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Filename : print.c
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/* -*- linux-c -*- 
 * Print Functions
 * Copyright (C) 2007-2018 Red Hat Inc.
 *
 * This file is part of systemtap, and is free software.  You can
 * redistribute it and/or modify it under the terms of the GNU General
 * Public License (GPL); either version 2, or (at your option) any
 * later version.
 */

#ifndef _STAPLINUX_PRINT_C_
#define _STAPLINUX_PRINT_C_


#include "stp_string.h"
#include "print.h"
#include "transport/transport.c"
#include "vsprintf.c"

/** @file print.c
 * Printing Functions.
 */

/** @addtogroup print Print Functions
 * The print buffer is for collecting output to send to the user daemon.
 * This is a per-cpu static buffer.  The buffer is sent when
 * _stp_print_flush() is called.
 *
 * The reason to do this is to allow multiple small prints to be combined then
 * timestamped and sent together to staprun. This is more efficient than sending
 * numerous small packets.
 *
 * This function is called automatically when the print buffer is full.
 * It MUST also be called at the end of every probe that prints something.
 * @{
 */

typedef struct __stp_pbuf {
	uint32_t len;			/* bytes used in the buffer */
	char buf[STP_BUFFER_SIZE];
} _stp_pbuf;

static void *Stp_pbuf = NULL;

/** private buffer for _stp_vlog() */
#ifndef STP_LOG_BUF_LEN
#define STP_LOG_BUF_LEN 256
#endif

typedef char _stp_lbuf[STP_LOG_BUF_LEN];
static void *Stp_lbuf = NULL;

/* create percpu print and io buffers */
static int _stp_print_init (void)
{
	Stp_pbuf = _stp_alloc_percpu(sizeof(_stp_pbuf));
	if (unlikely(Stp_pbuf == 0))
		return -1;

	/* now initialize IO buffer used in io.c */
	Stp_lbuf = _stp_alloc_percpu(sizeof(_stp_lbuf));
	if (unlikely(Stp_lbuf == 0)) {
		_stp_free_percpu(Stp_pbuf);
		return -1;
	}
	return 0;
}

static void _stp_print_cleanup (void)
{
	if (Stp_pbuf)
		_stp_free_percpu(Stp_pbuf);
	if (Stp_lbuf)
		_stp_free_percpu(Stp_lbuf);
}

#include "print_flush.c"

static inline void _stp_print_flush(void)
{
	stp_print_flush(per_cpu_ptr(Stp_pbuf, smp_processor_id()));
}
#ifndef STP_MAXBINARYARGS
#define STP_MAXBINARYARGS 127
#endif


/** Reserves space in the output buffer for direct I/O.
 */
static void * _stp_reserve_bytes (int numbytes)
{
	_stp_pbuf *pb = per_cpu_ptr(Stp_pbuf, smp_processor_id());
	int size = STP_BUFFER_SIZE - pb->len;
	void * ret;

	if (unlikely(numbytes == 0 || numbytes > STP_BUFFER_SIZE))
		return NULL;

	if (unlikely(numbytes > size))
		_stp_print_flush();

	ret = pb->buf + pb->len;
	pb->len += numbytes;
	return ret;
}


static void _stp_unreserve_bytes (int numbytes)
{
	_stp_pbuf *pb = per_cpu_ptr(Stp_pbuf, smp_processor_id());

	if (unlikely(numbytes == 0 || numbytes > pb->len))
		return;

	pb->len -= numbytes;
}

/** Write 64-bit args directly into the output stream.
 * This function takes a variable number of 64-bit arguments
 * and writes them directly into the output stream.  Marginally faster
 * than doing the same in _stp_vsnprintf().
 * @sa _stp_vsnprintf()
 */
static void _stp_print_binary (int num, ...)
{
	va_list vargs;
	int i;
	int64_t *args;
	
	if (unlikely(num > STP_MAXBINARYARGS))
		num = STP_MAXBINARYARGS;

	args = _stp_reserve_bytes(num * sizeof(int64_t));

	if (likely(args != NULL)) {
		va_start(vargs, num);
		for (i = 0; i < num; i++) {
			args[i] = va_arg(vargs, int64_t);
		}
		va_end(vargs);
	}
}

/** Print into the print buffer.
 * Like C printf.
 *
 * @sa _stp_print_flush()
 */
static void _stp_printf (const char *fmt, ...)
{
	va_list args;
	va_start(args, fmt);
	_stp_vsnprintf(NULL, 0, fmt, args);
	va_end(args);
}

/** Write a string into the print buffer.
 * @param str A C string (char *)
 */

static void _stp_print (const char *str)
{
	_stp_pbuf *pb = per_cpu_ptr(Stp_pbuf, smp_processor_id());
	char *end = pb->buf + STP_BUFFER_SIZE;
	char *ptr = pb->buf + pb->len;
	char *instr = (char *)str;

	while (ptr < end && *instr)
		*ptr++ = *instr++;

	/* Did loop terminate due to lack of buffer space? */
	if (unlikely(*instr)) {
		/* Don't break strings across subbufs. */
		/* Restart after flushing. */
		_stp_print_flush();
		end = pb->buf + STP_BUFFER_SIZE;
		ptr = pb->buf + pb->len;
		instr = (char *)str;
		while (ptr < end && *instr)
			*ptr++ = *instr++;
	}
	pb->len = ptr - pb->buf;
}

static void _stp_print_char (const char c)
{
	_stp_pbuf *pb = per_cpu_ptr(Stp_pbuf, smp_processor_id());
	int size = STP_BUFFER_SIZE - pb->len;
	if (unlikely(1 >= size))
		_stp_print_flush();
	
	pb->buf[pb->len] = c;
	pb->len ++;
}

static void _stp_print_kernel_info(char *sname, char *vstr, int ctx, int num_probes)
{
	printk(KERN_DEBUG
               "%s (%s): systemtap: %s, base: %p"
               ", memory: %ludata/%lutext/%uctx/%unet/%ualloc kb"
               ", probes: %d"
#if ! STP_PRIVILEGE_CONTAINS (STP_PRIVILEGE, STP_PR_STAPDEV)
               ", unpriv-uid: %d"
#endif
               "\n",
	       THIS_MODULE->name,
	       sname, /* name of source file */
	       vstr,  /* stap version */
#ifdef STAPCONF_MODULE_LAYOUT
	       THIS_MODULE->core_layout.base,
	       (unsigned long) (THIS_MODULE->core_layout.size - THIS_MODULE->core_layout.text_size)/1024,
	       (unsigned long) (THIS_MODULE->core_layout.text_size)/1024,
#else
#ifndef STAPCONF_GRSECURITY
	       THIS_MODULE->module_core,
	       (unsigned long) (THIS_MODULE->core_size - THIS_MODULE->core_text_size)/1024,
               (unsigned long) (THIS_MODULE->core_text_size)/1024,
#else
               THIS_MODULE->module_core_rx,
	       (unsigned long) (THIS_MODULE->core_size_rw - THIS_MODULE->core_size_rx)/1024,
               (unsigned long) (THIS_MODULE->core_size_rx)/1024,
#endif
#endif
	       ctx/1024,
	       _stp_allocated_net_memory/1024,
	       (_stp_allocated_memory - _stp_allocated_net_memory - ctx)/1024,
               /* (un-double-counting net/ctx because they're also stp_alloc'd) */
               num_probes
#if ! STP_PRIVILEGE_CONTAINS (STP_PRIVILEGE, STP_PR_STAPDEV)
               , _stp_uid
#endif
                );
}

/** @} */
#endif /* _STAPLINUX_PRINT_C_ */