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Comment:Add the "csv" virtual table for reading CSV files, as an extension in the ext/misc/ subfolder.
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SHA1: 00d3570c8bb96469c984903e20de589e998d4636
User & Date: drh 2016-05-31 16:22:48
Context
2016-05-31
18:08
Add the testflags parameter to the csv extension. check-in: b93fb2fe user: drh tags: trunk
16:22
Add the "csv" virtual table for reading CSV files, as an extension in the ext/misc/ subfolder. check-in: 00d3570c user: drh tags: trunk
2016-05-30
08:28
Fix an FTS5 problem (segfault or incorrect query results) with "... MATCH 'x OR y' ORDER BY rank" queries when either token 'x' or 'y' is completely absent from the dataset. check-in: 64ca1a83 user: dan tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Added ext/misc/csv.c.





























































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































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/*
** 2016-05-28
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file contains the implementation of an SQLite virtual table for
** reading CSV files.
**
** Usage:
**
**    .load ./csv
**    CREATE VIRTUAL TABLE temp.csv USING csv(filename=FILENAME);
**    SELECT * FROM csv;
**
** The columns are named "c1", "c2", "c3", ... by default.  But the
** application can define its own CREATE TABLE statement as an additional
** parameter.  For example:
**
**    CREATE VIRTUAL TABLE temp.csv2 USING csv(
**       filename = "../http.log",
**       schema = "CREATE TABLE x(date,ipaddr,url,referrer,userAgent)"
**    );
*/
#include <sqlite3ext.h>
SQLITE_EXTENSION_INIT1
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <stdarg.h>
#include <ctype.h>
#include <stdio.h>

/*
** A macro to hint to the compiler that a function should not be
** inlined.
*/
#if defined(__GNUC__)
#  define CSV_NOINLINE  __attribute__((noinline))
#elif defined(_MSC_VER) && _MSC_VER>=1310
#  define CSV_NOINLINE  __declspec(noinline)
#else
#  define CSV_NOINLINE
#endif


/* Max size of the error message in a CsvReader */
#define CSV_MXERR 200

/* A context object used when read a CSV file. */
typedef struct CsvReader CsvReader;
struct CsvReader {
  FILE *in;              /* Read the CSV text from this input stream */
  char *z;               /* Accumulated text for a field */
  int n;                 /* Number of bytes in z */
  int nAlloc;            /* Space allocated for z[] */
  int nLine;             /* Current line number */
  int cTerm;             /* Character that terminated the most recent field */
  char zErr[CSV_MXERR];  /* Error message */
};

/* Initialize a CsvReader object */
static void csv_reader_init(CsvReader *p){
  memset(p, 0, sizeof(*p));
}

/* Close and reset a CsvReader object */
static void csv_reader_reset(CsvReader *p){
  if( p->in ) fclose(p->in);
  sqlite3_free(p->z);
  csv_reader_init(p);
}

/* Report an error on a CsvReader */
static void csv_errmsg(CsvReader *p, const char *zFormat, ...){
  va_list ap;
  va_start(ap, zFormat);
  sqlite3_vsnprintf(CSV_MXERR, p->zErr, zFormat, ap);
  va_end(ap);
}

/* Open the file associated with a CsvReader
** Return the number of errors.
*/
static int csv_reader_open(CsvReader *p, const char *zFilename){
  p->in = fopen(zFilename, "rb");
  if( p->in==0 ){
    csv_errmsg(p, "cannot open '%s' for reading", zFilename);
    return 1;
  }
  return 0;
}

/* Increase the size of p->z and append character c to the end. 
** Return 0 on success and non-zero if there is an OOM error */
static CSV_NOINLINE int csv_resize_and_append(CsvReader *p, char c){
  char *zNew;
  int nNew = p->nAlloc*2 + 100;
  zNew = sqlite3_realloc64(p->z, nNew);
  if( zNew ){
    p->z = zNew;
    p->nAlloc = nNew;
    p->z[p->n++] = c;
    return 0;
  }else{
    csv_errmsg(p, "out of memory");
    return 1;
  }
}

/* Append a single character to the CsvReader.z[] array.
** Return 0 on success and non-zero if there is an OOM error */
static int csv_append(CsvReader *p, char c){
  if( p->n>=p->nAlloc-1 ) return csv_resize_and_append(p, c);
  p->z[p->n++] = c;
  return 0;
}

