Implement an ability to filter syscalls that operate on specific FDs

Introduce -e trace-fds= qualifier that allows specifying a set of FDs
of interest, operations on which are to be traced.  Works in conjunction
(or, more specifically, inclusive disjunction) with the path tracing
functionality.

* src/defs.h: Include "number_set.h".
(tracing_fds): New external variable.
(pathtrace_match_set): Add new fdset argument to the declaration.
(pathtrace_match): Pass trace_fd_set in the new argument
to the pathtrace_match_set call.
(qualify_trace_fd): New function declaration.
* src/filter_qualify.c (trace_fd_set): New variable.
(qualify_trace_fd): New function.
(qual_options): Add various FD tracing-related items.
* src/number_set.h (trace_fd_set): New external variable declaration.
* src/pathtrace.c (pathmatch, upathmatch): Bail out if set is NULL.
(fdmatch): Add fdset argument, check fd for non-negativity and presence
in fdset if fdset is non-NULL.
(match_xselect_args): Add fdset argument, pass it to the fdmatch call.
(pathtrace_match_set): Add fdset argument, pass it to fdmatch
and match_xselect_args calls.
* src/syscall.c (syscall_entering_trace): Check tracing_fds in addition
to tracing_paths as a predicate for performing pathtrace_match check.
* src/strace.c (tracing_fds): New variable.
(init) <GETOPT_QUAL_TRACE_FD>: New enum item.
(init) <longopts>: Add"trace-fds" option.
(init) <case GETOPT_QUAL_TRACE_FD>: Call qualify_trace_fd.
(usage): Document -e trace-fds.
* doc/strace.1.in: Likewise.
* tests/.gitignore: Add dup-trace-fds-0, dup-trace-fds-0-9,
dup-trace-fds-0-P, dup-trace-fds-not-9, dup2-e-fd-0, dup2-e-fd-0-9,
dup2-e-fd-0-P, dup2-e-fd-not-9, ppoll-e-trace-fds-23,
ppoll-e-trace-fds-23-42, ppoll-e-trace-fds-not-9-42-P,
select-trace-fd-7, select-trace-fd-7-9, and select-trace-fd-7-P.
* tests/Makefile.am (check_PROGRAMS): Add ppoll-e-trace-fds-23,
ppoll-e-trace-fds-23-42, ppoll-e-trace-fds-not-9-42-P,
select-trace-fd-7, select-trace-fd-7-9, and select-trace-fd-7-P.
* tests/dup-P.c (PATH_TRACING): Set to 1.
* tests/dup2-P.c (PATH_TRACING): Likewise.
* tests/dup.c: Accommodate test for checking tracing-fds functionality.
* tests/dup2.c: Likewise.
* tests/ppoll.c: Likewise.
* tests/xselect.c: Likewise.
* tests/gen_tests.in (dup-trace-fds-0, dup-trace-fds-0-9,
dup-trace-fds-0-P, dup-trace-fds-not-9, dup2-e-fd-0, dup2-e-fd-0-9,
dup2-e-fd-0-P, dup2-e-fd-not-9, ppoll-e-trace-fds-23,
ppoll-e-trace-fds-23-42, ppoll-e-trace-fds-not-9-42-P,
select-trace-fd-7, select-trace-fd-7-9, select-trace-fd-7-P): New tests.
* tests/options-syntax.test: Add trace-fds-related option syntax checks.
* tests/pure_executables.list: Add dup-trace-fds-0, dup-trace-fds-0-9,
dup-trace-fds-0-P, dup-trace-fds-not-9, dup2-e-fd-0, dup2-e-fd-0-9,
dup2-e-fd-0-P, and dup2-e-fd-not-9.
* tests/dup-trace-fds-0-9.c: New file.
* tests/dup-trace-fds-0-P.c: Likewise.
* tests/dup-trace-fds-0.c: Likewise.
* tests/dup-trace-fds-not-9.c: Likewise.
* tests/dup2-e-fd-0-9.c: Likewise.
* tests/dup2-e-fd-0-P.c: Likewise.
* tests/dup2-e-fd-0.c: Likewise.
* tests/dup2-e-fd-not-9.c: Likewise.
* tests/ppoll-e-trace-fds-23-42.c: Likewise.
* tests/ppoll-e-trace-fds-23.c: Likewise.
* tests/ppoll-e-trace-fds-not-9-42-P.c: Likewise.
* tests/select-trace-fd-7-9.c: Likewise.
* tests/select-trace-fd-7-P.c: Likewise.
* tests/select-trace-fd-7.c: Likewise.
* NEWS: Mention it.

Suggested-by: Marty Leisner <maleisner@gmail.com>
Link: https://lists.strace.io/pipermail/strace-devel/2023-March/011209.html

1 files changed, 2 insertions, 0 deletions

diff --git a/tests/select-trace-fd-7.c b/tests/select-trace-fd-7.c
new file mode 100644
index 000000000..6aeaf180f
--- /dev/null
+++ b/tests/select-trace-fd-7.c
@@ -0,0 +1,2 @@
+#define TRACING_FD 7
+#include "select.c"