The regex '^a|b' means "does the string start with a, or does it have
a b anywhere", not "does the string start with a or b" (the latter
should be spelled '^[ab]' or '^(a|b)'). It should match exactly the
same strings as 'b|^a'. But the current implementation hard-codes an
assumption that when the regex starts with a ^, the whole regex must
match from the beginning, i.e. it only attempts at offset 0.
It really should be completely symmetrical to 'b|c$' ("does it have a
b anywhere or end with c?"), which is treated correctly.
Another quirk is that currently the regex 'x*$', which should match
all strings (because it just means "does the string end
with 0 or more x'es"), does not, because in the unanchored case we
never attempt to match at ofs==len. In the anchored case, '^x*$', this
works correctly and matches exactly strings (including the empty
string) consisting entirely of x'es.
Fix both of these issues by dropping all use of the slre->anchored
member and always test at all possible offsets. If the regex does have
a ^ somewhere (including after a | branch character), that is
correctly handled by the match engine by only matching when *ofs is 0.
Reviewed-by: Simon Glass <s...@chromium.org>
Signed-off-by: Rasmus Villemoes <r...@prevas.dk>
---
include/slre.h | 1 -
lib/slre.c | 13 +++----------
2 files changed, 3 insertions(+), 11 deletions(-)
diff --git a/include/slre.h b/include/slre.h
index 4b41a4b276f..af5b1302d9c 100644
--- a/include/slre.h
+++ b/include/slre.h
@@ -63,7 +63,6 @@ struct slre {
int code_size;
int data_size;
int num_caps; /* Number of bracket pairs */
- int anchored; /* Must match from string start */
const char *err_str; /* Error string */
};
diff --git a/lib/slre.c b/lib/slre.c
index 277a59a03a7..4f455400d3a 100644
--- a/lib/slre.c
+++ b/lib/slre.c
@@ -413,10 +413,7 @@ int
slre_compile(struct slre *r, const char *re)
{
r->err_str = NULL;
- r->code_size = r->data_size = r->num_caps = r->anchored = 0;
-
- if (*re == '^')
- r->anchored++;
+ r->code_size = r->data_size = r->num_caps = 0;
emit(r, OPEN); /* This will capture what matches full RE */
emit(r, 0);
@@ -650,13 +647,9 @@ slre_match(const struct slre *r, const char *buf, int len,
{
int i, ofs = 0, res = 0;
- if (r->anchored) {
+ for (i = 0; i <= len && res == 0; i++) {
+ ofs = i;
res = match(r, 0, buf, len, &ofs, caps);
- } else {
- for (i = 0; i < len && res == 0; i++) {
- ofs = i;
- res = match(r, 0, buf, len, &ofs, caps);
- }
}
return res;
--
2.49.0
