prefork-interp: ident, options

[chiark-utils.git] / cprogs / prefork-interp.c

diff --git a/cprogs/prefork-interp.c b/cprogs/prefork-interp.c
index de9e0af399a33d554857b8bc73f56d8c40352382..61dcca93bf370a578bcd5a72cc5c4ad7b12c3360 100644 (file)
--- a/cprogs/prefork-interp.c
+++ b/cprogs/prefork-interp.c
@@ -7,11 +7,27 @@
  *   prefork-interp  [<option>,..],<interpreter>   <script> [<args> ...]
  *   prefork-interp '[<option> ..] <interpreter>'  <script> [<args> ...]
  *
- * Options must specify argument laundering mode.
- * Currently the only mode supported is:
+ * Options must specify argument mediation approach.
+ * Currently the only argument mediation supported is:
+ *
  *   -U    unlaundered: setup and executor both get all arguments and env vars
  *         ident covers only env vars specified  with -E
  *         ident covers only arguments interpreter and (if present) script
+ *
+ * Options for setting the operation mode:
+ *
+ *   (none)     Default: start new server if needed, then run service
+ *   -f         Force a fresh service (old one is terminated)
+ *   --kill     Kill any existing service; do not actually run anything
+ *
+ * Options for controlling whether different invocations share a server:
+ *
+ *   -E VAR      ident includes env var VAR (or its absence)
+ *   -G STRING   ident includes string STRING
+ *   -g IDENT    use IDENT rather than hex(SHA256(... identity things ...))
+ *
+ * (Ordering of -E and -G options is relevant; invocations with different
+ * -E -G options are different even if the env var settings are the same)
  */
 
 /*
@@ -259,7 +275,7 @@
      the first two words.  (There may or may not be
      further "words"; and if there are they might be binary data.)
      Then split each of the first two words (which will contain only
-     ASCII printing characters) on comma.  Take the initial items:
+     ASCII printing characters) on comma.  Take the first two items:
 
         v1    Protocol version indicator - literal.  If something else,
               fail (means installation is incompatible somehow).
@@ -276,6 +292,8 @@
         WATCHE   liveness watcher stderr          nonblocking
         WATCHI   liveness sentinel                unspecified
 
+        (any further descriptors should be ignored, not closed)
+
   3. Library should do the following:
 
      1. Read and understand the PREFORK_INTERP env var.
@@ -290,7 +308,7 @@
         and make a note to send all error messages to syslog
      7. Enter select loop, looking for the following:
 
-         * accept on LISTEN:
+        A. accept on LISTEN:
             i. see if we need to reload: is any file forming part
                of the program newer than the SECS.NSECS ?
                If so, log at LOG_INFO, and exit immediately
@@ -298,12 +316,13 @@
             ii. see if we can reap any children, possibly waiting
                for children if we are at our concurrency limit
                (limit should be configured through library, default 4)
+               Report child exit status if not zero or SIGPIPE.
             iii. fork service (monitor) child, using accepted fd
 
-         * WATCHE is readable:
-            * EOF:: log at LOG_INFO, and exit
-            * data to read: read what is available immediately,
-              log it as a message at LOG_ERR, and exit
+        B. WATCHE is readable:
+            * EOF: log at LOG_INFO, and exit
+            * data to read: read what is available immediately;
+              it will be an error message: log it at LOG_ERR, and exit
 
   4. service (monitor) child does the following:
 
@@ -340,9 +359,7 @@
       12. set SIGINT to ignored
       13. send SIGINT to the entire process group
       14. wait, blocking, for the executor child
-      15. write the wait status, in 32-bit big-endian, to CALL
-          (this may generate SIGPIPE/EPIPE; if so, die with SIGPIPE
-          or exit 0; do treat SIGPIPE/EPIPE as failure)
+      15. write the wait status, in 32-bit big-endian, to CAL
       16. exit 0
 
      Errors detected in the service monitor should be sent to
@@ -353,11 +370,16 @@
      or perhaps using logger(8) and redirecting stderr (but
      then be careful to ensure everyone gets only the necessary fds).
 
+     EOF on CALL, or EPIPE/SIGPIPE writing to it, are not errors.
+     In this case, exit zero or die with SIGPIPE, so parent
+     won't report error either (part 3 step 7(A)(ii)).
+
 ***************************************************************************
 \f
 */
 
 #include <arpa/inet.h>
+#include <sys/utsname.h>
 
 #include <uv.h>
 
@@ -399,9 +421,29 @@ const struct cmdinfo cmdinfos[]= {
   { 0 }
 };
 
+static void ident_add_stat(const char *path) {
+  struct stat stab;
+  int r = stat(path, &stab);
+  if (r) diee("failed to stat %s", path);
+
+  IDENT_ADD_OBJ(stab.st_dev);
+  IDENT_ADD_OBJ(stab.st_ino);
+}
+
 void ident_addinit(void) {
-  char ident_magic[1] = { 0 };
-  sha256_update(&identsc, sizeof(ident_magic), ident_magic);
+  char magic = 1;
+
+  IDENT_ADD_OBJ(magic);
+
+  struct utsname uts = { };
+  size_t utslen = sizeof(uts);
+  int r = uname(&uts);
+  if (r) diee("uname failed!");
+  IDENT_ADD_OBJ(utslen);
+  IDENT_ADD_OBJ(uts);
+
+  ident_add_stat(".");
+  ident_add_stat("/");
 }
 
 static void propagate_exit_status(int status, const char *what) {