const char *rt_print_buffer_name(void)
{
struct print_buffer *buffer = pthread_getspecific(buffer_key);
if (!buffer) {
int res = -1;
if (auto_init)
res = rt_print_init(0, NULL);
if (res)
return NULL;
buffer = pthread_getspecific(buffer_key);
}
return buffer->name;
}
static int
vprint_to_buffer(FILE *stream, int fortify_level, int priority,
unsigned int mode, size_t sz, const char *format, va_list args)
{
struct print_buffer *buffer = pthread_getspecific(buffer_key);
off_t write_pos, read_pos;
struct entry_head *head;
int len, str_len;
int res = 0;
if (!buffer) {
res = 0;
if (auto_init)
res = rt_print_init(0, NULL);
else
res = EIO;
if (res) {
errno = res;
return -1;
}
buffer = pthread_getspecific(buffer_key);
}
/* Take a snapshot of the ring buffer state */
write_pos = buffer->write_pos;
read_pos = buffer->read_pos;
smp_mb();
/* Is our write limit the end of the ring buffer? */
if (write_pos >= read_pos) {
/* Keep a safety margin to the end for at least an empty entry */
len = buffer->size - write_pos - sizeof(struct entry_head);
/* Special case: We were stuck at the end of the ring buffer
with space left there only for one empty entry. Now
read_pos was moved forward and we can wrap around. */
if (len == 0 && read_pos > sizeof(struct entry_head)) {
/* Write out empty entry */
head = buffer->ring + write_pos;
head->seq_no = seq_no;
head->priority = 0;
head->len = 0;
/* Forward to the ring buffer start */
write_pos = 0;
len = read_pos - 1;
}
} else {
/* Our limit is the read_pos ahead of our write_pos. One byte
margin is required to detect a full ring. */
len = read_pos - write_pos - 1;
}
/* Account for head length */
len -= sizeof(struct entry_head);
if (len < 0)
len = 0;
head = buffer->ring + write_pos;
if (mode == RT_PRINT_MODE_FORMAT) {
if (stream != RT_PRINT_SYSLOG_STREAM) {
/* We do not need the terminating \0 */
#ifdef CONFIG_XENO_FORTIFY
if (fortify_level > 0)
res = __vsnprintf_chk(head->data, len,
fortify_level - 1,
len > 0 ? len : 0,
format, args);
else
#else
(void)fortify_level;
#endif
res = vsnprintf(head->data, len, format, args);
if (res < len) {
/* Text was written completely, res contains its
length */
len = res;
} else {
/* Text was truncated */
res = len;
}
} else {
/* We DO need the terminating \0 */
#ifdef CONFIG_XENO_FORTIFY
if (fortify_level > 0)
res = __vsnprintf_chk(head->data, len,
fortify_level - 1,
len > 0 ? len : 0,
format, args);
else
#endif
res = vsnprintf(head->data, len, format, args);
if (res < len) {
/* Text was written completely, res contains its
length */
len = res + 1;
} else {
/* Text was truncated */
res = len;
}
}
} else if (len >= 1) {
str_len = sz;
len = (str_len < len) ? str_len : len;
memcpy(head->data, format, len);
} else
len = 0;
/* If we were able to write some text, finalise the entry */
if (len > 0) {
head->seq_no = ++seq_no;
head->priority = priority;
head->dest = stream;
head->len = len;
/* Move forward by text and head length */
write_pos += len + sizeof(struct entry_head);
}
/* Wrap around early if there is more space on the other side */
if (write_pos >= buffer->size - RT_PRINT_LINE_BREAK &&
read_pos <= write_pos && read_pos > buffer->size - write_pos) {
/* An empty entry marks the wrap-around */
head = buffer->ring + write_pos;
head->seq_no = seq_no;
head->priority = priority;
head->len = 0;
write_pos = 0;
}
/* All entry data must be written before we can update write_pos */
smp_wmb();
buffer->write_pos = write_pos;
return res;
}
int rt_vfprintf(FILE *stream, const char *format, va_list args)
{
struct print_buffer *buffer = pthread_getspecific(__buffer_key);
off_t write_pos, read_pos;
struct entry_head *head;
int len;
int res;
if (!buffer) {
res = 0;
if (__auto_init)
res = rt_print_init(0, NULL);
else
res = EIO;
if (res) {
errno = res;
return -1;
}
buffer = pthread_getspecific(__buffer_key);
}
/* Take a snapshot of the ring buffer state */
write_pos = buffer->write_pos;
read_pos = buffer->read_pos;
xnarch_read_memory_barrier();
/* Is our write limit the end of the ring buffer? */
if (write_pos >= read_pos) {
/* Keep a savety margin to the end for at least an empty entry */
len = buffer->size - write_pos - sizeof(struct entry_head);
/* Special case: We were stuck at the end of the ring buffer
with space left there only for one empty entry. Now
read_pos was moved forward and we can wrap around. */
if (len == 0 && read_pos > sizeof(struct entry_head)) {
/* Write out empty entry */
head = buffer->ring + write_pos;
head->seq_no = __seq_no;
head->text[0] = 0;
/* Forward to the ring buffer start */
write_pos = 0;
len = read_pos - 1;
}
} else {
/* Our limit is the read_pos ahead of our write_pos. One byte
margin is required to detect a full ring. */
len = read_pos - write_pos - 1;
}
/* Account for head length */
len -= sizeof(struct entry_head);
if (len < 0)
len = 0;
head = buffer->ring + write_pos;
res = vsnprintf(head->text, len, format, args);
if (res < len) {
/* Text was written completely, res contains its length */
len = res;
} else {
/* Text was truncated, remove closing \0 that entry_head
already includes */
len--;
}
/* If we were able to write some text, finalise the entry */
if (len > 0) {
head->seq_no = ++__seq_no;
head->dest = stream;
/* Move forward by text and head length */
write_pos += len + sizeof(struct entry_head);
}
/* Wrap around early if there is more space on the other side */
if (write_pos >= buffer->size - RT_PRINT_LINE_BREAK &&
read_pos <= write_pos && read_pos > buffer->size - write_pos) {
/* An empty entry marks the wrap-around */
head = buffer->ring + write_pos;
head->seq_no = __seq_no;
head->text[0] = 0;
write_pos = 0;
}
/* All entry data must be written before we can update write_pos */
xnarch_write_memory_barrier();
buffer->write_pos = write_pos;
return res;
}
