Compress cgroup names based on some heuristics

linux/CGroupUtils.c

@@ -0,0 +1,285 @@
+/*
+htop - CGroupUtils.h
+(C) 2021 htop dev team
+Released under the GNU GPLv2+, see the COPYING file
+in the source distribution for its full text.
+*/
+
+#include "linux/CGroupUtils.h"
+
+#include "XUtils.h"
+
+
+static bool CGroup_filterName_internal(const char *cgroup, char* buf, size_t bufsize) {
+   const char* str_slice_suffix = ".slice";
+   const char* str_system_slice = "system.slice";
+   const char* str_user_slice = "user.slice";
+   const char* str_machine_slice = "machine.slice";
+   const char* str_user_slice_prefix = "/user-";
+
+   const char* str_lxc_monitor_prefix = "lxc.monitor.";
+   const char* str_lxc_payload_prefix = "lxc.payload.";
+
+   const char* str_nspawn_scope_prefix = "machine-";
+   const char* str_nspawn_monitor_label = "/supervisor";
+
+   const char* str_service_suffix = ".service";
+   const char* str_scope_suffix = ".scope";
+
+   while(*cgroup) {
+      if ('/' == *cgroup) {
+         while ('/' == *cgroup)
+            cgroup++;
+
+         if (!bufsize)
+            return false;
+
+         *buf++ = '/';
+         bufsize--;
+
+         continue;
+      }
+
+      const char* labelStart = cgroup;
+      const char* nextSlash = strchrnul(labelStart, '/');
+      const size_t labelLen = nextSlash - labelStart;
+
+      if (String_startsWith(cgroup, str_system_slice)) {
+         cgroup += strlen(str_system_slice);
+
+         if (*cgroup && *cgroup != '/')
+            goto handle_default;
+
+         if (bufsize < 3)
+            return false;
+
+         *buf++ = '[';
+         *buf++ = 'S';
+         *buf++ = ']';
+         bufsize -= 3;
+
+         continue;
+      }
+
+      if (String_startsWith(cgroup, str_machine_slice)) {
+         cgroup += strlen(str_machine_slice);
+
+         if (*cgroup && *cgroup != '/')
+            goto handle_default;
+
+         if (bufsize < 3)
+            return false;
+
+         *buf++ = '[';
+         *buf++ = 'M';
+         *buf++ = ']';
+         bufsize -= 3;
+
+         continue;
+      }
+
+      if (String_startsWith(cgroup, str_user_slice)) {
+         cgroup += strlen(str_user_slice);
+
+         if (*cgroup && *cgroup != '/')
+            goto handle_default;
+
+         if (bufsize < 3)
+            return false;
+
+         *buf++ = '[';
+         *buf++ = 'U';
+         *buf++ = ']';
+         bufsize -= 3;
+
+         if (!String_startsWith(cgroup, str_user_slice_prefix))
+            continue;
+
+         const char* userSliceSlash = strchrnul(cgroup + strlen(str_user_slice_prefix), '/');
+         const char* sliceSpec = userSliceSlash - strlen(str_slice_suffix);
+
+         if (!String_startsWith(sliceSpec, str_slice_suffix))
+            continue;
+
+         const size_t sliceNameLen = sliceSpec - (cgroup + strlen(str_user_slice_prefix));
+
+         if (bufsize < sliceNameLen + 1)
+            return false;
+
+         buf[-1] = ':';
+
+         cgroup += strlen(str_user_slice_prefix);
+         while(cgroup < sliceSpec) {
+            *buf++ = *cgroup++;
+            bufsize--;
+         }
+         cgroup = userSliceSlash;
+
+         *buf++ = ']';
+         bufsize--;
+
+         continue;
+      }
+
+      if (labelLen > strlen(str_slice_suffix) && String_startsWith(nextSlash - strlen(str_slice_suffix), str_slice_suffix)) {
+         const size_t sliceNameLen = labelLen - strlen(str_slice_suffix);
+         if (bufsize < 2 + sliceNameLen)
+            return false;
+
+         *buf++ = '[';
+         bufsize--;
+
+         for(size_t i = sliceNameLen; i; i--) {
+            *buf++ = *cgroup++;
+            bufsize--;
+         }
+
+         *buf++ = ']';
+         bufsize--;
+
+         cgroup = nextSlash;
