consolidate getting home and data dir into helper functions (#2101)

Co-authored-by: Fabian Greffrath <fabian@brainbug>

CMakeLists.txt

@@ -53,6 +53,7 @@ check_library_exists(m pow "" HAVE_LIBM)
 check_include_file("dirent.h" HAVE_DIRENT_H)
 check_symbol_exists(strcasecmp "strings.h" HAVE_DECL_STRCASECMP)
 check_symbol_exists(strncasecmp "strings.h" HAVE_DECL_STRNCASECMP)
+check_symbol_exists(getpwuid "unistd.h;sys/types.h;pwd.h" HAVE_GETPWUID)
 check_c_source_compiles("
     #include <windows.h>
     int main()

config.h.in

@@ -6,6 +6,7 @@
 #cmakedefine HAVE_DIRENT_H
 #cmakedefine01 HAVE_DECL_STRCASECMP
 #cmakedefine01 HAVE_DECL_STRNCASECMP
+#cmakedefine HAVE_GETPWUID
 #cmakedefine HAVE_HIGH_RES_TIMER
 #cmakedefine HAVE__DIV64
 #cmakedefine HAVE_ALSA

src/d_iwad.c

@@ -486,33 +486,12 @@ static void AddIWADPath(const char *path, const char *suffix)
 // <http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html>
 static void AddXdgDirs(void)
 {
-    char *env, *tmp_env;
-
-    // Quote:
-    // > $XDG_DATA_HOME defines the base directory relative to which
-    // > user specific data files should be stored. If $XDG_DATA_HOME
-    // > is either not set or empty, a default equal to
-    // > $HOME/.local/share should be used.
-    env = M_getenv("XDG_DATA_HOME");
-    tmp_env = NULL;
-
-    if (env == NULL)
-    {
-        char *homedir = M_getenv("HOME");
-        if (homedir == NULL)
-        {
-            homedir = "/";
-        }
-
-        tmp_env = M_StringJoin(homedir, "/.local/share");
-        env = tmp_env;
-    }
+    char *env = M_DataDir();
 
     // We support $XDG_DATA_HOME/games/doom (which will usually be
     // ~/.local/share/games/doom) as a user-writeable extension to
     // the usual /usr/share/games/doom location.
     AddIWADDir(M_StringJoin(env, "/games/doom"));
-    free(tmp_env);
 
     // Quote:
     // > $XDG_DATA_DIRS defines the preference-ordered set of base
@@ -550,11 +529,7 @@ static void AddSteamDirs(void)
 {
     char *homedir, *steampath;
 
-    homedir = M_getenv("HOME");
-    if (homedir == NULL)
-    {
-        homedir = "/";
-    }
+    homedir = M_HomeDir();
     steampath = M_StringJoin(homedir, "/.steam/root/steamapps/common");
 
     AddIWADPath(steampath, "/Doom 2/base");
@@ -602,11 +577,8 @@ void BuildIWADDirList(void)
     }
 
     // [FG] Add plain HOME directory
-    env = M_getenv("HOME");
-    if (env != NULL)
-    {
-        AddIWADDir(env);
-    }
+    env = M_HomeDir();
+    AddIWADDir(env);
 
 #ifdef _WIN32
 

src/i_flmusic.c

@@ -121,21 +121,10 @@ static void ScanDir(const char *dir, boolean recursion)
         const char usr_share[] = "/usr/share";
         if (strncmp(dir, usr_share, strlen(usr_share)) == 0)
         {
-            char *home_dir = M_getenv("XDG_DATA_HOME");
-
-            if (home_dir == NULL)
-            {
-                home_dir = M_getenv("HOME");
-            }
-
-            if (home_dir)
-            {
-                char *local_share = M_StringJoin(home_dir, "/.local/share");
-                char *local_dir = M_StringReplace(dir, usr_share, local_share);
-                free(local_share);
-                ScanDir(local_dir, true);
-                free(local_dir);
-            }
+            char *local_share = M_DataDir();
+            char *local_dir = M_StringReplace(dir, usr_share, local_share);
+            ScanDir(local_dir, true);
+            free(local_dir);
         }
         else if (dir[0] == '.')
         {

src/m_misc.c

@@ -27,6 +27,13 @@
 #include "m_misc.h"
 #include "z_zone.h"
 
+#include "config.h"
+#ifdef HAVE_GETPWUID
+#include <unistd.h>
+#include <sys/types.h>
+#include <pwd.h>
+#endif
+
 // Check if a file exists
 
 boolean M_FileExists(const char *filename)
@@ -231,6 +238,53 @@ const char *M_BaseName(const char *path)
     }
 }
 
+char *M_HomeDir(void)
+{
+    static char *home_dir;
+
+    if (home_dir == NULL)
+    {
+        home_dir = M_getenv("HOME");
+
+        if (home_dir == NULL)
+        {
+#ifdef HAVE_GETPWUID
+            struct passwd *user_info = getpwuid(getuid());
+            if (user_info != NULL)
+                home_dir = user_info->pw_dir;
+            else
+#endif
+                home_dir = "/";
+        }
+    }
+
+    return home_dir;
+}
+
+// Quote:
+// > $XDG_DATA_HOME defines the base directory relative to which
+// > user specific data files should be stored. If $XDG_DATA_HOME
+// > is either not set or empty, a default equal to
+// > $HOME/.local/share should be used.
+
+char *M_DataDir(void)
+{
+    static char *data_dir;
+
+    if (data_dir == NULL)
+    {
+        data_dir = M_getenv("XDG_DATA_HOME");
+
+        if (data_dir == NULL || *data_dir == '\0')
+        {
+            const char *home_dir = M_HomeDir();
+            data_dir = M_StringJoin(home_dir, "/.local/share");
+        }
+    }
+
+    return data_dir;
+}
+
 // Change string to uppercase.
 
 char M_ToUpper(const char c)

src/m_misc.h

@@ -31,6 +31,8 @@ char *M_FileCaseExists(const char *file);
 boolean M_StrToInt(const char *str, int *result);
 char *M_DirName(const char *path);
 const char *M_BaseName(const char *path);
+char *M_HomeDir(void);
+char *M_DataDir(void);
 char M_ToUpper(const char c);
 void M_StringToUpper(char *text);
 char M_ToLower(const char c);