fuzz: add datadir for oss-fuzz compatability

This allows us to keep pc-bios in executable_dir/pc-bios, rather than
executable_dir/../pc-bios, which is incompatible with oss-fuzz' file
structure.

Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Message-id: 20200512030133.29896-2-alxndr@bu.edu
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

include/sysemu/sysemu.h

@@ -15,6 +15,8 @@ extern const char *qemu_name;
 extern QemuUUID qemu_uuid;
 extern bool qemu_uuid_set;
 
+void qemu_add_data_dir(const char *path);
+
 void qemu_add_exit_notifier(Notifier *notify);
 void qemu_remove_exit_notifier(Notifier *notify);
 

softmmu/vl.c

@@ -1993,7 +1993,7 @@ char *qemu_find_file(int type, const char *name)
     return NULL;
 }
 
-static void qemu_add_data_dir(const char *path)
+void qemu_add_data_dir(const char *path)
 {
     int i;
 

tests/qtest/fuzz/fuzz.c

@@ -137,6 +137,7 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp)
 {
 
     char *target_name;
+    char *dir;
 
     /* Initialize qgraph and modules */
     qos_graph_init();
@@ -147,6 +148,20 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp)
     target_name = strstr(**argv, "-target-");
     if (target_name) {        /* The binary name specifies the target */
         target_name += strlen("-target-");
+        /*
+         * With oss-fuzz, the executable is kept in the root of a directory (we
+         * cannot assume the path). All data (including bios binaries) must be
+         * in the same dir, or a subdir. Thus, we cannot place the pc-bios so
+         * that it would be in exec_dir/../pc-bios.
+         * As a workaround, oss-fuzz allows us to use argv[0] to get the
+         * location of the executable. Using this we add exec_dir/pc-bios to
+         * the datadirs.
+         */
+        dir = g_build_filename(g_path_get_dirname(**argv), "pc-bios", NULL);
+        if (g_file_test(dir, G_FILE_TEST_IS_DIR)) {
+            qemu_add_data_dir(dir);
+        }
+        g_free(dir);
     } else if (*argc > 1) {  /* The target is specified as an argument */
         target_name = (*argv)[1];
         if (!strstr(target_name, "--fuzz-target=")) {