+
+         continue;
+      }
+
+      if (String_startsWith(cgroup, str_lxc_payload_prefix)) {
+         const size_t cgroupNameLen = labelLen - strlen(str_lxc_payload_prefix);
+         if (bufsize < 6 + cgroupNameLen)
+            return false;
+
+         *buf++ = '[';
+         *buf++ = 'l';
+         *buf++ = 'x';
+         *buf++ = 'c';
+         *buf++ = ':';
+         bufsize -= 5;
+
+         cgroup += strlen(str_lxc_payload_prefix);
+         while(cgroup < nextSlash) {
+            *buf++ = *cgroup++;
+            bufsize--;
+         }
+
+         *buf++ = ']';
+         bufsize--;
+
+         continue;
+      }
+
+      if (String_startsWith(cgroup, str_lxc_monitor_prefix)) {
+         const size_t cgroupNameLen = labelLen - strlen(str_lxc_monitor_prefix);
+         if (bufsize < 6 + cgroupNameLen)
+            return false;
+
+         *buf++ = '[';
+         *buf++ = 'L';
+         *buf++ = 'X';
+         *buf++ = 'C';
+         *buf++ = ':';
+         bufsize -= 5;
+
+         cgroup += strlen(str_lxc_monitor_prefix);
+         while(cgroup < nextSlash) {
+            *buf++ = *cgroup++;
+            bufsize--;
+         }
+
+         *buf++ = ']';
+         bufsize--;
+
+         continue;
+      }
+
+      if (labelLen > strlen(str_service_suffix) && String_startsWith(nextSlash - strlen(str_service_suffix), str_service_suffix)) {
+         const size_t serviceNameLen = labelLen - strlen(str_service_suffix);
+
+         if (String_startsWith(cgroup, "user@")) {
+            cgroup = nextSlash;
+
+            while(*cgroup == '/')
+               cgroup++;
+
+            continue;
+         }
+
+         if (bufsize < serviceNameLen)
+            return false;
+
+         for(size_t i = serviceNameLen; i; i--) {
+            *buf++ = *cgroup++;
+            bufsize--;
+         }
+
+         cgroup = nextSlash;
+
+         continue;
+      }
+
+      if (labelLen > strlen(str_scope_suffix) && String_startsWith(nextSlash - strlen(str_scope_suffix), str_scope_suffix)) {
+         const size_t scopeNameLen = labelLen - strlen(str_scope_suffix);
+
+         if (String_startsWith(cgroup, str_nspawn_scope_prefix)) {
+            const size_t machineScopeNameLen = scopeNameLen - strlen(str_nspawn_scope_prefix);
+            if (bufsize < 6 + machineScopeNameLen)
+               return false;
+
+            const bool is_monitor = String_startsWith(nextSlash, str_nspawn_monitor_label);
+
+            *buf++ = '[';
+            *buf++ = is_monitor ? 'S' : 's';
+            *buf++ = is_monitor ? 'N' : 'n';
+            *buf++ = is_monitor ? 'C' : 'c';
+            *buf++ = ':';
+            bufsize -= 5;
+
+            cgroup += strlen(str_nspawn_scope_prefix);
+            for(size_t i = machineScopeNameLen; i; i--) {
+               *buf++ = *cgroup++;
+               bufsize--;
+            }
+
+            *buf++ = ']';
+            bufsize--;
+
+            cgroup = nextSlash;
+
+            continue;
+         }
+
+         if (bufsize < 1 + scopeNameLen)
+            return false;
+
+         *buf++ = '!';
+         bufsize--;
+
+         for(size_t i = scopeNameLen; i; i--) {
+            *buf++ = *cgroup++;
+            bufsize--;
+         }
+
+         cgroup = nextSlash;
+
+         continue;
+      }
+
+handle_default:
+      // Default behavior: Copy the full label
+      cgroup = labelStart;
+
+      if (bufsize < (size_t)(nextSlash - cgroup))
+         return false;
+
+      while(cgroup < nextSlash) {
+         *buf++ = *cgroup++;
+         bufsize--;
+      }
+   }
+
+   return true;
+}
+
+bool CGroup_filterName(const char *cgroup, char* buf, size_t bufsize) {
+   memset(buf, 0, bufsize);
+
+   return CGroup_filterName_internal(cgroup, buf, bufsize - 1);
+}