Read Me(libexplain) Read Me(libexplain) NAME libexplain - Explain errno values returned by libc functions DESCRIPTION The libexplain package provides a library which may be used to explain Unix and Linux system call errors. This will make your application's error messages much more informative to your users. The library is not quite a drop-in replacement for strerror(3), but it comes close. Each system call has a dedicated libexplain function, for example fd = open(path, flags, mode); if (fd < 0) { fprintf(stderr, "%s\n", explain_open(path, flags, mode)); exit(EXIT_FAILURE); } If, for example, you were to try to open no-such-dir/some-file, you would see a message like open(pathname = "no-such-dir/some-file", flags = O_RDONLY) failed, No such file or directory (2, ENOENT) because there is no "no-such-dir" directory in the current directory The good new is that for each of these functions there is a wrapper function, in this case explain_open_or_die(3), that includes the above code fragment. Adding good error reporting is as simple as using a different, but similarly named, function. The library also provides thread safe variants of each explanation function. Coverage includes 164 system calls and 444 ioctl requests. Tutorial Documentation There is a paper available in PDF format (http://libexplain.sourceforge.net/lca2010/lca2010.pdf) that describes the library and how to use LibExplain. The paper can also be accessed as explain_lca2010(1), which also appears in the reference manual (see below). HOME PAGE The latest version of libexplain is available on the Web from: URL: http://libexplain.sourceforge.net/ File: index.html # the libexplain page File: libexplain.0.40.README # Description, from the tar file File: libexplain.0.40.lsm # Description, LSM format File: libexplain.0.40.tar.gz # the complete source File: libexplain.0.40.pdf # Reference Manual BUILDING LIBEXPLAIN Full instructions for building libexplain may be found in the BUILDING file included in this distribution. COPYRIGHT libexplain version 0.40 Copyright (C) 2008, 2009, 2010 Peter Miller Library License The shared library, and its include files, are GNU LGPL licensed. This program is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. Non-Library License Everything else (all source files that do not constitute the shared library and its include files) are GNU GPL licensed. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. AUTHOR Peter Miller E-Mail: pmiller@opensource.org.au /\/\* WWW: http://www.canb.auug.org.au/~millerp/ RELEASE NOTES This section details the various features and bug fixes of the various releases. For excruciating and complete detail, and also credits for those of you who have generously sent me suggestions and bug reports, see the etc/CHANGES.* files. Coverage includes 164 system calls and 444 ioctl requests. Version 0.40 (2010-Oct-05) * The code now builds and tests successfully on FreeBSD. * Explanations are now available for errors reported by the calloc(3) and poll(2) system calls. Version 0.39 (2010-Sep-12) * A build problem has been fixed on Ubuntu Hardy, a number of symbols are absent from older versions of <linux/cdrom.h>, conditional code has been added for them. * A bug has been fixed in one of the documentation files, it was missing the conditional around the .XX macro, causing rpmlint(1) and lintian(1) to complain. Version 0.38 (2010-Sep-08) * Some build problems on Fedora 13 have been fixed. Version 0.37 (2010-Aug-27) * The library source files are supposed to be LGPL, however over 1000 of them were GPL (about 20%). This has been fixed. * A couple of problems building on Fedora 13 have been fixed. Version 0.36 (2010-Aug-25) * Several false negative reported by tests on the Linux "alpha" and "ia64" architectures have been fixed. Version 0.35 (2010-Aug-15) * A number of falve negatives from tests have been fixed, primarily due to random differences between Linux architectures. * The BUILDING document goes into more detail about things that can cause false negatives when testing. * The man pages have been fixed so that they no longer contain unescaped hyphen characters, as warned about by the lintian(1) program. Version 0.34 (2010-Aug-07) * Another test 33 false negative has been fixed. * There is a new "hanging-indent" option, that can be set from the EXPLAIN_OPTION environment variable. It defaults to zero for backwards compatibility. Applications may set it using the explain_option_hanging_indent_set(3) function. Version 0.33 (2010-Jul-04) * A number of testing false negatives (found by the Debian build farm) have been fixed. * There are new explain_output_error(3) and explain_output_error_and_die(3) functions