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Code rationale ============== by: Gabriel Krisman Bertazi This is a fix for bug 16297. The problem occurs when the user attempts to catch any syscall 0 (such as syscall read on Linux/x86_64). GDB was not able to catch the syscall and was missing the breakpoint. Now, breakpoint_hit_catch_syscall returns immediately when it finds the correct syscall number, avoiding a following check for the end of the search vector, that returns a no hit if the syscall number was zero. Testcase rationale ================== by: Sergio Durigan Junior This testcase is a little difficult to write. By doing a quick inspection at the Linux source, one can see that, in many targets, the syscall number 0 is restart_syscall, which is forbidden to be called from userspace. Therefore, on many targets, there's just no way to test this safely. My decision was to take the simpler route and just adds the "read" syscall on the default test. Its number on x86_64 is zero, which is "good enough" since many people here do their tests on x86_64 anyway and it is a popular architecture. However, there was another little gotcha. When using "read" passing 0 as the third parameter (i.e., asking it to read 0 bytes), current libc implementations could choose not to effectively call the syscall. Therefore, the best solution was to create a temporary pipe, write 1 byte into it, and then read this byte from it. gdb/ChangeLog 2013-12-19 Gabriel Krisman Bertazi <gabriel@krisman.be> PR breakpoints/16297 * breakpoint.c (breakpoint_hit_catch_syscall): Return immediately when expected syscall is hit. gdb/testsuite/ChangeLog 2013-12-19 Sergio Durigan Junior <sergiodj@redhat.com> PR breakpoints/16297 * gdb.base/catch-syscall.c (read_syscall, pipe_syscall) (write_syscall): New variables. (main): Create a pipe, write 1 byte in it, and read 1 byte from it. * gdb.base/catch-syscall.exp (all_syscalls): Include "pipe, "write" and "read" syscalls. (fill_all_syscalls_numbers): Improve the way to obtain syscalls numbers.
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.