Re: Areas for Solaris support modernization - Mailing list pgsql-hackers

I wrote:
> Also, while playing with said local OpenIndiana image, I noticed
> that ps_status.c isn't working: "ps auxww" shows all the child
> processes with the same command line as the postmaster.  I thought
> maybe we'd diked out something important in d2ea2d310, but none
> of the code removed there claims to apply to Solaris.  So maybe
> it never worked on Solaris?  Anyway, there's room for improvement
> there if anyone cares to investigate.

Huh: after a bit of testing, it seems that the PS_USE_CHANGE_ARGV
mode removed by d2ea2d310 is indeed the right thing to use on
Solaris.  Looking back at that discussion thread, we were a bit
confused about which predefined macros are provided on Solaris.
To believe that the pre-existing code actually worked on Solaris,
you'd have to assume that "BSD" is predefined on that platform.
It does not get defined on my OpenIndiana image, but maybe sometime
in the stone age Solaris defined it?

Anyway, here's a slightly cleaned-up reversion of the relevant
bits of d2ea2d310, with PS_USE_CHANGE_ARGV now selected by
"defined(__sun)" not the previous logic
"(defined(BSD) || defined(__hurd__)) && !defined(__darwin__)".

BTW, I notice that with this, PS_PADDING is set to '\0'
in exactly the cases that select PS_USE_CLOBBER_ARGV.
I'm not inclined to merge the logic, because maybe we'll
find some weird platform where the conditions are different.
But it seems plausible and comforting that there are
fewer underlying behaviors than we thought.

            regards, tom lane

diff --git a/src/backend/utils/misc/ps_status.c b/src/backend/utils/misc/ps_status.c
index 51dce24947a..f5fc7124211 100644
--- a/src/backend/utils/misc/ps_status.c
+++ b/src/backend/utils/misc/ps_status.c
@@ -39,6 +39,9 @@ bool        update_process_title = DEFAULT_UPDATE_PROCESS_TITLE;
  * PS_USE_SETPROCTITLE
  *       use the function setproctitle(const char *, ...)
  *       (other BSDs)
+ * PS_USE_CHANGE_ARGV
+ *       assign argv[0] = "string"
+ *       (Solaris)
  * PS_USE_CLOBBER_ARGV
  *       write over the argv and environment area
  *       (Linux and most SysV-like systems)
@@ -52,7 +55,9 @@ bool        update_process_title = DEFAULT_UPDATE_PROCESS_TITLE;
 #define PS_USE_SETPROCTITLE_FAST
 #elif defined(HAVE_SETPROCTITLE)
 #define PS_USE_SETPROCTITLE
-#elif defined(__linux__) || defined(_AIX) || defined(__sun) || defined(__darwin__) || defined(__GNU__)
+#elif defined(__sun)
+#define PS_USE_CHANGE_ARGV
+#elif defined(__linux__) || defined(_AIX) || defined(__darwin__) || defined(__GNU__)
 #define PS_USE_CLOBBER_ARGV
 #elif defined(WIN32)
 #define PS_USE_WIN32
@@ -223,6 +228,9 @@ save_ps_display_args(int argc, char **argv)
         ps_status_new_environ = new_environ;
 #endif
     }
+#endif                            /* PS_USE_CLOBBER_ARGV */
+
+#if defined(PS_USE_CHANGE_ARGV) || defined(PS_USE_CLOBBER_ARGV)

     /*
      * If we're going to change the original argv[] then make a copy for
@@ -268,7 +276,7 @@ save_ps_display_args(int argc, char **argv)

         argv = new_argv;
     }
-#endif                            /* PS_USE_CLOBBER_ARGV */
+#endif                            /* PS_USE_CHANGE_ARGV or PS_USE_CLOBBER_ARGV */

     return argv;
 }
@@ -305,7 +313,18 @@ init_ps_display(const char *fixed_part)
     /* If ps_buffer is a pointer, it might still be null */
     if (!ps_buffer)
         return;
+#endif

+    /*
+     * Overwrite argv[] to point at appropriate space, if needed
+     */
+
+#ifdef PS_USE_CHANGE_ARGV
+    save_argv[0] = ps_buffer;
+    save_argv[1] = NULL;
+#endif                            /* PS_USE_CHANGE_ARGV */
+
+#ifdef PS_USE_CLOBBER_ARGV
     /* make extra argv slots point at end_of_area (a NUL) */
     for (int i = 1; i < save_argc; i++)
         save_argv[i] = ps_buffer + ps_buffer_size;