finally () get smart about not leaving stray FDs lying around;

also get smart about blocking fd0 and fd1 for later use.

2 files changed, 93 insertions, 28 deletions

diff --git a/tools/hi-q.c b/tools/hi-q.c
index 5ee7688..3d654c5 100644
--- a/tools/hi-q.c
+++ b/tools/hi-q.c
@@ -22,10 +22,15 @@ using namespace std;
 #include <fstream>
 #include <sstream>
 #include <string>
+#include <list>
 #include <vector>
 #include <sstream>
 #include <map>
 
+#include <sys/types.h>          /* for fstat */
+#include <sys/stat.h>           /* .. */
+#include <unistd.h>             /* .. */
+
 //  error exit codes, mostly as stated in qmail.c
 #define bar \
 foo(good, 0) ;\
@@ -63,6 +68,13 @@ foo_sa(NOPERM,       77,  "permission denied") ;\
 foo_sa(CONFIG,       78,  "configuration error") ;\
 foo_sa(TOOBIG,       98,  "message was too big to process (see --max-size)"
 
+string progname;
+pid_t mypid;
+string progid;
+
+extern char** environ;
+const int rEnd(0);  // end of a pipe for reading
+const int wEnd(1);  // end of a pipe for writing
 
 typedef enum {MSG, ENV} channeler;
 
@@ -204,7 +216,9 @@ void slurp(const int inch, const int ouch){
       break;
     }
     if (got < 0) {
-      fprintf(stderr, "hi-q: input error: ");
+      cerr << progid
+        << " slurp: input error on fd " << inch
+        << " : ";
       perror(0);
       exeunt(ex_comerr);
     }
@@ -214,7 +228,9 @@ void slurp(const int inch, const int ouch){
       ssize_t sent = write(ouch, buf, todo);
       //xx cerr << "slurp: write returns " << sent << endl;
       if (sent < 0 && errno != EINTR) {
-        fprintf(stderr, "hi-q: output error on fd%d : ", ouch);
+        cerr << progid
+          << " slurp: output rror on fd " << ouch
+          << " : ";
         perror(0);
         exeunt(ex_comerr);
       }
@@ -261,10 +277,6 @@ void usage() {
 // we have data coming in on fd 0.
 // and envelope / control information coming in on fd 1.
 
-string progname;
-pid_t mypid;
-string progid;
-
 void dump(const string var){
   char* str = getenv(var.c_str());
   cerr << progid << var;
@@ -277,7 +289,39 @@ int xclose(int arg){
   return close(arg);
 }
 
-extern char** environ;
+typedef list<int> LI;
+void block_fd(const LI todo){
+  int blocker(-1);
+  int inplace(0);
+
+  for (LI::const_iterator ptr = todo.begin();
+        ptr != todo.end(); ptr++) {
+    int fd = *ptr;
+    struct stat statbuf;
+    int rslt = fstat(fd, &statbuf);
+    if (rslt) {
+      if (0) {
+        cerr << "definitely needed to block_fd unit " << fd << " : ";
+        perror(0);
+      }
+      if (blocker < 0) {
+        int blockex[2];
+        pipe(blockex);
+        close(blockex[rEnd]);
+        blocker = blockex[wEnd];
+      }
+      if (blocker != fd){
+        dup2(blocker, fd);
+        close(blocker);
+      } else {
+        inplace++;
+      }
+    } else {
+       if (0) cerr << "unit " << fd << " already blocked" << endl;
+    }
+  }
+  if (!inplace) close(blocker);
+}
 
 string basename(const string path){
   size_t where = path.rfind("/");
@@ -286,7 +330,7 @@ string basename(const string path){
 }
 
 void attach(const int pipe_end, const int fd, const int kidno){
-  cerr << "attaching current pipe_end " << pipe_end 
+  cerr << "attaching current pipe_end " << pipe_end
         << " to " << fd
         << " for " << kidno << endl;
   if (pipe_end != fd) {
@@ -298,7 +342,7 @@ void attach(const int pipe_end, const int fd, const int kidno){
     }
     close(pipe_end);
   }
-  
+
 }
 
 int main(int argc, char** argv) {
@@ -397,8 +441,6 @@ bar
 
   vector<pid_t> kidpid(nkids);  // indexed by kid number
 
-  const int rEnd(0);  // end of a pipe for reading
-  const int wEnd(1);  // end of a pipe for writing
   int sync[2];
   int resync[2];
   if (pipe(sync) != 0) cerr << "sync pipe failed" << endl;
@@ -419,19 +461,30 @@ bar
   int slurp_read(1);            // our original non-standard input
   int slurp_write = -1;         // effectively next_write[ENV];
   map<channeler,int> current_read;
-  map<channeler,int> cur_write;  // current kid writes here
-  cur_write[MSG] = -1;
-  cur_write[ENV] = -1;
+  map<channeler,int> current_write;  // current kid writes here
+  current_write[MSG] = -1;
+  current_write[ENV] = -1;
+  list<int> blockme;
+  blockme.push_back(0);
+  blockme.push_back(1);
 
