From 676979fa9cc7920e5e4d547814f9c0edb597fa0d Mon Sep 17 00:00:00 2001

From: Eugene Syromyatnikov <evgsyr@gmail.com>

Date: Thu, 30 Jun 2022 16:01:05 +0200

Subject: [PATCH] pathtrace, util: do not print " (deleted)" as part of the

 path

In order to allow to discern the unlinked paths from the paths that

do indeed end with " (deleted)".

* src/defs.h (getfdpath_pid): Add deleted parameter.

(getfdpath): Pass NULL as deleted parameter to getfdpath_pid.

* src/largefile_wrappers.h (lstat_file): New macro.

* src/pathtrace.c: Include <sys/stat.h>, <sys/types.h>, <unistd.h>,

and "largefile_wrappers.h".

(getfdpath_pid): Add deleted parameter, check if path ends with

" (deleted)", and if it is, try to figure out if it is a part

of the path by comparing device/inode numbers of the file procfs

link resolves into and the file pointed by the path read;  strip

" (deleted)";  set deleted (if it is non-NULL) to true if the fd

is turned out to be deleted and to false otherwise.

* src/util.c (print_quoted_string_in_angle_brackets): Add deleted

parameter, print "(deleted)" after the closing angle bracket if it is

non-NULL.

(printfd_pid): Add deleted local variable, pass it to getfdpath_pid

and print_quoted_string_in_angle_brackets calls.

* tests/fchmod.c: Add checks for a file with " (deleted)" in the path,

update expected output.

* NEWS: Mention the change.

---

 NEWS                     |  5 +++++

 src/defs.h               |  5 +++--

 src/largefile_wrappers.h |  2 ++

 src/pathtrace.c          | 48 +++++++++++++++++++++++++++++++++++++++++++++---

 src/util.c               | 10 +++++++---

 tests/fchmod.c           | 47 +++++++++++++++++++++++++++++++++++++++++++----

 6 files changed, 105 insertions(+), 12 deletions(-)

Index: strace-5.18/NEWS

===================================================================

--- strace-5.18.orig/NEWS	2022-07-13 12:52:48.219784860 +0200

+++ strace-5.18/NEWS	2022-07-13 12:52:48.451782122 +0200

@@ -1,6 +1,11 @@

 Noteworthy changes in release 5.18 (2022-06-18)

 ===============================================

+* Changes in behaviour

+  * The "(deleted)" marker for unlinked paths of file descriptors is now printed

+    outside angle brackets;  the matching of unlinked paths of file descriptors

+    no longer includes the " (deleted)" part into consideration.

+

 * Improvements

   * Added an interface of raising des Strausses awareness.

   * Added --tips option to print strace tips, tricks, and tweaks

Index: strace-5.18/src/defs.h

===================================================================

--- strace-5.18.orig/src/defs.h	2022-07-13 12:52:29.405006910 +0200

+++ strace-5.18/src/defs.h	2022-07-13 12:52:54.532710356 +0200

@@ -785,12 +785,13 @@

 	return pathtrace_match_set(tcp, &global_path_set);

 }

-extern int getfdpath_pid(pid_t pid, int fd, char *buf, unsigned bufsize);

+extern int getfdpath_pid(pid_t pid, int fd, char *buf, unsigned bufsize,

+			 bool *deleted);

 static inline int

 getfdpath(struct tcb *tcp, int fd, char *buf, unsigned bufsize)

 {

-	return getfdpath_pid(tcp->pid, fd, buf, bufsize);

+	return getfdpath_pid(tcp->pid, fd, buf, bufsize, NULL);

 }

 extern unsigned long getfdinode(struct tcb *, int);

Index: strace-5.18/src/largefile_wrappers.h

===================================================================

--- strace-5.18.orig/src/largefile_wrappers.h	2022-07-13 12:52:29.405006910 +0200

+++ strace-5.18/src/largefile_wrappers.h	2022-07-13 12:52:48.451782122 +0200

@@ -31,6 +31,7 @@

 #  endif

 #  define fstat_fd fstat64

 #  define strace_stat_t struct stat64

+#  define lstat_file lstat64

 #  define stat_file stat64

 #  define struct_dirent struct dirent64

 #  define read_dir readdir64

@@ -42,6 +43,7 @@

 #  define fcntl_fd fcntl

 #  define fstat_fd fstat

 #  define strace_stat_t struct stat

+#  define lstat_file lstat

 #  define stat_file stat

 #  define struct_dirent struct dirent

 #  define read_dir readdir

Index: strace-5.18/src/pathtrace.c

===================================================================

--- strace-5.18.orig/src/pathtrace.c	2022-07-13 12:52:29.405006910 +0200

+++ strace-5.18/src/pathtrace.c	2022-07-13 12:52:54.532710356 +0200

@@ -10,7 +10,11 @@

 #include "defs.h"

 #include <limits.h>

 #include <poll.h>

+#include <sys/stat.h>

+#include <sys/types.h>

+#include <unistd.h>

+#include "largefile_wrappers.h"

 #include "number_set.h"

 #include "sen.h"

 #include "xstring.h"

@@ -77,7 +81,7 @@

  * Get path associated with fd of a process with pid.