for printing formatted error messages. * Some systems have mmap(2) report (void*)(-1) instead of NULL for errors. This is now understood. Version 0.32 (2010-Jun-22) * Explanations are now available for errors reported by the mmap(2), munmap(2) and utimes(2) system calls. * A number of false negatives for tests on some less common architectures have been fixed. * Some build problems relating to ioctl(2) support have been fixed. * A bug has been fixed in the libexplain/output.h file, it was missing the C++ insulation. Version 0.31 (2010-May-01) * A number of build problems have been fixed. Version 0.30 (2010-Apr-28) * Several test false negatives have been fixed, on various Debian architectures. Version 0.29 (2010-Apr-25) * A number of build problems, discovered by the Debian build farm, have been fixed. Who would of thought that there could be some much inconsistency between Linux architectures? Version 0.28 (2010-Apr-19) * Several architecture-specific build problems, found by the Debian build farm, have been fixed. Version 0.27 (2010-Apr-17) * Several architecture-specific build problems, found by the Debian build farm, have been fixed. Version 0.26 (2010-Apr-06) * A build problem has been fixed on systems where va_list is not compatible with const void * * This change set removes the unused-result warning form explain_lseek_or_die(3), because it is very common to ignore the result. * Explanations are now available for errors reported by the socketpair(2) system call. Version 0.25 (2010-Mar-22) * Portability of the code has been improved. * The explain(3) man page now mentions AC_SYS_LARGEFILE in the building requirements. * Coverage now includes the fprintf(3), printf(3), snprintf(3), sprintf(3), vfprintf(3), vprintf(3), vsnprintf(3) and vsprintf(3) system calls. Version 0.24 (2010-Mar-03) * It is now possible to redirected libexplain output. For example, it is now possible to redirect all output to syslog(3). * Coverage now includes the fstatvfs(2) and statvfs(2) system call. * A number of problems found while building and testing on Solaris have been fixed. Version 0.23 (2010-Feb-21) * It turns out that on alpha architecture, you can't disambiguate the FIBMAP vs BMP_IOCTL case in the pre-processor. The code now uses a disambiguate function. This problem was discovered by the Debian build farm. Version 0.22 (2010-Feb-12) * This change set fixes a false negative found by the Debian automated build system. Version 0.21 (2010-Feb-09) * Explanations are now available for errors reported by the fpurge(3), getw(3) and putw(3) system calls. * Some build problems have been fixed. Version 0.20 (2010-Jan-20) * Several lintian warnings relating to the man pages have been fixed. * The LIBEXPLAIN_OPTIONS environment variable now understands a new symbolic-mode-bits=true option. It defaults to false, for shorter error explanations. * There is a new explain_lca2010(1) man page. This is a gentle introduction to libexplain, and the paper accompanying my LCA 2010 talk. * When process ID (pid) values are printed, they are now accompanied by the name of the process executable, when available. * Numerous build bugs and niggles have been fixed. * Explanations are now available for errors reported by the execlp(3), fdopendir(3), feof(3), fgetpos(3), fputs(3), fseek(3), fsetpos(3), fsync(2), ftell(3), mkdtemp(3), mknod(2), mkostemp(3), mkstemp(3), mktemp(3), putenv(3), puts(3), raise(3), setbuf(3), setbuffer(3), setenv(3), setlinebuf(3), setvbuf(3), stime(2), tempnam(3), tmpfile(3), tmpnam(3), ungetc(3), unsetenv(3) and vfork(2) system calls. * The ioctl requests from linux/sockios.h, linux/ext2_fs.h, linux/if_eql.h, PPP, linux/lp.h, and linux/vt.h are now understood. Several of the ioctl explanations have been improved. Version 0.19 (2009-Sep-07) * The ioctl requests from linux/hdreg.h are now understood. * Some build problems on Debian Lenny have been fixed. Version 0.18 (2009-Sep-05) * More ioctl requests are understood. * Explanations are now available for errors reported by the tcsendbreak(3), tcsetattr(3), tcgetattr(3), tcflush(3), tcdrain(3), system calls. Version 0.17 (2009-Sep-03) * Explanations are now available for errors reported by the telldir(3) system call. * A number of Linux build problems have been fixed. * Explanations for a number of corner-cases of the open(2) system call have been improved, where flags values interact with file types and mount options. * A number of BSD build problems have been fixed. * More ioctl(2) commands are understood. * A bug has been fixed in the way absolute symbolic links are processed by the path_resolution code. Version 0.16 (2009-Aug-03) * The