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| 1 /* | |
| 2 ** 2014-06-13 | |
| 3 ** | |
| 4 ** The author disclaims copyright to this source code. In place of | |
| 5 ** a legal notice, here is a blessing: | |
| 6 ** | |
| 7 ** May you do good and not evil. | |
| 8 ** May you find forgiveness for yourself and forgive others. | |
| 9 ** May you share freely, never taking more than you give. | |
| 10 ** | |
| 11 ****************************************************************************** | |
| 12 ** | |
| 13 ** This SQLite extension implements SQL compression functions | |
| 14 ** compress() and uncompress() using ZLIB. | |
| 15 */ | |
| 16 #include "sqlite3ext.h" | |
| 17 SQLITE_EXTENSION_INIT1 | |
| 18 #include <zlib.h> | |
| 19 | |
| 20 /* | |
| 21 ** Implementation of the "compress(X)" SQL function. The input X is | |
| 22 ** compressed using zLib and the output is returned. | |
| 23 ** | |
| 24 ** The output is a BLOB that begins with a variable-length integer that | |
| 25 ** is the input size in bytes (the size of X before compression). The | |
| 26 ** variable-length integer is implemented as 1 to 5 bytes. There are | |
| 27 ** seven bits per integer stored in the lower seven bits of each byte. | |
| 28 ** More significant bits occur first. The most significant bit (0x80) | |
| 29 ** is a flag to indicate the end of the integer. | |
| 30 */ | |
| 31 static void compressFunc( | |
| 32 sqlite3_context *context, | |
| 33 int argc, | |
| 34 sqlite3_value **argv | |
| 35 ){ | |
| 36 const unsigned char *pIn; | |
| 37 unsigned char *pOut; | |
| 38 unsigned int nIn; | |
| 39 unsigned long int nOut; | |
| 40 unsigned char x[8]; | |
| 41 int rc; | |
| 42 int i, j; | |
| 43 | |
| 44 pIn = sqlite3_value_blob(argv[0]); | |
| 45 nIn = sqlite3_value_bytes(argv[0]); | |
| 46 nOut = 13 + nIn + (nIn+999)/1000; | |
| 47 pOut = sqlite3_malloc( nOut+5 ); | |
| 48 for(i=4; i>=0; i--){ | |
| 49 x[i] = (nIn >> (7*(4-i)))&0x7f; | |
| 50 } | |
| 51 for(i=0; i<4 && x[i]==0; i++){} | |
| 52 for(j=0; i<=4; i++, j++) pOut[j] = x[i]; | |
| 53 pOut[j-1] |= 0x80; | |
| 54 rc = compress(&pOut[j], &nOut, pIn, nIn); | |
| 55 if( rc==Z_OK ){ | |
| 56 sqlite3_result_blob(context, pOut, nOut+j, sqlite3_free); | |
| 57 }else{ | |
| 58 sqlite3_free(pOut); | |
| 59 } | |
| 60 } | |
| 61 | |
| 62 /* | |
| 63 ** Implementation of the "uncompress(X)" SQL function. The argument X | |
| 64 ** is a blob which was obtained from compress(Y). The output will be | |
| 65 ** the value Y. | |
| 66 */ | |
| 67 static void uncompressFunc( | |
| 68 sqlite3_context *context, | |
| 69 int argc, | |
| 70 sqlite3_value **argv | |
| 71 ){ | |
| 72 const unsigned char *pIn; | |
| 73 unsigned char *pOut; | |
| 74 unsigned int nIn; | |
| 75 unsigned long int nOut; | |
| 76 int rc; | |
| 77 int i; | |
| 78 | |
| 79 pIn = sqlite3_value_blob(argv[0]); | |
| 80 nIn = sqlite3_value_bytes(argv[0]); | |
| 81 nOut = 0; | |
| 82 for(i=0; i<nIn && i<5; i++){ | |
| 83 nOut = (nOut<<7) | (pIn[i]&0x7f); | |
| 84 if( (pIn[i]&0x80)!=0 ){ i++; break; } | |
| 85 } | |
| 86 pOut = sqlite3_malloc( nOut+1 ); | |
| 87 rc = uncompress(pOut, &nOut, &pIn[i], nIn-i); | |
| 88 if( rc==Z_OK ){ | |
| 89 sqlite3_result_blob(context, pOut, nOut, sqlite3_free); | |
| 90 }else{ | |
| 91 sqlite3_free(pOut); | |
| 92 } | |
| 93 } | |
| 94 | |
| 95 | |
| 96 #ifdef _WIN32 | |
| 97 __declspec(dllexport) | |
| 98 #endif | |
| 99 int sqlite3_compress_init( | |
| 100 sqlite3 *db, | |
| 101 char **pzErrMsg, | |
| 102 const sqlite3_api_routines *pApi | |
| 103 ){ | |
| 104 int rc = SQLITE_OK; | |
| 105 SQLITE_EXTENSION_INIT2(pApi); | |
| 106 (void)pzErrMsg; /* Unused parameter */ | |
| 107 rc = sqlite3_create_function(db, "compress", 1, SQLITE_UTF8, 0, | |
| 108 compressFunc, 0, 0); | |
| 109 if( rc==SQLITE_OK ){ | |
| 110 rc = sqlite3_create_function(db, "uncompress", 1, SQLITE_UTF8, 0, | |
| 111 uncompressFunc, 0, 0); | |
| 112 } | |
| 113 return rc; | |
| 114 } | |
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Chromium Code Reviews
Issue 2846743003:
[sql] Remove SQLite 3.10.2 reference directory. (Closed)
