mirror of
git://sourceware.org/git/glibc.git
synced 2024-11-21 01:12:26 +08:00
ba1ffaa1c6
Thu Oct 31 00:01:39 1996 Ulrich Drepper <drepper@cygnus.com> * signal/Makefile (routines): Add sigwait. * signal/signal.h: Add prototype for sigwait. * sysdeps/posix/sigwait.c: New file. Implementation of sigwait function from POSIX.1c. * sysdeps/stub/sigwait.c: New file. Stub version of sigwait. Wed Oct 30 02:01:17 1996 Richard Henderson <rth@tamu.edu> * sunrpc/xdr_float.c (xdr_float): Handle sizeof(float)!=sizeof(long), but don't bother going farther than sizeof(float)==sizeof(int). (xdr_double): Handle little-endian machines! Handle sizeof(double) != 2*sizeof(long), though again don't bother with more than int. Thu Oct 29 16:09:42 1996 Craig Metz <cmetz@inner.net> * sysdeps/posix/getaddrinfo.c: Use buffer limits for inet_ntop function. Tue Oct 29 12:37:22 1996 Ulrich Drepper <drepper@cygnus.com> * Makerules: Create symbolic links for linking in $(libdir). (make-link): Use absolute path for destination if this is not in the same directory. * elf/rtld.c (dl_main): When verifying don't check the name of the dynamic linker. * shlib-versions: Change entries for Hurd specific libs from *-*-gnu* to *-*-gnu?* so that i586-pc-linux-gnu does not match these entries. * assert/assert.h: Reformat copyright. Change reference to ANSI into reference to ISO C. * ctype/ctype.h: Likewise. * errno.h: Likewise. * limits.h: Likewise. * math/math.h: Likewise. * setjmp/setjmp.h: Likewise. * stdio/stdio.h: Likewise. * libio/stdio.h: Likewise. * stdlib/stdlib.h: Likewise. * string/string.h: Likewise. * time/time.h: Likewise. * string/argz.h: Use __const is definitions. * elf/dlfcn.h: Use __const and __P. Reformat copyright. * misc/err.h: Likewise. * wctype/wctype.h (wctrans_t): Use __const instead of const. * Makeconfig ($(common-objpfx)soversions.mk): Generate list of sonames for versioned libraries. * Makefile: Remove code to generate libc-version.h. Generate gnu/lib-names.h with info from soversions.mk. * features.h: Define __GLIBC__ and __GLIBC_MINOR__. * dirent/tst-seekdir.c: Initialize save3. * grp/testgrp.c: Initialize my_group. * grp/fgetgrent_r.c: Change interface to follow POSIX.1c. * grp/grp.h: Likewise. * nss/getXXbyYY.c: Likewise. * nss/getXXbyYY_r.c: Likewise. * nss/getXXent.c: Likewise. * nss/getXXent_r.c: Likewise. * pwd/fgetpwent_r.c: Likewise. * pwd/pwd.h: Likewise. * shadow/fgetspent_r.c: Likewise. * shadow/sgetspent.c: Likewise. * shadow/sgetspent_r.c: Likewise. * grp/fgetgrent.c: Adapt for change in interface of fgetgrent_r. * pwd/fgetpwent.c: Likewise, for fgetpwent_r.c. * shadow/fgetspent.c: Likewise, for fgetpwent_r.c. * resolv/netdb.h: Adapt prototypes for reentrant functions to follow POSIX.1c. * sunrpc/rpc/netdb.h: Likewise, * shadow/shadow.h: Likewise. * inet/getnetgrent_r.c: Follow change in pwd/grp function interface. * sysdeps/unix/getlogin_r.c: Return ERANGE when buffer is too small. * inet/herrno.c: Don't define __h_errno. Only h_errno otherwise the ELF aliasing creates strange situations. * sysdeps/unix/sysv/linux/errnos.H: Define __set_errno as inline function. * sysdeps/unix/sysv/linux/i386/sysdep.S: Don't define __errno. * sysdeps/unix/sysv/linux/m68k/sysdep.S: Likewise. * libio/libio.h: Don't declare _IO_flockfile and _IO_funlockfile weak. * locale/programs/charmap.c: Add casts to prevent warnings. * locale/programs/linereader.h: Likewise. * locale/programs/ld-collate.c: Likewise. * locale/programs/stringtrans.c: Likewise. Change types for various variables to prevent warnings. * locale/programs/ld-ctype.c: Likewise. * locale/programs/linereader.h (lr_ungetc): Likewise. * locale/programs/charset.h (struct charset): Use `unsigned int' as type for width_default. * posix/regex.c: Change type of `this_reg' variables. * stdio-common/Makefile: Use -Wno-format for tstdiomisc.c. * stdio-common/bug5.c: De-ANSI-fy. Use correct types for variables. * stdio-common/printf_fp.c: Initialize