diff options
author | Julian Andres Klode <jak@debian.org> | 2016-09-27 18:20:02 +0200 |
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committer | Julian Andres Klode <jak@debian.org> | 2016-11-22 22:58:18 +0100 |
commit | 7a3b00b10b6a5a740e07fc1b68a4f3fb3bcdac23 (patch) | |
tree | 4a46568d49227b6ae8c6d614d247b8f1ed582997 /apt-pkg | |
parent | 1236419d67e119acc7c0df48f8b14a277e0b5683 (diff) | |
download | apt-7a3b00b10b6a5a740e07fc1b68a4f3fb3bcdac23.tar.gz |
Introduce tolower_ascii_unsafe() and use it for hashing
This one has some obvious collisions for non-alphabetical characters,
like some control characters also hashing to numbers, but we don't
really have those, and these are hash functions which are not
collision free to begin with.
Diffstat (limited to 'apt-pkg')
-rw-r--r-- | apt-pkg/contrib/strutl.h | 5 | ||||
-rw-r--r-- | apt-pkg/deb/deblistparser.cc | 2 | ||||
-rw-r--r-- | apt-pkg/pkgcache.cc | 6 |
3 files changed, 9 insertions, 4 deletions
diff --git a/apt-pkg/contrib/strutl.h b/apt-pkg/contrib/strutl.h index f3591d65f..918ac89c7 100644 --- a/apt-pkg/contrib/strutl.h +++ b/apt-pkg/contrib/strutl.h @@ -141,6 +141,11 @@ bool CheckDomainList(const std::string &Host, const std::string &List); #define isspace_ascii isspace_ascii_inline APT_CONST APT_HOT +static inline int tolower_ascii_unsafe(int const c) +{ + return c | 0x20; +} +APT_CONST APT_HOT static inline int tolower_ascii_inline(int const c) { return (c >= 'A' && c <= 'Z') ? c + 32 : c; diff --git a/apt-pkg/deb/deblistparser.cc b/apt-pkg/deb/deblistparser.cc index 43fc4aa3a..549e75952 100644 --- a/apt-pkg/deb/deblistparser.cc +++ b/apt-pkg/deb/deblistparser.cc @@ -369,7 +369,7 @@ unsigned short debListParser::VersionHash() { if (isspace_ascii(*Start) != 0) continue; - *J++ = tolower_ascii(*Start); + *J++ = tolower_ascii_unsafe(*Start); /* Normalize <= to < and >= to >. This is the wrong way around, but * more efficient that the right way. And since we're only hashing diff --git a/apt-pkg/pkgcache.cc b/apt-pkg/pkgcache.cc index e7e417a5a..b0ba1597f 100644 --- a/apt-pkg/pkgcache.cc +++ b/apt-pkg/pkgcache.cc @@ -213,14 +213,14 @@ map_id_t pkgCache::sHash(StringView Str) const { uint32_t Hash = 5381; for (auto I = Str.begin(); I != Str.end(); ++I) - Hash = 33 * Hash + tolower_ascii(*I); + Hash = 33 * Hash + tolower_ascii_unsafe(*I); return Hash % HeaderP->GetHashTableSize(); } map_id_t pkgCache::sHash(const string &Str) const { uint32_t Hash = 5381; for (string::const_iterator I = Str.begin(); I != Str.end(); ++I) - Hash = 33 * Hash + tolower_ascii((signed char)*I); + Hash = 33 * Hash + tolower_ascii_unsafe((signed char)*I); return Hash % HeaderP->GetHashTableSize(); } @@ -228,7 +228,7 @@ map_id_t pkgCache::sHash(const char *Str) const { uint32_t Hash = 5381; for (const char *I = Str; *I != 0; ++I) - Hash = 33 * Hash + tolower_ascii((signed char)*I); + Hash = 33 * Hash + tolower_ascii_unsafe((signed char)*I); return Hash % HeaderP->GetHashTableSize(); } |