOREACH_SAFE(e, elist, edge_list, next) {
+        if (e->type == QEDGE_CONTAINS || e->type == QEDGE_PRODUCES) {
+            qos_graph_node_set_availability(e->dest, av);
+        }
+    }
+}
+
+void qos_graph_foreach_test_path(QOSTestCallback fn)
+{
+    QOSGraphNode *root = qos_graph_get_node(QOS_ROOT);
+    qos_traverse_graph(root, fn);
+}
+
+QOSGraphObject *qos_machine_new(QOSGraphNode *node, QTestState *qts)
+{
+    QOSGraphObject *obj;
+
+    g_assert(node->type == QNODE_MACHINE);
+    obj = node->u.machine.constructor(qts);
+    obj->free = g_free;
+    return obj;
+}
+
+QOSGraphObject *qos_driver_new(QOSGraphNode *node, QOSGraphObject *parent,
+                               QGuestAllocator *alloc, void *arg)
+{
+    QOSGraphObject *obj;
+
+    g_assert(node->type == QNODE_DRIVER);
+    obj = node->u.driver.constructor(parent, alloc, arg);
+    obj->free = g_free;
+    return obj;
+}
+
+void qos_object_destroy(QOSGraphObject *obj)
+{
+    if (!obj) {
+        return;
+    }
+    if (obj->destructor) {
+        obj->destructor(obj);
+    }
+    if (obj->free) {
+        obj->free(obj);
+    }
+}
+
+void qos_object_queue_destroy(QOSGraphObject *obj)
+{
+    g_test_queue_destroy((GDestroyNotify) qos_object_destroy, obj);
+}
+
+void qos_object_start_hw(QOSGraphObject *obj)
+{
+    if (obj->start_hw) {
+        obj->start_hw(obj);
+    }
+}
+
+char *qos_get_machine_type(char *name)
+{
+    while (*name != '\0' && *name != '/') {
+        name++;
+    }
+
+    if (!*name || !name[1]) {
+        fprintf(stderr, "Machine name has to be of the form <arch>/<machine>\n");
+        abort();
+    }
+
+    return name + 1;
+}
+
+void qos_delete_cmd_line(const char *name)
+{
+    QOSGraphNode *node = search_node(name);
+    if (node) {
+        g_free(node->command_line);
+        node->command_line = NULL;
+    }
+}

tests/libqos/qgraph_internal.h

+/*
+ * libqos driver framework
+ *
+ * Copyright (c) 2018 Emanuele Giuseppe Esposito <e.emanuelegiuseppe@gmail.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2 as published by the Free Software Foundation.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>
+ */
+
+#ifndef QGRAPH_EXTRA_H
+#define QGRAPH_EXTRA_H
+
+/* This header is declaring additional helper functions defined in
+ * libqos/qgraph.c
+ * It should not be included in tests
+ */
+
+#include "libqos/qgraph.h"
+
+typedef struct QOSGraphMachine QOSGraphMachine;
+typedef enum QOSEdgeType QOSEdgeType;
+typedef enum QOSNodeType QOSNodeType;
+
+/* callback called when the walk path algorithm found a
+ * valid path
+ */
+typedef void (*QOSTestCallback) (QOSGraphNode *path, int len);
+
+/* edge types*/
+enum QOSEdgeType {
+    QEDGE_CONTAINS,
+    QEDGE_PRODUCES,
+    QEDGE_CONSUMED_BY
+};
+
+/* node types*/
+enum QOSNodeType {
+    QNODE_MACHINE,
+    QNODE_DRIVER,
+    QNODE_INTERFACE,
+    QNODE_TEST
+};
+
+/* Graph Node */
+struct QOSGraphNode {
+    QOSNodeType type;
+    bool available;     /* set by QEMU via QMP, used during graph walk */
+    bool visited;       /* used during graph walk */
+    char *name;         /* used to identify the node */
+    char *command_line; /* used to start QEMU at test execution */
+    union {
+        struct {
+            QOSCreateDriverFunc constructor;
+        } driver;
+        struct {
+            QOSCreateMachineFunc constructor;
+        } machine;
+        struct {
+            QOSTestFunc function;
+            void *arg;
+            QOSBeforeTest before;
+            bool subprocess;
+        } test;
+    } u;
+
+    /**
+     * only used when traversing the path, never rely on that except in the
+     * qos_traverse_graph callback function
+     */
+    QOSGraphEdge *path_edge;
+};
+
+/**
+ * qos_graph_get_node(): returns the node mapped to that @key.
+ * It performs an hash map search O(1)
+ *
+ * Returns: on success: the %QOSGraphNode
+ *          otherwise: #NULL
+ */
+QOSGraphNode *qos_graph_get_node(const char *key);
+
+/**
+ * qos_graph_has_node(): returns #TRUE if the node
+ * has map has a node mapped to that @key.
+ */
+bool qos_graph_has_node(const char *node);
+
+/**
+ * qos_graph_get_node_type(): returns the %QOSNodeType
+ * of the node @node.
+ * It performs an hash map search O(1)
+ * Returns: on success: the %QOSNodeType
+ *          otherwise: #-1
+ */
+QOSNodeType qos_graph_get_node_type(const char *node);
+
+/**
+ * qos_graph_get_node_availability(): returns the availability (boolean)
+ * of the node @node.
