qemu/qapi/string-output-visitor.c
Eric Blake e65d89bf1a qapi: Adjust layout of FooList types
By sticking the next pointer first, we don't need a union with
64-bit padding for smaller types.  On 32-bit platforms, this
can reduce the size of uint8List from 16 bytes (or 12, depending
on whether 64-bit ints can tolerate 4-byte alignment) down to 8.
It has no effect on 64-bit platforms (where alignment still
dictates a 16-byte struct); but fewer anonymous unions is still
a win in my book.

It requires visit_next_list() to gain a size parameter, to know
what size element to allocate; comparable to the size parameter
of visit_start_struct().

I debated about going one step further, to allow for fewer casts,
by doing:
    typedef GenericList GenericList;
    struct GenericList {
        GenericList *next;
    };
    struct FooList {
        GenericList base;
        Foo *value;
    };
so that you convert to 'GenericList *' by '&foolist->base', and
back by 'container_of(generic, GenericList, base)' (as opposed to
the existing '(GenericList *)foolist' and '(FooList *)generic').
But doing that would require hoisting the declaration of
GenericList prior to inclusion of qapi-types.h, rather than its
current spot in visitor.h; it also makes iteration a bit more
verbose through 'foolist->base.next' instead of 'foolist->next'.

Note that for lists of objects, the 'value' payload is still
hidden behind a boxed pointer.  Someday, it would be nice to do:

struct FooList {
    FooList *next;
    Foo value;
};

for one less level of malloc for each list element.  This patch
is a step in that direction (now that 'next' is no longer at a
fixed non-zero offset within the struct, we can store more than
just a pointer's-worth of data as the value payload), but the
actual conversion would be a task for another series, as it will
touch a lot of code.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1455778109-6278-10-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-02-19 11:08:57 +01:00

