qemu

block-qdict.c (22537B)

---

 /*
  * Special QDict functions used by the block layer
  *
  * Copyright (c) 2013-2018 Red Hat, Inc.
  *
  * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
  * See the COPYING.LIB file in the top-level directory.
  */
 
 #include "qemu/osdep.h"
 #include "block/qdict.h"
 #include "qapi/qmp/qbool.h"
 #include "qapi/qmp/qlist.h"
 #include "qapi/qmp/qnum.h"
 #include "qapi/qmp/qstring.h"
 #include "qapi/qobject-input-visitor.h"
 #include "qemu/cutils.h"
 #include "qapi/error.h"
 
 /**
  * qdict_copy_default(): If no entry mapped by 'key' exists in 'dst' yet, the
  * value of 'key' in 'src' is copied there (and the refcount increased
  * accordingly).
  */
 void qdict_copy_default(QDict *dst, QDict *src, const char *key)
 {
     QObject *val;
 
     if (qdict_haskey(dst, key)) {
         return;
     }
 
     val = qdict_get(src, key);
     if (val) {
         qdict_put_obj(dst, key, qobject_ref(val));
     }
 }
 
 /**
  * qdict_set_default_str(): If no entry mapped by 'key' exists in 'dst' yet, a
  * new QString initialised by 'val' is put there.
  */
 void qdict_set_default_str(QDict *dst, const char *key, const char *val)
 {
     if (qdict_haskey(dst, key)) {
         return;
     }
 
     qdict_put_str(dst, key, val);
 }
 
 static void qdict_flatten_qdict(QDict *qdict, QDict *target,
                                 const char *prefix);
 
 static void qdict_flatten_qlist(QList *qlist, QDict *target, const char *prefix)
 {
     QObject *value;
     const QListEntry *entry;
     QDict *dict_val;
     QList *list_val;
     char *new_key;
     int i;
 
     /* This function is never called with prefix == NULL, i.e., it is always
      * called from within qdict_flatten_q(list|dict)(). Therefore, it does not
      * need to remove list entries during the iteration (the whole list will be
      * deleted eventually anyway from qdict_flatten_qdict()). */
     assert(prefix);
 
     entry = qlist_first(qlist);
 
     for (i = 0; entry; entry = qlist_next(entry), i++) {
         value = qlist_entry_obj(entry);
         dict_val = qobject_to(QDict, value);
         list_val = qobject_to(QList, value);
         new_key = g_strdup_printf("%s.%i", prefix, i);
 
         /*
          * Flatten non-empty QDict and QList recursively into @target,
          * copy other objects to @target
          */
         if (dict_val && qdict_size(dict_val)) {
             qdict_flatten_qdict(dict_val, target, new_key);
         } else if (list_val && !qlist_empty(list_val)) {
             qdict_flatten_qlist(list_val, target, new_key);
         } else {
             qdict_put_obj(target, new_key, qobject_ref(value));
         }
 
         g_free(new_key);
     }
 }
 
 static void qdict_flatten_qdict(QDict *qdict, QDict *target, const char *prefix)
 {
     QObject *value;
     const QDictEntry *entry, *next;
     QDict *dict_val;
     QList *list_val;
     char *key, *new_key;
 
     entry = qdict_first(qdict);
 
     while (entry != NULL) {
         next = qdict_next(qdict, entry);
         value = qdict_entry_value(entry);
         dict_val = qobject_to(QDict, value);
         list_val = qobject_to(QList, value);
 
         if (prefix) {
             key = new_key = g_strdup_printf("%s.%s", prefix, entry->key);
         } else {
             key = entry->key;
             new_key = NULL;
         }
 
