[PATCH v3 1/6] pathtrace.c: add getfdpath_pid

[Ákos Uzonyi]

* defs.h (getfdpath_pid): New function definition.
* pathtrace.c (getfdpath_pid): New function, returns the path
associated with fd of the process with pid.
(getfdpath): Rewritten using getfdpath_pid.

Signed-off-by: Uzonyi Ákos <uzonyi.akos at gmail.com>
---
 defs.h      |  1 +
 pathtrace.c | 15 ++++++++++++---
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/defs.h b/defs.h
index 0231cbf2..a7d535d7 100644
--- a/defs.h
+++ b/defs.h
@@ -685,6 +685,7 @@ pathtrace_match(struct tcb *tcp)
 	return pathtrace_match_set(tcp, &global_path_set);
 }
 
+extern int getfdpath_pid(pid_t pid, int fd, char *buf, unsigned bufsize);
 extern int getfdpath(struct tcb *, int, char *, unsigned);
 extern unsigned long getfdinode(struct tcb *, int);
 extern enum sock_proto getfdproto(struct tcb *, int);
diff --git a/pathtrace.c b/pathtrace.c
index e62ff6fc..3178c447 100644
--- a/pathtrace.c
+++ b/pathtrace.c
@@ -76,10 +76,10 @@ storepath(const char *path, struct path_set *set)
 }
 
 /*
- * Get path associated with fd.
+ * Get path associated with fd of a process with pid.
  */
 int
-getfdpath(struct tcb *tcp, int fd, char *buf, unsigned bufsize)
+getfdpath_pid(pid_t pid, int fd, char *buf, unsigned bufsize)
 {
 	char linkpath[sizeof("/proc/%u/fd/%u") + 2 * sizeof(int)*3];
 	ssize_t n;
@@ -87,7 +87,7 @@ getfdpath(struct tcb *tcp, int fd, char *buf, unsigned bufsize)
 	if (fd < 0)
 		return -1;
 
-	xsprintf(linkpath, "/proc/%u/fd/%u", tcp->pid, fd);
+	xsprintf(linkpath, "/proc/%u/fd/%u", pid, fd);
 	n = readlink(linkpath, buf, bufsize - 1);
 	/*
 	 * NB: if buf is too small, readlink doesn't fail,
@@ -98,6 +98,15 @@ getfdpath(struct tcb *tcp, int fd, char *buf, unsigned bufsize)
 	return n;
 }
 
+/*
+ * Get path associated with fd of tracee.
+ */
+int
+getfdpath(struct tcb *tcp, int fd, char *buf, unsigned bufsize)
+{
+	return getfdpath_pid(tcp->pid, fd, buf, bufsize);
+}
+
 /*
  * Add a path to the set we're tracing.  Also add the canonicalized
  * version of the path.  Specifying NULL will delete all paths.
-- 
2.26.2