util: add functions getting proc cwd and root

/proc/[pid]/cwd and /proc/[pid]/root are symliks to corresponding
directories

The added functions returns values of that symlinks.

2 files changed, 37 insertions, 4 deletions

diff --git a/src/shared/util.c b/src/shared/util.c
index eeced4769a..01660526e4 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -797,19 +797,30 @@ int get_process_capeff(pid_t pid, char **capeff) {
         return get_status_field(p, "\nCapEff:", capeff);
 }
 
+static int get_process_link_contents(const char *proc_file, char **name) {
+        int r;
+
+        assert(proc_file);
+        assert(name);
+
+        r = readlink_malloc(proc_file, name);
+        if (r < 0)
+                return r == -ENOENT ? -ESRCH : r;
+
+        return 0;
+}
+
 int get_process_exe(pid_t pid, char **name) {
         const char *p;
         char *d;
         int r;
 
         assert(pid >= 0);
-        assert(name);
 
         p = procfs_file_alloca(pid, "exe");
-
-        r = readlink_malloc(p, name);
+        r = get_process_link_contents(p, name);
         if (r < 0)
-                return r == -ENOENT ? -ESRCH : r;
+                return r;
 
         d = endswith(*name, " (deleted)");
         if (d)
@@ -861,6 +872,26 @@ int get_process_gid(pid_t pid, gid_t *gid) {
         return get_process_id(pid, "Gid:", gid);
 }
 
+int get_process_cwd(pid_t pid, char **cwd) {
+        const char *p;
+
+        assert(pid >= 0);
+
+        p = procfs_file_alloca(pid, "cwd");
+
+        return get_process_link_contents(p, cwd);
+}
+
+int get_process_root(pid_t pid, char **root) {
+        const char *p;
+
+        assert(pid >= 0);
+
+        p = procfs_file_alloca(pid, "root");
+
+        return get_process_link_contents(p, root);
+}
+
 char *strnappend(const char *s, const char *suffix, size_t b) {
         size_t a;
         char *r;
diff --git a/src/shared/util.h b/src/shared/util.h
index 835fee496d..fc59481b99 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -295,6 +295,8 @@ int get_process_exe(pid_t pid, char **name);
 int get_process_uid(pid_t pid, uid_t *uid);
 int get_process_gid(pid_t pid, gid_t *gid);
 int get_process_capeff(pid_t pid, char **capeff);
+int get_process_cwd(pid_t pid, char **cwd);
+int get_process_root(pid_t pid, char **root);
 
 char hexchar(int x) _const_;
 int unhexchar(char c) _const_;