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| author | Jamie Couture <jamie.couture@gmail.com> | |
|---|---|---|
| committer | Lars Hjemli <hjemli@gmail.com> | |
| commit | ||
| parent | ||
| tree | ||
| download | ||
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.c | 33 |
1 file 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; } |