Merge pull request #3470 from ZyX-I/pr-3198

XDG base directory specification support

7 files changed, 201 insertions, 42 deletions

diff --git a/src/nvim/os/env.c b/src/nvim/os/env.c
index 7be8a868bd..bf6db97fcf 100644
--- a/src/nvim/os/env.c
+++ b/src/nvim/os/env.c
@@ -415,6 +415,74 @@ static char *remove_tail(char *p, char *pend, char *name)
   return pend;
 }
 
+/// Iterate over colon-separated list
+///
+/// @note Environment variables must not be modified during iteration.
+///
+/// @param[in]   val   Value of the environment variable to iterate over.
+/// @param[in]   iter  Pointer used for iteration. Must be NULL on first
+///                    iteration.
+/// @param[out]  dir   Location where pointer to the start of the current
+///                    directory name should be saved. May be set to NULL.
+/// @param[out]  len   Location where current directory length should be saved.
+///
+/// @return Next iter argument value or NULL when iteration should stop.
+const void *vim_colon_env_iter(const char *const val,
+                               const void *const iter,
+                               const char **const dir,
+                               size_t *const len)
+  FUNC_ATTR_NONNULL_ARG(1, 3, 4) FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  const char *varval = (const char *) iter;
+  if (varval == NULL) {
+    varval = val;
+  }
+  *dir = varval;
+  const char *const dirend = strchr(varval, ':');
+  if (dirend == NULL) {
+    *len = strlen(varval);
+    return NULL;
+  } else {
+    *len = (size_t) (dirend - varval);
+    return dirend + 1;
+  }
+}
+
+/// Iterate over colon-separated list in reverse order
+///
+/// @note Environment variables must not be modified during iteration.
+///
+/// @param[in]   val   Value of the environment variable to iterate over.
+/// @param[in]   iter  Pointer used for iteration. Must be NULL on first
+///                    iteration.
+/// @param[out]  dir   Location where pointer to the start of the current
+///                    directory name should be saved. May be set to NULL.
+/// @param[out]  len   Location where current directory length should be saved.
+///
+/// @return Next iter argument value or NULL when iteration should stop.
+const void *vim_colon_env_iter_rev(const char *const val,
+                                   const void *const iter,
+                                   const char **const dir,
+                                   size_t *const len)
+  FUNC_ATTR_NONNULL_ARG(1, 3, 4) FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  const char *varend = (const char *) iter;
+  if (varend == NULL) {
+    varend = val + strlen(val) - 1;
+  }
+  const size_t varlen = (size_t) (varend - val) + 1;
+  const char *const colon = xmemrchr(val, ':', varlen);
+  if (colon == NULL) {
+    *len = varlen;
+    *dir = val;
+    return NULL;
+  } else {
+    *dir = colon + 1;
+    *len = (size_t) (varend - colon);
+    return colon - 1;
+  }
+}
+
 /// Vim's version of getenv().
 /// Special handling of $HOME, $VIM and $VIMRUNTIME, allowing the user to
 /// override the vim runtime directory at runtime.  Also does ACP to 'enc'
diff --git a/src/nvim/os/fs.c b/src/nvim/os/fs.c
index 522e49950c..05f0f53c63 100644
--- a/src/nvim/os/fs.c
+++ b/src/nvim/os/fs.c
@@ -366,11 +366,17 @@ int os_mkdir_recurse(const char *const dir, int32_t mode,
   }
   while (e != real_end) {
     if (e > past_head) {
-      *e = '/';
+      *e = PATHSEP;
     } else {
       *past_head = past_head_save;
     }
-    e += strlen(e);
+    const size_t component_len = strlen(e);
+    e += component_len;
+    if (e == real_end
+        && memcnt(e - component_len, PATHSEP, component_len) == component_len) {
+      // Path ends with something like "////". Ignore this.
+      break;
+    }
     int ret;
     if ((ret = os_mkdir(curdir, mode)) != 0) {
       *failed_dir = curdir;
diff --git a/src/nvim/os/os.h b/src/nvim/os/os.h
index 69bd1ff4fd..3e89e5a94a 100644
--- a/src/nvim/os/os.h
+++ b/src/nvim/os/os.h
@@ -5,6 +5,7 @@
 #include <uv.h>
 
 #include "nvim/os/fs_defs.h"
+#include "nvim/os/stdpaths_defs.h"
 #include "nvim/vim.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
@@ -12,6 +13,7 @@
 # include "os/mem.h.generated.h"
 # include "os/env.h.generated.h"
 # include "os/users.h.generated.h"
+# include "os/stdpaths.h.generated.h"
 #endif
 
