emfdb.c

嵌入式Linux系统用的web server,开源代码,非常好用

	int			tid, colIndex, *pRow;
	dbTable_t	*pTable;

	a_assert(table);
	a_assert(column);

/*
 *	Make sure that this table exists
 */
	tid = dbGetTableId(0, table);
	a_assert(tid >= 0);

	if (tid < 0) {
		return DB_ERR_TABLE_NOT_FOUND;
	}

	pTable = dbListTables[tid];
	
	if (pTable) {
/*
 *		Make sure that the column exists
 */
		colIndex = GetColumnIndex(tid, column);
		a_assert(colIndex >= 0);
		if (colIndex >= 0) {
/*
 *			Make sure that the row exists
 */
			a_assert((row >= 0) && (row < pTable->nRows));
			if ((row >= 0) && (row < pTable->nRows)) {
				pRow = pTable->rows[row];
				if (pRow) {
					pRow[colIndex] = iData;
					return 0;
				}
				return DB_ERR_ROW_DELETED;
			}
			return DB_ERR_ROW_NOT_FOUND;
		}
		return DB_ERR_COL_NOT_FOUND;
	}

	return DB_ERR_TABLE_DELETED;
}

/******************************************************************************/
/*
 *	The dbWriteStr function writes a string value into a table at a given row 
 *	and column.  The existence of the row and column is verified before the 
 *	write.  The column is also checked to confirm it is a string field.
 *	0 is returned on succes, -1 is returned on error.
 */

int dbWriteStr(int did, char_t *table, char_t *column, int row, char_t *s)
{
	int			tid, colIndex;
	int			*pRow;
	char_t		*ptr;
	dbTable_t	*pTable;

	a_assert(table);
	a_assert(column);

	tid = dbGetTableId(0, table);
	a_assert(tid >= 0);

	if (tid < 0) {
		return DB_ERR_TABLE_NOT_FOUND;
	}

/*
 *	Make sure that this table exists
 */
	pTable = dbListTables[tid];
	a_assert(pTable);
	if (!pTable) {
		return DB_ERR_TABLE_DELETED;
	}

/*
 *	Make sure that this column exists
 */
	colIndex = GetColumnIndex(tid, column);
	if (colIndex < 0) {
		return DB_ERR_COL_NOT_FOUND;
	}

/*
 *	Make sure that this column is a string column
 */
	if (pTable->columnTypes[colIndex] != T_STRING) {
		return DB_ERR_BAD_FORMAT;
	}

/*
 *	Make sure that the row exists
 */
	a_assert((row >= 0) && (row < pTable->nRows));
	if ((row >= 0) && (row < pTable->nRows)) {
		pRow = pTable->rows[row];
	} else {
		return DB_ERR_ROW_NOT_FOUND;
	}

	if (!pRow) {
		return DB_ERR_ROW_DELETED;
	}

/*
 *	If the column already has a value, be sure to delete it to prevent
 *	memory leaks.
 */
	if (pRow[colIndex]) {
		bfree(B_L, (char_t *) pRow[colIndex]);
	}

/*
 *	Make sure we make a copy of the string to write into the column.
 *	This allocated string will be deleted when the row is deleted.
 */
	ptr = bstrdup(B_L, s);
	pRow[colIndex] = (int)ptr;

	return 0;
}

/******************************************************************************/
/*
 *	Print a key-value pair to a file
 */

static int dbWriteKeyValue(int fd, char_t *key, char_t *value)
{
	int		rc;
	int		len;
	char_t	*pLineOut;

	a_assert(key && *key);
	a_assert(value);
	
	fmtAlloc(&pLineOut, BUF_MAX, T("%s=%s\n"), key, value);

	if (pLineOut) {
		len = gstrlen(pLineOut);
#ifdef CE
		rc = writeUniToAsc(fd, pLineOut, len);
#else
		rc = gwrite(fd, pLineOut, len);
#endif
		bfree(B_L, pLineOut);
	} else {
		rc = -1;
	}

	return rc;
}

/******************************************************************************/
/*
 *	Persist a database to a file
 */

int dbSave(int did, char_t *filename, int flags)
{
	int			row, column, nColumns, nRows, fd, rc;
	int			*colTypes, *pRow, nRet, tid;
	char_t		*path, *tmpFile, *tmpNum;
	char_t		**colNames;
	dbTable_t	*pTable;

	trace(5, T("DB: About to save database to file\n"));

	a_assert(dbMaxTables > 0);

