From 8e32931a4fe98b9bc955cb97b4702123b204f139 Mon Sep 17 00:00:00 2001 From: Ian Lance Taylor Date: Wed, 17 Jul 2024 17:06:51 -0700 Subject: [PATCH] libbacktrace: add notes about dl_iterate_phdr to README * README: Add notes about dl_iterate_phdr. For #20 --- README.md | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/README.md b/README.md index c82834d..d180784 100644 --- a/README.md +++ b/README.md @@ -10,8 +10,18 @@ The libbacktrace library may be linked into a program or library and used to produce symbolic backtraces. Sample uses would be to print a detailed backtrace when an error occurs or to gather detailed profiling information. + In general the functions provided by this library are async-signal-safe, meaning that they may be safely called from a signal handler. +That said, on systems that use `dl_iterate_phdr`, such as GNU/Linux, +gitthe first call to a libbacktrace function will call `dl_iterate_phdr`, +which is not in general async-signal-safe. Therefore, programs +that call libbacktrace from a signal handler should ensure that they +make an initial call from outside of a signal handler. +Similar considerations apply when arranging to call libbacktrace +from within malloc; `dl_iterate_phdr` can also call malloc, +so make an initial call to a libbacktrace function outside of +malloc before trying to call libbacktrace functions within malloc. The libbacktrace library is provided under a BSD license. See the source files for the exact license text. @@ -25,7 +35,7 @@ will work. See the source file backtrace-supported.h.in for the macros that it defines. -As of October 2020, libbacktrace supports ELF, PE/COFF, Mach-O, and +As of July 2024, libbacktrace supports ELF, PE/COFF, Mach-O, and XCOFF executables with DWARF debugging information. In other words, it supports GNU/Linux, *BSD, macOS, Windows, and AIX. The library is written to make it straightforward to add support for