to_shift. * stdio-common/test_rdwr.c: Add cast. * stdio-common/vfprintf.c: Add casts and use correct types to prevent warnings. * stdio-common/vfscanf.c: Initialize str and strptr. * sysdeps/libm-ieee754/e_jnf.c: Use correct types to prevent warnings. * sysdeps/libm-ieee754/e_pow.c: Likewise. * sysdeps/libm-ieee754/e_powf.c: Likewise. * sysdeps/libm-ieee754/e_rem_pio2f.c: Likewise. * time/test-tz.c: Likewise. * manual/creature.texi: Document _REENTRANT and _THREAD_SAFE. * manual/libc.texinfo: Prevent makeinfo failure by avoiding libc.cp index. This must be fixed. * manual/nss.texi: Adapt for correct POSIX.1c interface of reentrant functions. * manual/users.texi: Document netgroup functions. * po/es.po: Updated. * po/fr.po: Updated. * posix/fnmatch.c: Change to match libit version. * posix/unistd.h: Change prototype for ttyname_r to match POSIX.1c. * sysdep/posix/ttyname_r.c: Likewise. * stdlib/atexit.h (__new_exitfn): Add internal locking. * stdlib/exit.c: De-ANSI-fy. Handle new ef_us value for flavor. * stdlib/exit.h: De-ANSI-fy. Define new ef_us value for flavor. * stdlib/random.c (__srandom): Add internal locking. (__initstate): Likewise. (__setstate): Likewise. (__random): Likewise. Mon Oct 28 22:28:37 1996 NIIBE Yutaka <gniibe@mri.co.jp> * sysdeps/generic/crypt-entry.c (crypt_r): Use __set_errno. (crypt): Likewise. * resolv/gethnamaddr.c (gethostbyname2): Likewise. * sysdeps/generic/uname.c: Likewise. * sysdeps/posix/rename.c: Likewise. * sysdeps/stub/setrlimit.c: Likewise. * nss/nss_db/db-netgrp.c (_nss_db_setnetgrent): Fix typo. Sun Oct 27 11:12:50 1996 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * locale/programs/ld-collate.c (collate_order_elem): Fix format string. (collate_element_to): Cast field width argument to `int' for format string. (collate_symbol): Likewise. (collate_order_elem): Likewise. (collate_weight_bsymbol): Likewise. (collate_simple_weight): Likewise. * locale/programs/ld-time.c (STRARR_ELEM): Fix format string. * locale/programs/ld-ctype.c (ctype_class_newP): Add missing argument for format string. (ctype_map_newP): Likewise. (set_class_defaults): Fix format string. * locale/programs/localedef.c (construct_output_path): Putting an explicit \0 into the format string does not work, use %c. Sat Oct 26 20:38:36 1996 Richard Henderson <rth@tamu.edu> * Makerules: Install all shared libraries in $(slibdir). * login/Makefile: Build libutil.so in others pass after libc.so is created. * misc/mntent.h: Include <paths.h> for _PATH_MNTTAB & _PATH_MOUNTED. * string/stratcliff.c: Allocate 3 pages instead of one, then use mprotect so that we know that the adjacent pages are inaccessible. * resource/sys/resource.h: Move all structures and enums to ... * sysdeps/generic/resourcebits.h: ... here ... * sysdeps/unix/bsd/sun/sunos4/resourcebits.h: ... and here. * sysdeps/unix/sysv/linux/alpha/resourcebits.h: Remove. * sysdeps/unix/sysv/linux/i386/resourcebits.h: Remove. * sysdeps/unix/sysv/linux/m68k/resourcebits.h: Remove. * sysdeps/unix/sysv/linux/mips/resourcebits.h: Remove. * sysdeps/unix/sysv/linux/resourcebits.h: New file. Use kernel header for RLIMIT_* definitions. The members of struct rlimit are longs. Thu Oct 24 17:43:34 1996 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * MakeTAGS (sysdep-dirs): Fix typo. Wed Oct 23 03:45:22 1996 Ulrich Drepper <drepper@cygnus.com> * Makefile (headers): Don't mention libc-version.h. (install-others): ...but here. * time/strptime.c: Recognize %s, %u, %g, and %G format. nothing is found. This guarantees all subsequent calls behave * sysdeps/unix/sysv/linux/syscalls.list: Change function name for * io/getwd.c (getwd) [! PATH_MAX]: Don't assume that the user's buffer is any longer than the amount necessary to hold the filename; the Hurd getcwd uses the *entire* contents of the buffer, however long it is specified to be. * posix/getconf.c: De-ANSI-fy. Recognize POSIX.2 constant names. since these do not depend on the platform.
