pacmd: don't enter busy loop when reading from stdin very early

pointed out in:

https://tango.0pointer.de/pipermail/pulseaudio-discuss/2010-January/006365.html

1 files changed, 100 insertions, 86 deletions

diff --git a/src/utils/pacmd.c b/src/utils/pacmd.c
index 59aae480..87661e31 100644
--- a/src/utils/pacmd.c
+++ b/src/utils/pacmd.c
@@ -45,13 +45,6 @@
 
 int main(int argc, char*argv[]) {
 
-    enum {
-        WATCH_STDIN,
-        WATCH_STDOUT,
-        WATCH_SOCKET,
-        N_WATCH
-    };
-
     pid_t pid ;
     int fd = -1;
     int ret = 1, i;
@@ -60,7 +53,9 @@ int main(int argc, char*argv[]) {
     size_t ibuf_index, ibuf_length, obuf_index, obuf_length;
     char *cli;
     pa_bool_t ibuf_eof, obuf_eof, ibuf_closed, obuf_closed;
-    struct pollfd pollfd[N_WATCH];
+    struct pollfd pollfd[3];
+    struct pollfd *watch_socket, *watch_stdin, *watch_stdout;
+
     int stdin_type = 0, stdout_type = 0, fd_type = 0;
 
     setlocale(LC_ALL, "");
@@ -129,32 +124,53 @@ int main(int argc, char*argv[]) {
         ibuf_eof = TRUE;
     }
 
-    pa_zero(pollfd);
-
-    pollfd[WATCH_STDIN].fd = STDIN_FILENO;
-    pollfd[WATCH_STDOUT].fd = STDOUT_FILENO;
-    pollfd[WATCH_SOCKET].fd = fd;
-
     for (;;) {
+        struct pollfd *p;
+
         if (ibuf_eof &&
             obuf_eof &&
             ibuf_length <= 0 &&
             obuf_length <= 0)
             break;
 
-        pollfd[WATCH_STDIN].events = pollfd[WATCH_STDOUT].events = pollfd[WATCH_SOCKET].events = 0;
+        if (ibuf_length <= 0 && ibuf_eof && !ibuf_closed) {
+            shutdown(fd, SHUT_WR);
+            ibuf_closed = TRUE;
+        }
 
-        if (obuf_length > 0)
-            pollfd[WATCH_STDOUT].events |= POLLOUT;
-        else if (!obuf_eof)
-            pollfd[WATCH_SOCKET].events |= POLLIN;
+        if (obuf_length <= 0 && obuf_eof && !obuf_closed) {
+            shutdown(fd, SHUT_RD);
+            obuf_closed = TRUE;
+        }
+
+        pa_zero(pollfd);
+
+        p = pollfd;
 
-        if (ibuf_length > 0)
-            pollfd[WATCH_SOCKET].events |= POLLOUT;
-        else if (!ibuf_eof)
-            pollfd[WATCH_STDIN].events |= POLLIN;
+        if (ibuf_length > 0 || (!obuf_eof && obuf_length <= 0)) {
+            watch_socket = p++;
+            watch_socket->fd = fd;
+            watch_socket->events =
+                (ibuf_length > 0 ? POLLOUT : 0) |
+                (!obuf_eof && obuf_length <= 0 ? POLLIN : 0);
+        } else
+            watch_socket = NULL;
 
-        if (poll(pollfd, N_WATCH, -1) < 0) {
+        if (!ibuf_eof && ibuf_length <= 0) {
+            watch_stdin = p++;
+            watch_stdin->fd = STDIN_FILENO;
+            watch_stdin->events = POLLIN;
+        } else
+            watch_stdin = NULL;
+
+        if (obuf_length > 0) {
+            watch_stdout = p++;
+            watch_stdout->fd = STDOUT_FILENO;
+            watch_stdout->events = POLLOUT;
+        } else
+            watch_stdout = NULL;
+
+        if (poll(pollfd, p-pollfd, -1) < 0) {
 
             if (errno == EINTR)
                 continue;
@@ -163,82 +179,80 @@ int main(int argc, char*argv[]) {
             goto fail;
         }
 
