corda/src/finder.cpp

#include "zlib-custom.h"
#include "system.h"
#include "finder.h"

using namespace vm;

namespace {

const char*
append(System* s, const char* a, const char* b, const char* c)
{
  unsigned al = strlen(a);
  unsigned bl = strlen(b);
  unsigned cl = strlen(c);
  char* p = static_cast<char*>(s->allocate(al + bl + cl + 1));
  memcpy(p, a, al);
  memcpy(p + al, b, bl);
  memcpy(p + al + bl, c, cl + 1);
  return p;
}

const char*
copy(System* s, const char* a)
{
  unsigned al = strlen(a);
  char* p = static_cast<char*>(s->allocate(al + 1));
  memcpy(p, a, al + 1);
  return p;
}

bool
equal(const void* a, unsigned al, const void* b, unsigned bl)
{
  if (al == bl) {
    return memcmp(a, b, al) == 0;
  } else {
    return false;
  }
}

class Element {
 public:
  Element(): next(0) { }
  virtual ~Element() { }
  virtual System::Region* find(const char* name) = 0;
  virtual bool exists(const char* name) = 0;
  virtual void dispose() = 0;

  Element* next;
};

class DirectoryElement: public Element {
 public:
  DirectoryElement(System* s, const char* name):
    s(s), name(name)
  { }

  virtual System::Region* find(const char* name) {
    const char* file = append(s, this->name, "/", name);
    System::Region* region;
    System::Status status = s->map(&region, file);
    s->free(file);

    if (s->success(status)) {
      return region;
    } else {
      return 0;
    }
  }

  virtual bool exists(const char* name)  {
    const char* file = append(s, this->name, "/", name);
    System::FileType type = s->identify(file);
    s->free(file);
    return type != System::DoesNotExist;
  }

  virtual void dispose() {
    s->free(name);
    s->free(this);
  }

  System* s;
  const char* name;
};

class PointerRegion: public System::Region {
 public:
  PointerRegion(System* s, const uint8_t* start, size_t length):
    s(s),
    start_(start),
    length_(length)
  { }

  virtual const uint8_t* start() {
    return start_;
  }

  virtual size_t length() {
    return length_;
  }

  virtual void dispose() {
    s->free(this);
  }

  System* s;
  const uint8_t* start_;
  size_t length_;
};

class DataRegion: public System::Region {
 public:
  DataRegion(System* s, size_t length):
    s(s),
    length_(length)
  { }

  virtual const uint8_t* start() {
    return data;
  }

  virtual size_t length() {
    return length_;
  }

  virtual void dispose() {
    s->free(this);
  }

  System* s;
  size_t length_;
  uint8_t data[0];
};

class JarIndex {
 public:
  static const unsigned HeaderSize = 30;

  enum CompressionMethod {
    Stored = 0,
    Deflated = 8
  };

  class Node {
   public:
    Node(uint32_t hash, const uint8_t* entry, Node* next):
      hash(hash), entry(entry), next(next)
    { }

    uint32_t hash;
    const uint8_t* entry;
    Node* next;
  };

  JarIndex(System* s, unsigned capacity):
    s(s),
    capacity(capacity),
    position(0),
    nodes(static_cast<Node*>(s->allocate(sizeof(Node) * capacity)))
  {
    memset(table, 0, sizeof(Node*) * capacity);
  }

  static uint16_t get2(const uint8_t* p) {
    return
      (static_cast<uint16_t>(p[1]) <<  8) |
      (static_cast<uint16_t>(p[0])      );
  }

  static uint32_t get4(const uint8_t* p) {
    return
      (static_cast<uint32_t>(p[3]) << 24) |
      (static_cast<uint32_t>(p[2]) << 16) |
      (static_cast<uint32_t>(p[1]) <<  8) |
      (static_cast<uint32_t>(p[0])      );
  }

  static uint32_t signature(const uint8_t* p) {
    return get4(p);
  }

  static uint16_t compressionMethod(const uint8_t* p) {
    return get2(p + 8);
  }

  static uint32_t compressedSize(const uint8_t* p) {
    return get4(p + 18);
  }

  static uint32_t uncompressedSize(const uint8_t* p) {
    return get4(p + 22);
  }

  static uint16_t fileNameLength(const uint8_t* p) {
    return get2(p + 26);
  }

  static uint16_t extraFieldLength(const uint8_t* p) {
    return get2(p + 28);
  }

  static const uint8_t* fileName(const uint8_t* p) {
    return p + 30;
  }

  static const uint8_t* fileData(const uint8_t* p) {
    return p + HeaderSize + fileNameLength(p) + extraFieldLength(p);
  }

  static const uint8_t* endOfEntry(const uint8_t* p) {
    return fileData(p) + compressedSize(p);
  }

  static JarIndex* make(System* s, unsigned capacity) {
    return new
      (s->allocate(sizeof(JarIndex) + (sizeof(Node*) * capacity)))
      JarIndex(s, capacity);
  }
  
  static JarIndex* open(System* s, System::Region* region) {
    JarIndex* index = make(s, 32);

    const uint8_t* p = region->start();
    const uint8_t* end = p + region->length();
    while (p < end) {
      if (signature(p) == 0x04034b50) {
        index = index->add(hash(fileName(p), fileNameLength(p)), p);

        p = endOfEntry(p);
      } else {
        break;
      }
    }

    return index;
  }

  JarIndex* add(uint32_t hash, const uint8_t* entry) {
    if (position < capacity) {
      unsigned i = hash & (capacity - 1);
      table[i] = new (nodes + (position++)) Node(hash, entry, table[i]);
      return this;
    } else {
      JarIndex* index = make(s, capacity * 2);
      for (unsigned i = 0; i < capacity; ++i) {
        index->add(nodes[i].hash, nodes[i].entry);
      }
      index->add(hash, entry);
      dispose();
      return index;
    }
  }

