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ui-ssdiff: move LCS table away from the stack

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Printing deferred line changes for files containing long lines would
cause a segfault.

- limit LCS table size: 128x128.
- move LCS table to global context: avoid allocating/freeing memory
  for every deferred line change.

Signed-off-by: Jamie Couture <jamie.couture@gmail.com>
This commit is contained in:
Jamie Couture 2011-09-17 18:25:01 -04:00 committed by Lars Hjemli
parent bebe89d7c1
commit e19f7d7180
2 changed files with 43 additions and 2 deletions
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33
ui-ssdiff.c
View File

@ -2,10 +2,12 @@
#include "html.h"
#include "ui-shared.h"
#include "ui-diff.h"
#include "ui-ssdiff.h"
extern int use_ssdiff;
static int current_old_line, current_new_line;
static int **L = NULL;
struct deferred_lines {
int line_no;
@ -16,16 +18,42 @@ struct deferred_lines {
static struct deferred_lines *deferred_old, *deferred_old_last;
static struct deferred_lines *deferred_new, *deferred_new_last;
static void create_or_reset_lcs_table()
{
int i;
if (L != NULL) {
memset(*L, 0, sizeof(*L) * MAX_SSDIFF_SIZE);
return;
}
// xcalloc will die if we ran out of memory;
// not very helpful for debugging
L = (int**)xcalloc(MAX_SSDIFF_M, sizeof(int *));
*L = (int*)xcalloc(MAX_SSDIFF_SIZE, sizeof(int));
for (i = 1; i < MAX_SSDIFF_M; i++) {
L[i] = *L + i * MAX_SSDIFF_N;
}
}
static char *longest_common_subsequence(char *A, char *B)
{
int i, j, ri;
int m = strlen(A);
int n = strlen(B);
int L[m + 1][n + 1];
int tmp1, tmp2;
int tmp1, tmp2, length;
int lcs_length;
char *result;
length = (m + 1) * (n + 1);
// We bail if the lines are too long
if (length > MAX_SSDIFF_SIZE)
return NULL;
create_or_reset_lcs_table();
for (i = m; i >= 0; i--) {
for (j = n; j >= 0; j--) {
if (A[i] == '\0' || B[j] == '\0') {
@ -59,6 +87,7 @@ static char *longest_common_subsequence(char *A, char *B)
j += 1;
}
}
return result;
}

12
ui-ssdiff.h
View File

@ -1,6 +1,18 @@
#ifndef UI_SSDIFF_H
#define UI_SSDIFF_H
/*
* ssdiff line limits
*/
#ifndef MAX_SSDIFF_M
#define MAX_SSDIFF_M 128
#endif
#ifndef MAX_SSDIFF_N
#define MAX_SSDIFF_N 128
#endif
#define MAX_SSDIFF_SIZE ((MAX_SSDIFF_M) * (MAX_SSDIFF_N))
extern void cgit_ssdiff_print_deferred_lines();
extern void cgit_ssdiff_line_cb(char *line, int len);