Compress cgroup names based on some heuristics

Makefile.am

@@ -153,6 +153,7 @@ linux_platform_headers = \
 	generic/gettime.h \
 	generic/hostname.h \
 	generic/uname.h \
+	linux/CGroupUtils.h \
 	linux/HugePageMeter.h \
 	linux/IOPriority.h \
 	linux/IOPriorityPanel.h \
@@ -174,6 +175,7 @@ linux_platform_sources = \
 	generic/gettime.c \
 	generic/hostname.c \
 	generic/uname.c \
+	linux/CGroupUtils.c \
 	linux/HugePageMeter.c \
 	linux/IOPriorityPanel.c \
 	linux/LibSensors.c \

htop.1.in

@@ -488,7 +488,23 @@ The I/O rate of write(2) in bytes per second, for the process.
 The I/O rate, IO_READ_RATE + IO_WRITE_RATE (see above).
 .TP
 .B CGROUP
-Which cgroup the process is in.
+Which cgroup the process is in. For a shortened view see the CCGROUP column below.
+.TP
+.B CCGROUP
+Shortened view of the cgroup name that the process is in.
+This performs some pattern-based replacements to shorten the displayed string and thus condense the information.
+   \fB/*.slice\fR is shortened to \fB/[*]\fR (exceptions below)
+   \fB/system.slice\fR is shortened to \fB/[S]\fR
+   \fB/user.slice\fR is shortened to \fB/[U]\fR
+   \fB/user-*.slice\fR is shortened to \fB/[U:*]\fR (directly preceeding \fB/[U]\fR before dropped)
+   \fB/machine.slice\fR is shortened to \fB/[M]\fR
+   \fB/machine-*.scope\fR is shortened to \fB/[SNC:*]\fR (SNC: systemd nspawn container), uppercase for the monitor
+   \fB/lxc.monitor.*\fR is shortened to \fB/[LXC:*]\fR
+   \fB/lxc.payload.*\fR is shortened to \fB/[lxc:*]\fR
+   \fB/*.scope\fR is shortened to \fB/!*\fR
+   \fB/*.service\fR is shortened to \fB/*\fR (suffix removed)
+
+Encountered escape sequences (e.g. from systemd) inside the cgroup name are not decoded.
 .TP
 .B OOM
 OOM killer score.

