>From e7066ce85e969e43c8142f4845bc843e9d53f5e4 Mon Sep 17 00:00:00 2001
From: Charles Duffy <Charles_Duffy@dell.com>
Date: Fri, 28 Aug 2009 23:18:49 -0500
Subject: [PATCH 2/2] stop using popen for incoming migrations

---
 migration-exec.c |   51 +++++++++++++++++++++++++++++++--------------------
 1 files changed, 31 insertions(+), 20 deletions(-)

diff --git a/migration-exec.c b/migration-exec.c
index c36e756..3dfea18 100644
--- a/migration-exec.c
+++ b/migration-exec.c
@@ -31,10 +31,10 @@
     do { } while (0)
 #endif
 
-// opaque is pid
 typedef struct ExecMigrationState
 {
     pid_t pid;
+    int fd; /* only used for incoming */
 } ExecMigrationState;
 
 static int exec_errno(FdMigrationState *s)
@@ -68,9 +68,9 @@ static int exec_close(FdMigrationState *s)
     return status;
 }
 
-static pid_t exec_start_migration(const char *command, int *fd) {
+static pid_t exec_start_migration(const char *command, int *fd, unsigned char incoming) {
     const char *argv[] = { "sh", "-c", command, NULL };
-    int fds[2];
+    int fds[2], parent_fd, child_fd;
     pid_t pid;
 
     if (pipe(fds) == -1) {
@@ -78,6 +78,16 @@ static pid_t exec_start_migration(const char *command, int *fd) {
         return 0;
     }
 
+    if(incoming) {
+        /* child writes, parent reads */
+        parent_fd = fds[0];
+        child_fd = fds[1];
+    } else {
+        /* parent writes, child reads */
+        parent_fd = fds[1];
+        child_fd = fds[0];
+    }
+
     pid = fork();
     if(pid == -1) {
         close(fds[0]);
@@ -86,16 +96,14 @@ static pid_t exec_start_migration(const char *command, int *fd) {
         return 0;
     } else if (pid == 0) {
         /* child process */
-        close(fds[1]);
-        dup2(fds[0], STDIN_FILENO);
+        close(parent_fd);
+        dup2(child_fd, incoming ? STDOUT_FILENO : STDIN_FILENO);
         execv("/bin/sh", (char **)argv);
         exit(1);
     }
-    close(fds[0]);
-
-    fcntl(fds[1], O_NONBLOCK);
-
-    *fd = fds[1];
+    close(child_fd);
+    fcntl(parent_fd, O_NONBLOCK);
+    *fd = parent_fd;
     return pid;
 }
 
@@ -106,7 +114,7 @@ MigrationState *exec_start_outgoing_migration(const char *command,
     FdMigrationState *s;
     int fd, pid;
 
-    pid = exec_start_migration(command, &fd);
+    pid = exec_start_migration(command, &fd, 0);
     if(!pid) return NULL;
 
     s = qemu_mallocz(sizeof(*s));
@@ -136,7 +144,8 @@ MigrationState *exec_start_outgoing_migration(const char *command,
 /* helper for incoming case */
 static void exec_accept_incoming_migration(void *opaque)
 {
-    QEMUFile *f = opaque;
+    ExecMigrationState *s = opaque;
+    QEMUFile *f = qemu_popen(fdopen(s->fd, "rb"), "r");
     int ret;
 
     ret = qemu_loadvm_state(f);
@@ -153,22 +162,24 @@ static void exec_accept_incoming_migration(void *opaque)
 
 err:
     qemu_fclose(f);
+    do {
+        waitpid(s->pid, NULL, 0);
+    } while (ret == -1 && errno == EINTR);
+    qemu_free(s);
 }
 
 int exec_start_incoming_migration(const char *command)
 {
-    QEMUFile *f;
+    ExecMigrationState *s;
+
+    s = qemu_mallocz(sizeof(*s));
 
-    dprintf("Attempting to start an incoming migration\n");
-    f = qemu_popen_cmd(command, "r");
-    if(f == NULL) {
-        dprintf("Unable to apply qemu wrapper to popen file\n");
+    s->pid = exec_start_migration(command, &(s->fd), 1);
+    if(!s->pid) {
         return -errno;
     }
 
-    qemu_set_fd_handler2(qemu_stdio_fd(f), NULL,
-			 exec_accept_incoming_migration, NULL,
-			 (void *)(unsigned long)f);
+    qemu_set_fd_handler2(s->fd, NULL, exec_accept_incoming_migration, NULL, (void*)s);
 
     return 0;
 }
-- 
1.6.4