startup: look for nanorc and history files also in the XDG directories

When not finding a .nanorc file in the user's home directory, nano will
look for a nanorc file in $XDG_CONFIG_HOME and in the ~/.config/nano/
fallback directory.  And when not finding a .nano/ subdir in the user's
home directory, nano will look for (or create) the history files in
$XDG_DATA_HOME or in the ~/.local/share/nano/ fallback directory.

This is a partial implementation of the XDG Base Directory Specification:
https://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html,
for the purpose of reducing the clutter in a user's home directory, and
to make it easier to back up just the configuration files.

Signed-off-by: Simon Ochsenreither <simon@ochsenreither.de>
Signed-off-by: Benno Schulenberg <bensberg@telfort.nl>

src/global.c

@@ -242,6 +242,8 @@ int interface_color_pair[] = {0};
 
 char *homedir = NULL;
 	/* The user's home directory, from $HOME or /etc/passwd. */
+char *statedir = NULL;
+	/* The directory for nano's history files. */
 char *rcfile_with_errors = NULL;
 	/* The first nanorc file, if any, that produced warnings. */
 

src/history.c

@@ -25,6 +25,19 @@
 #include <string.h>
 
 #ifdef ENABLE_HISTORIES
+
+#ifndef XDG_DATA_FALLBACK
+#define XDG_DATA_FALLBACK "/.local/share"
+#endif
+
+#ifndef SEARCH_HISTORY
+#define SEARCH_HISTORY "search_history"
+#endif
+
+#ifndef POSITION_HISTORY
+#define POSITION_HISTORY "filepos_history"
+#endif
+
 static bool history_changed = FALSE;
 	/* Whether any of the history lists has changed. */
 
@@ -216,29 +229,6 @@ char *get_history_completion(filestruct **h, char *s, size_t len)
 }
 #endif /* ENSABLE_TABCOMP */
 
-/* Return a dynamically-allocated path that is the concatenation of the
- * user's home directory and the given name. */
-char *construct_filename(const char *name)
-{
-    size_t homelen = strlen(homedir);
-    char *joined = charalloc(homelen + strlen(name) + 1);
-
-    strcpy(joined, homedir);
-    strcpy(joined + homelen, name);
-
-    return joined;
-}
-
-char *histfilename(void)
-{
-    return construct_filename("/.nano/search_history");
-}
-
-char *poshistfilename(void)
-{
-    return construct_filename("/.nano/filepos_history");
-}
-
 void history_error(const char *msg, ...)
 {
     va_list ap;
@@ -252,38 +242,56 @@ void history_error(const char *msg, ...)
 	;
 }
 
-/* Check whether the ~/.nano subdirectory for history files exists.  Return
- * TRUE if it exists or was successfully created, and FALSE otherwise. */
-bool have_dotnano(void)
+/* Check whether we have or could make a directory for history files. */
+bool have_statedir(void)
 {
-    bool retval = TRUE;
     struct stat dirstat;
-    char *nanodir = construct_filename("/.nano");
+    char *xdgdatadir;
 
-    if (stat(nanodir, &dirstat) == -1) {
-	if (mkdir(nanodir, S_IRWXU | S_IRWXG | S_IRWXO) == -1) {
+    get_homedir();
+
+    if (homedir != NULL) {
+	statedir = concatenate(homedir, "/.nano/");
+
+	if (stat(statedir, &dirstat) != 0 && S_ISDIR(dirstat.st_mode))
+	    return TRUE;
+    }
+
+    free(statedir);
+    xdgdatadir = getenv("XDG_DATA_HOME");
+
+    if (homedir == NULL && xdgdatadir == NULL)
+	return FALSE;
+
+    if (xdgdatadir != NULL) {
+	statedir = concatenate(xdgdatadir, "/nano/");
+	free(xdgdatadir);
+    } else
+	statedir = concatenate(homedir, XDG_DATA_FALLBACK "/nano/");
+
+    if (stat(statedir, &dirstat) == -1) {
+	if (mkdir(statedir, S_IRWXU | S_IRWXG | S_IRWXO) == -1) {
 	    history_error(N_("Unable to create directory %s: %s\n"
 				"It is required for saving/loading "
 				"search history or cursor positions.\n"),
-				nanodir, strerror(errno));
-	    retval = FALSE;
+				statedir, strerror(errno));
+	    return FALSE;
 	}
     } else if (!S_ISDIR(dirstat.st_mode)) {
 	history_error(N_("Path %s is not a directory and needs to be.\n"
 				"Nano will be unable to load or save "
 				"search history or cursor positions.\n"),
-				nanodir);
-	retval = FALSE;
+				statedir);
+	return FALSE;
     }
 
-    free(nanodir);
-    return retval;
+    return TRUE;
 }
 
 /* Load the histories for Search and Replace and Execute Command. */
 void load_history(void)
 {
-    char *histname = histfilename();
+    char *histname = concatenate(statedir, SEARCH_HISTORY);
     FILE *hisfile = fopen(histname, "rb");
 
     if (hisfile == NULL) {
@@ -356,7 +364,7 @@ void save_history(void)
     if (!history_changed)
 	return;
 