+ */
+bool qos_graph_get_node_availability(const char *node);
+
+/**
+ * qos_graph_get_edge(): returns the edge
+ * linking of the node @node with @dest.
+ *
+ * Returns: on success: the %QOSGraphEdge
+ *          otherwise: #NULL
+ */
+QOSGraphEdge *qos_graph_get_edge(const char *node, const char *dest);
+
+/**
+ * qos_graph_edge_get_type(): returns the edge type
+ * of the edge @edge.
+ *
+ * Returns: on success: the %QOSEdgeType
+ *          otherwise: #-1
+ */
+QOSEdgeType qos_graph_edge_get_type(QOSGraphEdge *edge);
+
+/**
+ * qos_graph_edge_get_dest(): returns the name of the node
+ * pointed as destination of edge @edge.
+ *
+ * Returns: on success: the destination
+ *          otherwise: #NULL
+ */
+char *qos_graph_edge_get_dest(QOSGraphEdge *edge);
+
+/**
+ * qos_graph_has_edge(): returns #TRUE if there
+ * exists an edge from @start to @dest.
+ */
+bool qos_graph_has_edge(const char *start, const char *dest);
+
+/**
+ * qos_graph_edge_get_arg(): returns the args assigned
+ * to that @edge.
+ *
+ * Returns: on success: the arg
+ *          otherwise: #NULL
+ */
+void *qos_graph_edge_get_arg(QOSGraphEdge *edge);
+
+/**
+ * qos_graph_edge_get_after_cmd_line(): returns the edge
+ * command line that will be added after all the node arguments
+ * and all the before_cmd_line arguments.
+ *
+ * Returns: on success: the char* arg
+ *          otherwise: #NULL
+ */
+char *qos_graph_edge_get_after_cmd_line(QOSGraphEdge *edge);
+
+/**
+ * qos_graph_edge_get_before_cmd_line(): returns the edge
+ * command line that will be added before the node command
+ * line argument.
+ *
+ * Returns: on success: the char* arg
+ *          otherwise: #NULL
+ */
+char *qos_graph_edge_get_before_cmd_line(QOSGraphEdge *edge);
+
+/**
+ * qos_graph_edge_get_extra_device_opts(): returns the arg
+ * command line that will be added to the node command
+ * line argument.
+ *
+ * Returns: on success: the char* arg
+ *          otherwise: #NULL
+ */
+char *qos_graph_edge_get_extra_device_opts(QOSGraphEdge *edge);
+
+/**
+ * qos_graph_edge_get_name(): returns the name
+ * assigned to the destination node (different only)
+ * if there are multiple devices with the same node name
+ * e.g. a node has two "generic-sdhci", "emmc" and "sdcard"
+ * there will be two edges with edge_name ="emmc" and "sdcard"
+ *
+ * Returns always the char* edge_name
+ */
+char *qos_graph_edge_get_name(QOSGraphEdge *edge);
+
+/**
+ * qos_graph_get_machine(): returns the machine assigned
+ * to that @node name.
+ *
+ * It performs a search only trough the list of machines
+ * (i.e. the QOS_ROOT child).
+ *
+ * Returns: on success: the %QOSGraphNode
+ *          otherwise: #NULL
+ */
+QOSGraphNode *qos_graph_get_machine(const char *node);
+
+/**
+ * qos_graph_has_machine(): returns #TRUE if the node
+ * has map has a node mapped to that @node.
+ */
+bool qos_graph_has_machine(const char *node);
+
+
+/**
+ * qos_print_graph(): walks the graph and prints
+ * all machine-to-test paths.
+ */
+void qos_print_graph(void);
+
+/**
+ * qos_graph_foreach_test_path(): executes the Depth First search
+ * algorithm and applies @fn to all discovered paths.
+ *
+ * See qos_traverse_graph() in qgraph.c for more info on
+ * how it works.
+ */
+void qos_graph_foreach_test_path(QOSTestCallback fn);
+
+/**
+ * qos_get_machine_type(): return QEMU machine type for a machine node.
+ * This function requires every machine @name to be in the form
+ * <arch>/<machine_name>, like "arm/raspi2" or "x86_64/pc".
+ *
+ * The function will validate the format and return a pointer to
+ * @machine to <machine_name>.  For example, when passed "x86_64/pc"
+ * it will return "pc".
+ *
+ * Note that this function *does not* allocate any new string.
+ */
+char *qos_get_machine_type(char *name);
+
+/**
+ * qos_delete_cmd_line(): delete the
+ * command line present in node mapped with key @name.
+ *
+ * This function is called when the QMP query returns a node with
+ * { "abstract" : true } attribute.
+ */
+void qos_delete_cmd_line(const char *name);
+
+/**
+ * qos_graph_node_set_availability(): sets the node identified
+ * by @node with availability @av.