583 lines
22 KiB
Plaintext
583 lines
22 KiB
Plaintext
Frequently Asked Question on GNU C Library
|
||
|
||
As every FAQ this one also tries to answer questions the user might have
|
||
when using the package. Please make sure you read this before sending
|
||
questions or bug reports to the maintainers.
|
||
|
||
The GNU C Library is very complex. The building process exploits the
|
||
features available in tools generally available. But many things can
|
||
only be done using GNU tools. Also the code is sometimes hard to
|
||
understand because it has to be portable but on the other hand must be
|
||
fast. But you need not understand the details to use GNU C Library.
|
||
This will only be necessary if you intend to contribute or change it.
|
||
|
||
If you have any questions you think should be answered in this document,
|
||
please let me know.
|
||
|
||
--drepper@cygnus.com
|
||
|
||
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
|
||
[Q1] ``What systems does the GNU C Library run on?''
|
||
|
||
[Q2] ``What compiler do I need to build GNU libc?''
|
||
|
||
[Q3] ``When starting make I get only error messages.
|
||
What's wrong?''
|
||
|
||
[Q4] ``After I changed configure.in I get `Autoconf version X.Y.
|
||
or higher is required for this script'. What can I do?''
|
||
|
||
[Q5] ``Do I need a special linker or archiver?''
|
||
|
||
[Q6] ``Do I need some more things to compile GNU C Library?''
|
||
|
||
[Q7] ``When I run `nm -u libc.so' on the produced library I still
|
||
find unresolved symbols? Can this be ok?''
|
||
|
||
[Q8] ``Can I replace the libc on my Linux system with GNU libc?''
|
||
|
||
[Q9] ``I expect GNU libc to be 100% source code compatible with
|
||
the old Linux based GNU libc. Why isn't it like this?''
|
||
|
||
[Q10] ``Why does getlogin() always return NULL on my Linux box?''
|
||
|
||
[Q11] ``Where are the DST_* constants found in <sys/time.h> on many
|
||
systems?''
|
||
|
||
[Q12] ``The `gencat' utility cannot process the input which are
|
||
successfully used on my Linux libc based system. Why?''
|
||
|
||
[Q13] ``How do I configure GNU libc so that the essential libraries
|
||
like libc.so go into /lib and the other into /usr/lib?''
|
||
|
||
[Q14] ``When linking with the new libc I get unresolved symbols
|
||
`crypt' and `setkey'. Why aren't these functions in the
|
||
libc anymore?''
|
||
|
||
[Q15] ``What are these `add-ons'?''
|
||
|
||
[Q16] ``When I use GNU libc on my Linux system by linking against
|
||
to libc.so which comes with glibc all I get is a core dump.''
|
||
|
||
[Q17] ``Looking through the shared libc file I haven't found the
|
||
functions `stat', `lstat', `fstat', and `mknod' and while
|
||
linking on my Linux system I get error messages. How is
|
||
this supposed to work?''
|
||
|
||
[Q18] ``The prototypes for `connect', `accept', `getsockopt',
|
||
`setsockopt', `getsockname', `getpeername', `send',
|
||
`sendto', and `recvfrom' are different in GNU libc than
|
||
on any other system I saw. This is a bug, isn't it?''
|
||
|
||
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
|
||
[Q1] ``What systems does the GNU C Library run on?''
|
||
|
||
[A1] {UD} This is difficult to answer. The file `README' lists the
|
||
architectures GNU libc is known to run *at some time*. This does not
|
||
mean that it still can be compiled and run on them in the moment.
|
||
|
||
The systems glibc is known to work on in the moment and most probably
|
||
in the future are:
|
||
|
||
*-*-gnu GNU Hurd
|
||
i[3456]86-*-linux-gnu Linux-2.0 on Intel
|
||
m68k-*-linux-gnu Linux-2.0 on Motorola 680x0
|
||
alpha-*-linux-gnu Linux-2.0 on DEC Alpha
|
||
|
||
Other Linux platforms are also on the way to be supported but I need
|
||
some success reports first.