         /*
          * Flatten non-empty QDict and QList recursively into @target,
          * copy other objects to @target.
          * On the root level (if @qdict == @target), remove flattened
          * nested QDicts and QLists from @qdict.
          *
          * (Note that we do not need to remove entries from nested
          * dicts or lists.  Their reference count is decremented on
          * the root level, so there are no leaks.  In fact, if they
          * have a reference count greater than one, we are probably
          * well advised not to modify them altogether.)
          */
         if (dict_val && qdict_size(dict_val)) {
             qdict_flatten_qdict(dict_val, target, key);
             if (target == qdict) {
                 qdict_del(qdict, entry->key);
             }
         } else if (list_val && !qlist_empty(list_val)) {
             qdict_flatten_qlist(list_val, target, key);
             if (target == qdict) {
                 qdict_del(qdict, entry->key);
             }
         } else if (target != qdict) {
             qdict_put_obj(target, key, qobject_ref(value));
         }
 
         g_free(new_key);
         entry = next;
     }
 }
 
 /**
  * qdict_flatten(): For each nested non-empty QDict with key x, all
  * fields with key y are moved to this QDict and their key is renamed
  * to "x.y". For each nested non-empty QList with key x, the field at
  * index y is moved to this QDict with the key "x.y" (i.e., the
  * reverse of what qdict_array_split() does).
  * This operation is applied recursively for nested QDicts and QLists.
  */
 void qdict_flatten(QDict *qdict)
 {
     qdict_flatten_qdict(qdict, qdict, NULL);
 }
 
 /* extract all the src QDict entries starting by start into dst.
  * If dst is NULL then the entries are simply removed from src. */
 void qdict_extract_subqdict(QDict *src, QDict **dst, const char *start)
 
 {
     const QDictEntry *entry, *next;
     const char *p;
 
     if (dst) {
         *dst = qdict_new();
     }
     entry = qdict_first(src);
 
     while (entry != NULL) {
         next = qdict_next(src, entry);
         if (strstart(entry->key, start, &p)) {
             if (dst) {
                 qdict_put_obj(*dst, p, qobject_ref(entry->value));
             }
             qdict_del(src, entry->key);
         }
         entry = next;
     }
 }
 
 static int qdict_count_prefixed_entries(const QDict *src, const char *start)
 {
     const QDictEntry *entry;
     int count = 0;
 
     for (entry = qdict_first(src); entry; entry = qdict_next(src, entry)) {
         if (strstart(entry->key, start, NULL)) {
             if (count == INT_MAX) {
                 return -ERANGE;
             }
             count++;
         }
     }
 
     return count;
 }
 
 /**
  * qdict_array_split(): This function moves array-like elements of a QDict into
  * a new QList. Every entry in the original QDict with a key "%u" or one
  * prefixed "%u.", where %u designates an unsigned integer starting at 0 and
  * incrementally counting up, will be moved to a new QDict at index %u in the
  * output QList with the key prefix removed, if that prefix is "%u.". If the
  * whole key is just "%u", the whole QObject will be moved unchanged without
  * creating a new QDict. The function terminates when there is no entry in the
  * QDict with a prefix directly (incrementally) following the last one; it also
  * returns if there are both entries with "%u" and "%u." for the same index %u.
  * Example: {"0.a": 42, "0.b": 23, "1.x": 0, "4.y": 1, "o.o": 7, "2": 66}
  *      (or {"1.x": 0, "4.y": 1, "0.a": 42, "o.o": 7, "0.b": 23, "2": 66})
  *       => [{"a": 42, "b": 23}, {"x": 0}, 66]
  *      and {"4.y": 1, "o.o": 7} (remainder of the old QDict)
  */
 void qdict_array_split(QDict *src, QList **dst)
 {
     unsigned i;
 
     *dst = qlist_new();
 
     for (i = 0; i < UINT_MAX; i++) {
         QObject *subqobj;
         bool is_subqdict;
         QDict *subqdict;
         char indexstr[32], prefix[32];
         size_t snprintf_ret;
 
         snprintf_ret = snprintf(indexstr, 32, "%u", i);
         assert(snprintf_ret < 32);
 
         subqobj = qdict_get(src, indexstr);
 
         snprintf_ret = snprintf(prefix, 32, "%u.", i);
         assert(snprintf_ret < 32);
 