  Node* findNode(const char* name) {
    unsigned length = strlen(name);
    unsigned i = hash(name) & (capacity - 1);
    for (Node* n = table[i]; n; n = n->next) {
      const uint8_t* p = n->entry;
      if (equal(name, length, fileName(p), fileNameLength(p))) {
        return n;
      }
    }
    return 0;
  }

  System::Region* find(const char* name) {
    Node* n = findNode(name);
    if (n) {
      const uint8_t* p = n->entry;
      switch (compressionMethod(p)) {
      case Stored: {
        return new (s->allocate(sizeof(PointerRegion)))
          PointerRegion(s, fileData(p), compressedSize(p));
      } break;

      case Deflated: {
        DataRegion* region = new
          (s->allocate(sizeof(DataRegion) + uncompressedSize(p)))
          DataRegion(s, uncompressedSize(p));
          
        z_stream zStream; memset(&zStream, 0, sizeof(z_stream));

        zStream.next_in = const_cast<uint8_t*>(fileData(p));
        zStream.avail_in = compressedSize(p);
        zStream.next_out = region->data;
        zStream.avail_out = region->length();

        // -15 means max window size and raw deflate (no zlib wrapper)
        int r = inflateInit2(&zStream, -15);
        expect(s, r == Z_OK);

        r = inflate(&zStream, Z_FINISH);
        expect(s, r == Z_STREAM_END);

        inflateEnd(&zStream);

        return region;
      } break;

      default:
        abort(s);
      }
    }

    return 0;
  }

  bool exists(const char* name) {
    return findNode(name) != 0;
  }

  void dispose() {
    s->free(nodes);
    s->free(this);
  }

  System* s;
  unsigned capacity;
  unsigned position;
  Node* nodes;
  Node* table[0];
};

class JarElement: public Element {
 public:
  JarElement(System* s, const char* name):
    s(s), name(name), region(0), index(0)
  { }

  void init() {
    if (index == 0) {
      System::Region* r;
      if (s->success(s->map(&r, this->name))) {
        region = r;
        index = JarIndex::open(s, r);
      }
    }
  }

  virtual System::Region* find(const char* name) {
    init();

    while (*name == '/') name++;

    return (index ? index->find(name) : 0);
  }

  virtual bool exists(const char* name)  {
    init();

    while (*name == '/') name++;

    return (index ? index->exists(name) : 0);
  }

  virtual void dispose() {
    s->free(name);
    if (index) {
      index->dispose();
      region->dispose();
    }
    s->free(this);
  }

  System* s;
  const char* name;
  System::Region* region;
  JarIndex* index;
};

Element*
parsePath(System* s, const char* path)
{
  class Tokenizer {
   public:
    class Token {
     public:
      Token(const char* s, unsigned length): s(s), length(length) { }

      const char* s;
      unsigned length;
    };

    Tokenizer(const char* s, char delimiter): s(s), delimiter(delimiter) { }

    bool hasMore() {
      while (*s == delimiter) ++s;
      return *s;
    }

    Token next() {
      const char* p = s;
      while (*s and *s != delimiter) ++s;
      return Token(p, s - p);
    }

    const char* s;
    char delimiter;
  };

  Element* first = 0;
  Element* prev = 0;
  for (Tokenizer t(path, s->pathSeparator()); t.hasMore();) {
    Tokenizer::Token token(t.next());
    char* name = static_cast<char*>(s->allocate(token.length + 1));
    memcpy(name, token.s, token.length);
    name[token.length] = 0;

    Element* e;
    switch (s->identify(name)) {
    case System::File: {
      e = new (s->allocate(sizeof(JarElement)))
        JarElement(s, name);
    } break;

    case System::Directory: {
      e = new (s->allocate(sizeof(DirectoryElement)))
        DirectoryElement(s, name);
    } break;

    default: {
      s->free(name);
      e = 0;
    } break;
    }

    if (e) {
      if (prev) {
        prev->next = e;
      } else {
        first = e;
      }
      prev = e;
    }
  }

  return first;
}

class MyFinder: public Finder {
 public:
  MyFinder(System* system, const char* path):
    system(system),
    path_(parsePath(system, path)),
    pathString(copy(system, path))
  { }

  virtual System::Region* find(const char* name) {
    for (Element* e = path_; e; e = e->next) {
      System::Region* r = e->find(name);
      if (r) {
        return r;
      }
    }
    
    return 0;
  }

  virtual bool exists(const char* name) {
    for (Element* e = path_; e; e = e->next) {
      if (e->exists(name)) {
        return true;
      }
    }
    
    return false;
  }

  virtual const char* path() {
    return pathString;
  }

  virtual void dispose() {
    for (Element* e = path_; e;) {
      Element* t = e;
      e = e->next;
      t->dispose();
    }
    system->free(pathString);
    system->free(this);
  }

  System* system;
  Element* path_;
  const char* pathString;
};

} // namespace

namespace vm {

Finder*
makeFinder(System* s, const char* path)
{
  return new (s->allocate(sizeof(MyFinder))) MyFinder(s, path);
}

} // namespace vm