|
||
|
||
If you have a system not listed above (or in the `README' file) and
|
||
you are really interested in porting it, contact
|
||
|
||
<bug-glibc@prep.ai.mit.edu>
|
||
|
||
|
||
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
|
||
[Q2] ``What compiler do I need to build GNU libc?''
|
||
|
||
[A2] {UD} It is (almost) impossible to compile GNU C Library using a
|
||
different compiler than GNU CC. A lot of extensions of GNU CC are
|
||
used to increase the portability and speed.
|
||
|
||
But this does not mean you have to use GNU CC for using the GNU C
|
||
Library. In fact you should be able to use the native C compiler
|
||
because the success only depends on the binutils: the linker and
|
||
archiver.
|
||
|
||
The GNU CC is found like all other GNU packages on
|
||
ftp://prep.ai.mit.edu/pub/gnu
|
||
or better one of the many mirror sites.
|
||
|
||
You always should try to use the latest official release. Older
|
||
versions might not have all the features GNU libc could use.
|
||
|
||
|
||
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
|
||
[Q3] ``When starting `make' I get only errors messages.
|
||
What's wrong?''
|
||
|
||
[A3] {UD} You definitely need GNU make to translate GNU libc. No
|
||
other make program has the needed functionality.
|
||
|
||
Versions before 3.74 have bugs which prevent correct execution so you
|
||
should upgrade to the latest version before starting the compilation.
|
||
|
||
|
||
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
|
||
[Q4] ``After I changed configure.in I get `Autoconf version X.Y.
|
||
or higher is required for this script'. What can I do?''
|
||
|
||
[A4] {UD} You have to get the specified autoconf version (or a later)
|
||
from your favourite mirror of prep.ai.mit.edu.
|
||
|
||
|
||
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
|
||
[Q5] ``Do I need a special linker or archiver?''
|
||
|
||
[A5] {UD} If your native versions are not too buggy you can probably
|
||
work with them. But GNU libc works best with GNU binutils.
|
||
|
||
On systems where the native linker does not support weak symbols you
|
||
will not get a really ISO C compliant C library. Generally speaking
|
||
you should use the GNU binutils if they provide at least the same
|
||
functionality as your system's tools.
|
||
|
||
Always get the newest release of GNU binutils available.
|
||
Older releases are known to have bugs that affect building the GNU C
|
||
Library.
|
||
|
||
|
||
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
|
||
[Q6] ``Do I need some more things to compile GNU C Library?''
|
||
|
||
[A6] {UD} Yes, there are some more :-).
|
||
|
||
* GNU gettext; the GNU libc is internationalized and partly localized.
|
||
For bringing the messages for the different languages in the needed
|
||
form the tools from the GNU gettext package are necessary. See
|
||
ftp://prep.ai.mit.edu/pub/gnu or better any mirror site.
|
||
|
||
* lots of diskspace (for i?86-linux this means, e.g., ~70MB).
|
||
|
||
You should avoid compiling on a NFS mounted device. This is very
|
||
slow.
|
||
|
||
* plenty of time (approx 1h for i?86-linux on i586@133 or 2.5h on
|
||
i486@66 or 4.5h on i486@33). For Hurd systems times are much higher.
|
||
|
||
If you have some more measurements let me know.
|
||
|
||
* When compiling for Linux:
|
||
|
||
+ the header files of the Linux kernel must be available in the
|
||
search path of the CPP as <linux/*.h> and <asm/*.h>.
|
||
|
||
* Some files depend on special tools. E.g., files ending in .gperf
|
||
need a `gperf' program. The GNU version (part of libg++) is known
|
||
to work while some vendor versions do not.
|
||
|
||
You should not need these tools unless you change the source files.
|
||
|
||
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
|
||
[Q7] ``When I run `nm -u libc.so' on the produced library I still
|
||
find unresolved symbols? Can this be ok?''
|
||
|
||
[A7] {UD} Yes, this is ok. There can be several kinds of unresolved
|
||
symbols:
|
||
|
||
* magic symbols automatically generated by the linker. Names are
|
||
often like __start_* and __stop_*
|
||
|
||
* symbols starting with _dl_* come from the dynamic linker
|
||
|
||
* symbols resolved by using libgcc.a
|
||
(__udivdi3, __umoddi3, or similar)
|
||
|
||
* weak symbols, which need not be resolved at all
|
||
(currently fabs among others; this gets resolved if the program
|
||
is linked against libm, too.)