  */

 int

-getfdpath_pid(pid_t pid, int fd, char *buf, unsigned bufsize)

+getfdpath_pid(pid_t pid, int fd, char *buf, unsigned bufsize, bool *deleted)

 {

 	char linkpath[sizeof("/proc/%u/fd/%u") + 2 * sizeof(int)*3];

 	ssize_t n;

@@ -91,12 +95,50 @@

 	xsprintf(linkpath, "/proc/%u/fd/%u", proc_pid, fd);

 	n = readlink(linkpath, buf, bufsize - 1);

+	if (n < 0)

+		goto end;

+

 	/*

 	 * NB: if buf is too small, readlink doesn't fail,

 	 * it returns truncated result (IOW: n == bufsize - 1).

 	 */

-	if (n >= 0)

-		buf[n] = '\0';

+	buf[n] = '\0';

+	if (deleted)

+		*deleted = false;

+

+	/*

+	 * Try to figure out if the kernel has appended " (deleted)"

+	 * to the end of a potentially unlinked path and set deleted

+	 * if it is the case.

+	 */

+	static const char del_sfx[] = " (deleted)";

+	if ((size_t) n <= sizeof(del_sfx))

+		goto end;

+

+	char *del = buf + n + 1 - sizeof(del_sfx);

+

+	if (memcmp(del, del_sfx, sizeof(del_sfx)))

+		goto end;

+

+	strace_stat_t st_link;

+	strace_stat_t st_path;

+	int rc = stat_file(linkpath, &st_link);

+

+	if (rc)

+		goto end;

+

+	rc = lstat_file(buf, &st_path);

+

+	if (rc ||

+	    (st_link.st_ino != st_path.st_ino) ||

+	    (st_link.st_dev != st_path.st_dev)) {

+		*del = '\0';

+		n = del - buf + 1;

+		if (deleted)

+			*deleted = true;

+	}

+

+end:

 	return n;

 }

Index: strace-5.18/src/util.c

===================================================================

--- strace-5.18.orig/src/util.c	2022-07-13 12:52:47.989787575 +0200

+++ strace-5.18/src/util.c	2022-07-13 12:52:48.452782111 +0200

@@ -735,12 +735,15 @@

 }

 static void

-print_quoted_string_in_angle_brackets(const char *str)

+print_quoted_string_in_angle_brackets(const char *str, const bool deleted)

 {

 	tprints("<");

 	print_quoted_string_ex(str, strlen(str),

 			       QUOTE_OMIT_LEADING_TRAILING_QUOTES, "<>");

 	tprints(">");

+

+	if (deleted)

+		tprints("(deleted)");

 }

 void

@@ -749,8 +752,9 @@

 	PRINT_VAL_D(fd);

 	char path[PATH_MAX + 1];

+	bool deleted;

 	if (pid > 0 && !number_set_array_is_empty(decode_fd_set, 0)

-	    && getfdpath_pid(pid, fd, path, sizeof(path)) >= 0) {

+	    && getfdpath_pid(pid, fd, path, sizeof(path), &deleted) >= 0) {

 		if (is_number_in_set(DECODE_FD_SOCKET, decode_fd_set) &&

 		    printsocket(tcp, fd, path))

 			goto printed;

@@ -761,7 +765,7 @@

 		    printpidfd(pid, fd, path))

 			goto printed;

 		if (is_number_in_set(DECODE_FD_PATH, decode_fd_set))

-			print_quoted_string_in_angle_brackets(path);

+			print_quoted_string_in_angle_brackets(path, deleted);

 printed:	;

 	}

Index: strace-5.18/tests/fchmod.c

===================================================================

--- strace-5.18.orig/tests/fchmod.c	2022-07-13 12:52:29.405006910 +0200

+++ strace-5.18/tests/fchmod.c	2022-07-13 12:52:48.452782111 +0200

@@ -35,10 +35,17 @@

 	(void) unlink(sample);

 	int fd = open(sample, O_CREAT|O_RDONLY, 0400);

 	if (fd == -1)

-		perror_msg_and_fail("open");

+		perror_msg_and_fail("open(\"%s\")", sample);

+

+	static const char sample_del[] = "fchmod_sample_file (deleted)";

+	(void) unlink(sample_del);

+	int fd_del = open(sample_del, O_CREAT|O_RDONLY, 0400);

+	if (fd_del == -1)

+		perror_msg_and_fail("open(\"%s\")", sample);

 # ifdef YFLAG

 	char *sample_realpath = get_fd_path(fd);

+	char *sample_del_realpath = get_fd_path(fd_del);

 # endif

 	const char *sample_secontext = SECONTEXT_FILE(sample);

@@ -56,12 +63,27 @@

 	       sample_secontext,

 	       sprintrc(rc));

+	const char *sample_del_secontext = SECONTEXT_FILE(sample_del);

+	rc = syscall(__NR_fchmod, fd_del, 0600);

