OpenE2K/glibc
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Update.

Browse Source 
2001-01-17  Ulrich Drepper  <drepper@redhat.com>

	* manual/Makefile (chapters): Add debug.
	* manual/debug.texi: New file.
	* manual/examples/execinfo.c: New file.
	Patch by suckfish@ihug.co.nz.
This commit is contained in:
Ulrich Drepper 2001-01-17 16:54:30 +00:00
parent 17abb551ce
commit 2244ddf2bf
4 changed files with 123 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
ChangeLog
View File

@ -1,3 +1,10 @@
2001-01-17 Ulrich Drepper <drepper@redhat.com>
* manual/Makefile (chapters): Add debug.
* manual/debug.texi: New file.
* manual/examples/execinfo.c: New file.
Patch by suckfish@ihug.co.nz.
2001-01-17 Andreas Schwab <schwab@suse.de>
* sysdeps/m68k/bits/byteswap.h (__bswap_32): Add cast to avoid

2
manual/Makefile
View File

@ -56,7 +56,7 @@ chapters = $(addsuffix .texi, \
message search pattern io stdio llio filesys \
pipe socket terminal syslog math arith time \
resource setjmp signal startup process job nss \
users sysinfo conf crypt)
users sysinfo conf crypt debug)
add-chapters = $(wildcard $(foreach d, $(add-ons), ../$d/$d.texi))
appendices = lang.texi header.texi install.texi maint.texi contrib.texi

10
manual/crypt.texi
View File

@ -1,6 +1,6 @@
@c This node must have no pointers.
@node Cryptographic Functions
@c @node Cryptographic Functions, , System Configuration, Top
@c @node Cryptographic Functions, Debugging Support, System Configuration, Top
@chapter DES Encryption and Password Handling
@c %MENU% DES encryption and password handling
@ -31,7 +31,7 @@ It also provides support for Secure RPC, and some library functions that
can be used to perform normal DES encryption.
The add-on is not included in the main distribution of the GNU C library
because some governments, most notably those of France, Russia,
because some governments, most notably those of France, Russia,
and the US, have very restrictive rules governing the distribution and
use of encryption software. The first section below tries to describe some
of those rules.
@ -213,7 +213,7 @@ The Data Encryption Standard is described in the US Government Federal
Information Processing Standards (FIPS) 46-3 published by the National
Institute of Standards and Technology. The DES has been very thoroughly
analysed since it was developed in the late 1970s, and no new
significant flaws have been found.
significant flaws have been found.
However, the DES uses only a 56-bit key (plus 8 parity bits), and a
machine has been built in 1998 which can search through all possible
@ -269,13 +269,13 @@ stored in a @code{char}, but there are no parity bits in @var{block}.
These are reentrant versions of @code{setkey} and @code{encrypt}. The
only difference is the extra parameter, which stores the expanded
version of @var{key}. Before calling @code{setkey_r} the first time,
version of @var{key}. Before calling @code{setkey_r} the first time,
@code{data->initialised} must be cleared to zero.
@end deftypefun
The @code{setkey_r} and @code{encrypt_r} functions are GNU extensions.
@code{setkey}, @code{encrypt}, @code{setkey_r}, and @code{encrypt_r} are
defined in @file{crypt.h}.
defined in @file{crypt.h}.
If the @code{crypt} add-on is not used to build the library, programs
that use these four functions will crash when the functions are called.

110
manual/debug.texi Normal file
View File

@ -0,0 +1,110 @@
@node Debugging Support
@c @node Debugging Support, , Cryptographic Functions, Top
@c %MENU% Functions to help debugging applications.
@chapter Debugging support
Applications often get debugged using dedicated debugger programs. But
sometimes this is not possible and it is in any case useful to provide
the developer at the time the problems are experienced with as much
information as possible. For this reason there exist a few functions
which a program can use to help the developer more easily locate the
problem.
@menu
* Backtraces:: Obtaining and printing a back trace of the
current stack.
@end menu
@node Backtraces, , , Debugging Support
@section Backtraces
@cindex backtrace
@cindex backtrace_symbols
@cindex backtrace_fd
A @dfn{backtrace} is a list of the function calls that are currently
active in a thread. The usual way to inspect a backtrace of a program
is to use an external debugger such as gdb. However, sometimes it is
useful to obtain a backtrace programatically from within a program,
e.g., for the purposes of logging or diagnostics.
The header file @file{execinfo.h} declares three functions that obtain
and manipulate backtraces of the current thread.
@pindex execinfo.h
@comment execinfo.h
@comment GNU
@deftypefun int backtrace (void **@var{buffer}, int @var{size})
The @code{backtrace} function obtains a backtrace for the current
thread, as a list of pointers, and places the information into
@var{buffer}. The argument @var{size} should be the number of
@w{@code{void *}} elements fitting into @var{buffer}. The return value
is the actual number of entries of @var{buffer} that are obtained, and
is at most @var{size}.
The pointers placed in @var{buffer} are actually return addresses
obtained by inspecting the stack, one return address per stack frame.
Note that certain compiler optimisations may interfere with obtaining a
valid backtrace. Function inlining causes the inlined function to not
have a stack frame; tail call optimisation replaces one stack frame with
another; frame pointer elimination will stop @code{backtrace} from
interpreting the stack contents correctly.
@end deftypefun
@comment execinfo.h
@comment GNU
@deftypefun {char **} backtrace_symbols (void *const *@var{buffer}, int @var{size})
The @code{backtrace_symbols} function translates the information
obtained from the @code{backtrace} function into an array of strings.
The argument @var{buffer} should be a pointer to an array of addresses
obtained via the @code{backtrace} function, and @var{size} is the number
of entries in that array (the return value of @code{backtrace}).
The return value is a pointer to an array of strings, which has
@var{size} entries just like the array @var{buffer}. Each string
contains a printable representation of the corresponding element of
@var{buffer}. It includes the function name (if this can be
determined), an offset into the function, and the actual return address
(in hexidecimal).
Currently, the function name and offset can currently only be obtained
on systems that use the ELF binary format for programs and libraries.
On other systems, only the hexidecimal return address will be present.
Also, you may need to pass additional flags to the linker
(@code{-rdynamic} on systems using GNU ld) to make the function names
available to the program.
The return value of @code{backtrace_symbols} is a pointer obtained via
the @code{malloc} function, and it is the responsibility of the caller
to @code{free} that pointer. Note that only the return value need be
freed, but not the individual strings.
The return value is @code{NULL} if sufficient memory for the strings
cannot be obtained.
@end deftypefun
@comment execinfo.h
@comment GNU
@deftypefun void backtrace_symbols_fd (void *const *@var{buffer}, int @var{size}, int @var{fd})
The @code{backtrace_symbols_fd} function performs the same translation
as the function @code{backtrace_symbols} function. Instead of returning
the strings to the caller, it writes the strings to the file descriptor
@var{fd}, one per line. It does not use the @code{malloc} function, and
can therefore be used in situations where that function might fail.
@end deftypefun
The following program illustrates the use of these functions. Note that
the array to contain the return addresses returned by @code{backtrace}
is allocated on the stack. Therefore code like this can be used in
situations where the memory handling via @code{malloc} does not work
anymore (in which case the @code{backtrace_symbols} has to be replaced
by a @code{backtrace_symbols_fd} call as well). The number of return
addresses is normally not very large. Even complicated programs rather
seldom have a nesting level of more than, say, 50 and with 200 possible
entries probably all programs should be covered.
@smallexample
@include execinfo.c.texi
@end smallexample