linux/CGroupUtils.c

@@ -0,0 +1,317 @@
+/*
+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"
+
+
+typedef struct StrBuf_state {
+   char *buf;
+   size_t size;
+   size_t pos;
+} StrBuf_state;
+
+typedef bool (*StrBuf_putc_t)(StrBuf_state* p, char c);
+
+static bool StrBuf_putc_count(StrBuf_state* p, ATTR_UNUSED char c) {
+   p->pos++;
+   return true;
+}
+
+static bool StrBuf_putc_write(StrBuf_state* p, char c) {
+   if (p->pos >= p->size)
+      return false;
+
+   p->buf[p->pos] = c;
+   p->pos++;
+   return true;
+}
+
+static bool StrBuf_putsn(StrBuf_state* p, StrBuf_putc_t w, const char* s, size_t count) {
+   while (count--)
+      if (!w(p, *s++))
+         return false;
+
+   return true;
+}
+
+static bool StrBuf_putsz(StrBuf_state* p, StrBuf_putc_t w, const char* s) {
+   while (*s)
+      if (!w(p, *s++))
+         return false;
+
+   return true;
+}
+
+static bool Label_checkEqual(const char* labelStart, size_t labelLen, const char* expected) {
+   return labelLen == strlen(expected) && String_startsWith(labelStart, expected);
+}
+
+static bool Label_checkPrefix(const char* labelStart, size_t labelLen, const char* expected) {
+   return labelLen > strlen(expected) && String_startsWith(labelStart, expected);
+}
+
+static bool Label_checkSuffix(const char* labelStart, size_t labelLen, const char* expected) {
+   return labelLen > strlen(expected) && String_startsWith(labelStart + labelLen - strlen(expected), expected);
+}
+
+static bool CGroup_filterName_internal(const char *cgroup, StrBuf_state* s, StrBuf_putc_t w) {
+   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_legacy = "lxc.monitor";
+   const char* str_lxc_payload_legacy = "lxc.payload";
+   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_nspawn_payload_label = "/payload";
+
+   const char* str_service_suffix = ".service";
+   const char* str_scope_suffix = ".scope";
+
+   while (*cgroup) {
+      if ('/' == *cgroup) {
+         while ('/' == *cgroup)
+            cgroup++;
+
+         if (!w(s, '/'))
+            return false;
+
+         continue;
+      }
+
+      const char* labelStart = cgroup;
+      const char* nextSlash = strchrnul(labelStart, '/');
+      const size_t labelLen = nextSlash - labelStart;
+
+      if (Label_checkEqual(labelStart, labelLen, str_system_slice)) {
+         cgroup = nextSlash;
+
+         if (!StrBuf_putsz(s, w, "[S]"))
+            return false;
+
+         continue;
+      }
+
+      if (Label_checkEqual(labelStart, labelLen, str_machine_slice)) {
+         cgroup = nextSlash;
+
+         if (!StrBuf_putsz(s, w, "[M]"))
+            return false;
+
+         continue;
+      }
+
+      if (Label_checkEqual(labelStart, labelLen, str_user_slice)) {
+         cgroup = nextSlash;
+
+         if (!StrBuf_putsz(s, w, "[U]"))
+            return false;
+
+         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));
+
+         s->pos--;
+         if (!w(s, ':'))
+            return false;
+
+         if (!StrBuf_putsn(s, w, cgroup + strlen(str_user_slice_prefix), sliceNameLen))
+            return false;
+
+         if (!w(s, ']'))
+            return false;
+
+         cgroup = userSliceSlash;
+
+         continue;
+      }
+
+      if (Label_checkSuffix(labelStart, labelLen, str_slice_suffix)) {
+         const size_t sliceNameLen = labelLen - strlen(str_slice_suffix);
+
+         if (!w(s, '['))
+            return false;
+
+         if (!StrBuf_putsn(s, w, cgroup, sliceNameLen))
+            return false;
+
+         if (!w(s, ']'))
+            return false;
+
+         cgroup = nextSlash;
+
+         continue;
+      }
+
+      if (Label_checkPrefix(labelStart, labelLen, str_lxc_payload_prefix)) {
+         const size_t cgroupNameLen = labelLen - strlen(str_lxc_payload_prefix);
+
+         if (!StrBuf_putsz(s, w, "[lxc:"))
+            return false;
+
+         if (!StrBuf_putsn(s, w, cgroup + strlen(str_lxc_payload_prefix), cgroupNameLen))
+            return false;
+
+         if (!w(s, ']'))
+            return false;
+
+         cgroup = nextSlash;
+
+         continue;
+      }
+