+ */
+void qos_graph_node_set_availability(const char *node, bool av);
+
+#endif

tests/libqtest.h

@@ -598,6 +598,9 @@ static inline QTestState *qtest_start(const char *args)
  */
 static inline void qtest_end(void)
 {
+    if (!global_qtest) {
+        return;
+    }
     qtest_quit(global_qtest);
     global_qtest = NULL;
 }

tests/qos-test.c

+/*
+ * libqos driver framework
+ *
+ * Copyright (c) 2018 Emanuele Giuseppe Esposito <e.emanuelegiuseppe@gmail.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2 as published by the Free Software Foundation.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>
+ */
+
+#include <getopt.h>
+#include "qemu/osdep.h"
+#include "libqtest.h"
+#include "qapi/qmp/qdict.h"
+#include "qapi/qmp/qbool.h"
+#include "qapi/qmp/qstring.h"
+#include "qapi/qmp/qlist.h"
+#include "libqos/malloc.h"
+#include "libqos/qgraph.h"
+#include "libqos/qgraph_internal.h"
+
+static char *old_path;
+
+static void apply_to_node(const char *name, bool is_machine, bool is_abstract)
+{
+    char *machine_name = NULL;
+    if (is_machine) {
+        const char *arch = qtest_get_arch();
+        machine_name = g_strconcat(arch, "/", name, NULL);
+        name = machine_name;
+    }
+    qos_graph_node_set_availability(name, true);
+    if (is_abstract) {
+        qos_delete_cmd_line(name);
+    }
+    g_free(machine_name);
+}
+
+/**
+ * apply_to_qlist(): using QMP queries QEMU for a list of
+ * machines and devices available, and sets the respective node
+ * as true. If a node is found, also all its produced and contained
+ * child are marked available.
+ *
+ * See qos_graph_node_set_availability() for more info
+ */
+static void apply_to_qlist(QList *list, bool is_machine)
+{
+    const QListEntry *p;
+    const char *name;
+    bool abstract;
+    QDict *minfo;
+    QObject *qobj;
+    QString *qstr;
+    QBool *qbool;
+
+    for (p = qlist_first(list); p; p = qlist_next(p)) {
+        minfo = qobject_to(QDict, qlist_entry_obj(p));
+        qobj = qdict_get(minfo, "name");
+        qstr = qobject_to(QString, qobj);
+        name = qstring_get_str(qstr);
+
+        qobj = qdict_get(minfo, "abstract");
+        if (qobj) {
+            qbool = qobject_to(QBool, qobj);
+            abstract = qbool_get_bool(qbool);
+        } else {
+            abstract = false;
+        }
+
+        apply_to_node(name, is_machine, abstract);
+        qobj = qdict_get(minfo, "alias");
+        if (qobj) {
+            qstr = qobject_to(QString, qobj);
+            name = qstring_get_str(qstr);
+            apply_to_node(name, is_machine, abstract);
+        }
+    }
+}
+
+/**
+ * qos_set_machines_devices_available(): sets availability of qgraph
+ * machines and devices.
+ *
+ * This function firstly starts QEMU with "-machine none" option,
+ * and then executes the QMP protocol asking for the list of devices
+ * and machines available.
+ *
+ * for each of these items, it looks up the corresponding qgraph node,
+ * setting it as available. The list currently returns all devices that
+ * are either machines or QEDGE_CONSUMED_BY other nodes.
+ * Therefore, in order to mark all other nodes, it recursively sets
+ * all its QEDGE_CONTAINS and QEDGE_PRODUCES child as available too.
+ */
+static void qos_set_machines_devices_available(void)
+{
+    QDict *response;
+    QDict *args = qdict_new();
+    QList *list;
+
+    qtest_start("-machine none");
+    response = qmp("{ 'execute': 'query-machines' }");
+    list = qdict_get_qlist(response, "return");
+
+    apply_to_qlist(list, true);
+
+    qobject_unref(response);
+
+    qdict_put_bool(args, "abstract", true);
+    qdict_put_str(args, "implements", "device");
+
+    response = qmp("{'execute': 'qom-list-types',"
+                   " 'arguments': %p }", args);
+    g_assert(qdict_haskey(response, "return"));
+    list = qdict_get_qlist(response, "return");
+
+    apply_to_qlist(list, false);
+
+    qtest_end();
+    qobject_unref(response);
+}
+
+static QGuestAllocator *get_machine_allocator(QOSGraphObject *obj)
+{
+    return obj->get_driver(obj, "memory");
+}
+
+static void restart_qemu_or_continue(char *path)
+{
+    /* compares the current command line with the
+     * one previously executed: if they are the same,
+     * don't restart QEMU, if they differ, stop previous
+     * QEMU subprocess (if active) and start over with
+     * the new command line
+     */
+    if (g_strcmp0(old_path, path)) {
+        qtest_end();
+        qos_invalidate_command_line();
+        old_path = g_strdup(path);
+        qtest_start(path);
+    } else { /* if cmd line is the same, reset the guest */
+        qobject_unref(qmp("{ 'execute': 'system_reset' }"));
+        qmp_eventwait("RESET");
+    }
+}
+
+void qos_invalidate_command_line(void)
+{
+    g_free(old_path);
+    old_path = NULL;
+}
+
+/**
+ * allocate_objects(): given an array of nodes @arg,
+ * walks the path invoking all constructors and
+ * passing the corresponding parameter in order to
+ * continue the objects allocation.
+ * Once the test is reached, return the object it consumes.
+ *
+ * Since the machine and QEDGE_CONSUMED_BY nodes allocate
+ * memory in the constructor, g_test_queue_destroy is used so
+ * that after execution they can be safely free'd.  (The test's
+ * ->before callback is also welcome to use g_test_queue_destroy).