367 lines
10 KiB
C

/*
* String printing Visitor
*
* Copyright Red Hat, Inc. 2012-2016
*
* Author: Paolo Bonzini <pbonzini@redhat.com>
*
* 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 "qemu-common.h"
#include "qapi/string-output-visitor.h"
#include "qapi/visitor-impl.h"
#include "qemu/host-utils.h"
#include <math.h>
#include "qemu/range.h"
enum ListMode {
LM_NONE, /* not traversing a list of repeated options */
LM_STARTED, /* start_list() succeeded */
LM_IN_PROGRESS, /* next_list() has been called.
*
* Generating the next list link will consume the most
* recently parsed QemuOpt instance of the repeated
* option.
*
* Parsing a value into the list link will examine the
* next QemuOpt instance of the repeated option, and
* possibly enter LM_SIGNED_INTERVAL or
* LM_UNSIGNED_INTERVAL.
*/
LM_SIGNED_INTERVAL, /* next_list() has been called.
*
* Generating the next list link will consume the most
* recently stored element from the signed interval,
* parsed from the most recent QemuOpt instance of the
* repeated option. This may consume QemuOpt itself
* and return to LM_IN_PROGRESS.
*
* Parsing a value into the list link will store the
* next element of the signed interval.
*/
LM_UNSIGNED_INTERVAL,/* Same as above, only for an unsigned interval. */
LM_END
};
typedef enum ListMode ListMode;
struct StringOutputVisitor
{
Visitor visitor;
bool human;
GString *string;
bool head;
ListMode list_mode;
union {
int64_t s;
uint64_t u;
} range_start, range_end;
GList *ranges;
};
static StringOutputVisitor *to_sov(Visitor *v)
{
return container_of(v, StringOutputVisitor, visitor);
}
static void string_output_set(StringOutputVisitor *sov, char *string)
{
if (sov->string) {
g_string_free(sov->string, true);
}
sov->string = g_string_new(string);
g_free(string);
}
static void string_output_append(StringOutputVisitor *sov, int64_t a)
{
Range *r = g_malloc0(sizeof(*r));
r->begin = a;
r->end = a + 1;
sov->ranges = g_list_insert_sorted_merged(sov->ranges, r, range_compare);
}
static void string_output_append_range(StringOutputVisitor *sov,
int64_t s, int64_t e)
{
Range *r = g_malloc0(sizeof(*r));
r->begin = s;
r->end = e + 1;
sov->ranges = g_list_insert_sorted_merged(sov->ranges, r, range_compare);
}
static void format_string(StringOutputVisitor *sov, Range *r, bool next,
bool human)
{
if (r->end - r->begin > 1) {
if (human) {
g_string_append_printf(sov->string, "0x%" PRIx64 "-0x%" PRIx64,
r->begin, r->end - 1);
} else {
g_string_append_printf(sov->string, "%" PRId64 "-%" PRId64,
r->begin, r->end - 1);
}
} else {
if (human) {
g_string_append_printf(sov->string, "0x%" PRIx64, r->begin);
} else {
g_string_append_printf(sov->string, "%" PRId64, r->begin);
}
}
if (next) {
g_string_append(sov->string, ",");
}
}
static void print_type_int64(Visitor *v, const char *name, int64_t *obj,
Error **errp)
{
StringOutputVisitor *sov = to_sov(v);
GList *l;
switch (sov->list_mode) {
case LM_NONE:
string_output_append(sov, *obj);
break;
case LM_STARTED:
sov->range_start.s = *obj;
sov->range_end.s = *obj;
sov->list_mode = LM_IN_PROGRESS;
return;
case LM_IN_PROGRESS:
if (sov->range_end.s + 1 == *obj) {
sov->range_end.s++;
} else {
if (sov->range_start.s == sov->range_end.s) {
string_output_append(sov, sov->range_end.s);
} else {
assert(sov->range_start.s < sov->range_end.s);
string_output_append_range(sov, sov->range_start.s,
sov->range_end.s);
}
sov->range_start.s = *obj;
sov->range_end.s = *obj;
}
return;
case LM_END:
if (sov->range_end.s + 1 == *obj) {
sov->range_end.s++;
assert(sov->range_start.s < sov->range_end.s);
string_output_append_range(sov, sov->range_start.s,
sov->range_end.s);
} else {
if (sov->range_start.s == sov->range_end.s) {
string_output_append(sov, sov->range_end.s);
} else {
assert(sov->range_start.s < sov->range_end.s);
string_output_append_range(sov, sov->range_start.s,
sov->range_end.s);
}
string_output_append(sov, *obj);
}
break;
default:
abort();
}
l = sov->ranges;
while (l) {
Range *r = l->data;
format_string(sov, r, l->next != NULL, false);
l = l->next;
}
if (sov->human) {
l = sov->ranges;
g_string_append(sov->string, " (");
while (l) {
Range *r = l->data;
format_string(sov, r, l->next != NULL, true);
l = l->next;
}
g_string_append(sov->string, ")");
}
}
static void print_type_uint64(Visitor *v, const char *name, uint64_t *obj,
Error **errp)
{
/* FIXME: print_type_int64 mishandles values over INT64_MAX */
int64_t i = *obj;
print_type_int64(v, name, &i, errp);
}
static void print_type_size(Visitor *v, const char *name, uint64_t *obj,
Error **errp)
{
StringOutputVisitor *sov = to_sov(v);
static const char suffixes[] = { 'B', 'K', 'M', 'G', 'T', 'P', 'E' };
uint64_t div, val;
char *out;
int i;
if (!sov->human) {
out = g_strdup_printf("%"PRIu64, *obj);
string_output_set(sov, out);
return;
}
val = *obj;
/* The exponent (returned in i) minus one gives us
* floor(log2(val * 1024 / 1000). The correction makes us
* switch to the higher power when the integer part is >= 1000.
*/
frexp(val / (1000.0 / 1024.0), &i);
i = (i - 1) / 10;
assert(i < ARRAY_SIZE(suffixes));
div = 1ULL << (i * 10);
out = g_strdup_printf("%"PRIu64" (%0.3g %c%s)", val,
(double)val/div, suffixes[i], i ? "iB" : "");
string_output_set(sov, out);
}
static void print_type_bool(Visitor *v, const char *name, bool *obj,
Error **errp)
{
StringOutputVisitor *sov = to_sov(v);
string_output_set(sov, g_strdup(*obj ? "true" : "false"));
}
static void print_type_str(Visitor *v, const char *name, char **obj,
Error **errp)
{
StringOutputVisitor *sov = to_sov(v);
char *out;
if (sov->human) {
out = *obj ? g_strdup_printf("\"%s\"", *obj) : g_strdup("<null>");
} else {
out = g_strdup(*obj ? *obj : "");
}
string_output_set(sov, out);
}
static void print_type_number(Visitor *v, const char *name, double *obj,
Error **errp)
{
StringOutputVisitor *sov = to_sov(v);
string_output_set(sov, g_strdup_printf("%f", *obj));
}
static void
start_list(Visitor *v, const char *name, Error **errp)
{
StringOutputVisitor *sov = to_sov(v);
/* we can't traverse a list in a list */
assert(sov->list_mode == LM_NONE);
sov->list_mode = LM_STARTED;
sov->head = true;
}
static GenericList *next_list(Visitor *v, GenericList **list, size_t size)
{
StringOutputVisitor *sov = to_sov(v);
GenericList *ret = NULL;
if (*list) {
if (sov->head) {
ret = *list;
} else {
ret = (*list)->next;
}
if (sov->head) {
if (ret && ret->next == NULL) {
sov->list_mode = LM_NONE;
}
sov->head = false;
} else {
if (ret && ret->next == NULL) {
sov->list_mode = LM_END;
}
}
}
return ret;
}
static void end_list(Visitor *v)
{
StringOutputVisitor *sov = to_sov(v);
assert(sov->list_mode == LM_STARTED ||
sov->list_mode == LM_END ||
sov->list_mode == LM_NONE ||
sov->list_mode == LM_IN_PROGRESS);
sov->list_mode = LM_NONE;
sov->head = true;
}
char *string_output_get_string(StringOutputVisitor *sov)
{
char *string = g_string_free(sov->string, false);
sov->string = NULL;
return string;
}
Visitor *string_output_get_visitor(StringOutputVisitor *sov)
{
return &sov->visitor;
}
static void free_range(void *range, void *dummy)
{
g_free(range);
}
void string_output_visitor_cleanup(StringOutputVisitor *sov)
{
if (sov->string) {
g_string_free(sov->string, true);
}
g_list_foreach(sov->ranges, free_range, NULL);
g_list_free(sov->ranges);
g_free(sov);
}
StringOutputVisitor *string_output_visitor_new(bool human)
{
StringOutputVisitor *v;
v = g_malloc0(sizeof(*v));
v->string = g_string_new(NULL);
v->human = human;
v->visitor.type_enum = output_type_enum;
v->visitor.type_int64 = print_type_int64;
v->visitor.type_uint64 = print_type_uint64;
v->visitor.type_size = print_type_size;
v->visitor.type_bool = print_type_bool;
v->visitor.type_str = print_type_str;
v->visitor.type_number = print_type_number;
v->visitor.start_list = start_list;
v->visitor.next_list = next_list;
v->visitor.end_list = end_list;
return v;
}