explain_strtoul(3)

NAME
explain_strtoul - explain strtoul(3) errors

SYNOPSIS
#include <libexplain/strtoul.h>

const char *explain_strtoul(const char *nptr, char **endptr, int base);
const char *explain_errno_strtoul(int errnum, const char *nptr, char **endptr, int base);
void explain_message_strtoul(char *message, int message_size, const char *nptr, char **endptr, int base);
void explain_message_errno_strtoul(char *message, int message_size, int errnum, const char *nptr, char **endptr, int base);

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

  explain_strtoul
const char *explain_strtoul(const char *nptr, char **endptr, int base);

The explain_strtoul function is used to obtain an explanation of an error returned by the strtoul(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.

nptr
    The original nptr, exactly as passed to the strtoul(3) system call.

endptr
    The original endptr, exactly as passed to the strtoul(3) system call.

base
    The original base, exactly as passed to the strtoul(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:
    unsigned long result = strtoul(nptr, endptr, base);
    if (result < 0)
    {
    fprintf(stderr, "%s\n", explain_strtoul(nptr, endptr, base));
        exit(EXIT_FAILURE);
    }

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

  explain_errno_strtoul
const char *explain_errno_strtoul(int errnum, const char *nptr, char **endptr, int base);

The explain_errno_strtoul function is used to obtain an explanation of an error returned by the strtoul(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.

nptr
    The original nptr, exactly as passed to the strtoul(3) system call.

endptr
    The original endptr, exactly as passed to the strtoul(3) system call.

base
    The original base, exactly as passed to the strtoul(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:
    unsigned long result = strtoul(nptr, endptr, base);
    if (result < 0)
    {
        int err = errno;
    fprintf(stderr, "%s\n", explain_errno_strtoul(err, nptr, endptr, base));
        exit(EXIT_FAILURE);
    }

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

  explain_message_strtoul
void explain_message_strtoul(char *message, int message_size, const char *nptr, char **endptr, int base);

The explain_message_strtoul function is used to obtain an explanation of an error returned by the strtoul(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.

nptr
    The original nptr, exactly as passed to the strtoul(3) system call.

endptr
    The original endptr, exactly as passed to the strtoul(3) system call.

base
    The original base, exactly as passed to the strtoul(3) system call.

Example: This function is intended to be used in a fashion similar to the following example:
    unsigned long result = strtoul(nptr, endptr, base);
    if (result < 0)
    {
        char message[3000];
    explain_message_strtoul(message, sizeof(message), nptr, endptr, base);
        fprintf(stderr, "%s\n", message);
        exit(EXIT_FAILURE);
    }

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

  explain_message_errno_strtoul
void explain_message_errno_strtoul(char *message, int message_size, int errnum, const char *nptr, char **endptr, int base);

The explain_message_errno_strtoul function is used to obtain an explanation of an error returned by the strtoul(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.

nptr
    The original nptr, exactly as passed to the strtoul(3) system call.

endptr
    The original endptr, exactly as passed to the strtoul(3) system call.

base
    The original base, exactly as passed to the strtoul(3) system call.

Example: This function is intended to be used in a fashion similar to the following example:
    unsigned long result = strtoul(nptr, endptr, base);
    if (result < 0)
    {
        int err = errno;
        char message[3000];
    explain_message_errno_strtoul(message, sizeof(message), err, nptr, endptr, base);
        fprintf(stderr, "%s\n", message);
        exit(EXIT_FAILURE);
    }

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

SEE ALSO

strtoul(3)
    convert a string to an unsigned long integer

explain_strtoul_or_die(3)
    convert a string to an unsigned long integer and report errors

COPYRIGHT
libexplain version
Copyright (C) 2009 Peter Miller