+ *
+ * Note: as specified in walk_path() too, @arg is an array of
+ * char *, where arg[0] is a pointer to the command line
+ * string that will be used to properly start QEMU when executing
+ * the test, and the remaining elements represent the actual objects
+ * that will be allocated.
+ */
+static void *allocate_objects(QTestState *qts, char **path, QGuestAllocator **p_alloc)
+{
+    int current = 0;
+    QGuestAllocator *alloc;
+    QOSGraphObject *parent = NULL;
+    QOSGraphEdge *edge;
+    QOSGraphNode *node;
+    void *edge_arg;
+    void *obj;
+
+    node = qos_graph_get_node(path[current]);
+    g_assert(node->type == QNODE_MACHINE);
+
+    obj = qos_machine_new(node, qts);
+    qos_object_queue_destroy(obj);
+
+    alloc = get_machine_allocator(obj);
+    if (p_alloc) {
+        *p_alloc = alloc;
+    }
+
+    for (;;) {
+        if (node->type != QNODE_INTERFACE) {
+            qos_object_start_hw(obj);
+            parent = obj;
+        }
+
+        /* follow edge and get object for next node constructor */
+        current++;
+        edge = qos_graph_get_edge(path[current - 1], path[current]);
+        node = qos_graph_get_node(path[current]);
+
+        if (node->type == QNODE_TEST) {
+            g_assert(qos_graph_edge_get_type(edge) == QEDGE_CONSUMED_BY);
+            return obj;
+        }
+
+        switch (qos_graph_edge_get_type(edge)) {
+        case QEDGE_PRODUCES:
+            obj = parent->get_driver(parent, path[current]);
+            break;
+
+        case QEDGE_CONSUMED_BY:
+            edge_arg = qos_graph_edge_get_arg(edge);
+            obj = qos_driver_new(node, obj, alloc, edge_arg);
+            qos_object_queue_destroy(obj);
+            break;
+
+        case QEDGE_CONTAINS:
+            obj = parent->get_device(parent, path[current]);
+            break;
+        }
+    }
+}
+
+/* The argument to run_one_test, which is the test function that is registered
+ * with GTest, is a vector of strings.  The first item is the initial command
+ * line (before it is modified by the test's "before" function), the remaining
+ * items are node names forming the path to the test node.
+ */
+static char **current_path;
+
+const char *qos_get_current_command_line(void)
+{
+    return current_path[0];
+}
+
+void *qos_allocate_objects(QTestState *qts, QGuestAllocator **p_alloc)
+{
+    return allocate_objects(qts, current_path + 1, p_alloc);
+}
+
+/**
+ * run_one_test(): given an array of nodes @arg,
+ * walks the path invoking all constructors and
+ * passing the corresponding parameter in order to
+ * continue the objects allocation.
+ * Once the test is reached, its function is executed.
+ *
+ * Since the machine and QEDGE_CONSUMED_BY nodes allocate
+ * memory in the constructor, g_test_queue_destroy is used so
+ * that after execution they can be safely free'd.  The test's
+ * ->before callback is also welcome to use g_test_queue_destroy.
+ *
+ * Note: as specified in walk_path() too, @arg is an array of
+ * char *, where arg[0] is a pointer to the command line
+ * string that will be used to properly start QEMU when executing
+ * the test, and the remaining elements represent the actual objects
+ * that will be allocated.
+ *
+ * The order of execution is the following:
+ * 1) @before test function as defined in the given QOSGraphTestOptions
+ * 2) start QEMU
+ * 3) call all nodes constructor and get_driver/get_device depending on edge,
+ *    start the hardware (*_device_enable functions)
+ * 4) start test
+ */
+static void run_one_test(const void *arg)
+{
+    QOSGraphNode *test_node;
+    QGuestAllocator *alloc = NULL;
+    void *obj;
+    char **path = (char **) arg;
+    GString *cmd_line = g_string_new(path[0]);
+    void *test_arg;
+
+    /* Before test */
+    current_path = path;
+    test_node = qos_graph_get_node(path[(g_strv_length(path) - 1)]);
+    test_arg = test_node->u.test.arg;
+    if (test_node->u.test.before) {
+        test_arg = test_node->u.test.before(cmd_line, test_arg);
+    }
+
+    restart_qemu_or_continue(cmd_line->str);
+    g_string_free(cmd_line, true);
+
+    obj = qos_allocate_objects(global_qtest, &alloc);
+    test_node->u.test.function(obj, test_arg, alloc);
+}
+
+static void subprocess_run_one_test(const void *arg)
+{
+    const gchar *path = arg;
+    g_test_trap_subprocess(path, 0, 0);
+    g_test_trap_assert_passed();
+}
+
+/*
+ * in this function, 2 path will be built:
+ * path_str, a one-string path (ex "pc/i440FX-pcihost/...")
+ * path_vec, a string-array path (ex [0] = "pc", [1] = "i440FX-pcihost").
+ *
+ * path_str will be only used to build the test name, and won't need the
+ * architecture name at beginning, since it will be added by qtest_add_func().
+ *
+ * path_vec is used to allocate all constructors of the path nodes.
+ * Each name in this array except position 0 must correspond to a valid
+ * QOSGraphNode name.
+ * Position 0 is special, initially contains just the <machine> name of
+ * the node, (ex for "x86_64/pc" it will be "pc"), used to build the test
+ * path (see below). After it will contain the command line used to start
+ * qemu with all required devices.
