explain_open(3) Library Functions Manual explain_open(3) NAME explain_open - explain open(2) errors SYNOPSIS #include <libexplain/open.h> const char *explain_open(const char *pathname, int flags, int mode); const char *explain_errno_open(int errnum, const char *pathname, int flags, int mode); void explain_message_open(char *message, int message_size, const char *pathname, int flags, int mode); void explain_message_errno_open(char *message, int message_size, int er- rnum, const char *pathname, int flags, int mode); DESCRIPTION These functions may be used to obtains explanations for open(2) errors. explain_open(const char *pathname, int flags, int mode); const char *explain_open(const char *pathname, int flags, int mode); The explain_open function is used to obtain an explanation of an error re- turned by the open(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. This function is intended to be used in a fashion similar to the following example: int fd = open(pathname, flags, mode); if (fd < 0) { fprintf(stderr, '%s0, explain_open(pathname, flags, mode)); exit(EXIT_FAILURE); } pathname The original pathname, exactly as passed to the open(2) system call. flags The original flags, exactly as passed to the open(2) system call. mode The original mode, exactly as passed to the open(2) system call (or zero if the original call didn't need a mode argument). 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. explain_errno_open const char *explain_errno_open(int errnum, const char *pathname, int flags, int mode); The explain_errno_open function is used to obtain an explanation of an er- ror returned by the open(2) system call. The least the message will con- tain 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: int fd = open(pathname, flags, mode); if (fd < 0) { int err = errno; fprintf(stderr, '%s0, explain_errno_open(err, pathname, flags, mode)); 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 nec- essary 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. pathname The original pathname, exactly as passed to the open(2) system call. flags The original flags, exactly as passed to the open(2) system call. mode The original mode, exactly as passed to the open(2) system call (or zero if the original call didn't need a mode argument). 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. explain_message_open void explain_message_open(char *message, int message_size, const char *pathname, int flags, int mode); The explain_message_open function is used to obtain an explanation of an error returned by the open(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. This function is intended to be used in a fashion similar to the following example: int fd = open(pathname, flags, mode); if (fd < 0) { char message[3000]; explain_message_open(message, sizeof(message), pathname, flags, mode); fprintf(stderr, '%s0, message); exit(EXIT_FAILURE); } message The location in which to store the returned message. Because a message return buffer has been supplied, this function is thread safe. message_size The size in bytes of the location in which to store the returned message. pathname The original pathname, exactly as passed to the open(2) system call. flags The original flags, exactly as passed to the open(2) system call. mode The original mode, exactly as passed to the open(2) system call (or zero if the original call didn't need a mode argument). explain_message_errno_open void explain_message_errno_open(char *message, int message_size, int er- rnum, const char *pathname, int flags, int mode); The explain_message_errno_open function is used to obtain an explanation of an error returned by the open(2) system call. The least the message will contain is the value of strerror(errnum), but usually it will do much bet- ter, and indicate the underlying cause in more detail. This function is intended to be used in a fashion similar to the following exameple: int fd = open(pathname, flags, mode); if (fd < 0) { int err = errno; char message[3000]; explain_message_errno_open(message, sizeof(message), err, pathname, flags, mode); fprintf(stderr, '%s0, message); exit(EXIT_FAILURE); } message The location in which to store the returned message. Because a message return buffer has been 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 nec- essary 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. pathname The original pathname, exactly as passed to the open(2) system call. flags The original flags, exactly as passed to the open(2) system call. mode The original mode, exactly as passed to the open(2) system call (or zero if the original call didn't need a mode argument). COPYRIGHT libexplain version 1.3 Copyright (C) 2008 Peter Miller AUTHOR Written by Peter Miller <pmiller@opensource.org.au> explain_open(3)
NAME | SYNOPSIS | DESCRIPTION | COPYRIGHT | AUTHOR
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