-    histname = histfilename();
+    histname = concatenate(statedir, SEARCH_HISTORY);
     hisfile = fopen(histname, "wb");
 
     if (hisfile == NULL)
@@ -381,7 +389,7 @@ void save_history(void)
 /* Load the recorded cursor positions for files that were edited. */
 void load_poshistory(void)
 {
-    char *poshist = poshistfilename();
+    char *poshist = concatenate(statedir, POSITION_HISTORY);
     FILE *hisfile = fopen(poshist, "rb");
 
     if (hisfile == NULL) {
@@ -447,7 +455,7 @@ void load_poshistory(void)
 /* Save the recorded cursor positions for files that were edited. */
 void save_poshistory(void)
 {
-    char *poshist = poshistfilename();
+    char *poshist = concatenate(statedir, POSITION_HISTORY);
     poshiststruct *posptr;
     FILE *hisfile = fopen(poshist, "wb");
 

src/nano.c

@@ -2357,8 +2357,7 @@ int main(int argc, char **argv)
     /* If we need any of the history files, verify that the user's home
      * directory and its .nano subdirctory exist. */
     if (ISSET(HISTORYLOG) || ISSET(POS_HISTORY)) {
-	get_homedir();
-	if (homedir == NULL || !have_dotnano()) {
+	if (!have_statedir()) {
 	    UNSET(HISTORYLOG);
 	    UNSET(POS_HISTORY);
 	}

src/proto.h

@@ -181,6 +181,7 @@ extern char* specified_color_combo[NUMBER_OF_ELEMENTS];
 extern int interface_color_pair[NUMBER_OF_ELEMENTS];
 
 extern char *homedir;
+extern char *statedir;
 extern char *rcfile_with_errors;
 
 typedef void (*functionptrtype)(void);
@@ -365,7 +366,7 @@ void get_history_newer_void(void);
 #ifdef ENABLE_TABCOMP
 char *get_history_completion(filestruct **h, char *s, size_t len);
 #endif
-bool have_dotnano(void);
+bool have_statedir(void);
 void load_history(void);
 void save_history(void);
 void load_poshistory(void);
@@ -581,6 +582,7 @@ void complete_a_word(void);
 
 /* All functions in utils.c. */
 void get_homedir(void);
+char *concatenate(const char *path, const char *name);
 #ifdef ENABLE_LINENUMBERS
 int digits(ssize_t n);
 #endif

src/rcfile.c

@@ -31,7 +31,7 @@
 #ifdef ENABLE_NANORC
 
 #ifndef RCFILE_NAME
-#define RCFILE_NAME ".nanorc"
+#define RCFILE_NAME "nanorc"
 #endif
 
 static const rcoption rcopts[] = {
@@ -504,11 +504,15 @@ void parse_binding(char *ptr, bool dobind)
     free(keycopy);
 }
 
-/* Verify that the given file is not a folder nor a device. */
+/* Verify that the given file exists, is not a folder nor a device. */
 bool is_good_file(char *file)
 {
     struct stat rcinfo;
 
+    /* First check that the file exists and is readable. */
+    if (access(file, R_OK) != 0)
+	return FALSE;
+
     /* If the thing exists, it may not be a directory nor a device. */
     if (stat(file, &rcinfo) != -1 && (S_ISDIR(rcinfo.st_mode) ||
 		S_ISCHR(rcinfo.st_mode) || S_ISBLK(rcinfo.st_mode))) {
@@ -1211,6 +1215,17 @@ void parse_one_nanorc(void)
 	rcfile_error(N_("Error reading %s: %s"), nanorc, strerror(errno));
 }
 
+bool have_nanorc(char *path, char *name)
+{
+    if (path == NULL)
+	return FALSE;
+
+    free(nanorc);
+    nanorc = concatenate(path, name);
+
+    return is_good_file(nanorc);
+}
+
 /* First read the system-wide rcfile, then the user's rcfile. */
 void do_rcfiles(void)
 {
@@ -1228,18 +1243,22 @@ void do_rcfiles(void)
 
     get_homedir();
 
-    if (homedir == NULL)
-	rcfile_error(N_("I can't find my home directory!  Wah!"));
-    else {
-	nanorc = charealloc(nanorc, strlen(homedir) + strlen(RCFILE_NAME) + 2);
-	sprintf(nanorc, "%s/%s", homedir, RCFILE_NAME);
+    char *xdgconfdir = getenv("XDG_CONFIG_HOME");
 
-	/* Process the current user's nanorc. */
+    /* Now try the to find a nanorc file in the user's home directory
+     * or in the XDG configuration directories. */
+    if (have_nanorc(homedir, "/." RCFILE_NAME))
 	parse_one_nanorc();
-    }
+    else if (have_nanorc(xdgconfdir, "/nano/" RCFILE_NAME))
+	parse_one_nanorc();
+    else if (have_nanorc(homedir, "/.config/nano/" RCFILE_NAME))
+	parse_one_nanorc();
+    else if (homedir == NULL && xdgconfdir == NULL)
+	rcfile_error(N_("I can't find my home directory!  Wah!"));
 
     check_vitals_mapped();
 
+    free(xdgconfdir);
     free(nanorc);
 }
 

src/utils.c

@@ -53,6 +53,18 @@ void get_homedir(void)
     }
 }
 
+/* Return a copy of the two given strings, welded together. */
+char *concatenate(const char *path, const char *name)
+{
+    size_t pathlen = strlen(path);
+    char *joined = charalloc(pathlen + strlen(name) + 1);
+
+    strcpy(joined, path);
+    strcpy(joined + pathlen, name);
+
+    return joined;
+}
+
 #ifdef ENABLE_LINENUMBERS
 /* Return the number of digits that the given integer n takes up. */
 int digits(ssize_t n)