 #endif  // NVIM_OS_OS_H
diff --git a/src/nvim/os/stdpaths.c b/src/nvim/os/stdpaths.c
new file mode 100644
index 0000000000..ce374828f9
--- /dev/null
+++ b/src/nvim/os/stdpaths.c
@@ -0,0 +1,108 @@
+#include <stdbool.h>
+
+#include "nvim/os/stdpaths_defs.h"
+#include "nvim/os/os.h"
+#include "nvim/path.h"
+#include "nvim/memory.h"
+#include "nvim/ascii.h"
+
+/// Names of the environment variables, mapped to XDGVarType values
+static const char *xdg_env_vars[] = {
+  [kXDGConfigHome] = "XDG_CONFIG_HOME",
+  [kXDGDataHome] = "XDG_DATA_HOME",
+  [kXDGCacheHome] = "XDG_CACHE_HOME",
+  [kXDGRuntimeDir] = "XDG_RUNTIME_DIR",
+  [kXDGConfigDirs] = "XDG_CONFIG_DIRS",
+  [kXDGDataDirs] = "XDG_DATA_DIRS",
+};
+
+/// Defaults for XDGVarType values
+///
+/// Used in case environment variables contain nothing. Need to be expanded.
+static const char *const xdg_defaults[] = {
+#ifdef WIN32
+  // Windows
+  [kXDGConfigHome] = "$LOCALAPPDATA\\nvim\\config",
+  [kXDGDataHome]   = "$LOCALAPPDATA\\nvim\\data",
+  [kXDGCacheHome]  = "$LOCALAPPDATA\\nvim\\cache",
+  [kXDGRuntimeDir] = "",
+  [kXDGConfigDirs] = NULL,
+  [kXDGDataDirs] = NULL,
+#else
+  // Linux, BSD, CYGWIN, Apple
+  [kXDGConfigHome] = "~/.config",
+  [kXDGDataHome] = "~/.local/share",
+  [kXDGCacheHome] = "~/.cache",
+  [kXDGRuntimeDir] = "",
+  [kXDGConfigDirs] = "/etc/xdg/",
+  [kXDGDataDirs] = "/usr/local/share/:/usr/share/",
+#endif
+};
+
+/// Return XDG variable value
+///
+/// @param[in]  idx  XDG variable to use.
+///
+/// @return [allocated] variable value.
+char *stdpaths_get_xdg_var(const XDGVarType idx)
+  FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  const char *const env = xdg_env_vars[idx];
+  const char *const fallback = xdg_defaults[idx];
+
+  const char *const env_val = os_getenv(env);
+  char *ret = NULL;
+  if (env_val != NULL) {
+    ret = xstrdup(env_val);
+  } else if (fallback) {
+    ret = (char *) expand_env_save((char_u *)fallback);
+  }
+
+  return ret;
+}
+
+/// Return nvim-specific XDG directory subpath
+///
+/// @param[in]  idx  XDG directory to use.
+///
+/// @return [allocated] `{xdg_directory}/nvim`
+static char *get_xdg_home(const XDGVarType idx)
+  FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  char *dir = stdpaths_get_xdg_var(idx);
+  if (dir) {
+    dir = concat_fnames_realloc(dir, "nvim", true);
+  }
+  return dir;
+}
+
+/// Return subpath of $XDG_CONFIG_HOME
+///
+/// @param[in]  fname  New component of the path.
+///
+/// @return [allocated] `$XDG_CONFIG_HOME/nvim/{fname}`
+char *stdpaths_user_conf_subpath(const char *fname)
+  FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ALL
+{
+  return concat_fnames_realloc(get_xdg_home(kXDGConfigHome), fname, true);
+}
+
+/// Return subpath of $XDG_DATA_HOME
+///
+/// @param[in]  fname  New component of the path.
+/// @param[in]  trailing_pathseps  Amount of trailing path separators to add.
+///
+/// @return [allocated] `$XDG_DATA_HOME/nvim/{fname}`
+char *stdpaths_user_data_subpath(const char *fname,
+                                 const size_t trailing_pathseps)
+  FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ALL
+{
+  char *ret = concat_fnames_realloc(get_xdg_home(kXDGDataHome), fname, true);
+  if (trailing_pathseps) {
+    const size_t len = strlen(ret);
+    ret = xrealloc(ret, len + trailing_pathseps + 1);
+    memset(ret + len, PATHSEP, trailing_pathseps);
+    ret[len + trailing_pathseps] = NUL;
+  }
+  return ret;
+}
diff --git a/src/nvim/os/stdpaths_defs.h b/src/nvim/os/stdpaths_defs.h
new file mode 100644
index 0000000000..1433e0bc62
--- /dev/null
+++ b/src/nvim/os/stdpaths_defs.h
@@ -0,0 +1,14 @@
+#ifndef NVIM_OS_STDPATHS_DEFS_H
+#define NVIM_OS_STDPATHS_DEFS_H
+
+/// List of possible XDG variables
+typedef enum {
+  kXDGConfigHome,  ///< XDG_CONFIG_HOME
+  kXDGDataHome,    ///< XDG_DATA_HOME
+  kXDGCacheHome,   ///< XDG_CACHE_HOME
+  kXDGRuntimeDir,  ///< XDG_RUNTIME_DIR
+  kXDGConfigDirs,  ///< XDG_CONFIG_DIRS
+  kXDGDataDirs,    ///< XDG_DATA_DIRS
+} XDGVarType;
+
+#endif  // NVIM_OS_STDPATHS_DEFS_H
diff --git a/src/nvim/os/unix_defs.h b/src/nvim/os/unix_defs.h
index 949973bf40..b1511d4b56 100644
--- a/src/nvim/os/unix_defs.h
+++ b/src/nvim/os/unix_defs.h
@@ -20,7 +20,7 @@
 
