fsdev: improve error handling of backend opts parsing

This patch changes some error messages in the backend opts parsing
code and convert backends to propagate QEMU Error objects instead
of calling error_report().

Signed-off-by: Greg Kurz <groug@kaod.org>

fsdev/file-op-9p.h

@@ -103,7 +103,7 @@ void cred_init(FsCred *);
 
 struct FileOperations
 {
-    int (*parse_opts)(QemuOpts *, FsDriverEntry *);
+    int (*parse_opts)(QemuOpts *, FsDriverEntry *, Error **errp);
     int (*init)(FsContext *);
     void (*cleanup)(FsContext *);
     int (*lstat)(FsContext *, V9fsPath *, struct stat *);

fsdev/qemu-fsdev.c

@@ -37,6 +37,7 @@ int qemu_fsdev_add(QemuOpts *opts)
     const char *fsdriver = qemu_opt_get(opts, "fsdriver");
     const char *writeout = qemu_opt_get(opts, "writeout");
     bool ro = qemu_opt_get_bool(opts, "readonly", 0);
+    Error *local_err = NULL;
 
     if (!fsdev_id) {
         error_report("fsdev: No id specified");
@@ -74,7 +75,8 @@ int qemu_fsdev_add(QemuOpts *opts)
     }
 
     if (fsle->fse.ops->parse_opts) {
-        if (fsle->fse.ops->parse_opts(opts, &fsle->fse)) {
+        if (fsle->fse.ops->parse_opts(opts, &fsle->fse, &local_err)) {
+            error_report_err(local_err);
             g_free(fsle->fse.fsdev_id);
             g_free(fsle);
             return -1;

hw/9pfs/9p-handle.c

@@ -652,7 +652,7 @@ static void handle_cleanup(FsContext *ctx)
     g_free(data);
 }
 
-static int handle_parse_opts(QemuOpts *opts, FsDriverEntry *fse)
+static int handle_parse_opts(QemuOpts *opts, FsDriverEntry *fse, Error **errp)
 {
     const char *sec_model = qemu_opt_get(opts, "security_model");
     const char *path = qemu_opt_get(opts, "path");

hw/9pfs/9p-local.c

@@ -1459,16 +1459,21 @@ static void local_cleanup(FsContext *ctx)
     g_free(data);
 }
 
-static int local_parse_opts(QemuOpts *opts, FsDriverEntry *fse)
+static void error_append_security_model_hint(Error **errp)
+{
+    error_append_hint(errp, "Valid options are: security_model="
+                      "[passthrough|mapped-xattr|mapped-file|none]\n");
+}
+
+static int local_parse_opts(QemuOpts *opts, FsDriverEntry *fse, Error **errp)
 {
     const char *sec_model = qemu_opt_get(opts, "security_model");
     const char *path = qemu_opt_get(opts, "path");
-    Error *err = NULL;
+    Error *local_err = NULL;
 
     if (!sec_model) {
-        error_report("Security model not specified, local fs needs security model");
-        error_printf("valid options are:"
-                     "\tsecurity_model=[passthrough|mapped-xattr|mapped-file|none]\n");
+        error_setg(errp, "security_model property not set");
+        error_append_security_model_hint(errp);
         return -1;
     }
 
@@ -1482,20 +1487,20 @@ static int local_parse_opts(QemuOpts *opts, FsDriverEntry *fse)
     } else if (!strcmp(sec_model, "mapped-file")) {
         fse->export_flags |= V9FS_SM_MAPPED_FILE;
     } else {
-        error_report("Invalid security model %s specified", sec_model);
-        error_printf("valid options are:"
-                     "\t[passthrough|mapped-xattr|mapped-file|none]\n");
+        error_setg(errp, "invalid security_model property '%s'", sec_model);
+        error_append_security_model_hint(errp);
         return -1;
     }
 
     if (!path) {
-        error_report("fsdev: No path specified");
+        error_setg(errp, "path property not set");
         return -1;
     }
 
-    fsdev_throttle_parse_opts(opts, &fse->fst, &err);
-    if (err) {
-        error_reportf_err(err, "Throttle configuration is not valid: ");
+    fsdev_throttle_parse_opts(opts, &fse->fst, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        error_prepend(errp, "invalid throttle configuration: ");
         return -1;
     }
 
@@ -1507,11 +1512,11 @@ static int local_parse_opts(QemuOpts *opts, FsDriverEntry *fse)
             qemu_opt_get_number(opts, "dmode", SM_LOCAL_DIR_MODE_BITS) & 0777;
     } else {
         if (qemu_opt_find(opts, "fmode")) {
-            error_report("fmode is only valid for mapped 9p modes");
+            error_setg(errp, "fmode is only valid for mapped security modes");
             return -1;
         }
         if (qemu_opt_find(opts, "dmode")) {
-            error_report("dmode is only valid for mapped 9p modes");
+            error_setg(errp, "dmode is only valid for mapped security modes");
             return -1;
         }
     }

hw/9pfs/9p-proxy.c

@@ -1111,17 +1111,27 @@ static int connect_namedsocket(const char *path)
     return sockfd;
 }
 
-static int proxy_parse_opts(QemuOpts *opts, FsDriverEntry *fs)
+static void error_append_socket_sockfd_hint(Error **errp)
+{
+    error_append_hint(errp, "Either specify socket=/some/path where /some/path"
+                      " points to a listening AF_UNIX socket or sock_fd=fd"
+                      " where fd is a file descriptor to a connected AF_UNIX"
+                      " socket\n");
+}
+
+static int proxy_parse_opts(QemuOpts *opts, FsDriverEntry *fs, Error **errp)
 {
     const char *socket = qemu_opt_get(opts, "socket");
     const char *sock_fd = qemu_opt_get(opts, "sock_fd");
 
     if (!socket && !sock_fd) {
-        error_report("Must specify either socket or sock_fd");
+        error_setg(errp, "both socket and sock_fd properties are missing");
+        error_append_socket_sockfd_hint(errp);
         return -1;
     }
     if (socket && sock_fd) {
-        error_report("Both socket and sock_fd options specified");
+        error_setg(errp, "both socket and sock_fd properties are set");
+        error_append_socket_sockfd_hint(errp);
         return -1;
     }
     if (socket) {