         /* Overflow is the same as positive non-zero results */
         is_subqdict = qdict_count_prefixed_entries(src, prefix);
 
         /*
          * There may be either a single subordinate object (named
          * "%u") or multiple objects (each with a key prefixed "%u."),
          * but not both.
          */
         if (!subqobj == !is_subqdict) {
             break;
         }
 
         if (is_subqdict) {
             qdict_extract_subqdict(src, &subqdict, prefix);
             assert(qdict_size(subqdict) > 0);
             qlist_append_obj(*dst, QOBJECT(subqdict));
         } else {
             qobject_ref(subqobj);
             qdict_del(src, indexstr);
             qlist_append_obj(*dst, subqobj);
         }
     }
 }
 
 /**
  * qdict_split_flat_key:
  * @key: the key string to split
  * @prefix: non-NULL pointer to hold extracted prefix
  * @suffix: non-NULL pointer to remaining suffix
  *
  * Given a flattened key such as 'foo.0.bar', split it into two parts
  * at the first '.' separator. Allows double dot ('..') to escape the
  * normal separator.
  *
  * e.g.
  *    'foo.0.bar' -> prefix='foo' and suffix='0.bar'
  *    'foo..0.bar' -> prefix='foo.0' and suffix='bar'
  *
  * The '..' sequence will be unescaped in the returned 'prefix'
  * string. The 'suffix' string will be left in escaped format, so it
  * can be fed back into the qdict_split_flat_key() key as the input
  * later.
  *
  * The caller is responsible for freeing the string returned in @prefix
  * using g_free().
  */
 static void qdict_split_flat_key(const char *key, char **prefix,
                                  const char **suffix)
 {
     const char *separator;
     size_t i, j;
 
     /* Find first '.' separator, but if there is a pair '..'
      * that acts as an escape, so skip over '..' */
     separator = NULL;
     do {
         if (separator) {
             separator += 2;
         } else {
             separator = key;
         }
         separator = strchr(separator, '.');
     } while (separator && separator[1] == '.');
 
     if (separator) {
         *prefix = g_strndup(key, separator - key);
         *suffix = separator + 1;
     } else {
         *prefix = g_strdup(key);
         *suffix = NULL;
     }
 
     /* Unescape the '..' sequence into '.' */
     for (i = 0, j = 0; (*prefix)[i] != '\0'; i++, j++) {
         if ((*prefix)[i] == '.') {
             assert((*prefix)[i + 1] == '.');
             i++;
         }
         (*prefix)[j] = (*prefix)[i];
     }
     (*prefix)[j] = '\0';
 }
 
 /**
  * qdict_is_list:
  * @maybe_list: dict to check if keys represent list elements.
  *
  * Determine whether all keys in @maybe_list are valid list elements.
  * If @maybe_list is non-zero in length and all the keys look like
  * valid list indexes, this will return 1. If @maybe_list is zero
  * length or all keys are non-numeric then it will return 0 to indicate
  * it is a normal qdict. If there is a mix of numeric and non-numeric
  * keys, or the list indexes are non-contiguous, an error is reported.
  *
  * Returns: 1 if a valid list, 0 if a dict, -1 on error
  */
 static int qdict_is_list(QDict *maybe_list, Error **errp)
 {
     const QDictEntry *ent;
     ssize_t len = 0;
     ssize_t max = -1;
     int is_list = -1;
     int64_t val;
 
     for (ent = qdict_first(maybe_list); ent != NULL;
          ent = qdict_next(maybe_list, ent)) {
         int is_index = !qemu_strtoi64(ent->key, NULL, 10, &val);
 
         if (is_list == -1) {
             is_list = is_index;
         }
 
         if (is_index != is_list) {
             error_setg(errp, "Cannot mix list and non-list keys");
             return -1;
         }
 
         if (is_index) {
             len++;
             if (val > max) {
                 max = val;
             }
         }
     }
 
     if (is_list == -1) {
         assert(!qdict_size(maybe_list));
         is_list = 0;
     }
 