/* Read a single field of CSV text.  Compatible with rfc4180 and extended
** with the option of having a separator other than ",".
**
**   +  Input comes from p->in.
**   +  Store results in p->z of length p->n.  Space to hold p->z comes
**      from sqlite3_malloc64().
**   +  Keep track of the line number in p->nLine.
**   +  Store the character that terminates the field in p->cTerm.  Store
**      EOF on end-of-file.
**
** Return "" at EOF.  Return 0 on an OOM error.
*/
static char *csv_read_one_field(CsvReader *p){
  int c;
  p->n = 0;
  c = fgetc(p->in);
  if( c==EOF ){
    p->cTerm = EOF;
    return "";
  }
  if( c=='"' ){
    int pc, ppc;
    int startLine = p->nLine;
    int cQuote = c;
    pc = ppc = 0;
    while( 1 ){
      c = fgetc(p->in);
      if( c=='\n' ) p->nLine++;
      if( c==cQuote ){
        if( pc==cQuote ){
          pc = 0;
          continue;
        }
      }
      if( (c==',' && pc==cQuote)
       || (c=='\n' && pc==cQuote)
       || (c=='\n' && pc=='\r' && ppc==cQuote)
       || (c==EOF && pc==cQuote)
      ){
        do{ p->n--; }while( p->z[p->n]!=cQuote );
        p->cTerm = c;
        break;
      }
      if( pc==cQuote && c!='\r' ){
        csv_errmsg(p, "line %d: unescaped %c character", p->nLine, cQuote);
        break;
      }
      if( c==EOF ){
        csv_errmsg(p, "line %d: unterminated %c-quoted field\n",
                   startLine, cQuote);
        p->cTerm = c;
        break;
      }
      if( csv_append(p, (char)c) ) return 0;
      ppc = pc;
      pc = c;
    }
  }else{
    while( c!=EOF && c!=',' && c!='\n' ){
      if( csv_append(p, (char)c) ) return 0;
      c = fgetc(p->in);
    }
    if( c=='\n' ){
      p->nLine++;
      if( p->n>0 && p->z[p->n-1]=='\r' ) p->n--;
    }
    p->cTerm = c;
  }
  if( p->z ) p->z[p->n] = 0;
  return p->z;
}


/* Forward references to the various virtual table methods implemented
** in this file. */
static int csvtabCreate(sqlite3*, void*, int, const char*const*, 
                           sqlite3_vtab**,char**);
static int csvtabConnect(sqlite3*, void*, int, const char*const*, 
                           sqlite3_vtab**,char**);
static int csvtabBestIndex(sqlite3_vtab*,sqlite3_index_info*);
static int csvtabDisconnect(sqlite3_vtab*);
static int csvtabOpen(sqlite3_vtab*, sqlite3_vtab_cursor**);
static int csvtabClose(sqlite3_vtab_cursor*);
static int csvtabFilter(sqlite3_vtab_cursor*, int idxNum, const char *idxStr,
                          int argc, sqlite3_value **argv);
static int csvtabNext(sqlite3_vtab_cursor*);
static int csvtabEof(sqlite3_vtab_cursor*);
static int csvtabColumn(sqlite3_vtab_cursor*,sqlite3_context*,int);
static int csvtabRowid(sqlite3_vtab_cursor*,sqlite3_int64*);

/* An instance of the CSV virtual table */
typedef struct CsvTable {
  sqlite3_vtab base;              /* Base class.  Must be first */
  char *zFilename;                /* Name of the CSV file */
  long iStart;                    /* Offset to start of data in zFilename */
  int nCol;                       /* Number of columns in the CSV file */
} CsvTable;

/* A cursor for the CSV virtual table */
typedef struct CsvCursor {
  sqlite3_vtab_cursor base;       /* Base class.  Must be first */
  CsvReader rdr;                  /* The CsvReader object */
  char **azVal;                   /* Value of the current row */
  sqlite3_int64 iRowid;           /* The current rowid.  Negative for EOF */
} CsvCursor;

/* Transfer error message text from a reader into a CsvTable */
static void csv_xfer_error(CsvTable *pTab, CsvReader *pRdr){
  sqlite3_free(pTab->base.zErrMsg);
  pTab->base.zErrMsg = sqlite3_mprintf("%s", pRdr->zErr);
}

/*
** This method is the destructor fo a CsvTable object.
*/
static int csvtabDisconnect(sqlite3_vtab *pVtab){
  CsvTable *p = (CsvTable*)pVtab;
  sqlite3_free(p->zFilename);
  sqlite3_free(p);
  return SQLITE_OK;
}

