Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging

Block layer patches:

- qemu-storage-daemon: Remove QemuOpts from --object parser
- monitor: Fix order in monitor_cleanup()
- Deprecate the sheepdog block driver

# gpg: Signature made Thu 15 Oct 2020 15:48:10 BST
# gpg:                using RSA key DC3DEB159A9AF95D3D7456FE7F09B272C88F2FD6
# gpg:                issuer "kwolf@redhat.com"
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>" [full]
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74  56FE 7F09 B272 C88F 2FD6

* remotes/kevin/tags/for-upstream:
  block: deprecate the sheepdog block driver
  block: drop moderated sheepdog mailing list from MAINTAINERS file
  monitor: Fix order in monitor_cleanup()
  qemu-storage-daemon: Remove QemuOpts from --object parser
  qom: Add user_creatable_print_help_from_qdict()
  qom: Factor out helpers from user_creatable_print_help()
  keyval: Parse help options
  keyval: Fix parsing of ',' in value of implied key
  test-keyval: Demonstrate misparse of ',' with implied key
  keyval: Fix and clarify grammar

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 76 insertions, 27 deletions

diff --git a/util/keyval.c b/util/keyval.c
index 13def4af54..7f625ad33c 100644
--- a/util/keyval.c
+++ b/util/keyval.c
@@ -14,10 +14,11 @@
  * KEY=VALUE,... syntax:
  *
  *   key-vals     = [ key-val { ',' key-val } [ ',' ] ]
- *   key-val      = key '=' val
+ *   key-val      = key '=' val | help
  *   key          = key-fragment { '.' key-fragment }
- *   key-fragment = / [^=,.]* /
- *   val          = { / [^,]* / | ',,' }
+ *   key-fragment = / [^=,.]+ /
+ *   val          = { / [^,]+ / | ',,' }
+ *   help         = 'help' | '?'
  *
  * Semantics defined by reduction to JSON:
  *
@@ -54,6 +55,9 @@
  *
  * The length of any key-fragment must be between 1 and 127.
  *
+ * If any key-val is help, the object is to be treated as a help
+ * request.
+ *
  * Design flaw: there is no way to denote an empty array or non-root
  * object.  While interpreting "key absent" as empty seems natural
  * (removing a key-val from the input string removes the member when
@@ -71,12 +75,16 @@
  * Awkward.  Note that we carefully restrict alternate types to avoid
  * similar ambiguity.
  *
- * Additional syntax for use with an implied key:
+ * Alternative syntax for use with an implied key:
+ *
+ *   key-vals     = [ key-val-1st { ',' key-val } [ ',' ] ]
+ *   key-val-1st  = val-no-key | key-val
+ *   val-no-key   = / [^=,]+ / - help
  *
- *   key-vals-ik  = val-no-key [ ',' key-vals ]
- *   val-no-key   = / [^=,]* /
+ * where val-no-key is syntactic sugar for implied-key=val-no-key.
  *
- * where no-key is syntactic sugar for implied-key=val-no-key.
+ * Note that you can't use the sugared form when the value contains
+ * '=' or ','.
  */
 
 #include "qemu/osdep.h"
@@ -85,6 +93,7 @@
 #include "qapi/qmp/qlist.h"
 #include "qapi/qmp/qstring.h"
 #include "qemu/cutils.h"
+#include "qemu/help_option.h"
 #include "qemu/option.h"
 
 /*
@@ -158,18 +167,23 @@ static QObject *keyval_parse_put(QDict *cur,
 }
 
 /*
- * Parse one KEY=VALUE from @params, store result in @qdict.
+ * Parse one parameter from @params.
+ *
+ * If we're looking at KEY=VALUE, store result in @qdict.
  * The first fragment of KEY applies to @qdict.  Subsequent fragments
  * apply to nested QDicts, which are created on demand.  @implied_key
  * is as in keyval_parse().
- * On success, return a pointer to the next KEY=VALUE, or else to '\0'.
+ *
+ * If we're looking at "help" or "?", set *help to true.
+ *
+ * On success, return a pointer to the next parameter, or else to '\0'.
  * On failure, return NULL.
  */
 static const char *keyval_parse_one(QDict *qdict, const char *params,
-                                    const char *implied_key,
+                                    const char *implied_key, bool *help,
                                     Error **errp)
 {
-    const char *key, *key_end, *s, *end;
+    const char *key, *key_end, *val_end, *s, *end;
     size_t len;
     char key_in_cur[128];
     QDict *cur;
@@ -178,11 +192,23 @@ static const char *keyval_parse_one(QDict *qdict, const char *params,
     QString *val;
 