+ *
+ * Note that the machine node name must be with format <arch>/<machine>
+ * (ex "x86_64/pc"), because it will identify the node "x86_64/pc"
+ * and start QEMU with "-M pc". For this reason,
+ * when building path_str, path_vec
+ * initially contains the <machine> at position 0 ("pc"),
+ * and the node name at position 1 (<arch>/<machine>)
+ * ("x86_64/pc"), followed by the rest of the nodes.
+ */
+static void walk_path(QOSGraphNode *orig_path, int len)
+{
+    QOSGraphNode *path;
+    QOSGraphEdge *edge;
+
+    /* etype set to QEDGE_CONSUMED_BY so that machine can add to the command line */
+    QOSEdgeType etype = QEDGE_CONSUMED_BY;
+
+    /* twice QOS_PATH_MAX_ELEMENT_SIZE since each edge can have its arg */
+    char **path_vec = g_new0(char *, (QOS_PATH_MAX_ELEMENT_SIZE * 2));
+    int path_vec_size = 0;
+
+    char *after_cmd = NULL, *before_cmd = NULL, *after_device = NULL;
+    char *node_name = orig_path->name, *path_str;
+
+    GString *cmd_line = g_string_new("");
+    GString *cmd_line2 = g_string_new("");
+
+    path = qos_graph_get_node(node_name); /* root */
+    node_name = qos_graph_edge_get_dest(path->path_edge); /* machine name */
+
+    path_vec[path_vec_size++] = node_name;
+    path_vec[path_vec_size++] = qos_get_machine_type(node_name);
+
+    for (;;) {
+        path = qos_graph_get_node(node_name);
+        if (!path->path_edge) {
+            break;
+        }
+
+        node_name = qos_graph_edge_get_dest(path->path_edge);
+
+        /* append node command line + previous edge command line */
+        if (path->command_line && etype == QEDGE_CONSUMED_BY) {
+            g_string_append(cmd_line, path->command_line);
+            if (after_device) {
+                g_string_append(cmd_line, after_device);
+            }
+        }
+
+        path_vec[path_vec_size++] = qos_graph_edge_get_name(path->path_edge);
+        /* detect if edge has command line args */
+        after_cmd = qos_graph_edge_get_after_cmd_line(path->path_edge);
+        after_device = qos_graph_edge_get_extra_device_opts(path->path_edge);
+        before_cmd = qos_graph_edge_get_before_cmd_line(path->path_edge);
+        edge = qos_graph_get_edge(path->name, node_name);
+        etype = qos_graph_edge_get_type(edge);
+
+        if (before_cmd) {
+            g_string_append(cmd_line, before_cmd);
+        }
+        if (after_cmd) {
+            g_string_append(cmd_line2, after_cmd);
+        }
+    }
+
+    path_vec[path_vec_size++] = NULL;
+    if (after_device) {
+        g_string_append(cmd_line, after_device);
+    }
+    g_string_append(cmd_line, cmd_line2->str);
+    g_string_free(cmd_line2, true);
+
+    /* here position 0 has <arch>/<machine>, position 1 has <machine>.
+     * The path must not have the <arch>, qtest_add_data_func adds it.
+     */
+    path_str = g_strjoinv("/", path_vec + 1);
+
+    /* put arch/machine in position 1 so run_one_test can do its work
+     * and add the command line at position 0.
+     */
+    path_vec[1] = path_vec[0];
+    path_vec[0] = g_string_free(cmd_line, false);
+
+    if (path->u.test.subprocess) {
+        gchar *subprocess_path = g_strdup_printf("/%s/%s/subprocess",
+                                                 qtest_get_arch(), path_str);
+        qtest_add_data_func(path_str, subprocess_path, subprocess_run_one_test);
+        g_test_add_data_func(subprocess_path, path_vec, run_one_test);
+    } else {
+        qtest_add_data_func(path_str, path_vec, run_one_test);
+    }
+
+    g_free(path_str);
+}
+
+
+
+/**
+ * main(): heart of the qgraph framework.
