user/electric-fence/print.c

#include "efence.h"
#include <signal.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

/*
 * These routines do their printing without using stdio. Stdio can't
 * be used because it calls malloc(). Internal routines of a malloc()
 * debugger should not re-enter malloc(), so stdio is out.
 */

/*
 * NUMBER_BUFFER_SIZE is the longest character string that could be needed
 * to represent an unsigned integer, assuming we might print in base 2.
 */
#define NUMBER_BUFFER_SIZE (sizeof(ef_number) * NBBY)

static void printNumber(ef_number number, ef_number base)
{
	char buffer[NUMBER_BUFFER_SIZE];
	char *s = &buffer[NUMBER_BUFFER_SIZE];
	int size;

	do {
		ef_number digit;

		if (--s == buffer)
			EF_Abort("Internal error printing number.");

		digit = number % base;

		if (digit < 10)
			*s = '0' + digit;
		else
			*s = 'a' + digit - 10;

	} while ((number /= base) > 0);

	size = &buffer[NUMBER_BUFFER_SIZE] - s;

	if (size > 0)
		write(2, s, size);
}

static void vprint(const char *pattern, va_list args)
{
	static const char bad_pattern[] =
	    "\nBad pattern specifier %%%c in EF_Print().\n";
	const char *s = pattern;
	char c;

	while ((c = *s++) != '\0') {
		if (c == '%') {
			c = *s++;
			switch (c) {
			case '%':
				(void)write(2, &c, 1);
				break;
			case 'a':
				/*
				 * Print an address passed as a void pointer.
				 * The type of ef_number must be set so that
				 * it is large enough to contain all of the
				 * bits of a void pointer.
				 */
				printNumber((ef_number)va_arg(args, void *), 0x10);
				break;
			case 's': {
				const char *string;
				size_t length;

				string = va_arg(args, char *);
				length = strlen(string);

				(void)write(2, string, length);
			} break;
			case 'd': {
				int n = va_arg(args, int);

				if (n < 0) {
					char c = '-';
					write(2, &c, 1);
					n = -n;
				}
				printNumber(n, 10);
			} break;
			case 'x':
				printNumber(va_arg(args, u_int), 0x10);
				break;
			case 'c': { /*Cast used, since char gets promoted to int in ... */
				char c = (char)va_arg(args, int);

				(void)write(2, &c, 1);
			} break;
			default: {
				EF_Print(bad_pattern, c);
			}
			}
		} else
			(void)write(2, &c, 1);
	}
}

void EF_Abort(const char *pattern, ...)
{
	va_list args;

	va_start(args, pattern);

	EF_Print("\nElectricFence Aborting: ");
	vprint(pattern, args);
	EF_Print("\n");

	va_end(args);

	/*
	 * I use kill(getpid(), SIGILL) instead of abort() because some
	 * mis-guided implementations of abort() flush stdio, which can
	 * cause malloc() or free() to be called.
	 */
	kill(getpid(), SIGILL);
	/* Just in case something handles SIGILL and returns, exit here. */
	_exit(-1);
}

void EF_Exit(const char *pattern, ...)
{
	va_list args;

	va_start(args, pattern);

	EF_Print("\nElectricFence Exiting: ");
	vprint(pattern, args);
	EF_Print("\n");

	va_end(args);

	/*
	 * I use _exit() because the regular exit() flushes stdio,
	 * which may cause malloc() or free() to be called.
	 */
	_exit(-1);
}

void EF_Print(const char *pattern, ...)
{
	va_list args;

	va_start(args, pattern);
	vprint(pattern, args);
	va_end(args);
}