From c5ff2059f619ac91c14d55412314d1c67de6a593 Mon Sep 17 00:00:00 2001
From: Tobias Klauser <tklauser@distanz.ch>
Date: Fri, 17 Jul 2015 14:55:15 +0200
Subject: flowtop, netsniff-ng: Move process name extraction to own function

flowtop and the netsniff-ng's netlink message dissector both need to get
the process name for a pid from /proc/<pid>/exe, thus move that
functionality to an own function.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
---
 flowtop.c        | 12 ++++--------
 flowtop/Makefile |  1 +
 proc.c           | 15 +++++++++++++++
 proc.h           |  3 +++
 proto_nlmsg.c    | 13 ++++---------
 5 files changed, 27 insertions(+), 17 deletions(-)

diff --git a/flowtop.c b/flowtop.c
index 7fd9055..a522daf 100644
--- a/flowtop.c
+++ b/flowtop.c
@@ -38,6 +38,7 @@
 #include "locking.h"
 #include "pkt_buff.h"
 #include "screen.h"
+#include "proc.h"
 
 struct flow_entry {
 	uint32_t flow_id, use, status;
@@ -474,14 +475,9 @@ static int walk_process(unsigned int pid, struct flow_entry *n)
 			continue;
 
 		if (S_ISSOCK(statbuf.st_mode) && (ino_t) n->inode == statbuf.st_ino) {
-			memset(n->cmdline, 0, sizeof(n->cmdline));
-
-			snprintf(path, sizeof(path), "/proc/%u/exe", pid);
-
-			ret = readlink(path, n->cmdline,
-				       sizeof(n->cmdline) - 1);
+			ret = proc_get_cmdline(pid, n->cmdline, sizeof(n->cmdline));
 			if (ret < 0)
-				panic("readlink error: %s\n", strerror(errno));
+				panic("Failed to get process cmdline: %s\n", strerror(errno));
 
 			n->procnum = pid;
 			closedir(dir);
@@ -501,7 +497,7 @@ static void walk_processes(struct flow_entry *n)
 
 	/* n->inode must be set */
 	if (n->inode <= 0) {
-		memset(n->cmdline, 0, sizeof(n->cmdline));
+		n->cmdline[0] = '\0';
 		return;
 	}
 
diff --git a/flowtop/Makefile b/flowtop/Makefile
index 1bd5a0f..85cb0b6 100644
--- a/flowtop/Makefile
+++ b/flowtop/Makefile
@@ -15,6 +15,7 @@ flowtop-objs =	xmalloc.o \
 		str.o \
 		sig.o \
 		sock.o \
+		proc.o \
 		dev.o \
 		link.o \
 		hash.o \
diff --git a/proc.c b/proc.c
index 39d661e..672f00d 100644
--- a/proc.c
+++ b/proc.c
@@ -64,3 +64,18 @@ int set_sched_status(int policy, int priority)
 
 	return 0;
 }
+
+ssize_t proc_get_cmdline(unsigned int pid, char *cmdline, size_t len)
+{
+	ssize_t ret;
+	char path[1024];
+
+	snprintf(path, sizeof(path), "/proc/%u/exe", pid);
+	ret = readlink(path, cmdline, len - 1);
+	if (ret < 0)
+		cmdline[0] = '\0';
+	else
+		cmdline[ret] = '\0';
+
+	return ret;
+}
diff --git a/proc.h b/proc.h
index 0a31f36..996ce06 100644
--- a/proc.h
+++ b/proc.h
@@ -1,8 +1,11 @@
 #ifndef PROC_H
 #define PROC_H
 
+#include <stdlib.h>
+
 extern void cpu_affinity(int cpu);
 extern int set_proc_prio(int prio);
 extern int set_sched_status(int policy, int priority);
+extern ssize_t proc_get_cmdline(unsigned int pid, char *cmdline, size_t len);
 
 #endif /* PROC_H */
diff --git a/proto_nlmsg.c b/proto_nlmsg.c
index 22d50a8..1dde5e1 100644
--- a/proto_nlmsg.c
+++ b/proto_nlmsg.c
@@ -17,6 +17,7 @@
 
 #include "dev.h"
 #include "pkt_buff.h"
+#include "proc.h"
 #include "proto.h"
 #include "protos.h"
 #include "timer.h"
@@ -226,7 +227,7 @@ static void rtnl_print_ifinfo(struct nlmsghdr *hdr)
 	uint32_t attrs_len = IFLA_PAYLOAD(hdr);
 	char flags[256];
 	char if_addr[64] = {};
-	char *af_link = "Unknown";
+	char *af_link = "unknown";
 
 	if (ifi->ifi_family == AF_UNSPEC)
 		af_link = "unspec";
@@ -717,14 +718,8 @@ static void nlmsg_print(uint16_t family, struct nlmsghdr *hdr)
 	 * PID and the information will not be printed.
 	 */
 	if (hdr->nlmsg_pid != 0) {
-		char path[1024];
-		int ret;
-
-		snprintf(path, sizeof(path), "/proc/%u/exe", hdr->nlmsg_pid);
-		ret = readlink(path, procname, sizeof(procname) - 1);
-		if (ret < 0)
-			ret = 0;
-		procname[ret] = '\0';
+		if (proc_get_cmdline(hdr->nlmsg_pid, procname, sizeof(procname)) < 0)
+			snprintf(procname, sizeof(procname), "unknown process");
 	} else
 		snprintf(procname, sizeof(procname), "kernel");
 
-- 
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