MDAC 2.5 SDK - ODBC Programmer's Reference
Chapter 23: Installer DLL API Reference

SQLReadFileDSN

Conformance

Version Introduced: ODBC 3.0

Summary

SQLReadFileDSN reads information from a File DSN.

Syntax

BOOL SQLReadFileDSN( LPCSTR lpszFileName, LPCSTR lpszAppName, LPCSTR lpszKeyName, LPSTR lpszString, WORD cbString, WORD * pcbString);

Arguments

lpszFileName

[Input]
Pointer to the data buffer containing the name of the .dsn file. A .dsn extension is appended to all file names that do not already have a .dsn extension. The value in *lpszFileName must be a null-terminated string.

lpszAppName

[Input]
Pointer to the data buffer containing the name of the application. This is "ODBC" for the ODBC section. The value in *lpszAppName must be a null-terminated string.

lpszKeyName

[Input]
Pointer to the data buffer containing the name of the key to be read. See "Comments" for reserved keywords. The value in *lpszAppName must be a null-terminated string.

lpszString

[Output]
Pointer to the data buffer containing the string associated with the key to be read.

If *lpszFileName is a valid .dsn file name but the lpszAppName argument is a null pointer and the lpszKeyName argument is a null pointer, then *lpszString contains a list of valid applications. If *lpszFileName is a valid .dsn file name and *lpszAppName is a valid application name, but the lpszKeyName argument is a null pointer, then *lpszString contains a list of valid reserved keywords in the appropriate section of the DSN file, delimited by semicolons. If *lpszFileName is a valid .dsn file name but *lpszAppName is a null pointer and the lpszKeyName argument is a null pointer, then *lpszString contains a list of the sections in the DSN file, delimited by semicolons.

cbString

[Input]
Length of the *lpszString buffer.

pcbString

[Output]
Total number of bytes available to return in *lpszString. If the number of bytes available to return is greater than or equal to cbString, the output string in *lpszString is truncated to cbString minus the null-termination character. The pcbString argument can be a null pointer.

Returns

The function returns TRUE if it is successful, FALSE if it fails.

Diagnostics

When SQLReadFileDSN returns FALSE, an associated *pfErrorCode value can be obtained by calling SQLInstallerError. The following table lists the *pfErrorCode values that can be returned by SQLInstallerError and explains each one in the context of this function.

*pfErrorCode	Error	Description
ODBC_ERROR_GENERAL_ERR	General installer error	An error occurred for which there was no specific installer error.
ODBC_ERROR_INVALID_BUFF_LEN	Invalid buffer length	The lpszString argument was NULL. The cbString argument was less than or equal to 0.
ODBC_ERROR_INVALID_PATH	Invalid install path	The path of the file name specified in the lpszFileName argument was invalid.
ODBC_ERROR_INVALID_REQUEST_TYPE	Invalid type of request	The lpszAppName argument was NULL, while the lpszKeyName argument was valid.
ODBC_ERROR_OUT_OF_MEM	Out of memory	The installer could not perform the function because of a lack of memory.
ODBC_ERROR_OUTPUT_STRING_TRUNCATED	Output string truncated	The string returned in lpszString was truncated because the value in cbString* was less than or equal to the value in *pcbString.
ODBC_ERROR_REQUEST_FAILED	Request failed	The keyword did not exist in the file DSN.

Comments

ODBC reserves the section name [ODBC] in which to store the connection information. The reserved keywords for this section are the same as those reserved for a connect string in SQLDriverConnect. (For more information, see the SQLDriverConnect function description.)

Applications can use these reserved keywords to read the information in a File DSN. If an applications wants to find out the DSN-less connection string associated with a File DSN, it can call SQLReadFileDSN for any of the reserved connection string keywords in the [ODBC] section. The full connection string passed in a DSN-less connection is a combination of all of the keywords (reserved and driver-specific) in the [ODBC] section.

Related Functions

For information about	See
Writing information to a File DSN	SQLWriteFileDSN