explain_calloc(3) Library Functions Manual 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 er- rnum, 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 de- coded. 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 ar- gument list. This will be overwritten by the next call to any lib- explain 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_cal- loc_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 bet- ter, 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 neces- sary if you need to call any code between the system call to be ex- plained 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 ar- gument list. This will be overwritten by the next call to any lib- explain 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_cal- loc_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 bet- ter, and indicate the underlying cause in more detail. The errno global variable will be used to obtain the error value to be de- coded. 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_cal- loc_or_die(3) function. explain_message_errno_calloc void explain_message_errno_calloc(char *message, int message_size, int er- rnum, 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 neces- sary if you need to call any code between the system call to be ex- plained 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_cal- loc_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 1.3 Copyright (C) 2010 Peter Miller explain_calloc(3)
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