     /* NB this isn't a perfect check - e.g. it won't catch
      * a list containing '1', '+1', '01', '3', but that
      * does not matter - we've still proved that the
      * input is a list. It is up the caller to do a
      * stricter check if desired */
     if (len != (max + 1)) {
         error_setg(errp, "List indices are not contiguous, "
                    "saw %zd elements but %zd largest index",
                    len, max);
         return -1;
     }
 
     return is_list;
 }
 
 /**
  * qdict_crumple:
  * @src: the original flat dictionary (only scalar values) to crumple
  *
  * Takes a flat dictionary whose keys use '.' separator to indicate
  * nesting, and values are scalars, empty dictionaries or empty lists,
  * and crumples it into a nested structure.
  *
  * To include a literal '.' in a key name, it must be escaped as '..'
  *
  * For example, an input of:
  *
  * { 'foo.0.bar': 'one', 'foo.0.wizz': '1',
  *   'foo.1.bar': 'two', 'foo.1.wizz': '2' }
  *
  * will result in an output of:
  *
  * {
  *   'foo': [
  *      { 'bar': 'one', 'wizz': '1' },
  *      { 'bar': 'two', 'wizz': '2' }
  *   ],
  * }
  *
  * The following scenarios in the input dict will result in an
  * error being returned:
  *
  *  - Any values in @src are non-scalar types
  *  - If keys in @src imply that a particular level is both a
  *    list and a dict. e.g., "foo.0.bar" and "foo.eek.bar".
  *  - If keys in @src imply that a particular level is a list,
  *    but the indices are non-contiguous. e.g. "foo.0.bar" and
  *    "foo.2.bar" without any "foo.1.bar" present.
  *  - If keys in @src represent list indexes, but are not in
  *    the "%zu" format. e.g. "foo.+0.bar"
  *
  * Returns: either a QDict or QList for the nested data structure, or NULL
  * on error
  */
 QObject *qdict_crumple(const QDict *src, Error **errp)
 {
     const QDictEntry *ent;
     QDict *two_level, *multi_level = NULL, *child_dict;
     QDict *dict_val;
     QList *list_val;
     QObject *dst = NULL, *child;
     size_t i;
     char *prefix = NULL;
     const char *suffix = NULL;
     int is_list;
 
     two_level = qdict_new();
 
     /* Step 1: split our totally flat dict into a two level dict */
     for (ent = qdict_first(src); ent != NULL; ent = qdict_next(src, ent)) {
         dict_val = qobject_to(QDict, ent->value);
         list_val = qobject_to(QList, ent->value);
         if ((dict_val && qdict_size(dict_val))
             || (list_val && !qlist_empty(list_val))) {
             error_setg(errp, "Value %s is not flat", ent->key);
             goto error;
         }
 
         qdict_split_flat_key(ent->key, &prefix, &suffix);
         child = qdict_get(two_level, prefix);
         child_dict = qobject_to(QDict, child);
 
         if (child) {
             /*
              * If @child_dict, then all previous keys with this prefix
              * had a suffix.  If @suffix, this one has one as well,
              * and we're good, else there's a clash.
              */
             if (!child_dict || !suffix) {
                 error_setg(errp, "Cannot mix scalar and non-scalar keys");
                 goto error;
             }
         }
 
         if (suffix) {
             if (!child_dict) {
                 child_dict = qdict_new();
                 qdict_put(two_level, prefix, child_dict);
             }
             qdict_put_obj(child_dict, suffix, qobject_ref(ent->value));
         } else {
             qdict_put_obj(two_level, prefix, qobject_ref(ent->value));
         }
 
         g_free(prefix);
         prefix = NULL;
     }
 
     /* Step 2: optionally process the two level dict recursively
      * into a multi-level dict */
     multi_level = qdict_new();
     for (ent = qdict_first(two_level); ent != NULL;
          ent = qdict_next(two_level, ent)) {
         dict_val = qobject_to(QDict, ent->value);
         if (dict_val && qdict_size(dict_val)) {
             child = qdict_crumple(dict_val, errp);
             if (!child) {
                 goto error;
             }
 
             qdict_put_obj(multi_level, ent->key, child);
         } else {
             qdict_put_obj(multi_level, ent->key, qobject_ref(ent->value));
         }
     }
     qobject_unref(two_level);
     two_level = NULL;
 
