libbacktrace: add notes about dl_iterate_phdr to README

* README: Add notes about dl_iterate_phdr.
This commit is contained in:
Ian Lance Taylor 2024-07-17 17:02:56 -07:00
parent 3bbc8ea2e3
commit a8b5ce1580

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@ -5,8 +5,18 @@ 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,
the 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.
@ -20,7 +30,7 @@ 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