[systemd-devel] [PATCHv2] "-" prefix for InaccessibleDirectories and ReadOnlyDirectories

[Maciej Wereski]

---
v2:
- modify manpage
---
 TODO                     |  3 ---
 man/systemd.exec.xml     |  6 +++++-
 src/core/namespace.c     | 12 +++++++++++-
 src/shared/conf-parser.c | 27 +++++++++++++++++----------
 4 files changed, 33 insertions(+), 15 deletions(-)

diff --git a/TODO b/TODO
index 9bc14fd..97f2bcf 100644
--- a/TODO
+++ b/TODO
@@ -287,9 +287,6 @@ Features:
 
 * timedate: have global on/off switches for auto-time (NTP), and auto-timezone that connman can subscribe to.
 
-* Honour "-" prefix for InaccessibleDirectories= and ReadOnlyDirectories= to
-  suppress errors of the specified path doesn't exist
-
 * dev-setup.c: when running in a container, create a tiny stub udev
   database with the systemd tag set for all network interfaces found,
   so that libudev reports them as present, and systemd's .device units
diff --git a/man/systemd.exec.xml b/man/systemd.exec.xml
index c0e1d86..93be660 100644
--- a/man/systemd.exec.xml
+++ b/man/systemd.exec.xml
@@ -828,7 +828,11 @@
                                 the empty string is assigned to this
                                 option the specific list is reset, and
                                 all prior assignments have no
-                                effect.</para></listitem>
+                                effect.</para>
+                                <para>If paths in <varname>ReadOnlyDirectories=</varname>
+                                or <varname>InaccessibleDirectories=</varname>
+                                start with "-", then errors will be
+                                supressed if path doesn't exist.</para></listitem>
                         </varlistentry>
 
                         <varlistentry>
diff --git a/src/core/namespace.c b/src/core/namespace.c
index 7e33d84..16b132b 100644
--- a/src/core/namespace.c
+++ b/src/core/namespace.c
@@ -51,6 +51,7 @@ typedef struct BindMount {
         const char *path;
         MountMode mode;
         bool done;
+        bool ignore;
 } BindMount;
 
 static int append_mounts(BindMount **p, char **strv, MountMode mode) {
@@ -58,6 +59,13 @@ static int append_mounts(BindMount **p, char **strv, MountMode mode) {
 
         STRV_FOREACH(i, strv) {
 
+                (*p)->ignore = false;
+
+                if ((mode == INACCESSIBLE || mode == READONLY) && (*i)[0] == '-') {
+                        (*p)->ignore = true;
+                        (*i)++;
+                }
+
                 if (!path_is_absolute(*i))
                         return -EINVAL;
 
@@ -155,6 +163,8 @@ static int apply_mount(
         r = mount(what, m->path, NULL, MS_BIND|MS_REC, NULL);
         if (r >= 0)
                 log_debug("Successfully mounted %s to %s", what, m->path);
+        else if (m->ignore && errno == ENOENT)
+                r = 0;
 
         return r;
 }
@@ -168,7 +178,7 @@ static int make_read_only(BindMount *m) {
                 return 0;
 
         r = mount(NULL, m->path, NULL, MS_BIND|MS_REMOUNT|MS_RDONLY|MS_REC, NULL);
-        if (r < 0)
+        if (r < 0 && !(m->ignore && errno == ENOENT))
                 return -errno;
 
         return 0;
diff --git a/src/shared/conf-parser.c b/src/shared/conf-parser.c
index 2303d9a..b27c7eb 100644
--- a/src/shared/conf-parser.c
+++ b/src/shared/conf-parser.c
@@ -611,11 +611,11 @@ int config_parse_path(const char *unit,
                 return 0;
         }
 
-        if (!path_is_absolute(rvalue)) {
-                log_syntax(unit, LOG_ERR, filename, line, EINVAL,
-                           "Not an absolute path, ignoring: %s", rvalue);
-                return 0;
-        }
+        if (streq(lvalue, "InaccessibleDirectories") || streq(lvalue, "ReadOnlyDirectories")) {
+                if (!path_is_absolute(rvalue) && (rvalue[0] != '-' || !path_is_absolute(rvalue+1)))
+                        goto fail;
+        } else if (!path_is_absolute(rvalue)) 
+                goto fail;
 
         n = strdup(rvalue);
         if (!n)
@@ -627,6 +627,9 @@ int config_parse_path(const char *unit,
         *s = n;
 
         return 0;
+fail:
+        log_syntax(unit, LOG_ERR, filename, line, EINVAL, "Not an absolute path, ignoring: %s", rvalue);
+        return 0;
 }
 
 int config_parse_strv(const char *unit,
@@ -724,11 +727,11 @@ int config_parse_path_strv(const char *unit,
                         continue;
                 }
 
-                if (!path_is_absolute(n)) {
-                        log_syntax(unit, LOG_ERR, filename, line, EINVAL,
-                                   "Not an absolute path, ignoring: %s", rvalue);
-                        continue;
-                }
+                if (streq(lvalue, "InaccessibleDirectories") || streq(lvalue, "ReadOnlyDirectories")) {
+                        if (!path_is_absolute(n) && (n[0] != '-' || !path_is_absolute(n+1)))
+                                goto fail;
+                } else if (!path_is_absolute(n))
+                        goto fail;
 
                 path_kill_slashes(n);
                 r = strv_extend(sv, n);
@@ -737,6 +740,10 @@ int config_parse_path_strv(const char *unit,
         }
 
         return 0;
+
+fail:
+        log_syntax(unit, LOG_ERR, filename, line, EINVAL, "Not an absolute path, ignoring: %s", rvalue);
+        return 0;
 }
 
 int config_parse_mode(const char *unit,
-- 
1.8.3.4