     /* Step 3: detect if we need to turn our dict into list */
     is_list = qdict_is_list(multi_level, errp);
     if (is_list < 0) {
         goto error;
     }
 
     if (is_list) {
         dst = QOBJECT(qlist_new());
 
         for (i = 0; i < qdict_size(multi_level); i++) {
             char *key = g_strdup_printf("%zu", i);
 
             child = qdict_get(multi_level, key);
             g_free(key);
 
             if (!child) {
                 error_setg(errp, "Missing list index %zu", i);
                 goto error;
             }
 
             qlist_append_obj(qobject_to(QList, dst), qobject_ref(child));
         }
         qobject_unref(multi_level);
         multi_level = NULL;
     } else {
         dst = QOBJECT(multi_level);
     }
 
     return dst;
 
  error:
     g_free(prefix);
     qobject_unref(multi_level);
     qobject_unref(two_level);
     qobject_unref(dst);
     return NULL;
 }
 
 /**
  * qdict_crumple_for_keyval_qiv:
  * @src: the flat dictionary (only scalar values) to crumple
  * @errp: location to store error
  *
  * Like qdict_crumple(), but additionally transforms scalar values so
  * the result can be passed to qobject_input_visitor_new_keyval().
  *
  * The block subsystem uses this function to prepare its flat QDict
  * with possibly confused scalar types for a visit.  It should not be
  * used for anything else, and it should go away once the block
  * subsystem has been cleaned up.
  */
 static QObject *qdict_crumple_for_keyval_qiv(QDict *src, Error **errp)
 {
     QDict *tmp = NULL;
     char *buf;
     const char *s;
     const QDictEntry *ent;
     QObject *dst;
 
     for (ent = qdict_first(src); ent; ent = qdict_next(src, ent)) {
         buf = NULL;
         switch (qobject_type(ent->value)) {
         case QTYPE_QNULL:
         case QTYPE_QSTRING:
             continue;
         case QTYPE_QNUM:
             s = buf = qnum_to_string(qobject_to(QNum, ent->value));
             break;
         case QTYPE_QDICT:
         case QTYPE_QLIST:
             /* @src isn't flat; qdict_crumple() will fail */
             continue;
         case QTYPE_QBOOL:
             s = qbool_get_bool(qobject_to(QBool, ent->value))
                 ? "on" : "off";
             break;
         default:
             abort();
         }
 
         if (!tmp) {
             tmp = qdict_clone_shallow(src);
         }
         qdict_put_str(tmp, ent->key, s);
         g_free(buf);
     }
 
     dst = qdict_crumple(tmp ?: src, errp);
     qobject_unref(tmp);
     return dst;
 }
 
 /**
  * qdict_array_entries(): Returns the number of direct array entries if the
  * sub-QDict of src specified by the prefix in subqdict (or src itself for
  * prefix == "") is valid as an array, i.e. the length of the created list if
  * the sub-QDict would become empty after calling qdict_array_split() on it. If
  * the array is not valid, -EINVAL is returned.
  */
 int qdict_array_entries(QDict *src, const char *subqdict)
 {
     const QDictEntry *entry;
     unsigned i;
     unsigned entries = 0;
     size_t subqdict_len = strlen(subqdict);
 
     assert(!subqdict_len || subqdict[subqdict_len - 1] == '.');
 
     /* qdict_array_split() loops until UINT_MAX, but as we want to return
      * negative errors, we only have a signed return value here. Any additional
      * entries will lead to -EINVAL. */
     for (i = 0; i < INT_MAX; i++) {
         QObject *subqobj;
         int subqdict_entries;
         char *prefix = g_strdup_printf("%s%u.", subqdict, i);
 
         subqdict_entries = qdict_count_prefixed_entries(src, prefix);
 