/* Skip leading whitespace.  Return a pointer to the first non-whitespace
** character, or to the zero terminator if the string has only whitespace */
static const char *csv_skip_whitespace(const char *z){
  while( isspace((unsigned char)z[0]) ) z++;
  return z;
}

/* Remove trailing whitespace from the end of string z[] */
static void csv_trim_whitespace(char *z){
  size_t n = strlen(z);
  while( n>0 && isspace((unsigned char)z[n]) ) n--;
  z[n] = 0;
}

/* Dequote the string */
static void csv_dequote(char *z){
  int i, j;
  char cQuote = z[0];
  size_t n;

  if( cQuote!='\'' && cQuote!='"' ) return;
  n = strlen(z);
  if( n<2 || z[n-1]!=z[0] ) return;
  for(i=1, j=0; i<n-1; i++){
    if( z[i]==cQuote && z[i+1]==cQuote ) i++;
    z[j++] = z[i];
  }
  z[j] = 0;
}

/* Check to see if the string is of the form:  "TAG = VALUE" with optional
** whitespace before and around tokens.  If it is, return a pointer to the
** first character of VALUE.  If it is not, return NULL.
*/
static const char *csv_parameter(const char *zTag, int nTag, const char *z){
  z = csv_skip_whitespace(z);
  if( strncmp(zTag, z, nTag)!=0 ) return 0;
  z = csv_skip_whitespace(z+nTag);
  if( z[0]!='=' ) return 0;
  return csv_skip_whitespace(z+1);
}

/* Return 0 if the argument is false and 1 if it is true.  Return -1 if
** we cannot really tell.
*/
static int csv_boolean(const char *z){
  if( sqlite3_stricmp("yes",z)==0
   || sqlite3_stricmp("on",z)==0
   || sqlite3_stricmp("true",z)==0
   || (z[0]=='1' && z[0]==0)
  ){
    return 1;
  }
  if( sqlite3_stricmp("no",z)==0
   || sqlite3_stricmp("off",z)==0
   || sqlite3_stricmp("false",z)==0
   || (z[0]=='0' && z[1]==0)
  ){
    return 0;
  }
  return -1;
}


/*
** Parameters:
**    filename=FILENAME          Required
**    schema=SCHEMA              Optional
**    header=YES|NO              First row of CSV defines the names of
**                               columns if "yes".  Default "no".
**
** If header=no and not columns are listed, then the columns are named
** "c0", "c1", "c2", and so forth.
*/
static int csvtabConnect(
  sqlite3 *db,
  void *pAux,
  int argc, const char *const*argv,
  sqlite3_vtab **ppVtab,
  char **pzErr
){
  CsvTable *pNew = 0;
  int bHeader = -1;
  int rc = SQLITE_OK;
  int i;
  char *zFilename = 0;
  char *zSchema = 0;
  CsvReader sRdr;