|
||
|
||
Generally, you should make sure you find a real program which produces
|
||
errors while linking before deciding there is a problem.
|
||
|
||
|
||
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
|
||
[Q8] ``Can I replace the libc on my Linux system with GNU libc?''
|
||
|
||
[A8] {UD} You cannot replace any existing libc for Linux with GNU
|
||
libc. There are different versions of C libraries and you can run
|
||
libcs with different major version independently.
|
||
|
||
For Linux there are today two libc versions:
|
||
libc-4 old a.out libc
|
||
libc-5 current ELF libc
|
||
|
||
GNU libc will have the major number 6 and therefore you can have this
|
||
additionally installed. For more information consult documentation for
|
||
shared library handling. The Makefiles of GNU libc will automatically
|
||
generate the needed symbolic links which the linker will use.
|
||
|
||
|
||
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
|
||
[Q9] ``I expect GNU libc to be 100% source code compatible with
|
||
the old Linux based GNU libc. Why isn't it like this?''
|
||
|
||
[A9] {DMT,UD} Not every extension in Linux libc's history was well
|
||
thought-out. In fact it had a lot of problems with standards compliance
|
||
and with cleanliness. With the introduction of a new version number these
|
||
errors now can be corrected. Here is a list of the known source code
|
||
incompatibilities:
|
||
|
||
* _GNU_SOURCE: glibc does not automatically define _GNU_SOURCE. Thus,
|
||
if a program depends on GNU extensions or some other non-standard
|
||
functionality, it is necessary to compile it with C compiler option
|
||
-D_GNU_SOURCE, or better, to put `#define _GNU_SOURCE' at the beginning
|
||
of your source files, before any C library header files are included.
|
||
This difference normally manifests itself in the form of missing
|
||
prototypes and/or data type definitions. Thus, if you get such errors,
|
||
the first thing you should do is try defining _GNU_SOURCE and see if
|
||
that makes the problem go away.
|
||
|
||
For more information consult the file `NOTES' part of the GNU C
|
||
library sources.
|
||
|
||
* reboot(): GNU libc sanitizes the interface of reboot() to be more
|
||
compatible with the interface used on other OSes. In particular,
|
||
reboot() as implemented in glibc takes just one argument. This argument
|
||
corresponds to the third argument of the Linux reboot system call.
|
||
That is, a call of the form reboot(a, b, c) needs to be changed into
|
||
reboot(c).
|
||
Beside this the header <sys/reboot.h> defines the needed constants
|
||
for the argument. These RB_* constants should be used instead of the
|
||
cryptic magic numbers.
|
||
|
||
* swapon(): the interface of this function didn't changed, but the
|
||
prototype is in a separate header file <sys/swap.h>. For the additional
|
||
argument of of swapon() you should use the SWAP_* constants from
|
||
<linux/swap.h>, which get defined when <sys/swap.h> is included.
|
||
|
||
* errno: If a program uses variable "errno", then it _must_ include header
|
||
file <errno.h>. The old libc often (erroneously) declared this variable
|
||
implicitly as a side-effect of including other libc header files. glibc
|
||
is careful to avoid such namespace pollution, which, in turn, means that
|
||
you really need to include the header files that you depend on. This
|
||
difference normally manifests itself in the form of the compiler
|
||
complaining about the references of the undeclared symbol "errno".
|
||
|
||
* Linux-specific syscalls: All Linux system calls now have appropriate
|
||
library wrappers and corresponding declarations in various header files.
|
||
This is because the syscall() macro that was traditionally used to
|
||
work around missing syscall wrappers are inherently non-portable and
|
||
error-prone. The following tables lists all the new syscall stubs,
|
||
the header-file declaring their interface and the system call name.
|
||
|
||
syscall name: wrapper name: declaring header file:
|
||
------------- ------------- ----------------------
|
||
bdflush bdflush <sys/kdaemon.h>
|
||
create_module create_module <sys/module.h>
|
||
delete_module delete_module <sys/module.h>
|
||
get_kernel_syms get_kernel_syms <sys/module.h>
|
||
init_module init_module <sys/module.h>
|
||
syslog ksyslog_ctl <sys/klog.h>
|
||
|
||
* lpd: Older versions of lpd depend on a routine called _validuser().
