The functions to modify a QString's string are all unused now. Drop
them, and make the string immutable. Saves 16 bytes per QString on my
system.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20201211171152.146877-21-armbru@redhat.com>
QString supports modifying its string, but it's quite limited: you can
only append. The remaining callers use it for building an initial
string, never for modifying it later.
Change parse_string() to do build the initial string with GString.
This is another step towards making QString immutable.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20201211171152.146877-18-armbru@redhat.com>
We have two JSON writers written in C: qobject/qjson.c provides
qobject_to_json(), and migration/qjson.c provides a more low level
imperative interface. They don't share code. The latter tacitly
limits numbers to int64_t, and strings contents to characters that
don't need escaping.
Factor out qobject_to_json()'s JSON writer as qobject/json-writer.c.
Straightforward, except for numbers: since the writer is to be
independent of QObject, it can't use qnum_to_string(). Open-code it
instead. This is actually an improvement of sorts, because it
liberates qnum_to_string() from JSON's needs: its JSON-related FIXMEs
move to the JSON writer, where they belong.
The next commit will replace migration/qjson.c.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20201211171152.146877-16-armbru@redhat.com>
No users left outside tests/, and the ones in tests/ can just as well
use qstring_get_str(). Do that, and drop the function.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20201211171152.146877-14-armbru@redhat.com>
This reverts commit 164c374b75.
A free function for a reference-counted object is in bad taste.
Fortunately, this one is now also unused. Drop it.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20201211171152.146877-7-armbru@redhat.com>
qobject_to_json() and qobject_to_json_pretty() build a GString, then
covert it to QString. Just one of the callers actually needs a
QString: qemu_rbd_parse_filename(). A few others need a string they
can modify: qmp_send_response(), qga's send_response(), to_json_str(),
and qmp_fd_vsend_fds(). The remainder just need a string.
Change qobject_to_json() and qobject_to_json_pretty() to return the
GString.
qemu_rbd_parse_filename() now has to convert to QString. All others
save a QString temporary. to_json_str() actually becomes a bit
simpler, because GString provides more convenient modification
functions.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20201211171152.146877-6-armbru@redhat.com>
QString supports modifying its string, but it's quite limited: you can
only append. The remaining callers use it for building an initial
string, never for modifying it later.
Use of GString for building the initial string is actually more
convenient here. Change qobject_to_json() & friends to do that.
Once all such uses are replaced this way, QString can become immutable.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20201211171152.146877-5-armbru@redhat.com>
We should serialize numbers to JSON so that they deserialize back to
the same number. We fail to do so.
The culprit is qnum_to_string(): it uses format %f with trailing '0'
trimmed. Results in pretty output for "nice" numbers, but is prone to
nasty rounding errors. For instance, numbers between 0 and 0.0000005
get flushed to zero.
Where exactly the incorrect rounding can bite is tiresome to gauge.
Here's my take.
* In QMP output, type 'number':
- query-blockstats value avg_rd_queue_depth
- QMP query-migrate values mbps, cache-miss-rate, encoding-rate,
busy-rate, compression-rate.
Relatively harmless, I guess.
* In tracing QMP input. Harmless.
* In qemu-ga output, type 'number': guest-get-users value login-time.
Harmless.
* In output of HMP qom-get. Harmless.
Not affected, because double values don't actually occur there (I
think):
* QMP output, type 'any':
* qom-get value
* qom-list, qom-list-properties value default-value
* query-cpu-model-comparison, query-cpu-model-baseline,
query-cpu-model-expansion value props.
* qemu-img --output json output.
* "json:" pseudo-filenames generated by bdrv_refresh_filename().
* The rbd block driver's "=keyvalue-pairs" hack.
* In -object help on property default values. Aside: use of JSON
feels inappropriate here.
* Output of HMP qom-get.
* Argument conversion to QemuOpts for qdev_device_add() and HMP with
qemu_opts_from_qdict()
QMP and HMP device_add, virtio-net failover primary creation,
xen-usb "usb-host" creation, HMP netdev_add, object_add.
* The uses of qobject_input_visitor_new_flat_confused()
As far as I can tell, none of the visited types contain double
values.
* Dumping ImageInfoSpecific with dump_qobject()
Fix by formatting with %.17g. 17 decimal digits always suffice for
IEEE double.
The change to expected test output illustrates the effect: the
rounding errors are gone, but some seemingly "nice" numbers now get
converted to not so nice strings, e.g. 0.42 to "0.41999999999999998".
This is because 0.42 is not representable exactly in double. It's
more accurate in this example than strictly necessary, though.