+ *
+ * - Initializes the glib test framework
+ * - Creates the graph by invoking the various _init constructors
+ * - Starts QEMU to mark the available devices
+ * - Walks the graph, and each path is added to
+ *   the glib test framework (walk_path)
+ * - Runs the tests, calling allocate_object() and allocating the
+ *   machine/drivers/test objects
+ * - Cleans up everything
+ */
+int main(int argc, char **argv)
+{
+    g_test_init(&argc, &argv, NULL);
+    qos_graph_init();
+    module_call_init(MODULE_INIT_QOM);
+    module_call_init(MODULE_INIT_LIBQOS);
+    qos_set_machines_devices_available();
+
+    qos_graph_foreach_test_path(walk_path);
+    g_test_run();
+    qtest_end();
+    qos_graph_destroy();
+    g_free(old_path);
+    return 0;
+}

tests/test-qgraph.c

+/*
+ * libqos driver framework
+ *
+ * Copyright (c) 2018 Emanuele Giuseppe Esposito <e.emanuelegiuseppe@gmail.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2 as published by the Free Software Foundation.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>
+ */
+
+#include "qemu/osdep.h"
+#include "libqtest.h"
+#include "libqos/qgraph.h"
+#include "libqos/qgraph_internal.h"
+
+#define MACHINE_PC "x86_64/pc"
+#define MACHINE_RASPI2 "arm/raspi2"
+#define I440FX "i440FX-pcihost"
+#define PCIBUS_PC "pcibus-pc"
+#define SDHCI "sdhci"
+#define PCIBUS "pci-bus"
+#define SDHCI_PCI "sdhci-pci"
+#define SDHCI_MM "generic-sdhci"
+#define REGISTER_TEST "register-test"
+
+int npath;
+
+static void *machinefunct(QTestState *qts)
+{
+    return NULL;
+}
+
+static void *driverfunct(void *obj, QGuestAllocator *machine, void *arg)
+{
+    return NULL;
+}
+
+static void testfunct(void *obj, void *arg, QGuestAllocator *alloc)
+{
+    return;
+}
+
+static void check_interface(const char *interface)
+{
+    g_assert_cmpint(qos_graph_has_machine(interface), ==, FALSE);
+    g_assert_nonnull(qos_graph_get_node(interface));
+    g_assert_cmpint(qos_graph_has_node(interface), ==, TRUE);
+    g_assert_cmpint(qos_graph_get_node_type(interface), ==, QNODE_INTERFACE);
+    qos_graph_node_set_availability(interface, TRUE);
+    g_assert_cmpint(qos_graph_get_node_availability(interface), ==, TRUE);
+}
+
+static void check_machine(const char *machine)
+{
+    qos_node_create_machine(machine, machinefunct);
+    g_assert_nonnull(qos_graph_get_machine(machine));
+    g_assert_cmpint(qos_graph_has_machine(machine), ==, TRUE);
+    g_assert_nonnull(qos_graph_get_node(machine));
+    g_assert_cmpint(qos_graph_get_node_availability(machine), ==, FALSE);
+    qos_graph_node_set_availability(machine, TRUE);
+    g_assert_cmpint(qos_graph_get_node_availability(machine), ==, TRUE);
+    g_assert_cmpint(qos_graph_has_node(machine), ==, TRUE);
+    g_assert_cmpint(qos_graph_get_node_type(machine), ==, QNODE_MACHINE);
+}
+
+static void check_contains(const char *machine, const char *driver)
+{
+    QOSGraphEdge *edge;
+    qos_node_contains(machine, driver, NULL);
+
+    edge = qos_graph_get_edge(machine, driver);
+    g_assert_nonnull(edge);
+    g_assert_cmpint(qos_graph_edge_get_type(edge), ==, QEDGE_CONTAINS);
+    g_assert_cmpint(qos_graph_has_edge(machine, driver), ==, TRUE);
+}
+
+static void check_produces(const char *machine, const char *interface)
+{
+    QOSGraphEdge *edge;
+
+    qos_node_produces(machine, interface);
+    check_interface(interface);
+    edge = qos_graph_get_edge(machine, interface);
+    g_assert_nonnull(edge);
+    g_assert_cmpint(qos_graph_edge_get_type(edge), ==,
+                    QEDGE_PRODUCES);
+    g_assert_cmpint(qos_graph_has_edge(machine, interface), ==, TRUE);
+}
+
+static void check_consumes(const char *driver, const char *interface)
+{
+    QOSGraphEdge *edge;
+
+    qos_node_consumes(driver, interface, NULL);
+    check_interface(interface);
+    edge = qos_graph_get_edge(interface, driver);
+    g_assert_nonnull(edge);
+    g_assert_cmpint(qos_graph_edge_get_type(edge), ==, QEDGE_CONSUMED_BY);
+    g_assert_cmpint(qos_graph_has_edge(interface, driver), ==, TRUE);
+}
+
+static void check_driver(const char *driver)
+{
+    qos_node_create_driver(driver, driverfunct);
+    g_assert_cmpint(qos_graph_has_machine(driver), ==, FALSE);
+    g_assert_nonnull(qos_graph_get_node(driver));
+    g_assert_cmpint(qos_graph_has_node(driver), ==, TRUE);
+    g_assert_cmpint(qos_graph_get_node_type(driver), ==, QNODE_DRIVER);
+    g_assert_cmpint(qos_graph_get_node_availability(driver), ==, FALSE);
+    qos_graph_node_set_availability(driver, TRUE);
+    g_assert_cmpint(qos_graph_get_node_availability(driver), ==, TRUE);
+}
+
+static void check_test(const char *test, const char *interface)