  memset(&sRdr, 0, sizeof(sRdr));
  for(i=3; i<argc; i++){
    const char *z = argv[i];
    const char *zValue;
    if( (zValue = csv_parameter("filename",8,z))!=0 ){
      if( zFilename ){
        csv_errmsg(&sRdr, "more than one 'filename' parameter");
        goto csvtab_connect_error;
      }
      zFilename = sqlite3_mprintf("%s", zValue);
      if( zFilename==0 ) goto csvtab_connect_oom;
      csv_trim_whitespace(zFilename);
      csv_dequote(zFilename);
    }else
    if( (zValue = csv_parameter("schema",6,z))!=0 ){
      if( zSchema ){
        csv_errmsg(&sRdr, "more than one 'schema' parameter");
        goto csvtab_connect_error;
      }
      zSchema = sqlite3_mprintf("%s", zValue);
      if( zSchema==0 ) goto csvtab_connect_oom;
      csv_trim_whitespace(zSchema);
      csv_dequote(zSchema);
    }else
    if( (zValue = csv_parameter("header",6,z))!=0 ){
      int x;
      if( bHeader>=0 ){
        csv_errmsg(&sRdr, "more than one 'header' parameter");
        goto csvtab_connect_error;
      }
      x = csv_boolean(zValue);
      if( x==1 ){
        bHeader = 1;
      }else if( x==0 ){
        bHeader = 0;
      }else{
        csv_errmsg(&sRdr, "unrecognized argument to 'header': %s", zValue);
        goto csvtab_connect_error;
      }
    }else
    {
      csv_errmsg(&sRdr, "unrecognized parameter '%s'", z);
      goto csvtab_connect_error;
    }
  }
  if( zFilename==0 ){
    csv_errmsg(&sRdr, "missing 'filename' parameter");
    goto csvtab_connect_error;
  }
  if( csv_reader_open(&sRdr, zFilename) ){
    goto csvtab_connect_error;
  }
  pNew = sqlite3_malloc( sizeof(*pNew) );
  *ppVtab = (sqlite3_vtab*)pNew;
  if( pNew==0 ) goto csvtab_connect_oom;
  memset(pNew, 0, sizeof(*pNew));
  do{
    const char *z = csv_read_one_field(&sRdr);
    if( z==0 ) goto csvtab_connect_oom;
    pNew->nCol++;
  }while( sRdr.cTerm==',' );
  pNew->zFilename = zFilename;
  zFilename = 0;
  pNew->iStart = bHeader==1 ? ftell(sRdr.in) : 0;
  csv_reader_reset(&sRdr);
  if( zSchema==0 ){
    char *zSep = "";
    zSchema = sqlite3_mprintf("CREATE TABLE x(");
    if( zSchema==0 ) goto csvtab_connect_oom;
    for(i=0; i<pNew->nCol; i++){
      zSchema = sqlite3_mprintf("%z%sc%d TEXT",zSchema, zSep, i);
      zSep = ",";
    }
    zSchema = sqlite3_mprintf("%z);", zSchema);
  }
  rc = sqlite3_declare_vtab(db, zSchema);
  if( rc ) goto csvtab_connect_error;
  sqlite3_free(zSchema);
  return SQLITE_OK;

csvtab_connect_oom:
  rc = SQLITE_NOMEM;
  csv_errmsg(&sRdr, "out of memory");

csvtab_connect_error:
  if( pNew ) csvtabDisconnect(&pNew->base);
  sqlite3_free(zFilename);
  sqlite3_free(zSchema);
  if( sRdr.zErr[0] ){
    sqlite3_free(*pzErr);
    *pzErr = sqlite3_mprintf("%s", sRdr.zErr);
  }
  csv_reader_reset(&sRdr);
  return rc;
}

/*
** Reset the current row content held by a CsvCursor.
*/
static void csvtabCursorRowReset(CsvCursor *pCur){
  CsvTable *pTab = (CsvTable*)pCur->base.pVtab;
  int i;
  for(i=0; i<pTab->nCol; i++){
    sqlite3_free(pCur->azVal[i]);
    pCur->azVal[i] = 0;
  }
}

/*
** The xConnect and xCreate methods do the same thing, but they must be
** different so that the virtual table is not an eponymous virtual table.
*/
static int csvtabCreate(
  sqlite3 *db,
  void *pAux,
  int argc, const char *const*argv,
  sqlite3_vtab **ppVtab,
  char **pzErr
){
 return csvtabConnect(db, pAux, argc, argv, ppVtab, pzErr);
}

/*
** Destructor for a CsvCursor.
*/
static int csvtabClose(sqlite3_vtab_cursor *cur){
  CsvCursor *pCur = (CsvCursor*)cur;
  csvtabCursorRowReset(pCur);
  csv_reader_reset(&pCur->rdr);
  sqlite3_free(cur);
  return SQLITE_OK;
}

/*
** Constructor for a new CsvTable cursor object.
*/
static int csvtabOpen(sqlite3_vtab *p, sqlite3_vtab_cursor **ppCursor){
  CsvTable *pTab = (CsvTable*)p;
  CsvCursor *pCur;
  pCur = sqlite3_malloc( sizeof(*pCur) * sizeof(char*)*pTab->nCol );
  if( pCur==0 ) return SQLITE_NOMEM;
  memset(pCur, 0, sizeof(*pCur) + sizeof(char*)*pTab->nCol );
  pCur->azVal = (char**)&pCur[1];
  *ppCursor = &pCur->base;
  if( csv_reader_open(&pCur->rdr, pTab->zFilename) ){
    csv_xfer_error(pTab, &pCur->rdr);
    return SQLITE_ERROR;
  }
  return SQLITE_OK;
}


