The Open Group Base Specifications Issue 6
IEEE Std 1003.1, 2004 Edition
Copyright © 2001-2004 The IEEE and The Open Group, All Rights reserved.

#### NAME

> dlerror - get diagnostic information

#### SYNOPSIS

> ``[XSI] #include <dlfcn.h>
> char *dlerror(void);``
> `
> `

#### DESCRIPTION

> The dlerror() function shall return a null-terminated character string (with no trailing <newline>) that describes the last error that occurred during dynamic linking processing. If no dynamic linking errors have occurred since the last invocation of dlerror(), dlerror() shall return NULL. Thus, invoking dlerror() a second time, immediately following a prior invocation, shall result in NULL being returned.

> The dlerror() function need not be reentrant. A function that is not required to be reentrant is not required to be thread-safe.

#### RETURN VALUE

> If successful, dlerror() shall return a null-terminated character string; otherwise, NULL shall be returned.

#### ERRORS

> No errors are defined.

The following sections are informative.

#### EXAMPLES

> The following example prints out the last dynamic linking error:

>     ...
>     #include <dlfcn.h>

>     char *errstr;

>     errstr = dlerror();
>     if (errstr != NULL)
>     printf ("A dynamic linking error occurred: (%s)\n", errstr);
>     ...

#### APPLICATION USAGE

> The messages returned by dlerror() may reside in a static buffer that is overwritten on each call to dlerror(). Application code should not write to this buffer. Programs wishing to preserve an error message should make their own copies of that message. Depending on the application environment with respect to asynchronous execution events, such as signals or other asynchronous computation sharing the address space, conforming applications should use a critical section to retrieve the error pointer and buffer.

#### RATIONALE

> None.

#### FUTURE DIRECTIONS

> None.

#### SEE ALSO

> dlclose(), dlopen(), dlsym(), the Base Definitions volume of IEEE Std 1003.1-2001, <dlfcn.h>

#### CHANGE HISTORY

> First released in Issue 5.

#### Issue 6

> In the DESCRIPTION the note about reentrancy and thread-safety is added.

End of informative text.

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