|
||
The library does not provide this function, but instead provides
|
||
__ivaliduser() which has a slightly different interfaces. Simply
|
||
upgrading to a newer lpd should fix this problem (e.g., the 4.4BSD
|
||
lpd is known to be working).
|
||
|
||
* resolver functions/BIND: like on many other systems the functions of
|
||
the resolver library are not included in the libc itself. There is
|
||
a separate library libresolv. If you find some symbols starting with
|
||
`res_*' undefined simply add -lresolv to your call of the linker.
|
||
|
||
|
||
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
|
||
[Q10] ``Why does getlogin() always return NULL on my Linux box?''
|
||
|
||
[A10] {UD} The GNU C library has a format for the UTMP and WTMP file
|
||
which differs from what your system currently has. It was extended to
|
||
fulfill the needs of the next years when IPv6 is introduced. So the
|
||
record size is different, fields might have a different position and
|
||
so reading the files written by functions from the one library cannot
|
||
be read by functions from the other library. Sorry, but this is what
|
||
a major release is for. It's better to have a cut now than having no
|
||
means to support the new techniques later.
|
||
|
||
|
||
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
|
||
[Q11] ``Where are the DST_* constants found in <sys/time.h> on many
|
||
systems?''
|
||
|
||
[A11] {UD} These constants come from the old BSD days and are not used
|
||
today anymore (even the Linux based glibc does not implement the handling
|
||
although the constants are defined).
|
||
|
||
Instead GNU libc contains the zone database handling and compatibility
|
||
code for POSIX TZ environment variable handling.
|
||
|
||
|
||
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
|
||
[Q12] ``The `gencat' utility cannot process the input which are
|
||
successfully used on my Linux libc based system. Why?''
|
||
|
||
[A12] {UD} Unlike the author of the `gencat' program which is distributed
|
||
with Linux libc I have read the underlying standards before writing the
|
||
code. It is completely compatible with the specification given in
|
||
X/Open Portability Guide.
|
||
|
||
To ease the transition from the Linux version some of the non-standard
|
||
features are also present in the `gencat' program of GNU libc. This
|
||
mainly includes the use of symbols for the message number and the automatic
|
||
generation of header files which contain the needed #defines to map the
|
||
symbols to integers.
|
||
|
||
Here is a simple SED script to convert at least some Linux specific
|
||
catalog files to the XPG4 form:
|
||
|
||
-----------------------------------------------------------------------
|
||
# Change catalog source in Linux specific format to standard XPG format.
|
||
# Ulrich Drepper <drepper@cygnus.com>, 1996.
|
||
#
|
||
/^\$ #/ {
|
||
h
|
||
s/\$ #\([^ ]*\).*/\1/
|
||
x
|
||
s/\$ #[^ ]* *\(.*\)/\$ \1/
|
||
}
|
||
|
||
/^# / {
|
||
s/^# \(.*\)/\1/
|
||
G
|
||
s/\(.*\)\n\(.*\)/\2 \1/
|
||
}
|
||
-----------------------------------------------------------------------
|
||
|
||
|
||
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
|
||
[Q13] ``How do I configure GNU libc so that the essential libraries
|
||
like libc.so go into /lib and the other into /usr/lib?''
|
||
|
||
[A13] {UD} Like all other GNU packages GNU libc is configured to use a
|
||
base directory and install all files relative to this. If you intend
|
||
to really use GNU libc on your system this base directory is /usr. I.e.,
|
||
you run
|
||
configure --prefix=/usr <other_options>
|
||
|
||
Some systems like Linux have a filesystem standard which makes a
|
||
difference between essential libraries and others. Essential
|
||
libraries are placed in /lib because this directory is required to be
|
||
located on the same disk partition as /. The /usr subtree might be
|
||
found on another partition/disk.
|
||
|
||
To install the essential libraries which come with GNU libc in /lib
|
||
one must explicitly tell this. Autoconf has no option for this so you
|
||
have to use the file where all user supplied additional information
|
||
should go in: `configparms' (see the `INSTALL' file). For Linux the
|
||
`configparms' file should contain:
|
||
|
||
slibdir=/lib
|
||
sysconfdir=/etc
|
||
|
||
The first line specifies the directory for the essential libraries,
|
||
the second line the directory for file which are by tradition placed
|
||
in a directory named /etc.