+{
+    QOSGraphEdge *edge;
+    const char *full_name = g_strdup_printf("%s-tests/%s", interface, test);
+
+    qos_add_test(test, interface, testfunct, NULL);
+    g_assert_cmpint(qos_graph_has_machine(test), ==, FALSE);
+    g_assert_cmpint(qos_graph_has_machine(full_name), ==, FALSE);
+    g_assert_nonnull(qos_graph_get_node(full_name));
+    g_assert_cmpint(qos_graph_has_node(full_name), ==, TRUE);
+    g_assert_cmpint(qos_graph_get_node_type(full_name), ==, QNODE_TEST);
+    edge = qos_graph_get_edge(interface, full_name);
+    g_assert_nonnull(edge);
+    g_assert_cmpint(qos_graph_edge_get_type(edge), ==,
+                    QEDGE_CONSUMED_BY);
+    g_assert_cmpint(qos_graph_has_edge(interface, full_name), ==, TRUE);
+    g_assert_cmpint(qos_graph_get_node_availability(full_name), ==, TRUE);
+    qos_graph_node_set_availability(full_name, FALSE);
+    g_assert_cmpint(qos_graph_get_node_availability(full_name), ==, FALSE);
+}
+
+static void count_each_test(QOSGraphNode *path, int len)
+{
+    npath++;
+}
+
+static void check_leaf_discovered(int n)
+{
+    npath = 0;
+    qos_graph_foreach_test_path(count_each_test);
+    g_assert_cmpint(n, ==, npath);
+}
+
+/* G_Test functions */
+
+static void init_nop(void)
+{
+    qos_graph_init();
+    qos_graph_destroy();
+}
+
+static void test_machine(void)
+{
+    qos_graph_init();
+    check_machine(MACHINE_PC);
+    qos_graph_destroy();
+}
+
+static void test_contains(void)
+{
+    qos_graph_init();
+    check_contains(MACHINE_PC, I440FX);
+    g_assert_null(qos_graph_get_machine(MACHINE_PC));
+    g_assert_null(qos_graph_get_machine(I440FX));
+    g_assert_null(qos_graph_get_node(MACHINE_PC));
+    g_assert_null(qos_graph_get_node(I440FX));
+    qos_graph_destroy();
+}
+
+static void test_multiple_contains(void)
+{
+    qos_graph_init();
+    check_contains(MACHINE_PC, I440FX);
+    check_contains(MACHINE_PC, PCIBUS_PC);
+    qos_graph_destroy();
+}
+
+static void test_produces(void)
+{
+    qos_graph_init();
+    check_produces(MACHINE_PC, I440FX);
+    g_assert_null(qos_graph_get_machine(MACHINE_PC));
+    g_assert_null(qos_graph_get_machine(I440FX));
+    g_assert_null(qos_graph_get_node(MACHINE_PC));
+    g_assert_nonnull(qos_graph_get_node(I440FX));
+    qos_graph_destroy();
+}
+
+static void test_multiple_produces(void)
+{
+    qos_graph_init();
+    check_produces(MACHINE_PC, I440FX);
+    check_produces(MACHINE_PC, PCIBUS_PC);
+    qos_graph_destroy();
+}
+
+static void test_consumes(void)
+{
+    qos_graph_init();
+    check_consumes(I440FX, SDHCI);
+    g_assert_null(qos_graph_get_machine(I440FX));
+    g_assert_null(qos_graph_get_machine(SDHCI));
+    g_assert_null(qos_graph_get_node(I440FX));
+    g_assert_nonnull(qos_graph_get_node(SDHCI));
+    qos_graph_destroy();
+}
+
+static void test_multiple_consumes(void)
+{
+    qos_graph_init();
+    check_consumes(I440FX, SDHCI);
+    check_consumes(PCIBUS_PC, SDHCI);
+    qos_graph_destroy();
+}
+
+static void test_driver(void)
+{
+    qos_graph_init();
+    check_driver(I440FX);
+    qos_graph_destroy();
+}
+
+static void test_test(void)
+{
+    qos_graph_init();
+    check_test(REGISTER_TEST, SDHCI);
+    qos_graph_destroy();
+}
+
+static void test_machine_contains_driver(void)
+{
+    qos_graph_init();
+    check_machine(MACHINE_PC);
+    check_driver(I440FX);
+    check_contains(MACHINE_PC, I440FX);
+    qos_graph_destroy();
+}
+
+static void test_driver_contains_driver(void)
+{
+    qos_graph_init();
+    check_driver(PCIBUS_PC);
+    check_driver(I440FX);
+    check_contains(PCIBUS_PC, I440FX);
+    qos_graph_destroy();
+}
+
+static void test_machine_produces_interface(void)
+{
+    qos_graph_init();
+    check_machine(MACHINE_PC);
+    check_produces(MACHINE_PC, SDHCI);
+    qos_graph_destroy();
+}
+
+static void test_driver_produces_interface(void)
+{
+    qos_graph_init();
+    check_driver(I440FX);
+    check_produces(I440FX, SDHCI);
+    qos_graph_destroy();
+}
+
+static void test_machine_consumes_interface(void)
+{
+    qos_graph_init();
+    check_machine(MACHINE_PC);
+    check_consumes(MACHINE_PC, SDHCI);
+    qos_graph_destroy();
+}
+
+static void test_driver_consumes_interface(void)
+{
+    qos_graph_init();
+    check_driver(I440FX);
+    check_consumes(I440FX, SDHCI);
+    qos_graph_destroy();
+}
+
+static void test_test_consumes_interface(void)
+{
+    qos_graph_init();
+    check_test(REGISTER_TEST, SDHCI);
+    qos_graph_destroy();
+}
+
+static void test_full_sample(void)
+{
+    qos_graph_init();
+    check_machine(MACHINE_PC);
+    check_contains(MACHINE_PC, I440FX);
+    check_driver(I440FX);
+    check_driver(PCIBUS_PC);
