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authorJamie Couture <jamie.couture@gmail.com>2011-09-17 22:25:01 +0000
committerLars Hjemli <hjemli@gmail.com>2012-01-03 15:16:01 +0000
commite19f7d7180d64c8ba9ca15f5fe164606f0ec88c1 (patch)
tree55faa59f4835bec90fa5d94643cf1600d699cdb7 /ui-ssdiff.c
parentbebe89d7c11a92bf206bf6e528c51ffa8ecbc0d5 (diff)
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ui-ssdiff: move LCS table away from the stack
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>
Diffstat (limited to 'ui-ssdiff.c')
-rw-r--r--ui-ssdiff.c33
1 files changed, 31 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;
}