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explain_setenv(3) Library Functions Manual explain_setenv(3) NAME explain_setenv - explain setenv(3) errors SYNOPSIS #include <libexplain/setenv.h> const char *explain_setenv(const char *name, const char *value, int overwrite); const char *explain_errno_setenv(int errnum, const char *name, const char *value, int overwrite); void explain_message_setenv(char *message, int message_size, const char *name, const char *value, int overwrite); void explain_message_errno_setenv(char *message, int message_size, int errnum, const char *name, const char *value, int overwrite); DESCRIPTION These functions may be used to obtain explanations for errors returned by the setenv(3) system call. explain_setenv const char *explain_setenv(const char *name, const char *value, int overwrite); The explain_setenv function is used to obtain an explanation of an er- ror returned by the setenv(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. name The original name, exactly as passed to the setenv(3) system call. value The original value, exactly as passed to the setenv(3) system call. overwrite The original overwrite, exactly as passed to the setenv(3) sys- tem 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 buf- fer 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: if (setenv(name, value, overwrite) < 0) { fprintf(stderr, "%s\n", explain_setenv(name, value, over- write)); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the ex- plain_setenv_or_die(3) function. explain_errno_setenv const char *explain_errno_setenv(int errnum, const char *name, const char *value, int overwrite); The explain_errno_setenv function is used to obtain an explanation of an error returned by the setenv(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. name The original name, exactly as passed to the setenv(3) system call. value The original value, exactly as passed to the setenv(3) system call. overwrite The original overwrite, exactly as passed to the setenv(3) sys- tem 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 buf- fer 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: if (setenv(name, value, overwrite) < 0) { int err = errno; fprintf(stderr, "%s\n", explain_errno_setenv(err, name, value, overwrite)); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the ex- plain_setenv_or_die(3) function. explain_message_setenv void explain_message_setenv(char *message, int message_size, const char *name, const char *value, int overwrite); The explain_message_setenv function is used to obtain an explanation of an error returned by the setenv(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 suit- able message return buffer is supplied, this function is thread safe. message_size The size in bytes of the location in which to store the re- turned message. name The original name, exactly as passed to the setenv(3) system call. value The original value, exactly as passed to the setenv(3) system call. overwrite The original overwrite, exactly as passed to the setenv(3) sys- tem call. Example: This function is intended to be used in a fashion similar to the following example: if (setenv(name, value, overwrite) < 0) { char message[3000]; explain_message_setenv(message, sizeof(message), name, value, overwrite); fprintf(stderr, "%s\n", message); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the ex- plain_setenv_or_die(3) function. explain_message_errno_setenv void explain_message_errno_setenv(char *message, int message_size, int errnum, const char *name, const char *value, int overwrite); The explain_message_errno_setenv function is used to obtain an explana- tion of an error returned by the setenv(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 suit- able message return buffer is supplied, this function is thread safe. message_size The size in bytes of the location in which to store the re- turned 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. name The original name, exactly as passed to the setenv(3) system call. value The original value, exactly as passed to the setenv(3) system call. overwrite The original overwrite, exactly as passed to the setenv(3) sys- tem call. Example: This function is intended to be used in a fashion similar to the following example: if (setenv(name, value, overwrite) < 0) { int err = errno; char message[3000]; explain_message_errno_setenv(message, sizeof(message), err, name, value, overwrite); fprintf(stderr, "%s\n", message); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the ex- plain_setenv_or_die(3) function. SEE ALSO setenv(3) change or add an environment variable explain_setenv_or_die(3) change or add an environment variable and report errors COPYRIGHT libexplain version 1.3 Copyright (C) 2010 Peter Miller explain_setenv(3)
NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT
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