EROFS and ENOMEDIUM explanations now greatly improved. * A number of build problems and false negatives have been fixed on x86_64 architecture. * The Linux floppy disk and CD-ROM ioctl requests are now supported. * Explanations are now available for the errors reported by the getdomainname(2), readv(2), setdomainname(2), ustat(2) and writev(2) system calls. Version 0.15 (2009-Jul-26) * A number of build errors and warnings on amd64 have been fixed. The problems were only detectable on 64-bit systems. Version 0.14 (2009-Jul-19) * Coverage now includes another 29 system calls: accept4(2), acct(2), adjtime(3), adjtimex(2), chroot(2), dirfd(3), eventfd(2), fflush(3), fileno(3), flock(2), fstatfs(2), ftime(3), getgroups(2), gethostname(2), kill(2), nice(2), pread(2), pwrite(2), sethostname(2), signalfd(2), strdup(3), strtod(3), strtof(3), strtol(3), strtold(3), strtoll(3), strtoul(3), strtoull(3), and timerfd_create(2). A total of 110 system calls are now supported * The ./configure script no longer demands lsof(1). The Linux libexplain code doesn't need lsof(1). On systems not supported by lsof(1), the error messages aren't quite as useful, but libexplain still works. * There is now an explain_*_on_error function for each system call, each reports errors but still returns the original return value to the caller. Version 0.13 (2009-May-17) * The web site now links to a number of services provided by SourceForge. * Several problems have been fixed with compiling libexplain on 64-bit systems. Version 0.12 (2009-May-04) * A build problem has been fixed on hosts that didn't need to do anything special for large file support. Version 0.11 (2009-Mar-29) * The current directory is replaced in messages with an absolute path in cases where the user's idea of the current directory may differ from that of the current process. Version 0.10 (2009-Mar-24) * The name prefix on all of the library functions has been changed from "libexplain_" to just "explain_". This was the most requested change. You will need to change your code and recompile. Apologies for the inconvenience. Version 0.9 (2009-Feb-27) * Two false negatives in the tests have been fixed. * The ./configure script now explicitly looks for bison(1), and complains if it cannot be found. * The socket(7) address family is now decoded. Version 0.8 (2009-Feb-14) * A problem with the Debian packaging has been fixed. * The decoding of IPv4 sockaddr structs has been improved. Version 0.7 (2009-Feb-10) * Coverage has been extended to include getsockopt(2), getpeername(2), getsockname(2) and setsockopt(2). * Build problems on Debian Sid have been fixed. * More magnetic tape ioctl controls, from operating systems other than Linux, have been added. Version 0.6 (2009-Jan-16) * Coverage has been extended to include execvp(3), ioctl(2), malloc(3), pclose(3), pipe(2), popen(3) and realloc(3) system calls. * The coverage for ioctl(2) includes linux console controls, magnetic tape controls, socket controls, and terminal controls. * A false negative from test 31 has been fixed. Version 0.5 (2009-Jan-03) * A build problem on Debian sid has been fixed. * There is a new explain_system_success(3) function, that performs all that explain_system_success_or_die(3) performs, except that it does not call exit(2). * There is more i18n support. * A bug with the pkg-config(1) support has been fixed. Version 0.4 (2008-Dec-24) * Coverage now includes accept(2), bind(2), connect(2), dup2(2), fchown(2), fdopen(3), fpathconf(2), fputc(2), futimes(2), getaddrinfo(2), getcwd(2), getrlimit(2), listen(2), pathconf(2), putc(2), putchar(2), select(2). * Internationalization has been improved. * The thread safety of the code has been improved. * The code is now able to be compiled on OpenBSD. The test suite still gives many false negatives, due to differences in strerror(3) results. Version 0.3 (2008-Nov-23) * Cover has been extended to include closedir(3), execve(2), ferror(3), fgetc(3), fgets(3), fork(2), fread(3), getc(3), gettimeofday(2), lchown(2), socket(2), system(3), utime(2), wait3(2), wait4(2), wait(2), waitpid(2), * More internationalization support has been added. * A bug has been fixed in the C++ insulation. Version 0.2 (2008-Nov-11) * Coverage now includes chmod(2), chown(2), dup(2), fchdir(2), fchmod(2), fstat(2), ftruncate(2), fwrite(3), mkdir(2), readdir(3), readlink(2), remove(3), rmdir(2) and truncate(2). * The lsof(1) command is used to obtain supplementary file information on those systems with limited /proc implementations. * The explanations now understand Linux capabilities. Version 0.1 (2008-Oct-26) First public release. Reference Manual libexplain Read Me(libexplain)