sort: fix -s. Closes 10671
function old new delta
sort_main 786 862 +76
compare_keys 720 794 +74
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 150/0) Total: 150 bytes
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/coreutils/sort.c b/coreutils/sort.c
index ceea244..8ffd0cf 100644
--- a/coreutils/sort.c
+++ b/coreutils/sort.c
@@ -62,9 +62,9 @@
//usage: "\n -u Suppress duplicate lines"
//usage: IF_FEATURE_SORT_BIG(
//usage: "\n -z Lines are terminated by NUL, not newline"
-////usage: "\n -m Ignored for GNU compatibility"
-////usage: "\n -S BUFSZ Ignored for GNU compatibility"
-////usage: "\n -T TMPDIR Ignored for GNU compatibility"
+///////: "\n -m Ignored for GNU compatibility"
+///////: "\n -S BUFSZ Ignored for GNU compatibility"
+///////: "\n -T TMPDIR Ignored for GNU compatibility"
//usage: )
//usage:
//usage:#define sort_example_usage
@@ -117,6 +117,7 @@
FLAG_k = 0x10000,
FLAG_t = 0x20000,
FLAG_bb = 0x80000000, /* Ignore trailing blanks */
+ FLAG_no_tie_break = 0x40000000,
};
#if ENABLE_FEATURE_SORT_BIG
@@ -340,10 +341,34 @@
#endif
} /* for */
- /* Perform fallback sort if necessary */
- if (!retval && !(option_mask32 & FLAG_s)) {
- flags = option_mask32;
- retval = strcmp(*(char **)xarg, *(char **)yarg);
+ if (retval == 0) {
+ /* So far lines are "the same" */
+
+ if (option_mask32 & FLAG_s) {
+ /* "Stable sort": later line is "smaller",
+ * IOW: do not allow qsort() to swap equal lines.
+ */
+ uint32_t *p32;
+ uint32_t x32, y32;
+ char *line;
+ unsigned len;
+
+ line = *(char**)xarg;
+ len = (strlen(line) + 4) & (~3u);
+ p32 = (void*)(line + len);
+ x32 = *p32;
+ line = *(char**)yarg;
+ len = (strlen(line) + 4) & (~3u);
+ p32 = (void*)(line + len);
+ y32 = *p32;
+
+ retval = x32 > y32;
+ } else
+ if (!(option_mask32 & FLAG_no_tie_break)) {
+ /* fallback sort */
+ flags = option_mask32;
+ retval = strcmp(*(char **)xarg, *(char **)yarg);
+ }
}
if (flags & FLAG_r)
@@ -368,7 +393,7 @@
int sort_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int sort_main(int argc UNUSED_PARAM, char **argv)
{
- char *line, **lines;
+ char **lines;
char *str_ignored, *str_o, *str_t;
llist_t *lst_k = NULL;
int i;
@@ -457,7 +482,7 @@
* do not continue to next file: */
FILE *fp = xfopen_stdin(*argv);
for (;;) {
- line = GET_LINE(fp);
+ char *line = GET_LINE(fp);
if (!line)
break;
lines = xrealloc_vector(lines, 6, linecount);
@@ -482,15 +507,35 @@
return EXIT_SUCCESS;
}
#endif
+
+ /* For stable sort, store original line position beyond terminating NUL */
+ if (option_mask32 & FLAG_s) {
+ for (i = 0; i < linecount; i++) {
+ uint32_t *p32;
+ char *line;
+ unsigned len;
+
+ line = lines[i];
+ len = (strlen(line) + 4) & (~3u);
+ lines[i] = line = xrealloc(line, len + 4);
+ p32 = (void*)(line + len);
+ *p32 = i;
+ }
+ /*option_mask32 |= FLAG_no_tie_break;*/
+ /* ^^^redundant: if FLAG_s, compare_keys() does no tie break */
+ }
+
/* Perform the actual sort */
qsort(lines, linecount, sizeof(lines[0]), compare_keys);
/* Handle -u */
if (option_mask32 & FLAG_u) {
int j = 0;
- /* coreutils 6.3 drop lines for which only key is the same */
- /* -- disabling last-resort compare... */
- option_mask32 |= FLAG_s;
+ /* coreutils 6.3 drop lines for which only key is the same
+ * -- disabling last-resort compare, or else compare_keys()
+ * will be the same only for completely identical lines.
+ */
+ option_mask32 |= FLAG_no_tie_break;
for (i = 1; i < linecount; i++) {
if (compare_keys(&lines[j], &lines[i]) == 0)
free(lines[i]);