 // important loop to start all kids
   for (unsigned int ii=0; ii < nkids; ii++){  /* loop starting all kids */
+    string kidid;
+    {
+      stringstream foo;
+      foo << ii
+          << "  mode " << filter[ii].mode
+          << "  " << filter[ii].cmd[0];
+      kidid = foo.str();
+    }
     current_read = next_read;
 
     cerr << "top of loop:  "
-         << "  cr.MSG: " << current_read[MSG] 
+         << "  cr.MSG: " << current_read[MSG]
          << "  cr.ENV: " << current_read[ENV]
-         << "  w.MSG: " << cur_write[MSG] 
-         << "  w.ENV: " << cur_write[ENV]
+         << "  w.MSG: " << current_write[MSG]
+         << "  w.ENV: " << current_write[ENV]
          << "  for " << ii << endl;
     if (current_read[MSG] > 20) exit(99);
     if (current_read[ENV] > 20) exit(99);
@@ -452,6 +505,7 @@ bar
 // this child's output to the next child's input ...
 // except for the special kid, which reads both fd0 and fd1,
 // while writing nothing.
+          block_fd(blockme);
           rslt = pipe(datapipe);
           if (rslt < 0) {
             fprintf(stderr, "hi-q: could not create datapipe: ");
@@ -473,10 +527,13 @@ bar
     }
 
 // figure out the intended bindings:
+    int pardang1(-1), pardang2(-1);     // used by current kid,
+                                        // but dangling, from parent's point of view
     switch (filter[ii].mode) {
       case sa:
       case series:
-          cur_write[MSG] = datapipe[wEnd];
+          pardang1 = current_write[MSG] = datapipe[wEnd];
+          pardang2 = current_read[MSG];
           next_read[MSG] = datapipe[rEnd];
         break;
       case qq:
@@ -484,11 +541,11 @@ bar
             cerr << "???? multiple qq jobs?" << endl;
           }
           slurp_write= datapipe[wEnd];
-          current_read[ENV] = datapipe[rEnd];
+          pardang1 = current_read[ENV] = datapipe[rEnd];
           next_read[ENV] = -1;
           next_read[MSG] = -1;
-          cur_write[ENV] = -1;
-          cur_write[MSG] = -1;
+          current_write[ENV] = -1;
+          current_write[MSG] = -1;
         break;
       case postspam:
       case stub:
@@ -561,7 +618,7 @@ bar
         case sa:
         case series:
             attach(current_read[MSG], 0, ii);
-            attach(cur_write[MSG], 1, ii);
+            attach(current_write[MSG], 1, ii);
           break;
         case stub:
         case postspam:
@@ -612,8 +669,16 @@ bar
     }
 
 // these tricks are for kid:
-    close(cur_write[MSG]);
-    close(cur_write[ENV]);
+    close(current_write[MSG]);
+    close(current_write[ENV]);
+    close(current_read[ENV]);
+    if (0) cerr << "closing " << pardang1
+            << "  for parent of " << kidid << endl;
+
+    close(pardang1);
+    if (0) cerr << "closing " << pardang2
+            << "  for parent of " << kidid << endl;
+    close(pardang2);
 
 // Let kid #0 run a little ways:
     if (ii==0) {
@@ -770,10 +835,10 @@ bar
 // Now it is safe to transfer the envelope information:
 
     if (0) cerr << "about to slurp:  "
-         << "  cr.MSG: " << current_read[MSG] 
+         << "  cr.MSG: " << current_read[MSG]
          << "  cr.ENV: " << current_read[ENV]
-         << "  w.MSG: " << cur_write[MSG] 
-         << "  w.ENV: " << cur_write[ENV]
+         << "  w.MSG: " << current_write[MSG]
+         << "  w.ENV: " << current_write[ENV]
          << "  slurp_read: " << slurp_read
          << "  slurp_write: " << slurp_write
                  << endl;
diff --git a/tools/hi-test4.conf b/tools/hi-test4.conf
index 850784e..c0ef589 100755
--- a/tools/hi-test4.conf
+++ b/tools/hi-test4.conf
@@ -5,7 +5,7 @@
 #! /usr/local/bin/bash-c  set -x ; /bin/echo "a b c " | 1</tmp/a TCPREMOTEHOST=asf TCPREMOTEIP=1.2.3.4  /var/qmail/bin/hi-q $0 ; echo $?
 
 series  /bin/echo "a b c"
-series  /bin/cat
+sa      /bin/cat
 stub    hi-test x0 -snooze 1
 series  /bin/cat
 qq      hi-test -count