|
||
|
||
|
||
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
|
||
[Q14] ``When linking with the new libc I get unresolved symbols
|
||
`crypt' and `setkey'. Why aren't these functions in the
|
||
libc anymore?''
|
||
|
||
[A14] {UD} Remember the US restrictions of exporting cryptographic
|
||
programs and source code. Until this law gets abolished we cannot
|
||
ship the cryptographic function together with the libc.
|
||
|
||
But of course we provide the code and there is an very easy way to use
|
||
this code. First get the extra package. People in the US way get it
|
||
from the same place they got the GNU libc from. People outside the US
|
||
should get the code from ftp.uni-c.dk [129.142.6.74], or another
|
||
archive site outside the USA. The README explains how to install the
|
||
sources.
|
||
|
||
If you already have the crypt code on your system the reason for the
|
||
failure is probably that you failed to link with -lcrypt. The crypto
|
||
functions are in a separate library to make it possible to export GNU
|
||
libc binaries from the US.
|
||
|
||
|
||
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
|
||
[Q15] ``What are these `add-ons'?''
|
||
|
||
[A15] {UD} To avoid complications with export rules or external source
|
||
code some optional parts of the libc are distributed as separate
|
||
packages (e.g., the crypt package, see Q14).
|
||
|
||
To ease the use as part of GNU libc the installer just has to unpack
|
||
the package and tell the configuration script about these additional
|
||
subdirectories using the --enable-add-ons option. When you add the
|
||
crypt add-on you just have to use
|
||
|
||
configure --enable-add-ons=des-crypt,XXX ...
|
||
|
||
where XXX are possible other add-ons and ... means the rest of the
|
||
normal option list.
|
||
|
||
You can use add-ons also to overwrite some files in glibc. The add-on
|
||
system dependent subdirs are search first. It is also possible to add
|
||
banner files (use a file named `Banner') or create shared libraries.
|
||
|
||
Using add-ons has the big advantage that the makefiles of the GNU libc
|
||
can be used. Only some few stub rules must be written to get
|
||
everything running. Even handling of architecture dependent
|
||
compilation is provided. The GNU libc's sysdeps/ directory shows how
|
||
to use this feature.
|
||
|
||
|
||
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
|
||
[Q16] ``When I use GNU libc on my Linux system by linking against
|
||
to libc.so which comes with glibc all I get is a core dump.''
|
||
|
||
[A16] {UD} It is not enough to simply link against the GNU libc
|
||
library itself. The GNU C library comes with its own dynamic linker
|
||
which really conforms to the ELF API standard. This dynamic linker
|
||
must be used.
|
||
|
||
Normally this is done by the compiler. The gcc will use
|
||
|
||
-dynamic-linker /lib/ld-linux.so.1
|
||
|
||
unless the user specifies her/himself a -dynamic-linker argument. But
|
||
this is not the correct name for the GNU dynamic linker. The correct
|
||
name is /lib/ld.so.1 which is the name specified in the SVr4 ABi.
|
||
|
||
To change your environment to use GNU libc for compiling you need to
|
||
change the `specs' file of your gcc. This file is normally found at
|
||
|
||
/usr/lib/gcc-lib/<arch>/<version>/specs
|
||
|
||
In this file you have to change a few things:
|
||
|
||
- change `ld-linux.so.1' to `ld.so.1' (or to ld-linux.so.2, see below)
|
||
|
||
- remove all expression `%{...:-lgmon}'; there is no libgmon in glibc
|
||
|
||
|
||
Things are getting a bit more complicated if you have GNU libc
|
||
installed in some other place than /usr, i.e., if you do not want to
|
||
use it instead of the old libc. In this case the needed startup files
|
||
and libraries are not found in the regular places. So the specs file
|
||
must tell the compiler and linker exactly what to use. Here is for
