Introduce --decode-pids=pidns as an alias for --pidns-translation

In preparation for the forthcoming -Y/--decode-pids=comm option.

* doc/strace.1.in (.SS Output format): Document --decode-pids=pidns
option.
* src/defs.h (pidns_translation): Remove.
(pid_decoding): New variable declaration.
(enum pid_decoding_flags): New enum.
(qualify_decode_pid): New function prototype.
* src/strace.c (pidns_translation): Remove.
(pid_decoding): New variable.
(usage): Describe --decode-pids=pidns option.
(init) <enum>: Add GETOPT_QUAL_DECODE_PID.
<longopts>: Add --decode-pids as a long option.
<case GETOPT_PIDNS_TRANSLATION>: Call qualify_decode_pid
to update pid_decoding indirectly.
<case GETOPT_QUAL_DECODE_PID>: New condition.
* src/filter_qualify.c (qualify_decode_pid): New function.
* src/pidns.c (printpid_translation): Refer to pid_decoding as
the replacement for pidns_translation.
* tests/init.sh (test_pidns_run_strace): Replace --pidns-translation
with --decode-pids=pidns.
* tests/options-syntax.test: Check invalid --decode-pids argument.
* NEWS: Mention this change.

Making --decode-pids option a super set of --pidns-translation option is
Suggested-by: by Eugene Syromyatnikov <evgsyr@gmail.com>.
Signed-off-by: Masatake YAMATO <yamato@redhat.com>
Co-authored-by: Dmitry V. Levin <ldv@strace.io>

8 files changed, 29 insertions, 5 deletions

diff --git a/NEWS b/NEWS
index 887fa2d09..86508c73f 100644
--- a/NEWS
+++ b/NEWS
@@ -4,6 +4,7 @@ Noteworthy changes in release ?.?? (????-??-??)
 * Improvements
   * Implemented --strings-in-hex=non-ascii-chars option for using hexadecimal
     numbers instead of octal ones in escape sequences in the output strings.
+  * Implemented --decode-pids=pidns as an alias to --pidns-translation option.
   * Improved printing of syscall names in places where the associated
     AUDIT_ARCH_* value is present (ptrace PTRACE_GET_SYSCALL_INFO request,
     SIGSYS siginfo_t).
diff --git a/doc/strace.1.in b/doc/strace.1.in
index 0de927694..aefb0096f 100644
--- a/doc/strace.1.in
+++ b/doc/strace.1.in
@@ -1124,6 +1124,8 @@ block/character device number associated with device file descriptors,
 and PIDs associated with pidfd file descriptors.
 .TP
 .B \-\-pidns\-translation
+.TQ
+.BR \-\-decode\-pids = pidns
 If strace and tracee are in different PID namespaces, print PIDs in
 strace's namespace, too.
 .if '@ENABLE_SECONTEXT_FALSE@'#' .TP
diff --git a/src/defs.h b/src/defs.h
index 45e2b4a71..2c00f4e1f 100644
--- a/src/defs.h
+++ b/src/defs.h
@@ -508,7 +508,10 @@ extern int Tflag_scale;
 extern int Tflag_width;
 extern bool iflag;
 extern bool count_wallclock;
-extern unsigned int pidns_translation;
+extern unsigned int pid_decoding;
+enum pid_decoding_flags {
+	PID_DECODING_NS_TRANSLATION = 1 << 0,
+};
 /* are we filtering traces based on paths? */
 extern struct path_set {
 	const char **paths_selected;
@@ -1328,6 +1331,7 @@ extern void qualify_signals(const char *);
 extern void qualify_status(const char *);
 extern void qualify_quiet(const char *);
 extern void qualify_decode_fd(const char *);
+extern void qualify_decode_pid(const char *);
 extern void qualify_read(const char *);
 extern void qualify_write(const char *);
 extern void qualify_fault(const char *);
diff --git a/src/filter_qualify.c b/src/filter_qualify.c
index 7fc2b23b6..1eb96021b 100644
--- a/src/filter_qualify.c
+++ b/src/filter_qualify.c
@@ -466,6 +466,15 @@ qualify_decode_fd(const char *const str)
 }
 
