Mercurial > gnulib
view doc/alloca-opt.texi @ 40206:770a5696761e
relocatable-prog: Use wrapper-free installation on Mac OS X, take 2.
This approach supports relocatable installation of shared libraries
which depend on other shared libraries from the same package.
* m4/relocatable.m4 (gl_RELOCATABLE_BODY): Determine use_macos_tools.
If use_macos_tools is true, use reloc-ldflags and set LIBTOOL to be a
wrapper around the original LIBTOOL.
* build-aux/reloc-ldflags: Add support for Mac OS X, which uses the
token '@loader_path' instead of '$ORIGIN'.
* build-aux/libtool-reloc: New file.
* modules/relocatable-prog (Files): Add it.
* doc/relocatable-maint.texi (Supporting Relocation): Update to match
the recent changes. Document the need to set the *_LDFLAGS of libraries.
RELOCATABLE_LIBRARY_PATH and RELOCATABLE_CONFIG_H_DIR should be set in
Makefile.am, not in configure.ac.
author | Bruno Haible <bruno@clisp.org> |
---|---|
date | Mon, 04 Mar 2019 17:25:09 +0100 |
parents | b06060465f09 |
children |
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@c Documentation of gnulib module 'alloca-opt'. @c Copyright (C) 2004, 2007, 2009-2019 Free Software Foundation, Inc. @c Permission is granted to copy, distribute and/or modify this document @c under the terms of the GNU Free Documentation License, Version 1.3 or @c any later version published by the Free Software Foundation; with no @c Invariant Sections, no Front-Cover Texts, and no Back-Cover @c Texts. A copy of the license is included in the ``GNU Free @c Documentation License'' file as part of this distribution. The @code{alloca-opt} module provides for a function @code{alloca} which allocates memory on the stack, where the system allows it. A memory block allocated with @code{alloca} exists only until the function that calls @code{alloca} returns or exits abruptly. There are a few systems where this is not possible: HP-UX systems, and some other platforms when the C++ compiler is used. On these platforms the @code{alloca-opt} module provides no replacement, just a preprocessor macro HAVE_ALLOCA. The user can @code{#include <alloca.h>} on all platforms, and use @code{alloca} on those platforms where the preprocessor macro HAVE_ALLOCA evaluates to true. If HAVE_ALLOCA is false, the code should use a heap-based memory allocation based on @code{malloc} or (in C++) @code{new}. Note that the @code{#include <alloca.h>} must be the first one after the autoconf-generated @file{config.h}, for AIX 3 compatibility. Thanks to IBM for this nice restriction! Note that GCC 3.1 and 3.2 can @emph{inline} functions that call @code{alloca}. When this happens, the memory blocks allocated with @code{alloca} will not be freed until @emph{the end of the calling function}. If this calling function runs a loop calling the function that uses @code{alloca}, the program easily gets a stack overflow and crashes. To protect against this compiler behaviour, you can mark the function that uses @code{alloca} with the following attribute: @smallexample #ifdef __GNUC__ __attribute__ ((__noinline__)) #endif @end smallexample