prefork-interp: break out protocol_exchange (nfc)

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

diff --git a/cprogs/prefork-interp.c b/cprogs/prefork-interp.c
index 018a7919ddaa5f0a623e04cbc762f561e64afc91..3ebcf019ccca2c7a84233baa51f75a7d0e770827 100644 (file)
--- a/cprogs/prefork-interp.c
+++ b/cprogs/prefork-interp.c
@@ -6,6 +6,12 @@
  *   prefork-interp  [<option> ..] <interpreter>  [<script> [<args> ...]]
  *   prefork-interp  [<option>,..],<interpreter>   <script> [<args> ...]
  *   prefork-interp '[<option> ..] <interpreter>'  <script> [<args> ...]
+ *
+ * Options must specify argument laundering mode.
+ * Currently the only mode 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
  */
 /*
  * Process structure:
@@ -33,7 +39,7 @@
  *                            forks for server
  *                [2]         exits
  *
- #        server (pm) [1]     [fd0: null],
+ *        server (pm) [1]     [fd0: null],
  *                            [fd[12]: fd2-from-outer]
  *                            right away, forks init monitor
  *                    [2]     closes outer caller fds and call(fake)
@@ -95,11 +101,19 @@ void fusagemessage(FILE *f) {
   fprintf(f, "usage: #!/usr/bin/prefork-interp [<options>]\n");
 }
 
+static int laundering;
+
 const struct cmdinfo cmdinfos[]= {
   PREFORK_CMDINFOS
+  { 0, 'U',   0,                    .iassignto= &laundering,    .arg= 'U' },
   { 0 }
 };
 
+void ident_addinit(void) {
+  char ident_magic[1] = { 0 };
+  sha256_update(&identsc, sizeof(ident_magic), ident_magic);
+}
+
 static void propagate_exit_status(int status, const char *what) {
   int r;
 
@@ -266,6 +280,22 @@ static bool was_eof(FILE *call_sock) {
   return feof(call_sock) || errno==ECONNRESET;
 }
 
+// Does protocol exchange.  Returns 0 if OK, -1 if peer was garbage.
+static int protocol_exchange(FILE *call_sock) {
+  char ack;
+  size_t sr = fread(&ack, sizeof(ack), 1, call_sock);
+  if (sr != 1) {
+    if (was_eof(call_sock)) return -1;
+    diee("read() ack byte");
+  }
+  if (ack != '\n') die("got ack byte 0x%02x, not '\n'", ack);
+
+  // We're committed now, send the request (or bail out)
+  send_request(call_sock);
+
+  return 0;
+}
+
 // Returns: call(client-end), or 0 to mean "is garbage"
 // find_socket_path must have been called
 static FILE *connect_existing(void) {
@@ -286,16 +316,8 @@ static FILE *connect_existing(void) {
   call_sock = call_sock_from_fd(fd);
   fd = -1;
 
-  char ack;
-  size_t sr = fread(&ack, sizeof(ack), 1, call_sock);
-  if (sr != 1) {
-    if (was_eof(call_sock)) goto x_garbage;
-    diee("read() ack byte");
-  }
-  if (ack != '\n') die("got ack byte 0x%02x, not '\n'", ack);
-
-  // We're committed now, send the request (or bail out)
-  send_request(call_sock);
+  if (protocol_exchange(call_sock) < 0)
+    goto x_garbage;
 
   return call_sock;
 
@@ -376,6 +398,11 @@ static FILE *connect_or_spawn(void) {
 }
 
 static void make_executor_argv(const char *const *argv) {
+  switch (laundering) {
+  case 'U': break;
+  default: die("need -U (specifying unlaundered argument handling)");
+  }
+
   const char *arg;
   #define EACH_NEW_ARG(EACH) {                 \
     arg = interp; { EACH }                     \