qemu/hw/char/sclpconsole-lm.c
Philippe Mathieu-Daudé 880a7817c1 misc: Replace zero-length arrays with flexible array member (manual)
Description copied from Linux kernel commit from Gustavo A. R. Silva
(see [3]):

--v-- description start --v--

  The current codebase makes use of the zero-length array language
  extension to the C90 standard, but the preferred mechanism to
  declare variable-length types such as these ones is a flexible
  array member [1], introduced in C99:

  struct foo {
      int stuff;
      struct boo array[];
  };

  By making use of the mechanism above, we will get a compiler
  warning in case the flexible array does not occur last in the
  structure, which will help us prevent some kind of undefined
  behavior bugs from being unadvertenly introduced [2] to the
  Linux codebase from now on.

--^-- description end --^--

Do the similar housekeeping in the QEMU codebase (which uses
C99 since commit 7be41675f7).

All these instances of code were found with the help of the
following command (then manual analysis, without modifying
structures only having a single flexible array member, such
QEDTable in block/qed.h):

  git grep -F '[0];'

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=76497732932f
[3] https://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux.git/commit/?id=17642a2fbd2c1

Inspired-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-03-16 22:07:42 +01:00

371 lines
10 KiB
C

/*
* SCLP event types
* Operations Command - Line Mode input
* Message - Line Mode output
*
* Copyright IBM, Corp. 2013
*
* Authors:
* Heinz Graalfs <graalfs@linux.vnet.ibm.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or (at your
* option) any later version. See the COPYING file in the top-level directory.
*
*/
#include "qemu/osdep.h"
#include "qemu/thread.h"
#include "qemu/error-report.h"
#include "qemu/module.h"
#include "chardev/char-fe.h"
#include "hw/s390x/sclp.h"
#include "migration/vmstate.h"
#include "hw/s390x/event-facility.h"
#include "hw/qdev-properties.h"
#include "hw/s390x/ebcdic.h"
#define SIZE_BUFFER 4096
#define NEWLINE "\n"
typedef struct OprtnsCommand {
EventBufferHeader header;
MDMSU message_unit;
char data[];
} QEMU_PACKED OprtnsCommand;
/* max size for line-mode data in 4K SCCB page */
#define SIZE_CONSOLE_BUFFER (SCCB_DATA_LEN - sizeof(OprtnsCommand))
typedef struct SCLPConsoleLM {
SCLPEvent event;
CharBackend chr;
bool echo; /* immediate echo of input if true */
uint32_t write_errors; /* errors writing to char layer */
uint32_t length; /* length of byte stream in buffer */
uint8_t buf[SIZE_CONSOLE_BUFFER];
} SCLPConsoleLM;
#define TYPE_SCLPLM_CONSOLE "sclplmconsole"
#define SCLPLM_CONSOLE(obj) \
OBJECT_CHECK(SCLPConsoleLM, (obj), TYPE_SCLPLM_CONSOLE)
/*
* Character layer call-back functions
*
* Allow 1 character at a time
*
* Accumulate bytes from character layer in console buffer,
* event_pending is set when a newline character is encountered
*
* The maximum command line length is limited by the maximum
* space available in an SCCB. Line mode console input is sent
* truncated to the guest in case it doesn't fit into the SCCB.
*/
static int chr_can_read(void *opaque)
{
SCLPConsoleLM *scon = opaque;
if (scon->event.event_pending) {
return 0;
}
return 1;
}
static void chr_read(void *opaque, const uint8_t *buf, int size)
{
SCLPConsoleLM *scon = opaque;
assert(size == 1);
if (*buf == '\r' || *buf == '\n') {
scon->event.event_pending = true;
sclp_service_interrupt(0);