+    check_contains(I440FX, PCIBUS_PC);
+    check_produces(PCIBUS_PC, PCIBUS);
+    check_driver(SDHCI_PCI);
+    qos_node_consumes(SDHCI_PCI, PCIBUS, NULL);
+    check_produces(SDHCI_PCI, SDHCI);
+    check_driver(SDHCI_MM);
+    check_produces(SDHCI_MM, SDHCI);
+    qos_add_test(REGISTER_TEST, SDHCI, testfunct, NULL);
+    check_leaf_discovered(1);
+    qos_print_graph();
+    qos_graph_destroy();
+}
+
+static void test_full_sample_raspi(void)
+{
+    qos_graph_init();
+    check_machine(MACHINE_PC);
+    check_contains(MACHINE_PC, I440FX);
+    check_driver(I440FX);
+    check_driver(PCIBUS_PC);
+    check_contains(I440FX, PCIBUS_PC);
+    check_produces(PCIBUS_PC, PCIBUS);
+    check_driver(SDHCI_PCI);
+    qos_node_consumes(SDHCI_PCI, PCIBUS, NULL);
+    check_produces(SDHCI_PCI, SDHCI);
+    check_machine(MACHINE_RASPI2);
+    check_contains(MACHINE_RASPI2, SDHCI_MM);
+    check_driver(SDHCI_MM);
+    check_produces(SDHCI_MM, SDHCI);
+    qos_add_test(REGISTER_TEST, SDHCI, testfunct, NULL);
+    qos_print_graph();
+    check_leaf_discovered(2);
+    qos_graph_destroy();
+}
+
+static void test_cycle(void)
+{
+    qos_graph_init();
+    check_machine(MACHINE_RASPI2);
+    check_driver("B");
+    check_driver("C");
+    check_driver("D");
+    check_contains(MACHINE_RASPI2, "B");
+    check_contains("B", "C");
+    check_contains("C", "D");
+    check_contains("D", MACHINE_RASPI2);
+    check_leaf_discovered(0);
+    qos_print_graph();
+    qos_graph_destroy();
+}
+
+static void test_two_test_same_interface(void)
+{
+    qos_graph_init();
+    check_machine(MACHINE_RASPI2);
+    check_produces(MACHINE_RASPI2, "B");
+    qos_add_test("C", "B", testfunct, NULL);
+    qos_add_test("D", "B", testfunct, NULL);
+    check_contains(MACHINE_RASPI2, "B");
+    check_leaf_discovered(4);
+    qos_print_graph();
+    qos_graph_destroy();
+}
+
+static void test_test_in_path(void)
+{
+    qos_graph_init();
+    check_machine(MACHINE_RASPI2);
+    check_produces(MACHINE_RASPI2, "B");
+    qos_add_test("C", "B", testfunct, NULL);
+    check_driver("D");
+    check_consumes("D", "B");
+    check_produces("D", "E");
+    qos_add_test("F", "E", testfunct, NULL);
+    check_leaf_discovered(2);
+    qos_print_graph();
+    qos_graph_destroy();
+}
+
+static void test_double_edge(void)
+{
+    qos_graph_init();
+    check_machine(MACHINE_RASPI2);
+    check_produces("B", "C");
+    qos_node_consumes("C", "B", NULL);
+    qos_add_test("D", "C", testfunct, NULL);
+    check_contains(MACHINE_RASPI2, "B");
+    qos_print_graph();
+    qos_graph_destroy();
+}
+
+int main(int argc, char **argv)
+{
+    g_test_init(&argc, &argv, NULL);
+    g_test_add_func("/qgraph/init_nop", init_nop);
+    g_test_add_func("/qgraph/test_machine", test_machine);
+    g_test_add_func("/qgraph/test_contains", test_contains);
+    g_test_add_func("/qgraph/test_multiple_contains", test_multiple_contains);
+    g_test_add_func("/qgraph/test_produces", test_produces);
+    g_test_add_func("/qgraph/test_multiple_produces", test_multiple_produces);
+    g_test_add_func("/qgraph/test_consumes", test_consumes);
+    g_test_add_func("/qgraph/test_multiple_consumes",
+                    test_multiple_consumes);
+    g_test_add_func("/qgraph/test_driver", test_driver);
+    g_test_add_func("/qgraph/test_test", test_test);
+    g_test_add_func("/qgraph/test_machine_contains_driver",
+                    test_machine_contains_driver);
+    g_test_add_func("/qgraph/test_driver_contains_driver",
+                    test_driver_contains_driver);
+    g_test_add_func("/qgraph/test_machine_produces_interface",
+                    test_machine_produces_interface);
+    g_test_add_func("/qgraph/test_driver_produces_interface",
+                    test_driver_produces_interface);
+    g_test_add_func("/qgraph/test_machine_consumes_interface",
+                    test_machine_consumes_interface);
+    g_test_add_func("/qgraph/test_driver_consumes_interface",
+                    test_driver_consumes_interface);
+    g_test_add_func("/qgraph/test_test_consumes_interface",
+                    test_test_consumes_interface);
+    g_test_add_func("/qgraph/test_full_sample", test_full_sample);
+    g_test_add_func("/qgraph/test_full_sample_raspi", test_full_sample_raspi);
+    g_test_add_func("/qgraph/test_cycle", test_cycle);
+    g_test_add_func("/qgraph/test_two_test_same_interface",
+                    test_two_test_same_interface);
+    g_test_add_func("/qgraph/test_test_in_path", test_test_in_path);
+    g_test_add_func("/qgraph/test_double_edge", test_double_edge);
+
+    g_test_run();
+    return 0;
+}