diff options
Diffstat (limited to 'util')
| -rw-r--r-- | util/Makefile.objs | 1 | ||||
| -rw-r--r-- | util/keyval.c | 231 |
2 files changed, 232 insertions, 0 deletions
diff --git a/util/Makefile.objs b/util/Makefile.objs index bc629e2aa2..06366b5828 100644 --- a/util/Makefile.objs +++ b/util/Makefile.objs @@ -24,6 +24,7 @@ util-obj-y += error.o qemu-error.o util-obj-y += id.o util-obj-y += iov.o qemu-config.o qemu-sockets.o uri.o notify.o util-obj-y += qemu-option.o qemu-progress.o +util-obj-y += keyval.o util-obj-y += hexdump.o util-obj-y += crc32c.o util-obj-y += uuid.o diff --git a/util/keyval.c b/util/keyval.c new file mode 100644 index 0000000000..089685db78 --- /dev/null +++ b/util/keyval.c @@ -0,0 +1,231 @@ +/* + * Parsing KEY=VALUE,... strings + * + * Copyright (C) 2017 Red Hat Inc. + * + * Authors: + * Markus Armbruster <armbru@redhat.com>, + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + */ + +/* + * KEY=VALUE,... syntax: + * + * key-vals = [ key-val { ',' key-val } [ ',' ] ] + * key-val = key '=' val + * key = key-fragment { '.' key-fragment } + * key-fragment = / [^=,.]* / + * val = { / [^,]* / | ',,' } + * + * Semantics defined by reduction to JSON: + * + * key-vals defines a tree of objects rooted at R + * where for each key-val = key-fragment . ... = val in key-vals + * R op key-fragment op ... = val' + * where (left-associative) op is member reference L.key-fragment + * val' is val with ',,' replaced by ',' + * and only R may be empty. + * + * Duplicate keys are permitted; all but the last one are ignored. + * + * The equations must have a solution. Counter-example: a.b=1,a=2 + * doesn't have one, because R.a must be an object to satisfy a.b=1 + * and a string to satisfy a=2. + * + * The length of any key-fragment must be between 1 and 127. + * + * Design flaw: there is no way to denote an empty non-root object. + * While interpreting "key absent" as empty object seems natural + * (removing a key-val from the input string removes the member when + * there are more, so why not when it's the last), it doesn't work: + * "key absent" already means "optional object absent", which isn't + * the same as "empty object present". + * + * Additional syntax for use with an implied key: + * + * key-vals-ik = val-no-key [ ',' key-vals ] + * val-no-key = / [^=,]* / + * + * where no-key is syntactic sugar for implied-key=val-no-key. + * + * TODO support lists + * TODO support key-fragment with __RFQDN_ prefix (downstream extensions) + */ + +#include "qemu/osdep.h" +#include "qapi/error.h" +#include "qapi/qmp/qstring.h" +#include "qemu/option.h" + +/* + * Ensure @cur maps @key_in_cur the right way. + * If @value is null, it needs to map to a QDict, else to this + * QString. + * If @cur doesn't have @key_in_cur, put an empty QDict or @value, + * respectively. + * Else, if it needs to map to a QDict, and already does, do nothing. + * Else, if it needs to map to this QString, and already maps to a + * QString, replace it by @value. + * Else, fail because we have conflicting needs on how to map + * @key_in_cur. + * In any case, take over the reference to @value, i.e. if the caller + * wants to hold on to a reference, it needs to QINCREF(). + * Use @key up to @key_cursor to identify the key in error messages. + * On success, return the mapped value. + * On failure, store an error through @errp and return NULL. + */ +static QObject *keyval_parse_put(QDict *cur, + const char *key_in_cur, QString *value, + const char *key, const char *key_cursor, + Error **errp) +{ + QObject *old, *new; + + old = qdict_get(cur, key_in_cur); + if (old) { + if (qobject_type(old) != (value ? QTYPE_QSTRING : QTYPE_QDICT)) { + error_setg(errp, "Parameters '%.*s.*' used inconsistently", + (int)(key_cursor - key), key); + QDECREF(value); + return NULL; + } + if (!value) { + return old; /* already QDict, do nothing */ + } + new = QOBJECT(value); /* replacement */ + } else { + new = value ? QOBJECT(value) : QOBJECT(qdict_new()); + } + qdict_put_obj(cur, key_in_cur, new); + return new; +} + +/* + * Parse one KEY=VALUE from @params, 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'. + * On failure, return NULL. + */ +static const char *keyval_parse_one(QDict *qdict, const char *params, + const char *implied_key, + Error **errp) +{ + const char *key, *key_end, *s; + size_t len; + char key_in_cur[128]; + QDict *cur; + QObject *next; + QString *val; + + key = params; + len = strcspn(params, "=,"); + if (implied_key && len && key[len] != '=') { + /* Desugar implied key */ + key = implied_key; + len = strlen(implied_key); + } + key_end = key + len; + + /* + * Loop over key fragments: @s points to current fragment, it + * applies to @cur. @key_in_cur[] holds the previous fragment. + */ + cur = qdict; + s = key; + for (;;) { + for (len = 0; s + len < key_end && s[len] != '.'; len++) { + } + if (!len) { + assert(key != implied_key); + error_setg(errp, "Invalid parameter '%.*s'", + (int)(key_end - key), key); + return NULL; + } + if (len >= sizeof(key_in_cur)) { + assert(key != implied_key); + error_setg(errp, "Parameter%s '%.*s' is too long", + s != key || s + len != key_end ? " fragment" : "", + (int)len, s); + return NULL; + } + + if (s != key) { + next = keyval_parse_put(cur, key_in_cur, NULL, + key, s - 1, errp); + if (!next) { + return NULL; + } + cur = qobject_to_qdict(next); + assert(cur); + } + + memcpy(key_in_cur, s, len); + key_in_cur[len] = 0; + s += len; + + if (*s != '.') { + break; + } + s++; + } + + if (key == implied_key) { + assert(!*s); + s = params; + } else { + if (*s != '=') { + error_setg(errp, "Expected '=' after parameter '%.*s'", + (int)(s - key), key); + return NULL; + } + s++; + } + + val = qstring_new(); + for (;;) { + if (!*s) { + break; + } else if (*s == ',') { + s++; + if (*s != ',') { + break; + } + } + qstring_append_chr(val, *s++); + } + + if (!keyval_parse_put(cur, key_in_cur, val, key, key_end, errp)) { + return NULL; + } + return s; +} + +/* + * 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 '='. + * 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) +{ + QDict *qdict = qdict_new(); + const char *s; + + s = params; + while (*s) { + s = keyval_parse_one(qdict, s, implied_key, errp); + if (!s) { + QDECREF(qdict); + return NULL; + } + implied_key = NULL; + } + + return qdict; +} |