config: Expand leading ~ in paths

cm_dir and CM_CONFIG do not expand a leading ~, which forces
absolute $HOME paths in shell configuration and scripts.

Expand leading ~ to $HOME for path settings and document the
behaviour, with integration coverage for CM_DIR and CM_CONFIG.

Author: cdown

man/clipmenu.conf.5

@@ -64,12 +64,14 @@ browsers). Set to 0 to disable partial merging entirely. Default: 2.
 Overrides the default directory for the clip store. This is by default at a
 subdirectory inside XDG_RUNTIME_DIR, TMPDIR, or if both are unset, inside /tmp.
 The path must be absolute.
+A leading ~ expands to $HOME.
 .SH FILE LOCATION
 Typically, clipmenu.conf is located at
 .BR ~/.config/clipmenu/clipmenu.conf
 .
 The file location can be overridden with $CM_CONFIG, which must be an absolute
 path.
+A leading ~ expands to $HOME.
 .SH SEE ALSO
 .BR clipctl (1),
 .BR clipdel (1),

src/config.c

@@ -53,6 +53,40 @@ static bool is_absolute_path(const char *path) {
     return path && path[0] == '/';
 }
 
+static int resolve_path(const char *input, void *output) {
+    char **out_path = output;
+    if (!input) {
+        return -EINVAL;
+    }
+
+    if (input[0] == '~') {
+        if (input[1] != '\0' && input[1] != '/') {
+            return -EINVAL;
+        }
+        const char *home = getenv("HOME");
+        if (!home) {
+            return -EINVAL;
+        }
+        size_t len = strlen(home) + strlen(input);
+        char *expanded = malloc(len);
+        expect(expanded);
+        snprintf_safe(expanded, len, "%s%s", home, input + 1);
+        *out_path = expanded;
+    } else {
+        char *dup = strdup(input);
+        expect(dup);
+        *out_path = dup;
+    }
+
+    if (!is_absolute_path(*out_path)) {
+        free(*out_path);
+        *out_path = NULL;
+        return -EINVAL;
+    }
+
+    return 0;
+}
+
 /**
  * This whole section consists of conversion functions to go from a string in
  * the config file to the type we expect for `struct Config`.
@@ -105,13 +139,7 @@ static int convert_cm_dir(const char *str, void *output) {
     if (!str) {
         str = get_runtime_directory();
     }
-    if (!is_absolute_path(str)) {
-        return -EINVAL;
-    }
-    char *rtd = strdup(str);
-    expect(rtd);
-    *(char **)output = rtd;
-    return 0;
+    return resolve_path(str, output);
 }
 
 static int _nonnull_ convert_launcher(const char *str, void *output) {
@@ -175,29 +203,39 @@ static int get_config_file(char *config_path, size_t config_path_len) {
     const char *cm_config = getenv("CM_CONFIG");
     const char *xdg_config_home = getenv("XDG_CONFIG_HOME");
     const char *home = getenv("HOME");
+    _drop_(free) char *resolved = NULL;
 
     if (cm_config) {
-        if (!is_absolute_path(cm_config)) {
-            fprintf(stderr, "Error parsing config file path\n");
-            return -EINVAL;
+        int ret = resolve_path(cm_config, &resolved);
+        if (ret != 0) {
+            fprintf(stderr,
+                    "Invalid config path from $CM_CONFIG: expected absolute "
+                    "path or leading ~\n");
+            return ret;
         }
-        snprintf_safe(config_path, config_path_len, "%s", cm_config);
+        snprintf_safe(config_path, config_path_len, "%s", resolved);
     } else if (xdg_config_home) {
-        if (!is_absolute_path(xdg_config_home)) {
-            fprintf(stderr, "Error parsing config file path\n");
-            return -EINVAL;
+        int ret = resolve_path(xdg_config_home, &resolved);
+        if (ret != 0) {
+            fprintf(stderr,
+                    "Invalid config path from $XDG_CONFIG_HOME: expected "
+                    "absolute path or leading ~\n");
+            return ret;
         }
         snprintf_safe(config_path, config_path_len, "%s/clipmenu/clipmenu.conf",
-                      xdg_config_home);
+                      resolved);
     } else {
         die_on(!home,
                "None of $CM_CONFIG, $XDG_CONFIG_HOME, or $HOME is set\n");
-        if (!is_absolute_path(home)) {
-            fprintf(stderr, "Error parsing config file path\n");
-            return -EINVAL;
+        int ret = resolve_path(home, &resolved);
+        if (ret != 0) {
+            fprintf(stderr,
+                    "Invalid config path from $HOME: expected absolute path or "
+                    "leading ~\n");
+            return ret;
         }
         snprintf_safe(config_path, config_path_len,
-                      "%s/.config/clipmenu/clipmenu.conf", home);
+                      "%s/.config/clipmenu/clipmenu.conf", resolved);
     }
 
     return 0;

tests/x_integration_tests

@@ -57,6 +57,22 @@ EOF
 chmod a+x "$launcher"
 export CM_LAUNCHER="$launcher"
 
+tilde_home=$(mktemp -d)
+tilde_dir="$tilde_home/clipmenu_tilde"
+mkdir -p "$tilde_dir"
+uid=$(id -u)
+HOME="$tilde_home" CM_DIR="~/clipmenu_tilde" CM_CONFIG="$(mktemp)" \
+    clipmenu || true
+[[ -d "$tilde_dir/clipmenu.7.$uid" ]]
+rm -rf "$tilde_home"
+
+tilde_conf_home=$(mktemp -d)
+printf 'max_clips nope\n' > "$tilde_conf_home/bad.conf"
+err=$(HOME="$tilde_conf_home" CM_CONFIG="~/bad.conf" CM_DIR="$(mktemp -d)" \
+    clipmenu 2>&1 || true)
+[[ "$err" == *"for max_clips"* ]]
+rm -rf "$tilde_conf_home"
+
 kill_background_jobs() {
     local -a bg
     readarray -t bg < <(jobs -p)