/*
 *	First write to a temporary file, then switch around later.
 */
	fmtAlloc(&tmpFile, FNAMESIZE, T("%s/data.tmp"), basicGetProductDir());
	if ((fd = gopen(tmpFile, 
		O_CREAT | O_TRUNC | O_WRONLY | O_BINARY, 0666)) < 0) {
		trace(1, T("WARNING: Failed to open file %s\n"), tmpFile);
		bfree(B_L, tmpFile);
		return -1;
	}

	nRet = 0;

	for (tid = 0; (tid < dbMaxTables) && (nRet != -1); tid++) {
		pTable = dbListTables[tid];

		if (pTable) {
/*
 *			Print the TABLE=tableName directive to the file
 */
			rc = dbWriteKeyValue(fd, KEYWORD_TABLE, pTable->name);

			nColumns = pTable->nColumns;
			nRows = pTable->nRows;

			for (row = 0; (row < nRows) && (nRet == 0); row++) {
				pRow = pTable->rows[row];
/*
 *				if row is NULL, the row has been deleted, so don't
 *				write it out.
 */
				if ((pRow == NULL) || (pRow[0] == '\0') || 
					(*(char_t *)(pRow[0]) == '\0')) {
					continue;
				}
/*
 *				Print the ROW=rowNumber directive to the file
 */
				fmtAlloc(&tmpNum, 20, T("%d"), row);		
				rc = dbWriteKeyValue(fd, KEYWORD_ROW, tmpNum);
				bfreeSafe(B_L, tmpNum);

				colNames = pTable->columnNames;
				colTypes = pTable->columnTypes;
/*
 *				Print the key-value pairs (COLUMN=value) for data cells
 */
				for (column = 0; (column < nColumns) && (rc >= 0); 
					column++, colNames++, colTypes++) {
					if (*colTypes == T_STRING) {
						rc = dbWriteKeyValue(fd, *colNames, 
							(char_t *)(pRow[column]));
					} else {
						fmtAlloc(&tmpNum, 20, T("%d"), pRow[column]);		
						rc = dbWriteKeyValue(fd, *colNames, tmpNum);
						bfreeSafe(B_L, tmpNum);
					}
				}

				if (rc < 0) {
					trace(1, T("WARNING: Failed to write to file %s\n"), 
						tmpFile);
					nRet = -1;
				}
			}
		}
	}

	gclose(fd);

/*
 *	Replace the existing file with the temporary file, if no errors
 */
	if (nRet == 0) {
		fmtAlloc(&path, FNAMESIZE, T("%s/%s"), basicGetProductDir(), filename);

		gunlink(path);
		if (grename(tmpFile, path) != 0) {
			trace(1, T("WARNING: Failed to rename %s to %s\n"), tmpFile, path);
			nRet = -1;
		}

		bfree(B_L, path);
	}

	bfree(B_L, tmpFile);

	return nRet;
}

/******************************************************************************/
/*
 *	Crack a keyword=value string into keyword and value. We can change buf.
 */

static int crack(char_t *buf, char_t **key, char_t **val)
{
	char_t	*ptr;

	if ((ptr = gstrrchr(buf, '\n')) != NULL ||
			(ptr = gstrrchr(buf, '\r')) != NULL) {
		*ptr = '\0';
	}

/*
 *	Find the = sign. It must exist.
 */
	if ((ptr = gstrstr(buf, T("="))) == NULL) {
		return -1;
	}

	*ptr++ = '\0';
	*key = trim(buf);
	*val = trim(ptr);

	return 0;
}

/******************************************************************************/
/*
 *	Parse the file. These files consist of key-value pairs, separated by the 
 *  "=" sign. Parsing of tables starts with the "TABLE=value" pair, and rows
 *	are parsed starting with the "ROW=value" pair.
 */

int dbLoad(int did, char_t *filename, int flags)
{
	gstat_t		sbuf;
	char_t		*buf, *keyword, *value, *path, *ptr;
	char_t		*tablename;
	int			fd, tid, row;
	dbTable_t	*pTable;

    a_assert(did >= 0);

	fmtAlloc(&path, FNAMESIZE, T("%s/%s"), basicGetProductDir(), filename);
	trace(4, T("DB: About to read data file <%s>\n"), path);

	if (gstat(path, &sbuf) < 0) {
		trace(3, T("DB: Failed to stat persistent data file.\n"));
		bfree(B_L, path);
		return -1;
	}

	fd = gopen(path, O_RDONLY | O_BINARY, 0666);
	bfree(B_L, path);

	if (fd < 0) {
		trace(3, T("DB: No persistent data file present.\n"));
		return -1;
	}