/*
** Advance a CsvCursor to its next row of input.
** Set the EOF marker if we reach the end of input.
*/
static int csvtabNext(sqlite3_vtab_cursor *cur){
  CsvCursor *pCur = (CsvCursor*)cur;
  CsvTable *pTab = (CsvTable*)cur->pVtab;
  int i = 0;
  char *z;
  csvtabCursorRowReset(pCur);
  do{
    z = csv_read_one_field(&pCur->rdr);
    if( z==0 ){
      csv_xfer_error(pTab, &pCur->rdr);
      break;
    }
    z = sqlite3_mprintf("%s", z);
    if( z==0 ){
      csv_errmsg(&pCur->rdr, "out of memory");
      csv_xfer_error(pTab, &pCur->rdr);
      break;
    }
    if( i<pTab->nCol ){
      pCur->azVal[i++] = z;
    }
  }while( z!=0 && pCur->rdr.cTerm==',' );
  if( z==0 || pCur->rdr.cTerm==EOF ){
    pCur->iRowid = -1;
  }else{
    pCur->iRowid++;
  }
  return SQLITE_OK;
}

/*
** Return values of columns for the row at which the CsvCursor
** is currently pointing.
*/
static int csvtabColumn(
  sqlite3_vtab_cursor *cur,   /* The cursor */
  sqlite3_context *ctx,       /* First argument to sqlite3_result_...() */
  int i                       /* Which column to return */
){
  CsvCursor *pCur = (CsvCursor*)cur;
  CsvTable *pTab = (CsvTable*)cur->pVtab;
  if( i>=0 && i<pTab->nCol && pCur->azVal[i]!=0 ){
    sqlite3_result_text(ctx, pCur->azVal[i], -1, SQLITE_STATIC);
  }
  return SQLITE_OK;
}

/*
** Return the rowid for the current row.
*/
static int csvtabRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
  CsvCursor *pCur = (CsvCursor*)cur;
  *pRowid = pCur->iRowid;
  return SQLITE_OK;
}

/*
** Return TRUE if the cursor has been moved off of the last
** row of output.
*/
static int csvtabEof(sqlite3_vtab_cursor *cur){
  CsvCursor *pCur = (CsvCursor*)cur;
  return pCur->iRowid<0;
}

/*
** Only a full table scan is supported.  So xFilter simply rewinds to
** the beginning.
*/
static int csvtabFilter(
  sqlite3_vtab_cursor *pVtabCursor, 
  int idxNum, const char *idxStr,
  int argc, sqlite3_value **argv
){
  CsvCursor *pCur = (CsvCursor*)pVtabCursor;
  CsvTable *pTab = (CsvTable*)pVtabCursor->pVtab;
  pCur->iRowid = 0;
  fseek(pCur->rdr.in, pTab->iStart, SEEK_SET);
  return csvtabNext(pVtabCursor);
}

/*
** Only a forwards full table scan is supported.  xBestIndex is a no-op.
*/
static int csvtabBestIndex(
  sqlite3_vtab *tab,
  sqlite3_index_info *pIdxInfo
){
  return SQLITE_OK;
}


static sqlite3_module CsvModule = {
  0,                       /* iVersion */
  csvtabCreate,            /* xCreate */
  csvtabConnect,           /* xConnect */
  csvtabBestIndex,         /* xBestIndex */
  csvtabDisconnect,        /* xDisconnect */
  csvtabDisconnect,        /* xDestroy */
  csvtabOpen,              /* xOpen - open a cursor */
  csvtabClose,             /* xClose - close a cursor */
  csvtabFilter,            /* xFilter - configure scan constraints */
  csvtabNext,              /* xNext - advance a cursor */
  csvtabEof,               /* xEof - check for end of scan */
  csvtabColumn,            /* xColumn - read data */
  csvtabRowid,             /* xRowid - read data */
  0,                       /* xUpdate */
  0,                       /* xBegin */
  0,                       /* xSync */
  0,                       /* xCommit */
  0,                       /* xRollback */
  0,                       /* xFindMethod */
  0,                       /* xRename */
};

#ifdef _WIN32
__declspec(dllexport)
#endif
/* 
** This routine is called when the extension is loaded.  The new
** CSV virtual table module is registered with the calling database
** connection.
*/
int sqlite3_csv_init(
  sqlite3 *db, 
  char **pzErrMsg, 
  const sqlite3_api_routines *pApi
){
  SQLITE_EXTENSION_INIT2(pApi);
  return sqlite3_create_module(db, "csv", &CsvModule, 0);
}