explain_mmap(3) Library Functions Manual explain_mmap(3) NAME explain_mmap - explain mmap(2) errors SYNOPSIS #include <libexplain/mmap.h> const char *explain_mmap(void *data, size_t data_size, int prot, int flags, int fildes, off_t offset); const char *explain_errno_mmap(int errnum, void *data, size_t data_size, int prot, int flags, int fildes, off_t offset); void explain_message_mmap(char *message, int message_size, void *data, size_t data_size, int prot, int flags, int fildes, off_t offset); void explain_message_errno_mmap(char *message, int message_size, int er- rnum, void *data, size_t data_size, int prot, int flags, int fildes, off_t offset); DESCRIPTION These functions may be used to obtain explanations for errors returned by the mmap(2) system call. explain_mmap const char *explain_mmap(void *data, size_t data_size, int prot, int flags, int fildes, off_t offset); The explain_mmap function is used to obtain an explanation of an error re- turned by the mmap(2) system call. The least the message will contain is the value of strerror(errno), but usually it will do much better, and indi- cate the underlying cause in more detail. The errno global variable will be used to obtain the error value to be de- coded. data The original data, exactly as passed to the mmap(2) system call. data_size The original data_size, exactly as passed to the mmap(2) system call. prot The original prot, exactly as passed to the mmap(2) system call. flags The original flags, exactly as passed to the mmap(2) system call. fildes The original fildes, exactly as passed to the mmap(2) system call. offset The original offset, exactly as passed to the mmap(2) 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: void *result = mmap(data, data_size, prot, flags, fildes, offset); if (!result) { fprintf(stderr, "%s\n", explain_mmap(data, data_size, prot, flags, fildes, offset)); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the ex- plain_mmap_or_die(3) function. explain_errno_mmap const char *explain_errno_mmap(int errnum, void *data, size_t data_size, int prot, int flags, int fildes, off_t offset); The explain_errno_mmap function is used to obtain an explanation of an er- ror returned by the mmap(2) 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 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. data The original data, exactly as passed to the mmap(2) system call. data_size The original data_size, exactly as passed to the mmap(2) system call. prot The original prot, exactly as passed to the mmap(2) system call. flags The original flags, exactly as passed to the mmap(2) system call. fildes The original fildes, exactly as passed to the mmap(2) system call. offset The original offset, exactly as passed to the mmap(2) 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: void *result = mmap(data, data_size, prot, flags, fildes, offset); if (!result) { int err = errno; fprintf(stderr, "%s\n", explain_errno_mmap(err, data, data_size, prot, flags, fildes, offset)); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the ex- plain_mmap_or_die(3) function. explain_message_mmap void explain_message_mmap(char *message, int message_size, void *data, size_t data_size, int prot, int flags, int fildes, off_t offset); The explain_message_mmap function is used to obtain an explanation of an error returned by the mmap(2) system call. The least the message will con- tain 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. 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. data The original data, exactly as passed to the mmap(2) system call. data_size The original data_size, exactly as passed to the mmap(2) system call. prot The original prot, exactly as passed to the mmap(2) system call. flags The original flags, exactly as passed to the mmap(2) system call. fildes The original fildes, exactly as passed to the mmap(2) system call. offset The original offset, exactly as passed to the mmap(2) system call. Example: This function is intended to be used in a fashion similar to the following example: void *result = mmap(data, data_size, prot, flags, fildes, offset); if (!result) { char message[3000]; explain_message_mmap(message, sizeof(message), data, data_size, prot, flags, fildes, offset); fprintf(stderr, "%s\n", message); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the ex- plain_mmap_or_die(3) function. explain_message_errno_mmap void explain_message_errno_mmap(char *message, int message_size, int er- rnum, void *data, size_t data_size, int prot, int flags, int fildes, off_t offset); The explain_message_errno_mmap function is used to obtain an explanation of an error returned by the mmap(2) 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. 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. data The original data, exactly as passed to the mmap(2) system call. data_size The original data_size, exactly as passed to the mmap(2) system call. prot The original prot, exactly as passed to the mmap(2) system call. flags The original flags, exactly as passed to the mmap(2) system call. fildes The original fildes, exactly as passed to the mmap(2) system call. offset The original offset, exactly as passed to the mmap(2) system call. Example: This function is intended to be used in a fashion similar to the following example: void *result = mmap(data, data_size, prot, flags, fildes, offset); if (!result) { int err = errno; char message[3000]; explain_message_errno_mmap(message, sizeof(message), err, data, data_size, prot, flags, fildes, offset); fprintf(stderr, "%s\n", message); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the ex- plain_mmap_or_die(3) function. SEE ALSO mmap(2) map file or device into memory explain_mmap_or_die(3) map file or device into memory and report errors COPYRIGHT libexplain version 1.3 Copyright (C) 2010 Peter Miller explain_mmap(3)
NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT
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