If ugly accuracy bothers us, we can we can try using the least number
of digits that still converts back to the same double. In this
example, "0.42" would do.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20201210161452.2813491-7-armbru@redhat.com>
In qobject_type(), NULL is returned when the 'QObject' returned from parse_value() is not of QString type,
and this 'QObject' memory will leaked.
So we need to first cache the 'QObject' returned from parse_value(), and finally
free 'QObject' memory at the end of the function.
Also, we add a testcast about invalid dict key.
The memleak stack is as follows:
Direct leak of 32 byte(s) in 1 object(s) allocated from:
#0 0xfffe4b3c34fb in __interceptor_malloc (/lib64/libasan.so.4+0xd34fb)
#1 0xfffe4ae48aa3 in g_malloc (/lib64/libglib-2.0.so.0+0x58aa3)
#2 0xaaab3557d9f7 in qnum_from_int qemu/qobject/qnum.c:25
#3 0xaaab35584d23 in parse_literal qemu/qobject/json-parser.c:511
#4 0xaaab35584d23 in parse_value qemu/qobject/json-parser.c:554
#5 0xaaab35583d77 in parse_pair qemu/qobject/json-parser.c:270
#6 0xaaab355845db in parse_object qemu/qobject/json-parser.c:327
#7 0xaaab355845db in parse_value qemu/qobject/json-parser.c:546
#8 0xaaab35585b1b in json_parser_parse qemu/qobject/json-parser.c:580
#9 0xaaab35583703 in json_message_process_token qemu/qobject/json-streamer.c:92
#10 0xaaab355ddccf in json_lexer_feed_char qemu/qobject/json-lexer.c:313
#11 0xaaab355de0eb in json_lexer_feed qemu/qobject/json-lexer.c:350
#12 0xaaab354aff67 in tcp_chr_read qemu/chardev/char-socket.c:525
#13 0xfffe4ae429db in g_main_context_dispatch (/lib64/libglib-2.0.so.0+0x529db)
#14 0xfffe4ae42d8f (/lib64/libglib-2.0.so.0+0x52d8f)
#15 0xfffe4ae430df in g_main_loop_run (/lib64/libglib-2.0.so.0+0x530df)
#16 0xaaab34d70bff in iothread_run qemu/iothread.c:82
#17 0xaaab3559d71b in qemu_thread_start qemu/util/qemu-thread-posix.c:519
Fixes: 532fb53284 ("qapi: Make more of qobject_to()")
Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Alex Chen <alex.chen@huawei.com>
Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20201113145525.85151-1-alex.chen@huawei.com>
[Commit message tweaked]
I found that there are many spelling errors in the comments of qemu,
so I used the spellcheck tool to check the spelling errors
and finally found some spelling errors in the folder.
Signed-off-by: zhaolichang <zhaolichang@huawei.com>
Reviewed-by: Alex Bennee <alex.bennee@linaro.org>
Message-Id: <20200917075029.313-2-zhaolichang@huawei.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
This shows how to do some "computations" in meson.build using its array
and dictionary data structures, and also a basic usage of the sourceset
module for conditional compilation.
Notice the new "if have_system" part of util/meson.build, which fixes
a bug in the old build system was buggy: util/dbus.c was built even for
non-softmmu builds, but the dependency on -lgio was lost when the linking
was done through libqemuutil.a. Because all of its users required gio
otherwise, the bug was hidden. Meson instead propagates libqemuutil's
dependencies down to its users, and shows the problem.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
qdict_iter() has just three uses and no test coverage. Replace by
qdict_first(), qdict_next() for more concise code and less type
punning.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200415083048.14339-5-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
qlist_iter() has just three uses outside tests/. Replace by
QLIST_FOREACH_ENTRY() for more concise code and less type punning.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200415083048.14339-4-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200415083048.14339-3-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[Coding style in moved code tidied up]
Similar to g_string_free(), optionally return the underlying char*.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20200110153039.1379601-10-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reported by GCC9 when building with CFLAG -Wimplicit-fallthrough=2:
qobject/json-parser.c: In function ‘parse_literal’:
qobject/json-parser.c:492:24: error: this statement may fall through [-Werror=implicit-fallthrough=]
492 | case JSON_INTEGER: {
| ^
qobject/json-parser.c:524:5: note: here
524 | case JSON_FLOAT:
| ^~~~
Correctly place the 'fall through' comment.
Reported-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190719131425.10835-2-philmd@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190523143508.25387-3-armbru@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
The assert checking if the value of lexer->state in next_state(),
which is used as an index to the 'json_lexer' array, incorrectly
checks for an index value less than or equal to ARRAY_SIZE(json_lexer).