return;
}
if (scon->length == SIZE_CONSOLE_BUFFER) {
/* Eat the character, but still process CR and LF. */
return;
}
scon->buf[scon->length] = *buf;
scon->length += 1;
if (scon->echo) {
/* XXX this blocks entire thread. Rewrite to use
* qemu_chr_fe_write and background I/O callbacks */
qemu_chr_fe_write_all(&scon->chr, buf, size);
}
}
/* functions to be called by event facility */
static bool can_handle_event(uint8_t type)
{
return type == SCLP_EVENT_MESSAGE || type == SCLP_EVENT_PMSGCMD;
}
static sccb_mask_t send_mask(void)
{
return SCLP_EVENT_MASK_OP_CMD | SCLP_EVENT_MASK_PMSGCMD;
}
static sccb_mask_t receive_mask(void)
{
return SCLP_EVENT_MASK_MSG | SCLP_EVENT_MASK_PMSGCMD;
}
/*
* Triggered by SCLP's read_event_data
* - convert ASCII byte stream to EBCDIC and
* - copy converted data into provided (SCLP) buffer
*/
static int get_console_data(SCLPEvent *event, uint8_t *buf, size_t *size,
int avail)
{
int len;
SCLPConsoleLM *cons = SCLPLM_CONSOLE(event);
len = cons->length;
/* data need to fit into provided SCLP buffer */
if (len > avail) {
return 1;
}
ebcdic_put(buf, (char *)&cons->buf, len);
*size = len;
cons->length = 0;
/* data provided and no more data pending */
event->event_pending = false;
qemu_notify_event();
return 0;
}
static int read_event_data(SCLPEvent *event, EventBufferHeader *evt_buf_hdr,
int *slen)
{
int avail, rc;
size_t src_len;
uint8_t *to;
OprtnsCommand *oc = (OprtnsCommand *) evt_buf_hdr;
if (!event->event_pending) {
/* no data pending */
return 0;
}
to = (uint8_t *)&oc->data;
avail = *slen - sizeof(OprtnsCommand);
rc = get_console_data(event, to, &src_len, avail);
if (rc) {
/* data didn't fit, try next SCCB */
return 1;
}
oc->message_unit.mdmsu.gds_id = GDS_ID_MDSMU;
oc->message_unit.mdmsu.length = cpu_to_be16(sizeof(struct MDMSU));
oc->message_unit.cpmsu.gds_id = GDS_ID_CPMSU;
oc->message_unit.cpmsu.length =
cpu_to_be16(sizeof(struct MDMSU) - sizeof(GdsVector));
oc->message_unit.text_command.gds_id = GDS_ID_TEXTCMD;
oc->message_unit.text_command.length =
cpu_to_be16(sizeof(struct MDMSU) - (2 * sizeof(GdsVector)));
oc->message_unit.self_def_text_message.key = GDS_KEY_SELFDEFTEXTMSG;
oc->message_unit.self_def_text_message.length =
cpu_to_be16(sizeof(struct MDMSU) - (3 * sizeof(GdsVector)));
oc->message_unit.text_message.key = GDS_KEY_TEXTMSG;
oc->message_unit.text_message.length =
cpu_to_be16(sizeof(GdsSubvector) + src_len);
oc->header.length = cpu_to_be16(sizeof(OprtnsCommand) + src_len);
oc->header.type = SCLP_EVENT_OPRTNS_COMMAND;
*slen = avail - src_len;
return 1;
}
/*
* Triggered by SCLP's write_event_data
* - write console data to character layer
* returns < 0 if an error occurred
*/
static int write_console_data(SCLPEvent *event, const uint8_t *buf, int len)
{
SCLPConsoleLM *scon = SCLPLM_CONSOLE(event);
if (!qemu_chr_fe_backend_connected(&scon->chr)) {
/* If there's no backend, we can just say we consumed all data. */
return len;
}
/* XXX this blocks entire thread. Rewrite to use
* qemu_chr_fe_write and background I/O callbacks */
return qemu_chr_fe_write_all(&scon->chr, buf, len);
}
static int process_mdb(SCLPEvent *event, MDBO *mdbo)
{
int rc;
int len;
uint8_t buffer[SIZE_BUFFER];
len = be16_to_cpu(mdbo->length);
len -= sizeof(mdbo->length) + sizeof(mdbo->type)
+ sizeof(mdbo->mto.line_type_flags)
+ sizeof(mdbo->mto.alarm_control)
+ sizeof(mdbo->mto._reserved);
assert(len <= SIZE_BUFFER);
/* convert EBCDIC SCLP contents to ASCII console message */
ascii_put(buffer, mdbo->mto.message, len);
