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diff --git a/contrib/libexecinfo/backtrace.3 b/contrib/libexecinfo/backtrace.3 new file mode 100644 index 0000000..b173dc3 --- /dev/null +++ b/contrib/libexecinfo/backtrace.3 @@ -0,0 +1,161 @@ +.\" $NetBSD: backtrace.3,v 1.4 2012/06/10 00:24:36 christos Exp $ +.\" $FreeBSD$ +.\" +.\" Copyright (c) 2012 The NetBSD Foundation, Inc. +.\" All rights reserved. +.\" +.\" This code is derived from software contributed to The NetBSD Foundation +.\" by Christos Zoulas +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS +.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED +.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR +.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS +.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR +.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF +.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS +.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN +.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) +.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE +.\" POSSIBILITY OF SUCH DAMAGE. +.\" +.Dd August 23, 2013 +.Dt BACKTRACE 3 +.Os +.Sh NAME +.Nm backtrace +.Nd fill in the backtrace of the currently executing thread +.Sh LIBRARY +.Lb libexecinfo +.Sh SYNOPSIS +.In execinfo.h +.Ft size_t +.Fn backtrace "void **addrlist" "size_t len" +.Ft "char **" +.Fn backtrace_symbols "void * const *addrlist" "size_t len" +.Ft int +.Fn backtrace_symbols_fd "void * const *addrlist" "size_t len" "int fd" +.Ft "char **" +.Fn backtrace_symbols_fmt "void * const *addrlist" "size_t len" "const char *fmt" +.Ft int +.Fn backtrace_symbols_fmt_fd "void * const *addrlist" "size_t len" "const char *fmt" "int fd" +.Sh DESCRIPTION +The +.Fn backtrace +function places into the array pointed by +.Fa addrlist +the array of the values of the program counter for each frame called up to +.Fa len +frames. +The number of frames found (which can be fewer than +.Fa len ) +is returned. +.Pp +The +.Fn backtrace_symbols_fmt +function takes an array of previously filled addresses from +.Fn backtrace +in +.Fa addrlist +of +.Fa len +elements, and uses +.Fa fmt +to format them. +The formatting characters available are: +.Bl -tag -width a -offset indent +.It Dv a +The numeric address of each element as would be printed using %p. +.It Dv n +The name of the nearest function symbol (smaller than the address element) +as determined by +.Xr dladdr 3 +if the symbol was dynamic, or looked up in the executable if static and +the /proc filesystem is available to determine the executable path. +.It Dv d +The difference of the symbol address and the address element printed +using 0x%tx. +.It Dv D +The difference of the symbol addresss and the address element printed using ++0x%tx if non-zero, or nothing if zero. +.It Dv f +The filename of the symbol as determined by +.Xr dladdr 3 . +.El +.Pp +The array of formatted strings is returned as a contiguous memory address which +can be freed by a single +.Xr free 3 . +.Pp +The +.Fn backtrace_symbols +function is equivalent of calling +.Fn backtrace_symbols_fmt +with a format argument of +.Dv "%a <%n%D> at %f" +.Pp +The +.Fn backtrace_symbols_fd +and +.Fn backtrace_symbols_fmt_fd +are similar to the non _fd named functions, only instead of returning +an array or strings, they print a new-line separated array of strings in +fd, and return +.Dv 0 +on success and +.Dv \-1 +on failure. +.Sh RETURN VALUES +The +.Fn backtrace +function returns the number of elements that were filled in the backtrace. +The +.Fn backtrace_symbols +and +.Fn backtrace_symbols_fmt +return a string array on success, and +.Dv NULL +on failure, setting +.Va errno . +Diagnostic output may also be produced by the ELF symbol lookup functions. +.Sh SEE ALSO +.Xr dladdr 3 , +.Xr elf 3 +.Sh HISTORY +The +.Fn backtrace +library of functions first appeared in +.Nx 7.0 +and +.Fx 10.0 . +.Sh BUGS +.Bl -enum +.It +Errors should not be printed but communicated to the caller differently. +.It +Because these functions use +.Xr elf 3 +this is a separate library instead of being part of libc/libutil +so that no library dependencies are introduced. +.It +The Linux versions of the functions (there are no _fmt variants) use +.Ft int +instead of +.Ft size_t +arguments. +.It +The +.Fn backtrace_symbols +functions currently rely on +.Xr procfs 5 +to locate the executable. +.El |
