extra characters displayed at ends of lines

["Philippe Lorin" <palpalpalpal@hotmail.com>]

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In GNU Emacs 21.2.1 (i386-msvc-windows98.2222)
of 2002-03-19 on buffy
configured using `configure --with-msvc (12.00)'
Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: fra
  locale-coding-system: iso-latin-1
  default-enable-multibyte-characters: t

How to make the bug happen:

Have the attached file ready to be visited.
Using the following .emacs (without the tags of course):
<.emacs>
; Don't wrap lines
(set-default 'truncate-lines t)

; Frame position
(add-to-list 'default-frame-alist '(width . 122))
</.emacs>

Do this:
C-x C-f <attached file name, apparently the bug doesn't care about what the 
file name is>
C-s . s i z e C-s C-s

Here is the bug. The display is incorrect. There are extra characters beyond 
the actual ends of lines. To see what it should be like, just type:
C-l

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#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <allegro.h>
#include "GMbase/system.h"
#include "GMbase/systems/Allegro/util.h"
#include "GMbase/systems/Allegro/error.h"
#include "GMbase/systems/Allegro/malloc.h"
#undef malloc
#undef realloc
#undef free



typedef struct {
	void*	result;		// pointer returned to the caller: this is the pointer to 
the data without the fences
	size_t	size;		// size asked by the caller: this is the size of the data 
without the fences
	bool	realloced;	// whether this pointer was ever realloced
	int	line;
	char*	file;
} Malloc_trace;

#define nb_max_malloced_pointers 4096
static Malloc_trace traces[nb_max_malloced_pointers];
static int nb_malloced_pointers = 0;
static char tmp_string[1024];
static size_t max_size_reached;
static size_t current_size;

#define fence_size (32 * sizeof(char))
#define fence_value ((char) 223)



/** Whether the closing function for this subsystem was called or this 
subsystem is not initialized. */
static bool proper_end_called = true;
static void end() {
	if (! proper_end_called) {
		System_internal_error(false, "Malloc subsystem not ended.\n");
		PrivateSystem_malloc_end();
	}
}


void System_log_memory_usage() {
	int nb_bytes;

	nb_bytes = max_size_reached / sizeof(char);
	System_log("Maximum memory usage was: ");

	if (nb_bytes >= 1*1024*1024) {
		System_log("%.1f MB (%d bytes).\n", ((float) nb_bytes) / (1024 * 1024), 
nb_bytes);

	} else if (nb_bytes >= 3*1024) {
		System_log("%.1f kB (%d bytes).\n", ((float) nb_bytes) / 1024, nb_bytes);

	} else	{
		System_log("%d bytes.\n", nb_bytes);
	}
}


void PrivateSystem_malloc_end() {
	int i;
	proper_end_called = true;

	System_log_memory_usage();
	for (i = 0; i < nb_malloced_pointers; i++) {
		System_internal_error(false, "Memory leak: Area malloced at %s: %d (size: 
%d) was never freed.\n", traces[i].file, traces[i].line, traces[i].size);
	}
}


void PrivateSystem_malloc_init() {
	current_size = 0;
	max_size_reached = 0;

	proper_end_called = false;
	atexit(end);
}


void* _System_malloc(char* file, int line, size_t size) {
	static bool too_many_mallocs = false;
	void* mem;

	if (size == 0) {
		return NULL;
	}

	mem = malloc(size + 2*fence_size);
//debug_log("malloc(%d) at %s:%d -> %p\n", size, file, line, mem);
	if (mem != NULL) {
		// Register mem
		if (! too_many_mallocs) {
			if (nb_malloced_pointers >= nb_max_malloced_pointers) {
				PrivateSystem_internal_error(false, "Too many mallocs.\n");
				too_many_mallocs = true;

			} else	{
				traces[nb_malloced_pointers].result	= mem + fence_size;
				traces[nb_malloced_pointers].size	= size;
				traces[nb_malloced_pointers].realloced	= false;
				traces[nb_malloced_pointers].line	= line;
				traces[nb_malloced_pointers].file	= file;
				current_size += size;
				if (current_size > max_size_reached) {
					max_size_reached = current_size;
				}
				nb_malloced_pointers++;
			}
		}


		memset(mem, fence_value, fence_size);
		memset(mem + fence_size + size, fence_value, fence_size);
		System_check_malloc(mem + fence_size, "Malloc auto-check\n");
		return mem + fence_size;
	}