-        if (pollfd[WATCH_STDIN].revents & POLLIN) {
-            ssize_t r;
-            pa_assert(!ibuf_length);
-
-            if ((r = pa_read(STDIN_FILENO, ibuf, sizeof(ibuf), &stdin_type)) <= 0) {
-                if (r < 0) {
-                    pa_log(_("read(): %s"), strerror(errno));
-                    goto fail;
+        if (watch_stdin) {
+            if (watch_stdin->revents & POLLIN) {
+                ssize_t r;
+                pa_assert(ibuf_length <= 0);
+
+                if ((r = pa_read(STDIN_FILENO, ibuf, sizeof(ibuf), &stdin_type)) <= 0) {
+                    if (r < 0) {
+                        pa_log(_("read(): %s"), strerror(errno));
+                        goto fail;
+                    }
+
+                    ibuf_eof = TRUE;
+                } else {
+                    ibuf_length = (size_t) r;
+                    ibuf_index = 0;
                 }
-
+            } else if (watch_stdin->revents & POLLHUP)
                 ibuf_eof = TRUE;
-            } else {
-                ibuf_length = (size_t) r;
-                ibuf_index = 0;
-            }
         }
 
-        if (pollfd[WATCH_SOCKET].revents & POLLIN) {
-            ssize_t r;
-            pa_assert(!obuf_length);
-
-            if ((r = pa_read(fd, obuf, sizeof(obuf), &fd_type)) <= 0) {
-                if (r < 0) {
-                    pa_log(_("read(): %s"), strerror(errno));
-                    goto fail;
+        if (watch_socket) {
+            if (watch_socket->revents & POLLIN) {
+                ssize_t r;
+                pa_assert(obuf_length <= 0);
+
+                if ((r = pa_read(fd, obuf, sizeof(obuf), &fd_type)) <= 0) {
+                    if (r < 0) {
+                        pa_log(_("read(): %s"), strerror(errno));
+                        goto fail;
+                    }
+
+                    obuf_eof = TRUE;
+                } else {
+                    obuf_length = (size_t) r;
+                    obuf_index = 0;
                 }
-
+            } else if (watch_socket->revents & POLLHUP)
                 obuf_eof = TRUE;
-            } else {
-                obuf_length = (size_t) r;
-                obuf_index = 0;
-            }
         }
 
-        if (pollfd[WATCH_STDOUT].revents & POLLHUP) {
-            obuf_eof = TRUE;
-            obuf_length = 0;
-        } else if (pollfd[WATCH_STDOUT].revents & POLLOUT) {
-            ssize_t r;
-            pa_assert(obuf_length);
-
-            if ((r = pa_write(STDOUT_FILENO, obuf + obuf_index, obuf_length, &stdout_type)) < 0) {
-                pa_log(_("write(): %s"), strerror(errno));
-                goto fail;
-            }
-
-            obuf_length -= (size_t) r;
-            obuf_index += obuf_index;
-        }
+        if (watch_stdout) {
+            if (watch_stdout->revents & POLLHUP) {
+                obuf_eof = TRUE;
+                obuf_length = 0;
+            } else if (watch_stdout->revents & POLLOUT) {
+                ssize_t r;
+                pa_assert(obuf_length > 0);
 
-        if (pollfd[WATCH_SOCKET].revents & POLLHUP) {
-            ibuf_eof = TRUE;
-            ibuf_length = 0;
-        } if (pollfd[WATCH_SOCKET].revents & POLLOUT) {
-            ssize_t r;
-            pa_assert(ibuf_length);
+                if ((r = pa_write(STDOUT_FILENO, obuf + obuf_index, obuf_length, &stdout_type)) < 0) {
+                    pa_log(_("write(): %s"), strerror(errno));
+                    goto fail;
+                }
 
-            if ((r = pa_write(fd, ibuf + ibuf_index, ibuf_length, &fd_type)) < 0) {
-                pa_log(_("write(): %s"), strerror(errno));
-                goto fail;
+                obuf_length -= (size_t) r;
+                obuf_index += obuf_index;
             }
-
-            ibuf_length -= (size_t) r;
-            ibuf_index += obuf_index;
         }
 
-        if (ibuf_length <= 0 && ibuf_eof && !ibuf_closed) {
-            pa_close(STDIN_FILENO);
-            shutdown(fd, SHUT_WR);
-            ibuf_closed = TRUE;
-        }
+        if (watch_socket) {
+            if (watch_socket->revents & POLLHUP) {
+                ibuf_eof = TRUE;
+                ibuf_length = 0;
+            } if (watch_socket->revents & POLLOUT) {
+                ssize_t r;
+                pa_assert(ibuf_length > 0);
 
-        if (obuf_length <= 0 && obuf_eof && !obuf_closed) {
-            shutdown(fd, SHUT_RD);
-            pa_close(STDOUT_FILENO);
-            obuf_closed = TRUE;
+                if ((r = pa_write(fd, ibuf + ibuf_index, ibuf_length, &fd_type)) < 0) {
+                    pa_log(_("write(): %s"), strerror(errno));
+                    goto fail;
+                }
+
+                ibuf_length -= (size_t) r;
+                ibuf_index += obuf_index;
+            }
         }
     }