 void
+qualify_decode_pid(const char *const str)
+{
+	if (strcmp(str, "pidns") == 0)
+		pid_decoding |= PID_DECODING_NS_TRANSLATION;
+	else
+		error_msg_and_die("invalid --decode-pids= argument: '%s'", str);
+}
+
+void
 qualify_trace(const char *const str)
 {
 	if (!trace_set)
diff --git a/src/pidns.c b/src/pidns.c
index 9c7b7ce1a..eda87aad9 100644
--- a/src/pidns.c
+++ b/src/pidns.c
@@ -527,7 +527,7 @@ get_proc_pid(int pid)
 static void
 printpid_translation(struct tcb *tcp, int pid, enum pid_type type)
 {
-	if (!pidns_translation)
+	if (!(pid_decoding & PID_DECODING_NS_TRANSLATION))
 		return;
 
 	int strace_pid = translate_pid(tcp, pid, type, NULL);
diff --git a/src/strace.c b/src/strace.c
index 21376b4fd..f08f1c996 100644
--- a/src/strace.c
+++ b/src/strace.c
@@ -137,7 +137,7 @@ static unsigned int daemonized_tracer;
 static int post_attach_sigstop = TCB_IGNORE_ONE_SIGSTOP;
 #define use_seize (post_attach_sigstop == 0)
 
-unsigned int pidns_translation;
+unsigned int pid_decoding;
 
 static bool detach_on_execve;
 
@@ -418,6 +418,8 @@ Output format:\n\
   -yy, --decode-fds=all\n\
                  print all available information associated with file\n\
                  descriptors in addition to paths\n\
+  --decode-pids=pidns\n\
+                 print PIDs in strace's namespace, too\n\
 "
 #ifdef ENABLE_SECONTEXT
 "\
@@ -2082,6 +2084,7 @@ init(int argc, char *argv[])
 		GETOPT_QUAL_KVM,
 		GETOPT_QUAL_QUIET,
 		GETOPT_QUAL_DECODE_FD,
+		GETOPT_QUAL_DECODE_PID,
 	};
 	static const struct option longopts[] = {
 		{ "columns",		required_argument, 0, 'a' },
@@ -2143,6 +2146,7 @@ init(int argc, char *argv[])
 		{ "silent",	optional_argument, 0, GETOPT_QUAL_QUIET },
 		{ "silence",	optional_argument, 0, GETOPT_QUAL_QUIET },
 		{ "decode-fds",	optional_argument, 0, GETOPT_QUAL_DECODE_FD },
+		{ "decode-pids",required_argument, 0, GETOPT_QUAL_DECODE_PID },
 
 		{ 0, 0, 0, 0 }
 	};
@@ -2340,7 +2344,7 @@ init(int argc, char *argv[])
 			yflag_short++;
 			break;
 		case GETOPT_PIDNS_TRANSLATION:
-			pidns_translation++;
+			qualify_decode_pid("pidns");
 			break;
 		case 'z':
 			clear_number_set_array(status_set, 1);
@@ -2405,6 +2409,9 @@ init(int argc, char *argv[])
 		case GETOPT_QUAL_DECODE_FD:
 			qualify_decode_fd(optarg ?: yflag_qual);
 			break;
+		case GETOPT_QUAL_DECODE_PID:
+			qualify_decode_pid(optarg);
+			break;
 		default:
 			error_msg_and_help(NULL);
 			break;
diff --git a/tests/init.sh b/tests/init.sh
index e39673fb0..23dacfcdc 100644
--- a/tests/init.sh
+++ b/tests/init.sh
@@ -481,7 +481,7 @@ test_pidns_run_strace()
 
 	run_prog > /dev/null
 	args="$prog_args"
-	run_strace --pidns-translation -f "$@" $args > "$EXP"
+	run_strace --decode-pids=pidns -f "$@" $args > "$EXP"
 
 	# filter out logs made by the parent or init process of the pidns test
 	parent_pid="$(tail -n 2 $LOG | head -n 1 | cut -d' ' -f1)"
diff --git a/tests/options-syntax.test b/tests/options-syntax.test
index 765b2f867..a6a5d53de 100755
--- a/tests/options-syntax.test
+++ b/tests/options-syntax.test
@@ -221,6 +221,7 @@ check_h 'deprecated option -F ignored
 check_e "invalid system call '/getcwd@ohmy'" -e trace=/getcwd@ohmy
 check_e "invalid -e kvm= argument: 'chdir'" -e kvm=chdir
 check_e "invalid -e kvm= argument: 'chdir'" --kvm=chdir
+check_e "invalid --decode-pids= argument: 'chdir'" --decode-pids=chdir
 
 case "$STRACE_NATIVE_ARCH" in
 x86_64)