From aad3a64d63db22db3e506de973f9577d8205554d Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Mon, 25 Nov 2019 14:55:50 +0100
Subject: [PATCH 1/3] process-util: tweak get_process_cwd() when calling for
 own process

Let's bypass /proc if we can.
---
 src/basic/process-util.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/basic/process-util.c b/src/basic/process-util.c
index aaec6a6a99..842c879c4e 100644
--- a/src/basic/process-util.c
+++ b/src/basic/process-util.c
@@ -21,8 +21,8 @@
 
 #include "alloc-util.h"
 #include "architecture.h"
-#include "escape.h"
 #include "env-util.h"
+#include "escape.h"
 #include "fd-util.h"
 #include "fileio.h"
 #include "fs-util.h"
@@ -34,6 +34,7 @@
 #include "missing_sched.h"
 #include "missing_syscall.h"
 #include "namespace-util.h"
+#include "path-util.h"
 #include "process-util.h"
 #include "raw-clone.h"
 #include "rlimit-util.h"
@@ -500,6 +501,9 @@ int get_process_cwd(pid_t pid, char **cwd) {
 
         assert(pid >= 0);
 
+        if (pid == 0 || pid == getpid_cached())
+                return safe_getcwd(cwd);
+
         p = procfs_file_alloca(pid, "cwd");
 
         return get_process_link_contents(p, cwd);

From cde93ba2a5e2b33ebaaaa0358ddfcc35ef21d70d Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Mon, 25 Nov 2019 14:58:24 +0100
Subject: [PATCH 2/3] process-util: shortcut get_process_comm() for our own
 process

Let's bypass /proc if we can.
---
 src/basic/process-util.c | 29 ++++++++++++++++++++---------
 1 file changed, 20 insertions(+), 9 deletions(-)

diff --git a/src/basic/process-util.c b/src/basic/process-util.c
index 842c879c4e..003aecbc49 100644
--- a/src/basic/process-util.c
+++ b/src/basic/process-util.c
@@ -81,24 +81,35 @@ static int get_process_state(pid_t pid) {
 
 int get_process_comm(pid_t pid, char **ret) {
         _cleanup_free_ char *escaped = NULL, *comm = NULL;
-        const char *p;
         int r;
 
         assert(ret);
         assert(pid >= 0);
 
+        if (pid == 0 || pid == getpid_cached()) {
+                comm = new0(char, TASK_COMM_LEN + 1); /* Must fit in 16 byte according to prctl(2) */
+                if (!comm)
+                        return -ENOMEM;
+
+                if (prctl(PR_GET_NAME, comm) < 0)
+                        return -errno;
+        } else {
+                const char *p;
+
+                p = procfs_file_alloca(pid, "comm");
+
+                /* Note that process names of kernel threads can be much longer than TASK_COMM_LEN */
+                r = read_one_line_file(p, &comm);
+                if (r == -ENOENT)
+                        return -ESRCH;
+                if (r < 0)
+                        return r;
+        }
+
         escaped = new(char, COMM_MAX_LEN);
         if (!escaped)
                 return -ENOMEM;
 
-        p = procfs_file_alloca(pid, "comm");
-
-        r = read_one_line_file(p, &comm);
-        if (r == -ENOENT)
-                return -ESRCH;
-        if (r < 0)
-                return r;
-
         /* Escape unprintable characters, just in case, but don't grow the string beyond the underlying size */
         cellescape(escaped, COMM_MAX_LEN, comm);
 

From 5c7b99745a7375ebae125f27c2872919089c0d5c Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Mon, 25 Nov 2019 14:59:01 +0100
Subject: [PATCH 3/3] process-util: shortcut get_process_state() for our own
 process

---
 src/basic/process-util.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/basic/process-util.c b/src/basic/process-util.c
index 003aecbc49..9b6c4c31f7 100644
--- a/src/basic/process-util.c
+++ b/src/basic/process-util.c
@@ -52,13 +52,17 @@
 #define COMM_MAX_LEN 128
 
 static int get_process_state(pid_t pid) {
+        _cleanup_free_ char *line = NULL;
         const char *p;
         char state;
         int r;
-        _cleanup_free_ char *line = NULL;
 
         assert(pid >= 0);
 
+        /* Shortcut: if we are enquired about our own state, we are obviously running */
+        if (pid == 0 || pid == getpid_cached())
+                return (unsigned char) 'R';
+
         p = procfs_file_alloca(pid, "stat");
 
         r = read_one_line_file(p, &line);