From: Eugene Syromyatnikov <evgsyr@gmail.com>
Date: Sat, 16 Sep 2017 01:02:16 +0000 (+0200)
Subject: kcmp: output fds using a separate function
X-Git-Tag: v4.20~66
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=76cf3b2a98366144fa8f64651ef4161c639476b7;p=strace

kcmp: output fds using a separate function

This is a preparation for the future introduction of cross-NS PID
derivation, which would enable us to print fd information for fds
related to all processes, not just traced ones.

Note the change in output type for idx1/idx2 in KCMP_FILE command from
unsigned to int, it follows printfd output format.

* kcmp.c (printpidfd): New function.
(PRINT_FIELD_PIDFD): New macro.
(SYS_FUNC(kcmp)) <case KCMP_FILE>: Use printpidfd for printing
idx1/idx2, as they are fds, after all.
---

diff --git a/kcmp.c b/kcmp.c
index 962952bd..e1c6e9ed 100644
--- a/kcmp.c
+++ b/kcmp.c
@@ -27,8 +27,25 @@
  */
 
 #include "defs.h"
+#include "print_fields.h"
 #include "xlat/kcmp_types.h"
 
+static void
+printpidfd(struct tcb *tcp, pid_t pid, int fd)
+{
+	/*
+	 * XXX We want to use printfd here, but we should figure out which
+	 *     process in strace's PID NS is referred to first.
+	 */
+	tprintf("%d", fd);
+}
+
+#define PRINT_FIELD_PIDFD(prefix_, where_, field_, tcp_, pid_)		\
+	do {								\
+		STRACE_PRINTF("%s%s=", (prefix_), #field_);		\
+		printpidfd((tcp_), (pid_), (where_).field_);		\
+	} while (0)
+
 SYS_FUNC(kcmp)
 {
 	pid_t pid1 = tcp->u_arg[0];
@@ -42,7 +59,11 @@ SYS_FUNC(kcmp)
 
 	switch (type) {
 		case KCMP_FILE:
-			tprintf(", %u, %u", (unsigned) idx1, (unsigned) idx2);
+			tprints(", ");
+			printpidfd(tcp, pid1, idx1);
+			tprints(", ");
+			printpidfd(tcp, pid1, idx2);
+
 			break;
 		case KCMP_FILES:
 		case KCMP_FS:
diff --git a/tests/kcmp.c b/tests/kcmp.c
index 46bb173c..62a24d91 100644
--- a/tests/kcmp.c
+++ b/tests/kcmp.c
@@ -55,6 +55,12 @@
 #  define KCMP_SYSVSEM	6
 # endif
 
+static void
+printpidfd(const char *prefix, pid_t pid, unsigned fd)
+{
+	printf("%s%d", prefix, fd);
+}
+
 static void
 do_kcmp(kernel_ulong_t pid1, kernel_ulong_t pid2, kernel_ulong_t type,
 	const char *type_str, kernel_ulong_t idx1, kernel_ulong_t idx2)
@@ -72,11 +78,13 @@ do_kcmp(kernel_ulong_t pid1, kernel_ulong_t pid2, kernel_ulong_t type,
 	else
 		printf("%#x /* KCMP_??? */", (int) type);
 
-	if (type == KCMP_FILE)
-		printf(", %u, %u", (unsigned) idx1, (unsigned) idx2);
-	else if (type > KCMP_SYSVSEM)
+	if (type == KCMP_FILE) {
+		printpidfd(", ", pid1, idx1);
+		printpidfd(", ", pid2, idx2);
+	} else if (type > KCMP_SYSVSEM) {
 		printf(", %#llx, %#llx",
 		       (unsigned long long) idx1, (unsigned long long) idx2);
+	}
 
 	printf(") = %s\n", errstr);
 }