explain_getgrouplist(3) Library Functions Manual explain_getgrouplist(3) NAME explain_getgrouplist - explain getgrouplist(3) errors SYNOPSIS #include <libexplain/getgrouplist.h> const char *explain_getgrouplist(const char *user, gid_t group, gid_t *groups, int *ngroups); const char *explain_errno_getgrouplist(int errnum, const char *user, gid_t group, gid_t *groups, int *ngroups); void explain_message_getgrouplist(char *message, int message_size, const char *user, gid_t group, gid_t *groups, int *ngroups); void explain_message_errno_getgrouplist(char *message, int message_size, int errnum, const char *user, gid_t group, gid_t *groups, int *ngroups); DESCRIPTION These functions may be used to obtain explanations for errors returned by the getgrouplist(3) system call. explain_getgrouplist const char *explain_getgrouplist(const char *user, gid_t group, gid_t *groups, int *ngroups); The explain_getgrouplist function is used to obtain an explanation of an error returned by the getgrouplist(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. user The original user, exactly as passed to the getgrouplist(3) system call. group The original group, exactly as passed to the getgrouplist(3) system call. groups The original groups, exactly as passed to the getgrouplist(3) sys- tem call. ngroups The original ngroups, exactly as passed to the getgrouplist(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 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; if (getgrouplist(user, group, groups, ngroups) < 0 && errno != 0) { fprintf(stderr, "%s\n", explain_getgrouplist(user, group, groups, ngroups)); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the explain_getgrou- plist_or_die(3) function. explain_errno_getgrouplist const char *explain_errno_getgrouplist(int errnum, const char *user, gid_t group, gid_t *groups, int *ngroups); The explain_errno_getgrouplist function is used to obtain an explanation of an error returned by the getgrouplist(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 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. user The original user, exactly as passed to the getgrouplist(3) system call. group The original group, exactly as passed to the getgrouplist(3) system call. groups The original groups, exactly as passed to the getgrouplist(3) sys- tem call. ngroups The original ngroups, exactly as passed to the getgrouplist(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 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; if (getgrouplist(user, group, groups, ngroups) < 0 && errno != 0) { int err = errno; fprintf(stderr, "%s\n", explain_errno_getgrouplist(err, user, group, groups, ngroups)); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the explain_getgrou- plist_or_die(3) function. explain_message_getgrouplist void explain_message_getgrouplist(char *message, int message_size, const char *user, gid_t group, gid_t *groups, int *ngroups); The explain_message_getgrouplist function is used to obtain an explanation of an error returned by the getgrouplist(3) system call. The least the mes- sage 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. 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. user The original user, exactly as passed to the getgrouplist(3) system call. group The original group, exactly as passed to the getgrouplist(3) system call. groups The original groups, exactly as passed to the getgrouplist(3) sys- tem call. ngroups The original ngroups, exactly as passed to the getgrouplist(3) sys- tem call. Example: This function is intended to be used in a fashion similar to the following example: errno = 0; if (getgrouplist(user, group, groups, ngroups) < 0 && errno != 0) { char message[3000]; explain_message_getgrouplist(message, sizeof(message), user, group, groups, ngroups); fprintf(stderr, "%s\n", message); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the explain_getgrou- plist_or_die(3) function. explain_message_errno_getgrouplist void explain_message_errno_getgrouplist(char *message, int message_size, int errnum, const char *user, gid_t group, gid_t *groups, int *ngroups); The explain_message_errno_getgrouplist function is used to obtain an expla- nation of an error returned by the getgrouplist(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. user The original user, exactly as passed to the getgrouplist(3) system call. group The original group, exactly as passed to the getgrouplist(3) system call. groups The original groups, exactly as passed to the getgrouplist(3) sys- tem call. ngroups The original ngroups, exactly as passed to the getgrouplist(3) sys- tem call. Example: This function is intended to be used in a fashion similar to the following example: errno = 0; if (getgrouplist(user, group, groups, ngroups) < 0 && errno != 0) { int err = errno; char message[3000]; explain_message_errno_getgrouplist(message, sizeof(message), err, user, group, groups, ngroups); fprintf(stderr, "%s\n", message); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the explain_getgrou- plist_or_die(3) function. SEE ALSO getgrouplist(3) get list of groups to which a user belongs explain_getgrouplist_or_die(3) get list of groups to which a user belongs and report errors COPYRIGHT libexplain version 1.3 Copyright (C) 2013 Peter Miller explain_getgrouplist(3)
NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT
Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=explain_getgrouplist&sektion=3&manpath=FreeBSD+Ports+15.1.quarterly>