164 lines
3.6 KiB
C
164 lines
3.6 KiB
C
/* buf.c - by Alen Stojanov and David van Moolenbroek, taken from procfs */
|
|
#define _SYSTEM 1 /* tell headers that this is the kernel */
|
|
#define DEVMAN_SERVER 1
|
|
|
|
#include <minix/config.h>
|
|
#include <errno.h>
|
|
#include <unistd.h>
|
|
#include <stdlib.h>
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#include <lib.h>
|
|
#include <minix/timers.h>
|
|
|
|
#include <minix/callnr.h>
|
|
#include <minix/type.h>
|
|
#include <minix/const.h>
|
|
#include <minix/com.h>
|
|
#include <minix/syslib.h>
|
|
#include <minix/sysutil.h>
|
|
#include <minix/vfsif.h>
|
|
#include <minix/endpoint.h>
|
|
#include <minix/sysinfo.h>
|
|
#include <minix/u64.h>
|
|
#include <minix/sysinfo.h>
|
|
#include <minix/type.h>
|
|
#include <minix/ipc.h>
|
|
|
|
#include <sys/time.h>
|
|
#include <sys/times.h>
|
|
#include <sys/types.h>
|
|
#include <sys/stat.h>
|
|
|
|
#include <minix/vtreefs.h>
|
|
|
|
#include <minix/devman.h>
|
|
|
|
|
|
#include <stdarg.h>
|
|
#include <assert.h>
|
|
#include <string.h>
|
|
#define BUF_SIZE 4096
|
|
|
|
static char buf[BUF_SIZE + 1];
|
|
static size_t off, left, used;
|
|
static off_t skip;
|
|
|
|
/*===========================================================================*
|
|
* buf_init *
|
|
*===========================================================================*/
|
|
void buf_init(off_t start, size_t len)
|
|
{
|
|
/* Initialize the buffer for fresh use. The first 'start' bytes of the
|
|
* produced output are to be skipped. After that, up to a total of
|
|
* 'len' bytes are requested.
|
|
*/
|
|
|
|
skip = start;
|
|
left = MIN(len, BUF_SIZE);
|
|
off = 0;
|
|
used = 0;
|
|
}
|
|
|
|
/*===========================================================================*
|
|
* buf_printf *
|
|
*===========================================================================*/
|
|
void buf_printf(char *fmt, ...)
|
|
{
|
|
/* Add formatted text to the end of the buffer.
|
|
*/
|
|
va_list args;
|
|
ssize_t len, max;
|
|
|
|
if (left == 0)
|
|
return;
|
|
|
|
/* There is no way to estimate how much space the result will take, so
|
|
* we need to produce the string even when skipping part of the start.
|
|
* If part of the result is to be skipped, do not memcpy; instead, save
|
|
* the offset of where the result starts within the buffer.
|
|
*
|
|
* The null terminating character is not part of the result, so room
|
|
* must be given for it to be stored after completely filling up the
|
|
* requested part of the buffer.
|
|
*/
|
|
max = MIN(skip + left, BUF_SIZE);
|
|
|
|
va_start(args, fmt);
|
|
len = vsnprintf(&buf[off + used], max + 1, fmt, args);
|
|
va_end(args);
|
|
|
|
if (skip > 0) {
|
|
assert(off == 0);
|
|
assert(used == 0);
|
|
|
|
if (skip >= len) {
|
|
skip -= len;
|
|
|
|
return;
|
|
}
|
|
|
|
off = skip;
|
|
if (left > BUF_SIZE - off)
|
|
left = BUF_SIZE - off;
|
|
len -= off;
|
|
skip = 0;
|
|
}
|
|
|
|
assert(skip == 0);
|
|
assert(len >= 0);
|
|
assert((long) left >= 0);
|
|
|
|
if (len > (ssize_t) left)
|
|
len = left;
|
|
|
|
used += len;
|
|
left -= len;
|
|
}
|
|
|
|
/*===========================================================================*
|
|
* buf_append *
|
|
*===========================================================================*/
|
|
void buf_append(char *data, size_t len)
|
|
{
|
|
/* Add arbitrary data to the end of the buffer.
|
|
*/
|
|
|
|
if (left == 0)
|
|
return;
|
|
|
|
if (skip > 0) {
|
|
if (skip >= (ssize_t) len) {
|
|
skip -= len;
|
|
|
|
return;
|
|
}
|
|
|
|
data += skip;
|
|
len -= skip;
|
|
skip = 0;
|
|
}
|
|
|
|
if (len > left)
|
|
len = left;
|
|
|
|
memcpy(&buf[off + used], data, len);
|
|
|
|
used += len;
|
|
left -= len;
|
|
}
|
|
|
|
/*===========================================================================*
|
|
* buf_get *
|
|
*===========================================================================*/
|
|
size_t buf_get(char **ptr)
|
|
{
|
|
/* Return the buffer's starting address and the length of the used
|
|
* part, not counting the trailing null character for the latter.
|
|
*/
|
|
|
|
*ptr = &buf[off];
|
|
|
|
return used;
|
|
}
|