	// TODO handle this properly
	System_error(true, "Not enough memory.\n");
	return NULL; // compiler candy
}


void* _System_realloc(char* file, int line, void* p, size_t size) {
	void* mem;

	if (p == NULL) {
		return System_malloc(size);
	}

	System_check_malloc(p, "Realloc check before work\n");
	mem = realloc(p - fence_size, size + 2*fence_size);
//debug_log("realloc(%p, %d) at %s:%d -> %p\n", p, size, file, line, mem);
	if (mem != NULL) {
		int i;
		for (i = 0; i < nb_malloced_pointers; i++) {
			if (p == traces[i].result) {
				current_size += size - traces[i].size;
				if (current_size > max_size_reached) {
					max_size_reached = current_size;
				}
				traces[i].result = mem + fence_size;
				traces[i].size = size;
				traces[i].realloced = true;
				break;
			}

		}
		if (i == nb_malloced_pointers) {
			System_internal_error(false, "%s: %d: Bad pointer realloced (this pointer 
was never malloced).\n", file, line);
		}

		memset(mem, fence_value, fence_size);
		memset(mem + fence_size + size, fence_value, fence_size);
		System_check_malloc(mem + fence_size, "Realloc auto-check\n");
		return mem + fence_size;
	}

	// TODO handle this properly
	System_error(true, "Not enough memory.\n");
	return NULL; // compiler candy
}


void _System_free(char* file, int line, void* p) {
	int i;
//debug_log("free(%p) at %s:%d\n", p, file, line);
	if (p == NULL) {
		return;
	}

	System_check_malloc(p, "Free check before work\n");
	for (i = 0; i < nb_malloced_pointers; i++) {
		if (p == traces[i].result) {
			free(p);
			nb_malloced_pointers--;
			traces[i] = traces[nb_malloced_pointers];
//debug_log("}free\n");
			return;
		}

	}

//debug_log("}free:ERROR\n");
	System_internal_error(false, "%s: %d: Bad pointer freed. This pointer was 
never malloced.\n", file, line);
}


/**
* If p is inside any previously malloced memory, returns the corresponding 
trace's index.
* Otherwise returns -1.
// * Returns whether p is inside any previously malloced memory. Returns 
true when p == NULL.
*/
static int _check_malloc(void* p) {
	int i;

	if (p == NULL) return -1;

	for (i = 0; i < nb_malloced_pointers; i++) {
		if ((p >= traces[i].result) && (p < traces[i].result + traces[i].size)) {
			return i;
		}
	}

	return -1;
}


void System_check_malloc(void* p, char* format, ...) {
	int trace_index;

	if (p == NULL) return;

	trace_index = _check_malloc(p);
	if (trace_index == -1) {
		sprintf(tmp_string, "Bad pointer: ");
		sprintf_args(format, tmp_string + strlen(tmp_string));
		System_internal_error(true, tmp_string);

	} else	{
		int i;
		for (i = 0; i < fence_size / sizeof(char); i++) {
			if ((((char*) p) - fence_size + i != fence_value) || (((char*) p) + 
traces[trace_index].size + i != fence_value)) {
				sprintf(tmp_string, "Malloced area overflown: Memory around area 
malloced at %s: %d (size: %d) was illegally written into.\n", 
traces[trace_index].file, traces[trace_index].line, 
traces[trace_index].size);
				sprintf_args(format, tmp_string + strlen(tmp_string));
				System_internal_error(true, tmp_string);
			}
		}
	}
}






/*

// MEMC

static bool is_memc_on = false;

void set_memc_on() {
	is_memc_on = true;
}

void set_memc_off() {
	is_memc_on = false;
}

void memc_check(void* p, char* file, long line) {
	if (p == NULL) {
		debug_log("NULL pointer at %s:%d\n", file, line);
	}

	if (! is_memc_on) return;

	if (! _check_malloc(p)) {
		debug_log("Pointer to non-malloced area at %s:%d\n", file, line);
	}
}
*/


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