|
||
example the gcc-2.7.2 specs file when GNU libc is installed at
|
||
/home/gnu:
|
||
|
||
-----------------------------------------------------------------------
|
||
*asm:
|
||
%{V} %{v:%{!V:-V}} %{Qy:} %{!Qn:-Qy} %{n} %{T} %{Ym,*} %{Yd,*} %{Wa,*:%*}
|
||
|
||
*asm_final:
|
||
%{pipe:-}
|
||
|
||
*cpp:
|
||
%{fPIC:-D__PIC__ -D__pic__} %{fpic:-D__PIC__ -D__pic__} %{!m386:-D__i486__} %{posix:-D_POSIX_SOURCE} -I/home/gnu/include
|
||
|
||
*cc1:
|
||
|
||
|
||
*cc1plus:
|
||
|
||
|
||
*endfile:
|
||
%{!shared:crtend.o%s} %{shared:crtendS.o%s} /home/gnu/lib/crtn.o%s
|
||
|
||
*link:
|
||
-m elf_i386 -rpath=/home/gnu/lib -L/home/gnu/lib %{shared:-shared} %{!shared: %{!ibcs: %{!static: %{rdynamic:-export-dynamic} %{!dynamic-linker:-dynamic-linker=/home/gnu/lib/ld.so.1}} %{static:-static}}}
|
||
|
||
*lib:
|
||
%{!shared: %{mieee-fp:-lieee} %{p:-lc_p} %{!p:%{pg:-lc_p} %{!pg:-lc}}}
|
||
|
||
*libgcc:
|
||
%{!shared:-lgcc}
|
||
|
||
*startfile:
|
||
%{!shared: %{pg:/home/gnu/lib/gcrt1.o%s} %{!pg:%{p:/home/gnu/lib/gcrt1.o} %{!p:/home/gnu/lib/crt1.o%s}}} /home/gnu/lib/crti.o%s %{!shared:crtbegin.o%s} %{shared:crtbeginS.o%s}
|
||
|
||
*switches_need_spaces:
|
||
|
||
|
||
*signed_char:
|
||
%{funsigned-char:-D__CHAR_UNSIGNED__}
|
||
|
||
*predefines:
|
||
-D__ELF__ -Dunix -Di386 -Dlinux -Asystem(unix) -Asystem(posix) -Acpu(i386) -Amachine(i386)
|
||
|
||
*cross_compile:
|
||
0
|
||
|
||
*multilib:
|
||
. ;
|
||
|
||
-----------------------------------------------------------------------
|
||
|
||
The above is currently correct for all systems but ix86/Linux.
|
||
Because of compatibility issues on this platform the dynamic linker
|
||
must have a different name: ld-linux.so.2. So you have to replace
|
||
|
||
%{!dynamic-linker:-dynamic-linker=/home/gnu/lib/ld.so.1}
|
||
by
|
||
%{!dynamic-linker:-dynamic-linker=/home/gnu/lib/ld-linux.so.2}
|
||
|
||
in the above example specs file.
|
||
|
||
Future versions of GCC will automatically provide the correct specs.
|
||
|
||
|
||
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
|
||
[Q17] ``Looking through the shared libc file I haven't found the
|
||
functions `stat', `lstat', `fstat', and `mknod' and while
|
||
linking on my Linux system I get error messages. How is
|
||
this supposed to work?''
|
||
|
||
[A17] {RM} Believe it or not, stat and lstat (and fstat, and mknod)
|
||
are supposed to be undefined references in libc.so.6! Your problem is
|
||
probably a missing or incorrect /usr/lib/libc.so file; note that this
|
||
is a small text file now, not a symlink to libc.so.6. It should look
|
||
something like this:
|
||
|
||
GROUP ( libc.so.6 ld.so.1 libc.a )
|
||
|
||
|
||
{UD} The Linux ldconfig file probably generates a link libc.so ->
|
||
libc.so.6 in /lib. This is not correct. There must not be such a
|
||
link. The linker script with the above contents is placed in
|
||
/usr/lib which is enough for the linker.
|
||
|
||
|
||
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
|
||
[Q18] ``The prototypes for `connect', `accept', `getsockopt',
|
||
`setsockopt', `getsockname', `getpeername', `send',
|
||
`sendto', and `recvfrom' are different in GNU libc from
|
||
any other system I saw. This is a bug, isn't it?''
|
||
|
||
[A18] {UD} No, this is no bug. This version of the GNU libc already
|
||
follows the to-be-released POSIX.1g standard. In this standard
|
||
the type `size_t' is used for all parameters which describe a size.
|
||
So better change now.
|
||
|
||
This change is critical for system which have
|
||
sizeof (int) != sizeof (size_t)
|
||
like the Alpha.
|
||
|
||
|
||
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
|
||
|
||
Answers were given by:
|
||
{UD} Ulrich Drepper, <drepper@cygnus.com>
|
||
{DMT} David Mosberger-Tang, <davidm@AZStarNet.com>
|
||
{RM} Roland McGrath, <roland@gnu.ai.mit.edu>
|
||
|
||
Local Variables:
|
||
mode:text
|
||
End:
|