---
name: "explain_mmap_or_die"
section: "3"
platform: "linux"
package: "libexplain-dev"
version: "1.4.D001-16"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/explain_mmap_or_die"
---

# explain\_mmap\_or\_die(3)

map file or device into memory and report errors

## NAME

explain\_mmap\_or\_die - map file or device into memory and report errors

## SYNOPSIS

\#include \<libexplain/mmap.h\>

void \*explain\_mmap\_or\_die(void \*data, size\_t data\_size, int prot, int flags, int fildes, off\_t offset);\
 void \*explain\_mmap\_on\_error(void \*data, size\_t data\_size, int prot, int flags, int fildes, off\_t offset);

## DESCRIPTION

The **explain\_mmap\_or\_die** function is used to call the [*mmap*(2)](/mmap/2.md) system call. On failure an explanation will be printed to *stderr*, obtained from the [*explain\_mmap*(3)](/explain_mmap/3.md) function, and then the process terminates by calling `exit(EXIT_FAILURE)`.

The **explain\_mmap\_on\_error** function is used to call the [*mmap*(2)](/mmap/2.md) system call. On failure an explanation will be printed to *stderr*, obtained from the [*explain\_mmap*(3)](/explain_mmap/3.md) function, but still returns to the caller.

- *data*

  The data, exactly as to be passed to the [*mmap*(2)](/mmap/2.md) system call.

- *data\_size*

  The data\_size, exactly as to be passed to the [*mmap*(2)](/mmap/2.md) system call.

- *prot*

  The prot, exactly as to be passed to the [*mmap*(2)](/mmap/2.md) system call.

- *flags*

  The flags, exactly as to be passed to the [*mmap*(2)](/mmap/2.md) system call.

- *fildes*

  The fildes, exactly as to be passed to the [*mmap*(2)](/mmap/2.md) system call.

- *offset*

  The offset, exactly as to be passed to the [*mmap*(2)](/mmap/2.md) system call.

## RETURN VALUE

The **explain\_mmap\_or\_die** function only returns on success, see [*mmap*(2)](/mmap/2.md) for more information. On failure, prints an explanation and exits, it does not return.

The **explain\_mmap\_on\_error** function always returns the value return by the wrapped [*mmap*(2)](/mmap/2.md) system call.

## EXAMPLE

The **explain\_mmap\_or\_die** function is intended to be used in a fashion similar to the following example:

```
explain_mmap_or_die(data, data_size, prot, flags, fildes, offset);
```

## SEE ALSO

- [*mmap*(2)](/mmap/2.md)

  map file or device into memory

- [*explain\_mmap*(3)](/explain_mmap/3.md)

  explain [*mmap*(2)](/mmap/2.md) errors

- [*exit*(2)](/exit/2.md)

  terminate the calling process

## COPYRIGHT

libexplain version 1.4\
 Copyright (C) 2010 Peter Miller