Add fallback for HOME environment variable

If the environment variable HOME is not set, try to get the home
directory from the systems password database.

Settings.c

@@ -10,6 +10,7 @@ in the source distribution for its full text.
 #include <ctype.h>
 #include <errno.h>
 #include <limits.h>
+#include <pwd.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -702,9 +703,10 @@ Settings* Settings_new(unsigned int initialCpuCount, Hashtable* dynamicColumns)
       this->filename = xStrdup(rcfile);
    } else {
       const char* home = getenv("HOME");
-      if (!home)
-         home = "";
-
+      if (!home) {
+         const struct passwd* pw = getpwuid(getuid());
+         home = pw ? pw->pw_dir : "";
+      }
       const char* xdgConfigHome = getenv("XDG_CONFIG_HOME");
       char* configDir = NULL;
       char* htopDir = NULL;

pcp/PCPDynamicColumn.c

@@ -14,6 +14,7 @@ in the source distribution for its full text.
 #include <ctype.h>
 #include <dirent.h>
 #include <errno.h>
+#include <pwd.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -194,6 +195,12 @@ void PCPDynamicColumns_init(PCPDynamicColumns* columns) {
    const char* home = getenv("HOME");
    char* path;
 
+   if (!xdgConfigHome && !home) {
+      const struct passwd* pw = getpwuid(getuid());
+      if (pw)
+         home = pw->pw_dir;
+   }
+
    columns->table = Hashtable_new(0, true);
 
    /* developer paths - PCP_HTOP_DIR=./pcp ./pcp-htop */

pcp/PCPDynamicMeter.c

@@ -12,12 +12,14 @@ in the source distribution for its full text.
 #include <ctype.h>
 #include <dirent.h>
 #include <errno.h>
-#include <pcp/pmapi.h>
+#include <pwd.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
+#include <pcp/pmapi.h>
+
 #include "Macros.h"
 #include "Platform.h"
 #include "RichString.h"
@@ -251,6 +253,12 @@ void PCPDynamicMeters_init(PCPDynamicMeters* meters) {
    const char* home = getenv("HOME");
    char* path;
 
+   if (!xdgConfigHome && !home) {
+      const struct passwd* pw = getpwuid(getuid());
+      if (pw)
+         home = pw->pw_dir;
+   }
+
    meters->table = Hashtable_new(0, true);
 
    /* developer paths - PCP_HTOP_DIR=./pcp ./pcp-htop */