explain_calloc(3)

NAME
explain_calloc - explain calloc(3) errors

SYNOPSIS
#include <libexplain/calloc.h>

const char *explain_calloc(size_t nmemb, size_t size);
const char *explain_errno_calloc(int errnum, size_t nmemb, size_t size);
void explain_message_calloc(char *message, int message_size, size_t nmemb, size_t size);
void explain_message_errno_calloc(char *message, int message_size, int errnum, size_t nmemb, size_t size);

DESCRIPTION
These functions may be used to obtain explanations for errors returned by the calloc(3) system call.

  explain_calloc
const char *explain_calloc(size_t nmemb, size_t size);

The explain_calloc function is used to obtain an explanation of an error returned by the calloc(3) 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.

nmemb
    The original nmemb, exactly as passed to the calloc(3) system call.

size
    The original size, exactly as passed to the calloc(3) 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:
    errno = 0;
    void *result = calloc(nmemb, size);
    if (!result && errno != 0)
    {
    fprintf(stderr, "%s\n", explain_calloc(nmemb, size));
        exit(EXIT_FAILURE);
    }

The above code example is available pre-packaged as the explain_calloc_or_die(3) function.

  explain_errno_calloc
const char *explain_errno_calloc(int errnum, size_t nmemb, size_t size);

The explain_errno_calloc function is used to obtain an explanation of an error returned by the calloc(3) 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.

nmemb
    The original nmemb, exactly as passed to the calloc(3) system call.

size
    The original size, exactly as passed to the calloc(3) 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:
    errno = 0;
    void *result = calloc(nmemb, size);
    if (!result && errno != 0)
    {
        int err = errno;
    fprintf(stderr, "%s\n", explain_errno_calloc(err, nmemb, size));
        exit(EXIT_FAILURE);
    }

The above code example is available pre-packaged as the explain_calloc_or_die(3) function.

  explain_message_calloc
void explain_message_calloc(char *message, int message_size, size_t nmemb, size_t size);

The explain_message_calloc function is used to obtain an explanation of an error returned by the calloc(3) 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.

nmemb
    The original nmemb, exactly as passed to the calloc(3) system call.

size
    The original size, exactly as passed to the calloc(3) system call.

Example: This function is intended to be used in a fashion similar to the following example:
    errno = 0;
    void *result = calloc(nmemb, size);
    if (!result && errno != 0)
    {
        char message[3000];
    explain_message_calloc(message, sizeof(message), nmemb, size);
        fprintf(stderr, "%s\n", message);
        exit(EXIT_FAILURE);
    }

The above code example is available pre-packaged as the explain_calloc_or_die(3) function.

  explain_message_errno_calloc
void explain_message_errno_calloc(char *message, int message_size, int errnum, size_t nmemb, size_t size);

The explain_message_errno_calloc function is used to obtain an explanation of an error returned by the calloc(3) 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.

nmemb
    The original nmemb, exactly as passed to the calloc(3) system call.

size
    The original size, exactly as passed to the calloc(3) system call.

Example: This function is intended to be used in a fashion similar to the following example:
    errno = 0;
    void *result = calloc(nmemb, size);
    if (!result && errno != 0)
    {
        int err = errno;
        char message[3000];
    explain_message_errno_calloc(message, sizeof(message), err, nmemb, size);
        fprintf(stderr, "%s\n", message);
        exit(EXIT_FAILURE);
    }

The above code example is available pre-packaged as the explain_calloc_or_die(3) function.

SEE ALSO

calloc(3)
    Allocate and clear memory

explain_calloc_or_die(3)
    Allocate and clear memory and report errors

COPYRIGHT
libexplain version 0.46
Copyright (C) 2010 Peter Miller