	if (sbuf.st_size <= 0) {
		trace(3, T("DB: Persistent data file is empty.\n"));
		gclose(fd);
		return -1;
	}
/*
 *	Read entire file into temporary buffer
 */
	buf = balloc(B_L, sbuf.st_size + 1);
#ifdef CE
	if (readAscToUni(fd, &buf, sbuf.st_size) != (int)sbuf.st_size) {
#else
	if (gread(fd, buf, sbuf.st_size) != (int)sbuf.st_size) {
#endif
		trace(3, T("DB: Persistent data read failed.\n"));
		bfree(B_L, buf);
		gclose(fd);
		return -1;
	}

	gclose(fd);
	*(buf + sbuf.st_size) = '\0';

	row = -1;
	tid = -1;
	pTable = NULL;
	ptr = gstrtok(buf, T("\n"));
	tablename = NULL;

	do {
		if (crack(ptr, &keyword, &value) < 0) {
			trace(5, T("DB: Failed to crack line %s\n"), ptr);
			continue;
		}

		a_assert(keyword && *keyword);

		if (gstrcmp(keyword, KEYWORD_TABLE) == 0) {
/*
 *			Table name found, check to see if it's registered
 */
			if (tablename) {
				bfree(B_L, tablename);
			}

			tablename = bstrdup(B_L, value);
			tid = dbGetTableId(did, tablename);

			if (tid >= 0) {
				pTable = dbListTables[tid];
			} else {
				pTable = NULL;
			}

		} else if (gstrcmp(keyword, KEYWORD_ROW) == 0) {
/*
 *			Row/Record indicator found, add a new row to table
 */
			if (tid >= 0) {
				int nRows = dbGetTableNrow(did, tablename);

				if (dbSetTableNrow(did, tablename, nRows + 1) == 0) {
					row = nRows;
				}
			}

		} else if (row != -1) {
/*
 *			some other data found, assume it's a COLUMN=value
 */
			int nColumn = GetColumnIndex(tid, keyword);

			if ((nColumn >= 0) && (pTable != NULL)) {
				int nColumnType = pTable->columnTypes[nColumn];
				if (nColumnType == T_STRING) {
					dbWriteStr(did, tablename, keyword, row, value);
				} else {
					dbWriteInt(did, tablename, keyword, row, gstrtoi(value));
				}
			}
		}
	} while ((ptr = gstrtok(NULL, T("\n"))) != NULL);

	if (tablename) {
		bfree(B_L, tablename);
	}

	bfree(B_L, buf);

	return 0;
}

/******************************************************************************/
/*
 *	Return a table id given the table name
 */

int dbGetTableId(int did, char_t *tablename)
{
	int			tid;
	dbTable_t	*pTable;

	a_assert(tablename);

	for (tid = 0; (tid < dbMaxTables); tid++) {
		if ((pTable = dbListTables[tid]) != NULL) {
			if (gstrcmp(tablename, pTable->name) == 0) {
				return tid;
			}
		}
	}
	
	return -1;
}

/******************************************************************************/
/*	
 *	Return a pointer to the table name, given its ID
 */

char_t *dbGetTableName(int did, int tid)
{
	if ((tid >= 0) && (tid < dbMaxTables) && (dbListTables[tid] != NULL)) {
		return (dbListTables[tid])->name;
	}

	return NULL;
}

/******************************************************************************/
/*
 *	Trim leading white space.
 */

static char_t *trim(char_t *str)
{
	while (isspace((int)*str)) {
		str++;
	}
	return str;
}

/******************************************************************************/
/*
 *	Return a column index given the column name
 */

static int GetColumnIndex(int tid, char_t *colName) 
{
	int			column;
	dbTable_t	*pTable;

	a_assert(colName);

	if ((tid >= 0) && (tid < dbMaxTables) && (dbListTables[tid] != NULL)) {
		pTable = dbListTables[tid];

		for (column = 0; (column < pTable->nColumns); column++) {
			if (gstrcmp(colName, pTable->columnNames[column]) == 0)
				return column;
		}
	}

	return -1;
}

/******************************************************************************/
/*
 *	Set the prefix-directory
 */

void basicSetProductDir(char_t *proddir)
{
	int len;

	if (basicProdDir != NULL) {	
      bfree(B_L, basicProdDir);
	}
    
	basicProdDir = bstrdup(B_L, proddir);
/*
 *	Make sure that prefix-directory doesn't end with a '/'
 */
	len = gstrlen(basicProdDir);
	if ((len > 0) && *(basicProdDir + len - 1) == '/') {
		*(basicProdDir+len-1) = '\0';
	}
}

/******************************************************************************/
/*
 *	Return the prefix-directory
 */

char_t *basicGetProductDir()
{
	if (basicProdDir) {
		return basicProdDir;
	} else {
		return basicDefaultDir;
	}
}

/******************************************************************************/