87 lines
3.2 KiB
Diff
87 lines
3.2 KiB
Diff
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From edcff741698c9519dc44f3aa13de421baad7ff43 Mon Sep 17 00:00:00 2001
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From: Willy Tarreau <w@1wt.eu>
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Date: Tue, 8 Aug 2023 15:23:19 +0200
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Subject: [PATCH] MINOR: ist: add new function ist_find_range() to find a
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character range
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This looks up the character range <min>..<max> in the input string and
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returns a pointer to the first one found. It's essentially the equivalent
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of ist_find_ctl() in that it searches by 32 or 64 bits at once, but deals
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with a range.
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(cherry picked from commit 197668de975e495f0c0f0e4ff51b96203fa9842d)
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[ad: backported for following fix : BUG/MINOR: h2: reject more chars
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from the :path pseudo header]
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Signed-off-by: Amaury Denoyelle <adenoyelle@haproxy.com>
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(cherry picked from commit 451ac6628acc4b9eed3260501a49c60d4e4d4e55)
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Signed-off-by: Amaury Denoyelle <adenoyelle@haproxy.com>
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(cherry picked from commit 3468f7f8e04c9c5ca5c985c7511e05e78fe1eded)
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Signed-off-by: Amaury Denoyelle <adenoyelle@haproxy.com>
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(cherry picked from commit b375df60341c7f7a4904c2d8041a09c66115c754)
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Signed-off-by: Willy Tarreau <w@1wt.eu>
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---
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include/import/ist.h | 47 ++++++++++++++++++++++++++++++++++++++++++++
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1 file changed, 47 insertions(+)
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diff --git a/include/import/ist.h b/include/import/ist.h
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index 539a27d26..31566b105 100644
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--- a/include/import/ist.h
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+++ b/include/import/ist.h
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@@ -746,6 +746,53 @@ static inline const char *ist_find_ctl(const struct ist ist)
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return NULL;
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}
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+/* Returns a pointer to the first character found <ist> that belongs to the
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+ * range [min:max] inclusive, or NULL if none is present. The function is
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+ * optimized for strings having no such chars by processing up to sizeof(long)
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+ * bytes at once on architectures supporting efficient unaligned accesses.
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+ * Despite this it is not very fast (~0.43 byte/cycle) and should mostly be
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+ * used on low match probability when it can save a call to a much slower
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+ * function. Will not work for characters 0x80 and above. It's optimized for
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+ * min and max to be known at build time.
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+ */
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+static inline const char *ist_find_range(const struct ist ist, unsigned char min, unsigned char max)
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+{
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+ const union { unsigned long v; } __attribute__((packed)) *u;
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+ const char *curr = (void *)ist.ptr - sizeof(long);
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+ const char *last = curr + ist.len;
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+ unsigned long l1, l2;
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+
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+ /* easier with an exclusive boundary */
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+ max++;
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+
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+ do {
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+ curr += sizeof(long);
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+ if (curr > last)
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+ break;
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+ u = (void *)curr;
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+ /* add 0x<min><min><min><min>..<min> then subtract
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+ * 0x<max><max><max><max>..<max> to the value to generate a
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+ * carry in the lower byte if the byte contains a lower value.
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+ * If we generate a bit 7 that was not there, it means the byte
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+ * was min..max.
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+ */
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+ l2 = u->v;
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+ l1 = ~l2 & ((~0UL / 255) * 0x80); /* 0x808080...80 */
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+ l2 += (~0UL / 255) * min; /* 0x<min><min>..<min> */
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+ l2 -= (~0UL / 255) * max; /* 0x<max><max>..<max> */
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+ } while ((l1 & l2) == 0);
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+
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+ last += sizeof(long);
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+ if (__builtin_expect(curr < last, 0)) {
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+ do {
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+ if ((unsigned char)(*curr - min) < (unsigned char)(max - min))
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+ return curr;
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+ curr++;
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+ } while (curr < last);
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+ }
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+ return NULL;
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+}
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+
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/* looks for first occurrence of character <chr> in string <ist> and returns
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* the tail of the string starting with this character, or (ist.end,0) if not
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* found.
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--
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2.43.0
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