 // Unix system-dependent file names
 #ifndef SYS_VIMRC_FILE
-# define SYS_VIMRC_FILE "$VIM/nvimrc"
+# define SYS_VIMRC_FILE "$VIM/sysinit.vim"
 #endif
 #ifndef DFLT_HELPFILE
 # define DFLT_HELPFILE  "$VIMRUNTIME/doc/help.txt"
@@ -28,46 +28,11 @@
 #ifndef SYNTAX_FNAME
 # define SYNTAX_FNAME   "$VIMRUNTIME/syntax/%s.vim"
 #endif
-#ifndef USR_EXRC_FILE
-# define USR_EXRC_FILE "~/.exrc"
-#endif
-#ifndef USR_VIMRC_FILE
-# define USR_VIMRC_FILE "~/.nvimrc"
-#endif
-#ifndef USR_VIMRC_FILE2
-# define USR_VIMRC_FILE2     "~/.nvim/nvimrc"
-#endif
 #ifndef EXRC_FILE
 # define EXRC_FILE      ".exrc"
 #endif
 #ifndef VIMRC_FILE
 # define VIMRC_FILE     ".nvimrc"
 #endif
-#ifndef SHADA_FILE
-# define SHADA_FILE "~/.nvim/shada/main.shada"
-#endif
-
-// Default for 'backupdir'.
-#ifndef DFLT_BDIR
-# define DFLT_BDIR    ".,~/tmp,~/"
-#endif
-
-// Default for 'directory'.
-#ifndef DFLT_DIR
-# define DFLT_DIR     ".,~/tmp,/var/tmp,/tmp"
-#endif
-
-// Default for 'viewdir'.
-#ifndef DFLT_VDIR
-# define DFLT_VDIR    "~/.nvim/view"
-#endif
-
-#ifdef RUNTIME_GLOBAL
-# define DFLT_RUNTIMEPATH "~/.nvim," RUNTIME_GLOBAL ",$VIMRUNTIME," \
-  RUNTIME_GLOBAL "/after,~/.nvim/after"
-#else
-# define DFLT_RUNTIMEPATH \
-  "~/.nvim,$VIM/vimfiles,$VIMRUNTIME,$VIM/vimfiles/after,~/.nvim/after"
-#endif
 
 #endif  // NVIM_OS_UNIX_DEFS_H
diff --git a/src/nvim/os/win_defs.h b/src/nvim/os/win_defs.h
index b7ec50a109..d614582250 100644
--- a/src/nvim/os/win_defs.h
+++ b/src/nvim/os/win_defs.h
@@ -7,13 +7,9 @@
 #define TEMP_FILE_PATH_MAXLEN _MAX_PATH
 
 // Defines needed to fix the build on Windows:
-// - USR_EXRC_FILE
-// - USR_VIMRC_FILE
-// - SHADA_FILE
 // - DFLT_DIR
 // - DFLT_BDIR
 // - DFLT_VDIR
-// - DFLT_RUNTIMEPATH
 // - EXRC_FILE
 // - VIMRC_FILE
 // - SYNTAX_FNAME