- Reinstate the 'atfork' from 2.4.0, which was more powerful, and expose it to
  tools.
- Factor out 'execv' from 'system' and expose it to tools.

Partly based on a patch from Robert O'Callahan.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@8669 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/coregrind/m_libcproc.c b/coregrind/m_libcproc.c
index 4ea181a..e24ad2c 100644
--- a/coregrind/m_libcproc.c
+++ b/coregrind/m_libcproc.c
@@ -271,36 +271,37 @@
    return newenv;
 }
 
+void VG_(execv) ( Char* filename, Char** argv )
+{
+   Char** envp;
+   SysRes res;
+
+   /* restore the DATA rlimit for the child */
+   VG_(setrlimit)(VKI_RLIMIT_DATA, &VG_(client_rlimit_data));
+
+   envp = VG_(env_clone)(VG_(client_envp));
+   VG_(env_remove_valgrind_env_stuff)( envp );
+
+   res = VG_(do_syscall3)(__NR_execve,
+                          (UWord)filename, (UWord)argv, (UWord)envp);
+
+   VG_(printf)("EXEC failed, errno = %ld\n", res.res);
+}
+
 /* Return -1 if error, else 0.  NOTE does not indicate return code of
    child! */
 Int VG_(system) ( Char* cmd )
 {
-   Int    pid;
-   SysRes res;
+   Int pid;
    if (cmd == NULL)
       return 1;
-   res = VG_(do_syscall0)(__NR_fork);
-   if (res.isError)
+   pid = VG_(fork)();
+   if (pid < 0)
       return -1;
-   pid = res.res;
    if (pid == 0) {
       /* child */
-      static Char** envp = NULL;
-      Char* argv[4];
-
-      /* restore the DATA rlimit for the child */
-      VG_(setrlimit)(VKI_RLIMIT_DATA, &VG_(client_rlimit_data));
-
-      envp = VG_(env_clone)(VG_(client_envp));
-      VG_(env_remove_valgrind_env_stuff)( envp ); 
-
-      argv[0] = "/bin/sh";
-      argv[1] = "-c";
-      argv[2] = cmd;
-      argv[3] = 0;
-
-      (void)VG_(do_syscall3)(__NR_execve, 
-                             (UWord)"/bin/sh", (UWord)argv, (UWord)envp);
+      Char* argv[4] = { "/bin/sh", "-c", cmd, 0 };
+      VG_(execv)(argv[0], argv);
 
       /* If we're still alive here, execve failed. */
       VG_(exit)(1);
@@ -569,26 +570,67 @@
 }
 
 /* ---------------------------------------------------------------------
-   A trivial atfork() facility for Valgrind's internal use
+   atfork()
    ------------------------------------------------------------------ */
 
-// Trivial because it only supports a single post-fork child action, which
-// is all we need.
+struct atfork {
+   vg_atfork_t  pre;
+   vg_atfork_t  parent;
+   vg_atfork_t  child;
+};
 
-static vg_atfork_t atfork_child = NULL;
+#define VG_MAX_ATFORK 10
 
-void VG_(atfork_child)(vg_atfork_t child)
+static struct atfork atforks[VG_MAX_ATFORK];
+static Int n_atfork = 0;
+
+void VG_(atfork)(vg_atfork_t pre, vg_atfork_t parent, vg_atfork_t child)
 {
-   if (NULL != atfork_child)
-      VG_(core_panic)("More than one atfork_child handler requested");
+   Int i;
 
-   atfork_child = child;
+   for (i = 0; i < n_atfork; i++) {
+      if (atforks[i].pre == pre &&
+          atforks[i].parent == parent &&
+          atforks[i].child == child)
+         return;
+   }
+
+   if (n_atfork >= VG_MAX_ATFORK)
+      VG_(core_panic)(
+         "Too many VG_(atfork) handlers requested: raise VG_MAX_ATFORK");
+
+   atforks[n_atfork].pre    = pre;
+   atforks[n_atfork].parent = parent;
+   atforks[n_atfork].child  = child;
+
+   n_atfork++;
+}
+
+void VG_(do_atfork_pre)(ThreadId tid)
+{
+   Int i;
+
+   for (i = 0; i < n_atfork; i++)
+      if (atforks[i].pre != NULL)
+         (*atforks[i].pre)(tid);
+}
+
+void VG_(do_atfork_parent)(ThreadId tid)
+{
+   Int i;
+
+   for (i = 0; i < n_atfork; i++)
+      if (atforks[i].parent != NULL)
+         (*atforks[i].parent)(tid);
 }
 
 void VG_(do_atfork_child)(ThreadId tid)
 {
-   if (NULL != atfork_child)
-      (*atfork_child)(tid);
+   Int i;
+
+   for (i = 0; i < n_atfork; i++)
+      if (atforks[i].child != NULL)
+         (*atforks[i].child)(tid);
 }
 
 /*--------------------------------------------------------------------*/