Re: [PATCH 0/1] Fix internal warning when "gdb -p xxx"

[Hui Zhu <hui_zhu at mentor dot com>]

On 03/19/14 18:16, Pedro Alves wrote:
> On 03/19/2014 03:57 AM, Hui Zhu wrote:
> > > > Same with the nul termination.  The most standard solution is:
> > > >
> > > >     static char buf[PATH_MAX];
> > > >     char name[PATH_MAX];
> > > >     ssize_t len;
> > > >
> > > >     xsnprintf (name, PATH_MAX, "/proc/%d/exe", pid);
> > > >     len = readlink (name, buf, PATH_MAX - 1);
> > > >     if (len != -1)
> > > >       {
> > > >         buf[len] = '\0';
> > > >         return buf;
> > > >       }
> > > >     return NULL;
> > I make a new patch according to your comments.
> > Please help me review it.
>
> The patch changes the bsd implementations's behavior, because
> you made them return the /proc path when readlink fails (like
> the Linux version does), instead of what the current code does
> or what I suggested above.

I made a new version that change fbsd_pid_to_exec_file and nbsd_pid_to_exec_file
to your suggested above.

Please help me review it.

Thanks,
Hui

2014-03-20  Hui Zhu  <hui@codesourcery.com>
	    Pedro Alves  <palves@redhat.com>

	* darwin-nat.c (darwin_pid_to_exec_file): Change xmalloc to
	static buffer.
	* fbsd-nat.c (fbsd_pid_to_exec_file): Ditto.
	* linux-nat.c (linux_child_pid_to_exec_file): Ditto.
	* nbsd-nat.c (nbsd_pid_to_exec_file): Ditto.

--- a/gdb/darwin-nat.c
+++ b/gdb/darwin-nat.c
@@ -1991,12 +1991,9 @@ set_enable_mach_exceptions (char *args,
 static char *
 darwin_pid_to_exec_file (struct target_ops *self, int pid)
 {
-  char *path;
+  static char path[PATH_MAX];
   int res;
 
-  path = xmalloc (PATH_MAX);
-  make_cleanup (xfree, path);
-
   res = proc_pidinfo (pid, PROC_PIDPATHINFO, 0, path, PATH_MAX);
   if (res >= 0)
     return path;
--- a/gdb/fbsd-nat.c
+++ b/gdb/fbsd-nat.c
@@ -40,8 +40,8 @@ char *
 fbsd_pid_to_exec_file (struct target_ops *self, int pid)
 {
   size_t len = PATH_MAX;
-  char *buf = xcalloc (len, sizeof (char));
-  char *path;
+  static char buf[PATH_MAX];
+  char name[PATH_MAX];
 
 #ifdef KERN_PROC_PATHNAME
   int mib[4];
@@ -54,15 +54,15 @@ fbsd_pid_to_exec_file (struct target_ops
     return buf;
 #endif
 
-  path = xstrprintf ("/proc/%d/file", pid);
-  if (readlink (path, buf, PATH_MAX - 1) == -1)
+  xsnprintf (name, PATH_MAX, "/proc/%d/exe", pid);
+  len = readlink (name, buf, PATH_MAX - 1);
+  if (len != -1)
     {
-      xfree (buf);
-      buf = NULL;
+      buf[len] = '\0';
+      return buf;
     }
 
-  xfree (path);
-  return buf;
+  return NULL;
 }
 
 static int
--- a/gdb/linux-nat.c
+++ b/gdb/linux-nat.c
@@ -4011,19 +4011,15 @@ linux_nat_thread_name (struct target_ops
 static char *
 linux_child_pid_to_exec_file (struct target_ops *self, int pid)
 {
-  char *name1, *name2;
+  static char buf[PATH_MAX];
+  char name[PATH_MAX];
 
-  name1 = xmalloc (PATH_MAX);
-  name2 = xmalloc (PATH_MAX);
-  make_cleanup (xfree, name1);
-  make_cleanup (xfree, name2);
-  memset (name2, 0, PATH_MAX);
+  xsnprintf (name, PATH_MAX, "/proc/%d/exe", pid);
+  memset (buf, 0, PATH_MAX);
+  if (readlink (name, buf, PATH_MAX - 1) <= 0)
+    strcpy (buf, name);
 
-  xsnprintf (name1, PATH_MAX, "/proc/%d/exe", pid);
-  if (readlink (name1, name2, PATH_MAX - 1) > 0)
-    return name2;
-  else
-    return name1;
+  return buf;
 }
 
 /* Records the thread's register state for the corefile note
--- a/gdb/nbsd-nat.c
+++ b/gdb/nbsd-nat.c
@@ -27,17 +27,17 @@
 char *
 nbsd_pid_to_exec_file (struct target_ops *self, int pid)
 {
-  size_t len = PATH_MAX;
-  char *buf = xcalloc (len, sizeof (char));
-  char *path;
+  size_t len;
+  static char buf[PATH_MAX];
+  char name[PATH_MAX];
 
-  path = xstrprintf ("/proc/%d/exe", pid);
-  if (readlink (path, buf, PATH_MAX - 1) == -1)
+  xsnprintf (name, PATH_MAX, "/proc/%d/exe", pid);
+  len = readlink (name, buf, PATH_MAX - 1);
+  if (len != -1)
     {
-      xfree (buf);
-      buf = NULL;
+      buf[len] = '\0';
+      return buf;
     }
 
-  xfree (path);
-  return buf;
+  return NULL;
 }