rc = write_console_data(event, (uint8_t *)NEWLINE, 1);
if (rc < 0) {
return rc;
}
return write_console_data(event, buffer, len);
}
static int write_event_data(SCLPEvent *event, EventBufferHeader *ebh)
{
int len;
int written;
int errors = 0;
MDBO *mdbo;
SclpMsg *data = (SclpMsg *) ebh;
SCLPConsoleLM *scon = SCLPLM_CONSOLE(event);
len = be16_to_cpu(data->mdb.header.length);
if (len < sizeof(data->mdb.header)) {
return SCLP_RC_INCONSISTENT_LENGTHS;
}
len -= sizeof(data->mdb.header);
/* first check message buffers */
mdbo = data->mdb.mdbo;
while (len > 0) {
if (be16_to_cpu(mdbo->length) > len
|| be16_to_cpu(mdbo->length) == 0) {
return SCLP_RC_INCONSISTENT_LENGTHS;
}
len -= be16_to_cpu(mdbo->length);
mdbo = (void *) mdbo + be16_to_cpu(mdbo->length);
}
/* then execute */
len = be16_to_cpu(data->mdb.header.length) - sizeof(data->mdb.header);
mdbo = data->mdb.mdbo;
while (len > 0) {
switch (be16_to_cpu(mdbo->type)) {
case MESSAGE_TEXT:
/* message text object */
written = process_mdb(event, mdbo);
if (written < 0) {
/* character layer error */
errors++;
}
break;
default: /* ignore */
break;
}
len -= be16_to_cpu(mdbo->length);
mdbo = (void *) mdbo + be16_to_cpu(mdbo->length);
}
if (errors) {
scon->write_errors += errors;
}
data->header.flags = SCLP_EVENT_BUFFER_ACCEPTED;
return SCLP_RC_NORMAL_COMPLETION;
}
/* functions for live migration */
static const VMStateDescription vmstate_sclplmconsole = {
.name = "sclplmconsole",
.version_id = 0,
.minimum_version_id = 0,
.fields = (VMStateField[]) {
VMSTATE_BOOL(event.event_pending, SCLPConsoleLM),
VMSTATE_UINT32(write_errors, SCLPConsoleLM),
VMSTATE_UINT32(length, SCLPConsoleLM),
VMSTATE_UINT8_ARRAY(buf, SCLPConsoleLM, SIZE_CONSOLE_BUFFER),
VMSTATE_END_OF_LIST()
}
};
/* qemu object creation and initialization functions */
/* tell character layer our call-back functions */
static int console_init(SCLPEvent *event)
{
static bool console_available;
SCLPConsoleLM *scon = SCLPLM_CONSOLE(event);
if (console_available) {
error_report("Multiple line-mode operator consoles are not supported");
return -1;
}
console_available = true;
qemu_chr_fe_set_handlers(&scon->chr, chr_can_read,
chr_read, NULL, NULL, scon, NULL, true);
return 0;
}
static void console_reset(DeviceState *dev)
{
SCLPEvent *event = SCLP_EVENT(dev);
SCLPConsoleLM *scon = SCLPLM_CONSOLE(event);
event->event_pending = false;
scon->length = 0;
scon->write_errors = 0;
}
static Property console_properties[] = {
DEFINE_PROP_CHR("chardev", SCLPConsoleLM, chr),
DEFINE_PROP_UINT32("write_errors", SCLPConsoleLM, write_errors, 0),
DEFINE_PROP_BOOL("echo", SCLPConsoleLM, echo, true),
DEFINE_PROP_END_OF_LIST(),
};
static void console_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
SCLPEventClass *ec = SCLP_EVENT_CLASS(klass);
device_class_set_props(dc, console_properties);
dc->reset = console_reset;
dc->vmsd = &vmstate_sclplmconsole;
ec->init = console_init;
ec->get_send_mask = send_mask;
ec->get_receive_mask = receive_mask;
ec->can_handle_event = can_handle_event;
ec->read_event_data = read_event_data;
ec->write_event_data = write_event_data;
set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
}
static const TypeInfo sclp_console_info = {
.name = "sclplmconsole",
.parent = TYPE_SCLP_EVENT,
.instance_size = sizeof(SCLPConsoleLM),
.class_init = console_class_init,
.class_size = sizeof(SCLPEventClass),
};
static void register_types(void)
{
type_register_static(&sclp_console_info);
}
type_init(register_types)