Fix assert so that it just checks for an index less than the array size.
Signed-off-by: Liam Merwick <liam.merwick@oracle.com>
Message-Id: <1553169472-25325-1-git-send-email-liam.merwick@oracle.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Commit 8bca4613 added support for %% in json strings when interpolating,
but in doing so broke handling of % when not interpolating.
When parse_string() is fed a string token containing '%', it skips the
'%' regardless of ctxt->ap, i.e. even it's not interpolating. If the
'%' is the string's last character, it fails an assertion. Else, it
"merely" swallows the '%'.
Fix parse_string() to handle '%' specially only when interpolating.
To gauge the bug's impact, let's review non-interpolating users of this
parser, i.e. code passing NULL context to json_message_parser_init():
* tests/check-qjson.c, tests/test-qobject-input-visitor.c,
tests/test-visitor-serialization.c
Plenty of tests, but we still failed to cover the buggy case.
* monitor.c: QMP input
* qga/main.c: QGA input
* qobject_from_json():
- qobject-input-visitor.c: JSON command line option arguments of
-display and -blockdev
Reproducer: -blockdev '{"%"}'
- block.c: JSON pseudo-filenames starting with "json:"
Reproducer: https://bugzilla.redhat.com/show_bug.cgi?id=1668244#c3
- block/rbd.c: JSON key pairs
Pseudo-filenames starting with "rbd:".
Command line, QMP and QGA input are trusted.
Filenames are trusted when they come from command line, QMP or HMP.
They are untrusted when they come from from image file headers.
Example: QCOW2 backing file name. Note that this is *not* the security
boundary between host and guest. It's the boundary between host and an
image file from an untrusted source.
Neither failing an assertion nor skipping a character in a filename of
your choice looks exploitable. Note that we don't support compiling
with NDEBUG.
Fixes: 8bca4613e6
Cc: qemu-stable@nongnu.org
Signed-off-by: Christophe Fergeau <cfergeau@redhat.com>
Message-Id: <20190102140535.11512-1-cfergeau@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Tested-by: Richard W.M. Jones <rjones@redhat.com>
[Commit message extended to discuss impact]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
The lexer ignores whitespace like this:
on whitespace on non-ws spontaneously
IN_START --> IN_WHITESPACE --> JSON_SKIP --> IN_START
^ |
\__/ on whitespace
This accumulates a whitespace token in state IN_WHITESPACE, only to
throw it away on the transition via JSON_SKIP to the start state.
Wasteful. Go from IN_START to IN_START on whitespace directly,
dropping the whitespace character.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180831075841.13363-7-armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180831075841.13363-6-armbru@redhat.com>
When the lexer chokes on an input character, it consumes the
character, emits a JSON error token, and enters its start state. This
can lead to suboptimal error recovery. For instance, input
0123 ,
produces the tokens
JSON_ERROR 01
JSON_INTEGER 23
JSON_COMMA ,
Make the lexer skip characters after a lexical error until a
structural character ('[', ']', '{', '}', ':', ','), an ASCII control
character, or '\xFE', or '\xFF'.
Note that we must not skip ASCII control characters, '\xFE', '\xFF',
because those are documented to force the JSON parser into known-good
state, by docs/interop/qmp-spec.txt.
The lexer now produces
JSON_ERROR 01
JSON_COMMA ,
Update qmp-test for the nicer error recovery: QMP now reports just one
error for input %p instead of two. Also drop the newline after %p; it
was needed to tease out the second error.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180831075841.13363-5-armbru@redhat.com>
[Conflict with commit ebb4d82d88 resolved]
The lexer uses macro TERMINAL_NEEDED_LOOKAHEAD() to decide whether a
state transition consumes the input character. It returns true when
the state transition is defined with the TERMINAL() macro. To detect
that, it checks whether input '\0' would have resulted in the same
state transition, and the new state is not IN_ERROR.
Why does that even work? For all states, the new state on input '\0'
is either IN_ERROR or defined with TERMINAL(). If the state
transition equals the one we'd get for input '\0', it goes to IN_ERROR
or to the argument of TERMINAL(). We never use TERMINAL(IN_ERROR),
because it makes no sense. Thus, if it doesn't go to IN_ERROR, it
must be defined with TERMINAL().
Since this isn't quite confusing enough, we negate the result to get
@char_consumed, and ignore it when @flush is true.
Instead of deriving the lookahead bit from the state transition, make
it explicit. This is easier to understand, and a bit more flexible,
too.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180831075841.13363-4-armbru@redhat.com>
When the lexer isn't in its start state at the end of input, it's
working on a token. To flush it out, it needs to transit to its start
state on "end of input" lookahead.