+# ifdef YFLAG

+	printf("%s%s(%d<%s>%s, 0600) = %s\n",

+# else

+	printf("%s%s(%d%s, 0600) = %s\n",

+# endif

+	       my_secontext, "fchmod",

+	       fd_del,

+# ifdef YFLAG

+	       sample_del_realpath,

+# endif

+	       sample_del_secontext,

+	       sprintrc(rc));

+

 	if (unlink(sample))

-		perror_msg_and_fail("unlink");

+		perror_msg_and_fail("unlink(\"%s\")", sample);

 	rc = syscall(__NR_fchmod, fd, 051);

 # ifdef YFLAG

-	printf("%s%s(%d<%s (deleted)>%s, 051) = %s\n",

+	printf("%s%s(%d<%s>(deleted)%s, 051) = %s\n",

 # else

 	printf("%s%s(%d%s, 051) = %s\n",

 # endif

@@ -73,9 +95,26 @@

 	       sample_secontext,

 	       sprintrc(rc));

+	if (unlink(sample_del))

+		perror_msg_and_fail("unlink(\"%s\")", sample_del);

+

+	rc = syscall(__NR_fchmod, fd_del, 051);

+# ifdef YFLAG

+	printf("%s%s(%d<%s>(deleted)%s, 051) = %s\n",

+# else

+	printf("%s%s(%d%s, 051) = %s\n",

+# endif

+	       my_secontext, "fchmod",

+	       fd_del,

+# ifdef YFLAG

+	       sample_del_realpath,

+# endif

+	       sample_del_secontext,

+	       sprintrc(rc));

+

 	rc = syscall(__NR_fchmod, fd, 004);

 # ifdef YFLAG

-	printf("%s%s(%d<%s (deleted)>%s, 004) = %s\n",

+	printf("%s%s(%d<%s>(deleted)%s, 004) = %s\n",

 # else

 	printf("%s%s(%d%s, 004) = %s\n",

 # endif

Index: strace-5.18/tests-m32/fchmod.c

===================================================================

--- strace-5.18.orig/tests-m32/fchmod.c	2022-07-13 12:52:29.405006910 +0200

+++ strace-5.18/tests-m32/fchmod.c	2022-07-13 12:52:48.452782111 +0200

@@ -35,10 +35,17 @@

 	(void) unlink(sample);

 	int fd = open(sample, O_CREAT|O_RDONLY, 0400);

 	if (fd == -1)

-		perror_msg_and_fail("open");

+		perror_msg_and_fail("open(\"%s\")", sample);

+

+	static const char sample_del[] = "fchmod_sample_file (deleted)";

+	(void) unlink(sample_del);

+	int fd_del = open(sample_del, O_CREAT|O_RDONLY, 0400);

+	if (fd_del == -1)

+		perror_msg_and_fail("open(\"%s\")", sample);

 # ifdef YFLAG

 	char *sample_realpath = get_fd_path(fd);

+	char *sample_del_realpath = get_fd_path(fd_del);

 # endif

 	const char *sample_secontext = SECONTEXT_FILE(sample);

@@ -56,12 +63,27 @@

 	       sample_secontext,

 	       sprintrc(rc));

+	const char *sample_del_secontext = SECONTEXT_FILE(sample_del);

+	rc = syscall(__NR_fchmod, fd_del, 0600);

+# ifdef YFLAG

+	printf("%s%s(%d<%s>%s, 0600) = %s\n",

+# else

+	printf("%s%s(%d%s, 0600) = %s\n",

+# endif

+	       my_secontext, "fchmod",

+	       fd_del,

+# ifdef YFLAG

+	       sample_del_realpath,

+# endif

+	       sample_del_secontext,

+	       sprintrc(rc));

+

 	if (unlink(sample))

-		perror_msg_and_fail("unlink");

+		perror_msg_and_fail("unlink(\"%s\")", sample);

 	rc = syscall(__NR_fchmod, fd, 051);

 # ifdef YFLAG

-	printf("%s%s(%d<%s (deleted)>%s, 051) = %s\n",

+	printf("%s%s(%d<%s>(deleted)%s, 051) = %s\n",

 # else

 	printf("%s%s(%d%s, 051) = %s\n",

 # endif

@@ -73,9 +95,26 @@

 	       sample_secontext,

 	       sprintrc(rc));

+	if (unlink(sample_del))

+		perror_msg_and_fail("unlink(\"%s\")", sample_del);

+

+	rc = syscall(__NR_fchmod, fd_del, 051);

+# ifdef YFLAG

+	printf("%s%s(%d<%s>(deleted)%s, 051) = %s\n",

+# else

+	printf("%s%s(%d%s, 051) = %s\n",

+# endif

+	       my_secontext, "fchmod",

+	       fd_del,

+# ifdef YFLAG

+	       sample_del_realpath,

+# endif

+	       sample_del_secontext,

+	       sprintrc(rc));

+

 	rc = syscall(__NR_fchmod, fd, 004);

 # ifdef YFLAG

-	printf("%s%s(%d<%s (deleted)>%s, 004) = %s\n",

+	printf("%s%s(%d<%s>(deleted)%s, 004) = %s\n",

 # else

 	printf("%s%s(%d%s, 004) = %s\n",

 # endif