From: jamie.couture at gmail.com (Jamie Couture)
Subject: [PATCH 1/1] move LCS table away from the stack
Date: Sat, 17 Sep 2011 18:25:01 -0400 [thread overview]
Message-ID: <1316298301-13180-1-git-send-email-jamie.couture@gmail.com> (raw)
In-Reply-To: <CAFXTnz6=p2cUfTR6baBdasUn2ugznUbWQ+=-Gz7b6YbYeVVTDQ@mail.gmail.com>
From: Jamie Couture <jamie.couture at gmail.com>
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 at gmail.com>
---
ui-ssdiff.c | 33 +++++++++++++++++++++++++++++++--
ui-ssdiff.h | 12 ++++++++++++
2 files changed, 43 insertions(+), 2 deletions(-)
diff --git a/ui-ssdiff.c b/ui-ssdiff.c
index 2481585..9fb5b11 100644
--- a/ui-ssdiff.c
+++ b/ui-ssdiff.c
@@ -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;
}
diff --git a/ui-ssdiff.h b/ui-ssdiff.h
index 64b4b12..88627e2 100644
--- a/ui-ssdiff.h
+++ b/ui-ssdiff.h
@@ -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);
--
1.7.6
next prev parent reply other threads:[~2011-09-17 22:25 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-09 4:43 [PATCH 0/1] segfault in cgit jamie.couture
2011-09-09 4:43 ` [PATCH 1/1] move LCS table away from the stack jamie.couture
2011-09-11 0:44 ` jamie.couture
2011-09-11 0:44 ` [PATCH] " jamie.couture
2011-09-14 6:38 ` hjemli
2011-09-17 22:25 ` jamie.couture [this message]
2012-01-03 15:12 ` [PATCH 1/1] " hjemli
2012-01-04 8:59 ` normalperson
2012-01-04 16:57 ` jamie.couture
2012-01-12 3:38 ` jamie.couture
2012-01-12 3:38 ` [PATCH 1/2] correct length check for LCS table jamie.couture
2012-01-12 3:38 ` [PATCH 2/2] use correct type for sizeof jamie.couture
2012-03-18 9:22 ` hjemli
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