There are two ways to the start state, depending on the current state:
* If the lexer is in a TERMINAL(JSON_FOO) state, it can emit a
JSON_FOO token.
* Else, it can go to IN_ERROR state, and emit a JSON_ERROR token.
There are complications, however:
* The transition to IN_ERROR state consumes the input character and
adds it to the JSON_ERROR token. The latter is inappropriate for
the "end of input" character, so we suppress that. See also recent
commit a2ec6be72b "json: Fix lexer to include the bad character in
JSON_ERROR token".
* The transition to a TERMINAL(JSON_FOO) state doesn't consume the
input character. In that case, the lexer normally loops until it is
consumed. We have to suppress that for the "end of input" input
character. If we didn't, the lexer would consume it by entering
IN_ERROR state, emitting a bogus JSON_ERROR token. We fixed that in
commit bd3924a33a.
However, simply breaking the loop this way assumes that the lexer
needs exactly one state transition to reach its start state. That
assumption is correct now, but it's unclean, and I'll soon break it.
Clean up: instead of breaking the loop after one iteration, break it
after it reached the start state.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180831075841.13363-3-armbru@redhat.com>
The lexer fails to end a valid token when the lookahead character is
beyond '\x7F'. For instance, input
true\xC2\xA2
produces the tokens
JSON_ERROR true\xC2
JSON_ERROR \xA2
This should be
JSON_KEYWORD true
JSON_ERROR \xC2
JSON_ERROR \xA2
instead.
The culprit is
#define TERMINAL(state) [0 ... 0x7F] = (state)
It leaves [0x80..0xFF] zero, i.e. IN_ERROR. Has always been broken.
Fix it to initialize the complete array.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180831075841.13363-2-armbru@redhat.com>
The previous commit makes JSON strings containing '%' awkward to
express in templates: you'd have to mask the '%' with an Unicode
escape \u0025. No template currently contains such JSON strings.
Support the printf conversion specification %% in JSON strings as a
convenience anyway, because it's trivially easy to do.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-58-armbru@redhat.com>
The JSON parser optionally supports interpolation. This is used to
build QObjects by parsing string templates. The templates are C
literals, so parse errors (such as invalid interpolation
specifications) are actually programming errors. Consequently, the
functions providing parsing with interpolation
(qobject_from_jsonf_nofail(), qobject_from_vjsonf_nofail(),
qdict_from_jsonf_nofail(), qdict_from_vjsonf_nofail()) pass
&error_abort to the parser.
However, there's another, more dangerous kind of programming error:
since we use va_arg() to get the value to interpolate, behavior is
undefined when the variable argument isn't consistent with the
interpolation specification.
The same problem exists with printf()-like functions, and the solution
is to have the compiler check consistency. This is what
GCC_FMT_ATTR() is about.
To enable this type checking for interpolation as well, we carefully
chose our interpolation specifications to match printf conversion
specifications, and decorate functions parsing templates with
GCC_FMT_ATTR().
Note that this only protects against undefined behavior due to type
errors. It can't protect against use of invalid interpolation
specifications that happen to be valid printf conversion
specifications.
However, there's still a gaping hole in the type checking: GCC
recognizes '%' as start of printf conversion specification anywhere in
the template, but the parser recognizes it only outside JSON strings.
For instance, if someone were to pass a "{ '%s': %d }" template, GCC
would require a char * and an int argument, but the parser would
va_arg() only an int argument, resulting in undefined behavior.
Avoid undefined behavior by catching the programming error at run
time: have the parser recognize and reject '%' in JSON strings.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-57-armbru@redhat.com>
The recursive descent parser passes along a pointer to
JSONParserContext. It additionally passes a pointer to interpolation
state (a va_alist *) as needed to reach its consumer
parse_interpolation().
Stuffing the latter pointer into JSONParserContext saves us the
trouble of passing it along, so do that.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-56-armbru@redhat.com>
The JSON parser has three public headers, json-lexer.h, json-parser.h,
json-streamer.h. They all contain stuff that is of no interest
outside qobject/json-*.c.
Collect the public interface in include/qapi/qmp/json-parser.h, and
everything else in qobject/json-parser-int.h.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-54-armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-53-armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-52-armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-51-armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-50-armbru@redhat.com>
Token count and size limits exist to guard against excessive heap
usage. We check them only after we created the token on the heap.
That's assigning a cowboy to the barn to lasso the horse after it has
bolted. Close the barn door instead: check before we create the
token.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-49-armbru@redhat.com>
The last case where qobject_from_json() & friends return null without
setting an error is empty or blank input. Callers:
* block.c's parse_json_protocol() reports "Could not parse the JSON
options". It's marked as a work-around, because it also covered
actual bugs, but they got fixed in the previous few commits.
