explain_calloc_or_die(3) [debian man page]
explain_calloc_or_die(3) Library Functions Manual explain_calloc_or_die(3) NAME
explain_calloc_or_die - Allocate and clear memory and report errors SYNOPSIS
#include <libexplain/calloc.h> void *explain_calloc_or_die(size_t nmemb, size_t size); void *explain_calloc_on_error(size_t nmemb, size_t size); DESCRIPTION
The explain_calloc_or_die function is used to call the calloc(3) system call. On failure an explanation will be printed to stderr, obtained from the explain_calloc(3) function, and then the process terminates by calling exit(EXIT_FAILURE). The explain_calloc_on_error function is used to call the calloc(3) system call. On failure an explanation will be printed to stderr, obtained from the explain_calloc(3) function, but still returns to the caller. nmemb The nmemb, exactly as to be passed to the calloc(3) system call. size The size, exactly as to be passed to the calloc(3) system call. RETURN VALUE
The explain_calloc_or_die function only returns on success, see calloc(3) for more information. On failure, prints an explanation and exits, it does not return. The explain_calloc_on_error function always returns the value return by the wrapped calloc(3) system call. EXAMPLE
The explain_calloc_or_die function is intended to be used in a fashion similar to the following example: void *result = explain_calloc_or_die(nmemb, size); SEE ALSO
calloc(3) Allocate and clear memory explain_calloc(3) explain calloc(3) errors exit(2) terminate the calling process COPYRIGHT
libexplain version 0.52 Copyright (C) 2010 Peter Miller explain_calloc_or_die(3)
Check Out this Related Man Page
explain_fread(3) Library Functions Manual explain_fread(3) NAME
explain_fread - explain fread(3) errors SYNOPSIS
#include <libexplain/fread.h> const char *explain_fread(void *ptr, size_t size, size_t nmemb, FILE *fp); const char *explain_errno_fread(int errnum, void *ptr, size_t size, size_t nmemb, FILE *fp); void explain_message_fread(char *message, int message_size, void *ptr, size_t size, size_t nmemb, FILE *fp); void explain_message_errno_fread(char *message, int message_size, int errnum, void *ptr, size_t size, size_t nmemb, FILE *fp); DESCRIPTION
These functions may be used to obtain explanations for errors returned by the fread(3) system call. explain_fread const char *explain_fread(void *ptr, size_t size, size_t nmemb, FILE *fp); The explain_fread function is used to obtain an explanation of an error returned by the fread(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. This function is intended to be used in a fashion similar to the following example: size_t how_many = fread(ptr, size, nmemb, fp); if (how_many == 0 && ferror(fp)) { fprintf(stderr, "%s ", explain_fread(ptr, size, nmemb, fp)); exit(EXIT_FAILURE); } ptr The original ptr, exactly as passed to the fread(3) system call. size The original size, exactly as passed to the fread(3) system call. nmemb The original nmemb, exactly as passed to the fread(3) system call. fp The original fp, exactly as passed to the fread(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. explain_errno_fread const char *explain_errno_fread(int errnum, void *ptr, size_t size, size_t nmemb, FILE *fp); The explain_errno_fread function is used to obtain an explanation of an error returned by the fread(3) system call. The least the message will contain is the value of strerror(errnum), but usually it will do much better, and indicate the underlying cause in more detail. This function is intended to be used in a fashion similar to the following example: size_t how_many = fread(ptr, size, nmemb, fp); if (how_many == 0 && ferror(fp)) { int err = errno; fprintf(stderr, "%s ", explain_errno_fread(err, ptr, size, nmemb, fp)); exit(EXIT_FAILURE); } errnum The error value to be decoded, usually obtained from the errno global variable just before this function is called. This is neces- sary 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. ptr The original ptr, exactly as passed to the fread(3) system call. size The original size, exactly as passed to the fread(3) system call. nmemb The original nmemb, exactly as passed to the fread(3) system call. fp The original fp, exactly as passed to the fread(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. explain_message_fread void explain_message_fread(char *message, int message_size, void *ptr, size_t size, size_t nmemb, FILE *fp); The explain_message_fread function may be used to obtain an explanation of an error returned by the fread(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. This function is intended to be used in a fashion similar to the following example: size_t how_many = fread(ptr, size, nmemb, fp); if (how_many == 0 && ferror(fp)) { char message[3000]; explain_message_fread(message, sizeof(message), ptr, size, nmemb, fp); fprintf(stderr, "%s ", message); exit(EXIT_FAILURE); } 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. ptr The original ptr, exactly as passed to the fread(3) system call. size The original size, exactly as passed to the fread(3) system call. nmemb The original nmemb, exactly as passed to the fread(3) system call. fp The original fp, exactly as passed to the fread(3) system call. explain_message_errno_fread void explain_message_errno_fread(char *message, int message_size, int errnum, void *ptr, size_t size, size_t nmemb, FILE *fp); The explain_message_errno_fread function may be used to obtain an explanation of an error returned by the fread(3) system call. The least the message will contain is the value of strerror(errnum), but usually it will do much better, and indicate the underlying cause in more detail. This function is intended to be used in a fashion similar to the following example: size_t how_many = fread(ptr, size, nmemb, fp); if (how_many == 0 && ferror(fp)) { int err = errno; char message[3000]; explain_message_errno_fread(message, sizeof(message), err, ptr, size, nmemb, fp); fprintf(stderr, "%s ", message); exit(EXIT_FAILURE); } 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 neces- sary 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. ptr The original ptr, exactly as passed to the fread(3) system call. size The original size, exactly as passed to the fread(3) system call. nmemb The original nmemb, exactly as passed to the fread(3) system call. fp The original fp, exactly as passed to the fread(3) system call. SEE ALSO
fread(3) binary stream input explain_fread_or_die(3) binary stream input and report errors COPYRIGHT
libexplain version 0.52 Copyright (C) 2008 Peter Miller explain_fread(3)