core: allow to specify errno number in SystemCallErrorNumber=

src/core/dbus-execute.c

@@ -1334,20 +1334,18 @@ int bus_exec_context_set_transient_property(
 
         } else if (streq(name, "SystemCallErrorNumber")) {
                 int32_t n;
-                const char *str;
 
                 r = sd_bus_message_read(message, "i", &n);
                 if (r < 0)
                         return r;
 
-                str = errno_to_name(n);
-                if (!str)
+                if (n <= 0 || n > ERRNO_MAX)
                         return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid SystemCallErrorNumber");
 
                 if (mode != UNIT_CHECK) {
                         c->syscall_errno = n;
 
-                        unit_write_drop_in_private_format(u, mode, name, "SystemCallErrorNumber=%s", str);
+                        unit_write_drop_in_private_format(u, mode, name, "SystemCallErrorNumber=%d", n);
                 }
 
                 return 1;

src/core/execute.c

@@ -4129,10 +4129,17 @@ void exec_context_dump(ExecContext *c, FILE* f, const char *prefix) {
                                 prefix, s);
         }
 
-        if (c->syscall_errno > 0)
-                fprintf(f,
-                        "%sSystemCallErrorNumber: %s\n",
-                        prefix, strna(errno_to_name(c->syscall_errno)));
+        if (c->syscall_errno > 0) {
+                const char *errno_name;
+
+                fprintf(f, "%sSystemCallErrorNumber: ", prefix);
+
+                errno_name = errno_to_name(c->syscall_errno);
+                if (errno_name)
+                        fprintf(f, "%s\n", errno_name);
+                else
+                        fprintf(f, "%d\n", c->syscall_errno);
+        }
 
         if (c->apparmor_profile)
                 fprintf(f,

src/core/load-fragment.c

@@ -2839,8 +2839,8 @@ int config_parse_syscall_errno(
                 return 0;
         }
 
-        e = errno_from_name(rvalue);
-        if (e < 0) {
+        e = parse_errno(rvalue);
+        if (e <= 0) {
                 log_syntax(unit, LOG_ERR, filename, line, 0, "Failed to parse error number, ignoring: %s", rvalue);
                 return 0;
         }