* qobject_input_visitor_new_str() reports "JSON parse error". Also
marked as work-around. The recent fixes have made this unreachable,
because it currently gets called only for input starting with '{'.
* check-qjson.c's empty_input() and blank_input() demonstrate the
behavior.
* The other callers are not affected since they only pass input with
exactly one JSON value or, in the case of negative tests, one error.
Fail with "Expecting a JSON value" instead of returning null, and
simplify callers.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-48-armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-47-armbru@redhat.com>
json_message_process_token() accumulates tokens until it got the
sequence of tokens that comprise a single JSON value (it counts curly
braces and square brackets to decide). It feeds those token sequences
to json_parser_parse(). If a non-empty sequence of tokens remains at
the end of the parse, it's silently ignored. check-qjson.c cases
unterminated_array(), unterminated_array_comma(), unterminated_dict(),
unterminated_dict_comma() demonstrate this bug.
Fix as follows. Introduce a JSON_END_OF_INPUT token. When the
streamer receives it, it feeds the accumulated tokens to
json_parser_parse().
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-46-armbru@redhat.com>
json-parser.c carefully reports end of input like this:
token = parser_context_pop_token(ctxt);
if (token == NULL) {
parse_error(ctxt, NULL, "premature EOI");
goto out;
}
Except parser_context_pop_token() can't return null, it fails its
assertion instead. Same for parser_context_peek_token(). Broken in
commit 65c0f1e955, and faithfully preserved in commit 95385fe9ac.
Only a latent bug, because the streamer throws away any input that
could trigger it.
Drop the assertions, so we can fix the streamer in the next commit.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-45-armbru@redhat.com>
qobject_from_json() & friends use the consume_json() callback to
receive either a value or an error from the parser.
When they are fed a string that contains more than either one JSON
value or one JSON syntax error, consume_json() gets called multiple
times.
When the last call receives a value, qobject_from_json() returns that
value. Any other values are leaked.
When any call receives an error, qobject_from_json() sets the first
error received. Any other errors are thrown away.
When values follow errors, qobject_from_json() returns both a value
and sets an error. That's bad. Impact:
* block.c's parse_json_protocol() ignores and leaks the value. It's
used to to parse pseudo-filenames starting with "json:". The
pseudo-filenames can come from the user or from image meta-data such
as a QCOW2 image's backing file name.
* vl.c's parse_display_qapi() ignores and leaks the error. It's used
to parse the argument of command line option -display.
* vl.c's main() case QEMU_OPTION_blockdev ignores the error and leaves
it in @err. main() will then pass a pointer to a non-null Error *
to net_init_clients(), which is forbidden. It can lead to assertion
failure or other misbehavior.
* check-qjson.c's multiple_values() demonstrates the badness.
* The other callers are not affected since they only pass strings with
exactly one JSON value or, in the case of negative tests, one
error.
The impact on the _nofail() functions is relatively harmless. They
abort when any call receives an error. Else they return the last
value, and leak the others, if any.
Fix consume_json() as follows. On the first call, save value and
error as before. On subsequent calls, if any, don't save them. If
the first call saved a value, the next call, if any, replaces the
value by an "Expecting at most one JSON value" error. Take care not
to leak values or errors that aren't saved.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-44-armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-43-armbru@redhat.com>
Support for %I64d got added in commit 2c0d4b36e7 "json: fix PRId64 on
Win32". We had to hard-code I64d because we used the lexer's finite
state machine to check interpolations. No more, so clean this up.
Additional conversion specifications would be easy enough to implement
when needed.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-42-armbru@redhat.com>
Both lexer and parser reject invalid interpolation specifications.
The parser's check is useless.
The lexer ends the token right after the first bad character. This
tends to lead to suboptimal error reporting. For instance, input
[ %04d ]
produces the tokens
JSON_LSQUARE [
JSON_ERROR %0
JSON_INTEGER 4
JSON_KEYWORD d
JSON_RSQUARE ]
The parser then yields an error, an object and two more errors:
error: Invalid JSON syntax
object: 4
error: JSON parse error, invalid keyword
error: JSON parse error, expecting value
Dumb down the lexer to accept [A-Za-z0-9]*. The parser's check is now
used. Emit a proper error there.
The lexer now produces
JSON_LSQUARE [
JSON_INTERP %04d
JSON_RSQUARE ]
and the parser reports just
JSON parse error, invalid interpolation '%04d'
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-41-armbru@redhat.com>
