Author: Jamie Couture <jamie.couture@gmail.com>
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>
ui-ssdiff.c | 33 +++++++++++++++++++++++++++++++-- ui-ssdiff.h | 12 ++++++++++++
diff --git a/ui-ssdiff.c b/ui-ssdiff.c index 2481585fb619966173fcde2e4d35ba1614482093..9fb5b1139af12c05d9817d9fcef884b843d928ca 100644 --- a/ui-ssdiff.c +++ b/ui-ssdiff.c @@ -2,10 +2,12 @@ #include "cgit.h" #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; @@ -16,15 +18,41 @@ 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--) { @@ -59,6 +87,7 @@ } else { j += 1; } } + return result; } diff --git a/ui-ssdiff.h b/ui-ssdiff.h index 64b4b1215adced788d2145cf9b771ed9d669d464..88627e297c8b2091919e6274010d2bb7812ca067 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);