zip.c

   1 #define ZIP_BIGLEN 254
   2 #define ZIP_END 255
   3
   4 /* Entry encoding */
   5 #define ZIP_ENC_RAW     0
   6 #define ZIP_ENC_SHORT   1
   7 #define ZIP_ENC_INT     2
   8 #define ZIP_ENC_LLONG   3
   9 #define ZIP_ENCODING(p) ((p)[0] >> 6)
  10
  11 /* Length encoding for raw entries */
  12 #define ZIP_LEN_INLINE  0
  13 #define ZIP_LEN_UINT16  1
  14 #define ZIP_LEN_UINT32  2
  15
  16 static unsigned int zipEncodingSize(char encoding) {
  17     if (encoding == ZIP_ENC_SHORT) {
  18         return sizeof(short int);
  19     } else if (encoding == ZIP_ENC_INT) {
  20         return sizeof(int);
  21     } else if (encoding == ZIP_ENC_LLONG) {
  22         return sizeof(long long);
  23     }
  24     assert(NULL);
  25 }
  26
  27 /* Decode the encoded length pointed by 'p'. If a pointer to 'lensize' is
  28  * provided, it is set to the number of bytes required to encode the length. */
  29 static unsigned int zipDecodeLength(unsigned char *p, unsigned int *lensize) {
  30     unsigned char encoding = ZIP_ENCODING(p), lenenc;
  31     unsigned int len;
  32
  33     if (encoding == ZIP_ENC_RAW) {
  34         lenenc = (p[0] >> 4) & 0x3;
  35         if (lenenc == ZIP_LEN_INLINE) {
  36             len = p[0] & 0xf;
  37             if (lensize) *lensize = 1;
  38         } else if (lenenc == ZIP_LEN_UINT16) {
  39             len = p[1] | (p[2] << 8);
  40             if (lensize) *lensize = 3;
  41         } else {
  42             len = p[1] | (p[2] << 8) | (p[3] << 16) | (p[4] << 24);
  43             if (lensize) *lensize = 5;
  44         }
  45     } else {
  46         len = zipEncodingSize(encoding);
  47         if (lensize) *lensize = 1;
  48     }
  49     return len;
  50 }
  51
  52 /* Encode the length 'l' writing it in 'p'. If p is NULL it just returns
  53  * the amount of bytes required to encode such a length. */
  54 static unsigned int zipEncodeLength(unsigned char *p, char encoding, unsigned int rawlen) {
  55     unsigned char len = 1, lenenc, buf[5];
  56     if (encoding == ZIP_ENC_RAW) {
  57         if (rawlen <= 0xf) {
  58             if (!p) return len;
  59             lenenc = ZIP_LEN_INLINE;
  60             buf[0] = rawlen;
  61         } else if (rawlen <= 0xffff) {
  62             len += 2;
  63             if (!p) return len;
  64             lenenc = ZIP_LEN_UINT16;
  65             buf[1] = (rawlen     ) & 0xff;
  66             buf[2] = (rawlen >> 8) & 0xff;
  67         } else {
  68             len += 4;
  69             if (!p) return len;
  70             lenenc = ZIP_LEN_UINT32;
  71             buf[1] = (rawlen      ) & 0xff;
  72             buf[2] = (rawlen >>  8) & 0xff;
  73             buf[3] = (rawlen >> 16) & 0xff;
  74             buf[4] = (rawlen >> 24) & 0xff;
  75         }
  76         buf[0] = (lenenc << 4) | (buf[0] & 0xf);
  77     }
  78     if (!p) return len;
  79
  80     /* Apparently we need to store the length in 'p' */
  81     buf[0] = (encoding << 6) | (buf[0] & 0x3f);
  82     memcpy(p,buf,len);
  83     return len;
  84 }
  85
  86 /* Check if string pointed to by 'entry' can be encoded as an integer.
  87  * Stores the integer value in 'v' and its encoding in 'encoding'.
  88  * Warning: this function requires a NULL-terminated string! */
  89 static int zipTryEncoding(unsigned char *entry, long long *v, char *encoding) {
  90     long long value;
  91     char *eptr;
  92
  93     if (entry[0] == '-' || (entry[0] >= '0' && entry[0] <= '9')) {
  94         value = strtoll(entry,&eptr,10);
  95         if (eptr[0] != '\0') return 0;
  96         if (value >= SHRT_MIN && value <= SHRT_MAX) {
  97             *encoding = ZIP_ENC_SHORT;
  98         } else if (value >= INT_MIN && value <= INT_MAX) {
  99             *encoding = ZIP_ENC_INT;
 100         } else {
 101             *encoding = ZIP_ENC_LLONG;
 102         }
 103         *v = value;
 104         return 1;
 105     }
 106     return 0;
 107 }
 108
 109 static void zipSaveInteger(unsigned char *p, long long value, char encoding) {
 110     short int s;
 111     int i;
 112     long long l;
 113     if (encoding == ZIP_ENC_SHORT) {
 114         s = value;
 115         memcpy(p,&s,sizeof(s));
 116     } else if (encoding == ZIP_ENC_INT) {
 117         i = value;
 118         memcpy(p,&i,sizeof(i));
 119     } else if (encoding == ZIP_ENC_LLONG) {
 120         l = value;
 121         memcpy(p,&l,sizeof(l));
 122     } else {
 123         assert(NULL);
 124     }
 125 }
 126
 127 static long long zipLoadInteger(unsigned char *p, char encoding) {
 128     short int s;
 129     int i;
 130     long long l, ret;
 131     if (encoding == ZIP_ENC_SHORT) {
 132         memcpy(&s,p,sizeof(s));
 133         ret = s;
 134     } else if (encoding == ZIP_ENC_INT) {
 135         memcpy(&i,p,sizeof(i));
 136         ret = i;
 137     } else if (encoding == ZIP_ENC_LLONG) {
 138         memcpy(&l,p,sizeof(l));
 139         ret = l;
 140     } else {
 141         assert(NULL);
 142     }
 143     return ret;
 144 }
 145
 146 /* Return the total amount used by an entry (encoded length + payload). */
 147 static unsigned int zipRawEntryLength(unsigned char *p) {
 148     unsigned int lensize, len;
 149     len = zipDecodeLength(p, &lensize);
 150     return lensize + len;
 151 }
 152
 153 /* Resize the zip* structure. */
 154 static unsigned char *zipResize(unsigned char *z, unsigned int len) {
 155     z = zrealloc(z,len);
 156     z[len-1] = ZIP_END;
 157     return z;
 158 }