         /* Remove ending "." */
         prefix[strlen(prefix) - 1] = 0;
         subqobj = qdict_get(src, prefix);
 
         g_free(prefix);
 
         if (subqdict_entries < 0) {
             return subqdict_entries;
         }
 
         /* There may be either a single subordinate object (named "%u") or
          * multiple objects (each with a key prefixed "%u."), but not both. */
         if (subqobj && subqdict_entries) {
             return -EINVAL;
         } else if (!subqobj && !subqdict_entries) {
             break;
         }
 
         entries += subqdict_entries ? subqdict_entries : 1;
     }
 
     /* Consider everything handled that isn't part of the given sub-QDict */
     for (entry = qdict_first(src); entry; entry = qdict_next(src, entry)) {
         if (!strstart(qdict_entry_key(entry), subqdict, NULL)) {
             entries++;
         }
     }
 
     /* Anything left in the sub-QDict that wasn't handled? */
     if (qdict_size(src) != entries) {
         return -EINVAL;
     }
 
     return i;
 }
 
 /**
  * qdict_join(): Absorb the src QDict into the dest QDict, that is, move all
  * elements from src to dest.
  *
  * If an element from src has a key already present in dest, it will not be
  * moved unless overwrite is true.
  *
  * If overwrite is true, the conflicting values in dest will be discarded and
  * replaced by the corresponding values from src.
  *
  * Therefore, with overwrite being true, the src QDict will always be empty when
  * this function returns. If overwrite is false, the src QDict will be empty
  * iff there were no conflicts.
  */
 void qdict_join(QDict *dest, QDict *src, bool overwrite)
 {
     const QDictEntry *entry, *next;
 
     entry = qdict_first(src);
     while (entry) {
         next = qdict_next(src, entry);
 
         if (overwrite || !qdict_haskey(dest, entry->key)) {
             qdict_put_obj(dest, entry->key, qobject_ref(entry->value));
             qdict_del(src, entry->key);
         }
 
         entry = next;
     }
 }
 
 /**
  * qdict_rename_keys(): Rename keys in qdict according to the replacements
  * specified in the array renames. The array must be terminated by an entry
  * with from = NULL.
  *
  * The renames are performed individually in the order of the array, so entries
  * may be renamed multiple times and may or may not conflict depending on the
  * order of the renames array.
  *
  * Returns true for success, false in error cases.
  */
 bool qdict_rename_keys(QDict *qdict, const QDictRenames *renames, Error **errp)
 {
     QObject *qobj;
 
     while (renames->from) {
         if (qdict_haskey(qdict, renames->from)) {
             if (qdict_haskey(qdict, renames->to)) {
                 error_setg(errp, "'%s' and its alias '%s' can't be used at the "
                            "same time", renames->to, renames->from);
                 return false;
             }
 
             qobj = qdict_get(qdict, renames->from);
             qdict_put_obj(qdict, renames->to, qobject_ref(qobj));
             qdict_del(qdict, renames->from);
         }
 
         renames++;
     }
     return true;
 }
 
 /*
  * Create a QObject input visitor for flat @qdict with possibly
  * confused scalar types.
  *
  * The block subsystem uses this function to visit its flat QDict with
  * possibly confused scalar types.  It should not be used for anything
  * else, and it should go away once the block subsystem has been
  * cleaned up.
  */
 Visitor *qobject_input_visitor_new_flat_confused(QDict *qdict,
                                                  Error **errp)
 {
     QObject *crumpled;
     Visitor *v;
 
     crumpled = qdict_crumple_for_keyval_qiv(qdict, errp);
     if (!crumpled) {
         return NULL;
     }
 
     v = qobject_input_visitor_new_keyval(crumpled);
     qobject_unref(crumpled);
     return v;
 }