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

# explain\_timerfd\_create(3)

explain timerfd\_create(2) errors

## NAME

explain\_timerfd\_create - explain [timerfd\_create(2)](/timerfd_create/2.md) errors

## SYNOPSIS

\#include \<libexplain/timerfd\_create.h\>

const char \*explain\_timerfd\_create(int clockid, int flags);\
 const char \*explain\_errno\_timerfd\_create(int errnum, int clockid, int flags);\
 void explain\_message\_timerfd\_create(char \*message, int message\_size, int clockid, int flags);\
 void explain\_message\_errno\_timerfd\_create(char \*message, int message\_size, int errnum, int clockid, int flags);

## DESCRIPTION

These functions may be used to obtain explanations for errors returned by the [*timerfd\_create*(2)](/timerfd_create/2.md) system call.

### explain\_timerfd\_create

const char \*explain\_timerfd\_create(int clockid, int flags);

The **explain\_timerfd\_create** function is used to obtain an explanation of an error returned by the [*timerfd\_create*(2)](/timerfd_create/2.md) system call. The least the message will contain is the value of `strerror(errno)`, but usually it will do much better, and indicate the underlying cause in more detail.

The *errno* global variable will be used to obtain the error value to be decoded.

- *clockid*

  The original clockid, exactly as passed to the [*timerfd\_create*(2)](/timerfd_create/2.md) system call.

- *flags*

  The original flags, exactly as passed to the [*timerfd\_create*(2)](/timerfd_create/2.md) system call.

- Returns:

  The message explaining the error. This message buffer is shared by all libexplain functions which do not supply a buffer in their argument list. This will be overwritten by the next call to any libexplain function which shares this buffer, including other threads.

**Note:** This function is **not** thread safe, because it shares a return buffer across all threads, and many other functions in this library.

**Example:** This function is intended to be used in a fashion similar to the following example:

`int result = timerfd_create(clockid, flags);`\
 `if (result < 0)`

```
{
```

`fprintf(stderr, "%s\n", explain_timerfd_create(clockid, flags));`

```
    exit(EXIT_FAILURE);
}
```

The above code example is available pre‐packaged as the [*explain\_timerfd\_create\_or\_die*(3)](/explain_timerfd_create_or_die/3.md) function.

### explain\_errno\_timerfd\_create

const char \*explain\_errno\_timerfd\_create(int errnum, int clockid, int flags);

The **explain\_errno\_timerfd\_create** function is used to obtain an explanation of an error returned by the [*timerfd\_create*(2)](/timerfd_create/2.md) system call. The least the message will contain is the value of `strerror(errno)`, but usually it will do much better, and indicate the underlying cause in more detail.

- *errnum*

  The error value to be decoded, usually obtained from the *errno* global variable just before this function is called. This is necessary if you need to call **any** code between the system call to be explained and this function, because many libc functions will alter the value of *errno*.

- *clockid*

  The original clockid, exactly as passed to the [*timerfd\_create*(2)](/timerfd_create/2.md) system call.

- *flags*

  The original flags, exactly as passed to the [*timerfd\_create*(2)](/timerfd_create/2.md) system call.

- Returns:

  The message explaining the error. This message buffer is shared by all libexplain functions which do not supply a buffer in their argument list. This will be overwritten by the next call to any libexplain function which shares this buffer, including other threads.

**Note:** This function is **not** thread safe, because it shares a return buffer across all threads, and many other functions in this library.

**Example:** This function is intended to be used in a fashion similar to the following example:

`int result = timerfd_create(clockid, flags);`\
 `if (result < 0)`

```
{
    int err = errno;
```

`fprintf(stderr, "%s\n", explain_errno_timerfd_create(err, clockid,` `flags));`

```
    exit(EXIT_FAILURE);
}
```

The above code example is available pre‐packaged as the [*explain\_timerfd\_create\_or\_die*(3)](/explain_timerfd_create_or_die/3.md) function.

### explain\_message\_timerfd\_create

void explain\_message\_timerfd\_create(char \*message, int message\_size, int clockid, int flags);

The **explain\_message\_timerfd\_create** function is used to obtain an explanation of an error returned by the [*timerfd\_create*(2)](/timerfd_create/2.md) system call. The least the message will contain is the value of `strerror(errno)`, but usually it will do much better, and indicate the underlying cause in more detail.

The *errno* global variable will be used to obtain the error value to be decoded.

- *message*

  The location in which to store the returned message. If a suitable message return buffer is supplied, this function is thread safe.

- *message\_size*

  The size in bytes of the location in which to store the returned message.

- *clockid*

  The original clockid, exactly as passed to the [*timerfd\_create*(2)](/timerfd_create/2.md) system call.

- *flags*

  The original flags, exactly as passed to the [*timerfd\_create*(2)](/timerfd_create/2.md) system call.

**Example:** This function is intended to be used in a fashion similar to the following example:

`int result = timerfd_create(clockid, flags);`\
 `if (result < 0)`

```
{
    char message[3000];
```

`explain_message_timerfd_create(message, sizeof(message), clockid, flags);`

```
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}
```

The above code example is available pre‐packaged as the [*explain\_timerfd\_create\_or\_die*(3)](/explain_timerfd_create_or_die/3.md) function.

### explain\_message\_errno\_timerfd\_create

void explain\_message\_errno\_timerfd\_create(char \*message, int message\_size, int errnum, int clockid, int flags);

The **explain\_message\_errno\_timerfd\_create** function is used to obtain an explanation of an error returned by the [*timerfd\_create*(2)](/timerfd_create/2.md) system call. The least the message will contain is the value of `strerror(errno)`, but usually it will do much better, and indicate the underlying cause in more detail.

- *message*

  The location in which to store the returned message. If a suitable message return buffer is supplied, this function is thread safe.

- *message\_size*

  The size in bytes of the location in which to store the returned message.

- *errnum*

  The error value to be decoded, usually obtained from the *errno* global variable just before this function is called. This is necessary if you need to call **any** code between the system call to be explained and this function, because many libc functions will alter the value of *errno*.

- *clockid*

  The original clockid, exactly as passed to the [*timerfd\_create*(2)](/timerfd_create/2.md) system call.

- *flags*

  The original flags, exactly as passed to the [*timerfd\_create*(2)](/timerfd_create/2.md) system call.

**Example:** This function is intended to be used in a fashion similar to the following example:

`int result = timerfd_create(clockid, flags);`\
 `if (result < 0)`

```
{
    int err = errno;
    char message[3000];
```

`explain_message_errno_timerfd_create(message, sizeof(message), err,` `clockid, flags);`

```
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}
```

The above code example is available pre‐packaged as the [*explain\_timerfd\_create\_or\_die*(3)](/explain_timerfd_create_or_die/3.md) function.

## SEE ALSO

- [*timerfd\_create*(2)](/timerfd_create/2.md)

  timers that notify via file descriptors

- [*explain\_timerfd\_create\_or\_die*(3)](/explain_timerfd_create_or_die/3.md)

  timers that notify via file descriptors and report errors

## COPYRIGHT

libexplain version 1.4\
 Copyright (C) 2009 Peter Miller