+      if (Label_checkPrefix(labelStart, labelLen, str_lxc_monitor_prefix)) {
+         const size_t cgroupNameLen = labelLen - strlen(str_lxc_monitor_prefix);
+
+         if (!StrBuf_putsz(s, w, "[LXC:"))
+            return false;
+
+         if (!StrBuf_putsn(s, w, cgroup + strlen(str_lxc_monitor_prefix), cgroupNameLen))
+            return false;
+
+         if (!w(s, ']'))
+            return false;
+
+         cgroup = nextSlash;
+
+         continue;
+      }
+
+      // LXC legacy cgroup naming
+      if (Label_checkEqual(labelStart, labelLen, str_lxc_monitor_legacy) ||
+         Label_checkEqual(labelStart, labelLen, str_lxc_payload_legacy)) {
+         bool isMonitor = Label_checkEqual(labelStart, labelLen, str_lxc_monitor_legacy);
+
+         labelStart = nextSlash;
+         while (*labelStart == '/')
+            labelStart++;
+
+         nextSlash = strchrnul(labelStart, '/');
+         if (nextSlash - labelStart > 0) {
+            if (!StrBuf_putsz(s, w, isMonitor ? "[LXC:" : "[lxc:"))
+               return false;
+
+            if (!StrBuf_putsn(s, w, labelStart, nextSlash - labelStart))
+               return false;
+
+            if (!w(s, ']'))
+               return false;
+
+            cgroup = nextSlash;
+            continue;
+         }
+
+         labelStart = cgroup;
+         nextSlash = labelStart + labelLen;
+      }
+
+      if (Label_checkSuffix(labelStart, labelLen, str_service_suffix)) {
+         const size_t serviceNameLen = labelLen - strlen(str_service_suffix);
+
+         if (String_startsWith(cgroup, "user@")) {
+            cgroup = nextSlash;
+
+            while(*cgroup == '/')
+               cgroup++;
+
+            continue;
+         }
+
+         if (!StrBuf_putsn(s, w, cgroup, serviceNameLen))
+            return false;
+
+         cgroup = nextSlash;
+
+         continue;
+      }
+
+      if (Label_checkSuffix(labelStart, labelLen, str_scope_suffix)) {
+         const size_t scopeNameLen = labelLen - strlen(str_scope_suffix);
+
+         if (Label_checkPrefix(labelStart, scopeNameLen, str_nspawn_scope_prefix)) {
+            const size_t machineScopeNameLen = scopeNameLen - strlen(str_nspawn_scope_prefix);
+
+            const bool is_monitor = String_startsWith(nextSlash, str_nspawn_monitor_label);
+
+            if (!StrBuf_putsz(s, w, is_monitor ? "[SNC:" : "[snc:"))
+               return false;
+
+            if (!StrBuf_putsn(s, w, cgroup + strlen(str_nspawn_scope_prefix), machineScopeNameLen))
+               return false;
+
+            if (!w(s, ']'))
+               return false;
+
+            cgroup = nextSlash;
+            if (String_startsWith(nextSlash, str_nspawn_monitor_label))
+               cgroup += strlen(str_nspawn_monitor_label);
+            else if (String_startsWith(nextSlash, str_nspawn_payload_label))
+               cgroup += strlen(str_nspawn_payload_label);
+
+            continue;
+         }
+
+         if (!w(s, '!'))
+            return false;
+
+         if (!StrBuf_putsn(s, w, cgroup, scopeNameLen))
+            return false;
+
+         cgroup = nextSlash;
+
+         continue;
+      }
+
+      // Default behavior: Copy the full label
+      cgroup = labelStart;
+
+      if (!StrBuf_putsn(s, w, cgroup, labelLen))
+         return false;
+
+      cgroup = nextSlash;
+   }
+
+   return true;
+}
+
+char* CGroup_filterName(const char *cgroup) {
+   StrBuf_state s = {
+      .buf = NULL,
+      .size = 0,
+      .pos = 0,
+   };
+
+   if (!CGroup_filterName_internal(cgroup, &s, StrBuf_putc_count)) {
+      return NULL;
+   }
+
+   s.buf = xCalloc(s.pos + 1, sizeof(char));
+   s.size = s.pos;
+   s.pos = 0;
+
+   if (!CGroup_filterName_internal(cgroup, &s, StrBuf_putc_write)) {
+      free(s.buf);
+      return NULL;
+   }
+
+   s.buf[s.size] = '\0';
+   return s.buf;
+}

linux/CGroupUtils.h

@@ -0,0 +1,16 @@
+#ifndef HEADER_CGroupUtils
+#define HEADER_CGroupUtils
+/*
+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 <stdbool.h>
+#include <stddef.h>
+
+
+char* CGroup_filterName(const char *cgroup);
+
+#endif /* HEADER_CGroupUtils */