qobject: Move block-specific qdict code to block-qdict.c

Pure code motion, except for two brace placements and a comment
tweaked to appease checkpatch.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 640 insertions, 0 deletions

diff --git a/qobject/block-qdict.c b/qobject/block-qdict.c
new file mode 100644
index 0000000000..fb92010dc5
--- /dev/null
+++ b/qobject/block-qdict.c
@@ -0,0 +1,640 @@
+/*
+ * 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/qlist.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;
+    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);
+        new_key = g_strdup_printf("%s.%i", prefix, i);
+
+        if (qobject_type(value) == QTYPE_QDICT) {
+            qdict_flatten_qdict(qobject_to(QDict, value), target, new_key);
+        } else if (qobject_type(value) == QTYPE_QLIST) {
+            qdict_flatten_qlist(qobject_to(QList, value), target, new_key);
+        } else {
+            /* All other types are moved to the target unchanged. */
+            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;
+    char *new_key;
+    bool delete;
+
+    entry = qdict_first(qdict);
+
+    while (entry != NULL) {
+
+        next = qdict_next(qdict, entry);
+        value = qdict_entry_value(entry);
+        new_key = NULL;
+        delete = false;
+
+        if (prefix) {
+            new_key = g_strdup_printf("%s.%s", prefix, entry->key);
+        }
+
+        if (qobject_type(value) == QTYPE_QDICT) {
+            /* Entries of QDicts are processed recursively, the QDict object
+             * itself disappears. */
+            qdict_flatten_qdict(qobject_to(QDict, value), target,
+                                new_key ? new_key : entry->key);
+            delete = true;
+        } else if (qobject_type(value) == QTYPE_QLIST) {
+            qdict_flatten_qlist(qobject_to(QList, value), target,
+                                new_key ? new_key : entry->key);
+            delete = true;
+        } else if (prefix) {
+            /* All other objects are moved to the target unchanged. */
+            qdict_put_obj(target, new_key, qobject_ref(value));
+            delete = true;
+        }
+
+        g_free(new_key);
+
+        if (delete) {
+            qdict_del(qdict, entry->key);
+
+            /* Restart loop after modifying the iterated QDict */
+            entry = qdict_first(qdict);
+            continue;
+        }
+
+        entry = next;
+    }
+}
+
+/**
+ * qdict_flatten(): For each nested 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
+ * 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 */
+void qdict_extract_subqdict(QDict *src, QDict **dst, const char *start)
+
+{
+    const QDictEntry *entry, *next;
+    const char *p;
+
+    *dst = qdict_new();
+    entry = qdict_first(src);
+
+    while (entry != NULL) {
+        next = qdict_next(src, entry);
+        if (strstart(entry->key, start, &p)) {
+            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);
+        } else {
+            qobject_ref(subqobj);
+            qdict_del(src, indexstr);
+        }
+
+        qlist_append_obj(*dst, subqobj ?: QOBJECT(subqdict));
+    }
+}
+
+/**
+ * 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)) {
+
+        if (qemu_strtoi64(ent->key, NULL, 10, &val) == 0) {
+            if (is_list == -1) {
+                is_list = 1;
+            } else if (!is_list) {
+                error_setg(errp,
+                           "Cannot mix list and non-list keys");
+                return -1;
+            }
+            len++;
+            if (val > max) {
+                max = val;
+            }
+        } else {
+            if (is_list == -1) {
+                is_list = 0;
+            } else if (is_list) {
+                error_setg(errp,
+                           "Cannot mix list and non-list keys");
+                return -1;
+            }
+        }
+    }
+
+    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, 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;
+    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)) {
+        if (qobject_type(ent->value) == QTYPE_QDICT ||
+            qobject_type(ent->value) == QTYPE_QLIST) {
+            error_setg(errp, "Value %s is not a scalar",
+                       ent->key);
+            goto error;
+        }
+
+        qdict_split_flat_key(ent->key, &prefix, &suffix);
+
+        child = qdict_get(two_level, prefix);
+        if (suffix) {
+            QDict *child_dict = qobject_to(QDict, child);
+            if (!child_dict) {
+                if (child) {
+                    error_setg(errp, "Key %s prefix is already set as a scalar",
+                               prefix);
+                    goto error;
+                }
+
+                child_dict = qdict_new();
+                qdict_put_obj(two_level, prefix, QOBJECT(child_dict));
+            }
+
+            qdict_put_obj(child_dict, suffix, qobject_ref(ent->value));
+        } else {
+            if (child) {
+                error_setg(errp, "Key %s prefix is already set as a dict",
+                           prefix);
+                goto error;
+            }
+            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)) {
+        QDict *dict = qobject_to(QDict, ent->value);
+        if (dict) {
+            child = qdict_crumple(dict, 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_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;
+}