Get process identifier from cmdline

Signed-off-by: Sangwan Kwon <sangwan.kwon@samsung.com>

diff --git a/src/vist/process.hpp b/src/vist/process.hpp
index b17bd1e..29e4ebc 100644 (file)
--- a/src/vist/process.hpp
+++ b/src/vist/process.hpp
@@ -17,7 +17,10 @@
 #pragma once
 
 #include <vist/exception.hpp>
+#include <vist/logger.hpp>
 
+#include <algorithm>
+#include <cctype>
 #include <cstdio>
 #include <memory>
 #include <string>
@@ -26,6 +29,7 @@
 #include <errno.h>
 #include <sys/types.h>
 #include <unistd.h>
+#include <fcntl.h>
 
 namespace vist {
 
@@ -35,17 +39,45 @@ struct Process {
                return ::getpid();
        }
 
+       /// TODO(Sangwan): Unify the method which get process identifier
        static std::string GetPath(pid_t pid)
        {
-               std::string cmdline = "/proc/" + std::to_string(pid) + "/exe";
+               std::string exe = "/proc/" + std::to_string(pid) + "/exe";
 
                /// c++17 std::filesystem::read_symlink
                std::vector<char> buf(1024);
-               auto size = ::readlink(cmdline.c_str(), buf.data(), buf.size());
-               if (size == -1)
-                       THROW(ErrCode::RuntimeError) << "Failed to get process path: " << errno;
+               errno = 0;
+               auto size = ::readlink(exe.c_str(), buf.data(), buf.size());
+               if (size == -1) {
+                       WARN(VIST) << "Failed to get process path by exe: " << exe
+                                          << ", errno: " << errno;
 
-               return std::string(buf.begin(), buf.begin() + size);
+                       std::string cmdline = "/proc/" + std::to_string(pid) + "/cmdline";
+                       int fd = ::open(cmdline.c_str(), O_RDONLY);
+                       if (fd == -1)
+                               THROW(ErrCode::RuntimeError) << "Failed to get process path: " << cmdline;
+
+                       errno = 0;
+                       size = ::read(fd, buf.data(), buf.size());
+                       ::close(fd);
+
+                       if (size == -1)
+                               THROW(ErrCode::RuntimeError) << "Failed to get process path: " << cmdline
+                                                                                        << ", errno: " << errno;
+
+                       buf[size - 1] = '\0';
+               }
+
+               return canonicalize(std::string(buf.begin(), buf.begin() + size));
+       }
+
+private:
+       static std::string canonicalize(std::string&& s)
+       {
+               auto predicate = [](unsigned char c){ return std::isspace(c) || c == '\0'; };
+               auto base = std::find_if(s.begin(), s.end(), predicate);
+               s.erase(base, s.end());
+               return s;
        }
 };