Changed realpath to readlink

/proc/pid/exe already seems to be a link to the absolute path to the
executable. This fixes bugs related to containerised applications.

src/proc_operations.c

@@ -8,8 +8,10 @@
 
 #include "proc_operations.h"
 #include <linux/limits.h>
+#include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <unistd.h>
 
 /**
  * @brief Returns the PID of the main thread (i.e., the process ID) of the
@@ -54,11 +56,38 @@ char *get_process_name_by_pid(const int pid) {
   char path[1024];
   sprintf(path, "/proc/%d/exe", pid);
 
-  char *name = realpath(path, NULL);
+  size_t size = 128;
+  char *name = malloc(size);
   if (name == NULL) {
     fprintf(stderr, "Could not get process name by pid %d", pid);
     perror("");
+    return NULL;
   }
+
+  while (1) {
+    ssize_t len = readlink(path, name, size);
+
+    if (len == -1) {
+      fprintf(stderr, "Could not get process name by pid %d", pid);
+      perror("");
+      free(name);
+      return NULL;
+    }
+    if ((size_t)len >= size) {
+      size *= 2;
+      char *new_name = realloc(name, size);
+      if (!new_name) {
+        free(name);
+        return NULL;
+      }
+      name = new_name;
+    } else {
+      // readlink does not set the null character
+      name[len] = 0;
+      break;
+    }
+  }
+
   return name;
 }