     key = params;
+    val_end = NULL;
     len = strcspn(params, "=,");
-    if (implied_key && len && key[len] != '=') {
-        /* Desugar implied key */
-        key = implied_key;
-        len = strlen(implied_key);
+    if (len && key[len] != '=') {
+        if (starts_with_help_option(key) == len) {
+            *help = true;
+            s = key + len;
+            if (*s == ',') {
+                s++;
+            }
+            return s;
+        }
+        if (implied_key) {
+            /* Desugar implied key */
+            key = implied_key;
+            val_end = params + len;
+            len = strlen(implied_key);
+        }
     }
     key_end = key + len;
 
@@ -237,7 +263,11 @@ static const char *keyval_parse_one(QDict *qdict, const char *params,
 
     if (key == implied_key) {
         assert(!*s);
-        s = params;
+        val = qstring_from_substr(params, 0, val_end - params);
+        s = val_end;
+        if (*s == ',') {
+            s++;
+        }
     } else {
         if (*s != '=') {
             error_setg(errp, "Expected '=' after parameter '%.*s'",
@@ -245,19 +275,19 @@ static const char *keyval_parse_one(QDict *qdict, const char *params,
             return NULL;
         }
         s++;
-    }
 
-    val = qstring_new();
-    for (;;) {
-        if (!*s) {
-            break;
-        } else if (*s == ',') {
-            s++;
-            if (*s != ',') {
+        val = qstring_new();
+        for (;;) {
+            if (!*s) {
                 break;
+            } else if (*s == ',') {
+                s++;
+                if (*s != ',') {
+                    break;
+                }
             }
+            qstring_append_chr(val, *s++);
         }
-        qstring_append_chr(val, *s++);
     }
 
     if (!keyval_parse_put(cur, key_in_cur, val, key, key_end, errp)) {
@@ -388,21 +418,32 @@ static QObject *keyval_listify(QDict *cur, GSList *key_of_cur, Error **errp)
 
 /*
  * Parse @params in QEMU's traditional KEY=VALUE,... syntax.
+ *
  * If @implied_key, the first KEY= can be omitted.  @implied_key is
  * implied then, and VALUE can't be empty or contain ',' or '='.
+ *
+ * A parameter "help" or "?" without a value isn't added to the
+ * resulting dictionary, but instead is interpreted as help request.
+ * All other options are parsed and returned normally so that context
+ * specific help can be printed.
+ *
+ * If @p_help is not NULL, store whether help is requested there.
+ * If @p_help is NULL and help is requested, fail.
+ *
  * On success, return a dictionary of the parsed keys and values.
  * On failure, store an error through @errp and return NULL.
  */
 QDict *keyval_parse(const char *params, const char *implied_key,
-                    Error **errp)
+                    bool *p_help, Error **errp)
 {
     QDict *qdict = qdict_new();
     QObject *listified;
     const char *s;
+    bool help = false;
 
     s = params;
     while (*s) {
-        s = keyval_parse_one(qdict, s, implied_key, errp);
+        s = keyval_parse_one(qdict, s, implied_key, &help, errp);
         if (!s) {
             qobject_unref(qdict);
             return NULL;
@@ -410,6 +451,14 @@ QDict *keyval_parse(const char *params, const char *implied_key,
         implied_key = NULL;
     }
 
+    if (p_help) {
+        *p_help = help;
+    } else if (help) {
+        error_setg(errp, "Help is not available for this option");
+        qobject_unref(qdict);
+        return NULL;
+    }
+
     listified = keyval_listify(qdict, NULL, errp);
     if (!listified) {
         qobject_unref(qdict);