1 files changed, 524 insertions, 0 deletions
diff --git a/src/backend/utils/misc/ps_status.c b/src/backend/utils/misc/ps_status.c
new file mode 100644
index 0000000..104c01d
--- /dev/null
+++ b/src/backend/utils/misc/ps_status.c
@@ -0,0 +1,524 @@
+/*--------------------------------------------------------------------
+ * ps_status.c
+ *
+ * Routines to support changing the ps display of PostgreSQL backends
+ * to contain some useful information. Mechanism differs wildly across
+ * platforms.
+ *
+ * src/backend/utils/misc/ps_status.c
+ *
+ * Copyright (c) 2000-2023, PostgreSQL Global Development Group
+ * various details abducted from various places
+ *--------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include <unistd.h>
+#if defined(__darwin__)
+#include <crt_externs.h>
+#endif
+
+#include "libpq/libpq.h"
+#include "miscadmin.h"
+#include "pgstat.h"
+#include "utils/guc.h"
+#include "utils/ps_status.h"
+
+extern char **environ;
+
+/* GUC variable */
+bool		update_process_title = DEFAULT_UPDATE_PROCESS_TITLE;
+
+/*
+ * Alternative ways of updating ps display:
+ *
+ * PS_USE_SETPROCTITLE_FAST
+ *	   use the function setproctitle_fast(const char *, ...)
+ *	   (FreeBSD)
+ * PS_USE_SETPROCTITLE
+ *	   use the function setproctitle(const char *, ...)
+ *	   (other BSDs)
+ * PS_USE_CLOBBER_ARGV
+ *	   write over the argv and environment area
+ *	   (Linux and most SysV-like systems)
+ * PS_USE_WIN32
+ *	   push the string out as the name of a Windows event
+ * PS_USE_NONE
+ *	   don't update ps display
+ *	   (This is the default, as it is safest.)
+ */
+#if defined(HAVE_SETPROCTITLE_FAST)
+#define PS_USE_SETPROCTITLE_FAST
+#elif defined(HAVE_SETPROCTITLE)
+#define PS_USE_SETPROCTITLE
+#elif defined(__linux__) || defined(_AIX) || defined(__sun) || defined(__darwin__)
+#define PS_USE_CLOBBER_ARGV
+#elif defined(WIN32)
+#define PS_USE_WIN32
+#else
+#define PS_USE_NONE
+#endif
+
+
+/* Different systems want the buffer padded differently */
+#if defined(_AIX) || defined(__linux__) || defined(__darwin__)
+#define PS_PADDING '\0'
+#else
+#define PS_PADDING ' '
+#endif
+
+
+#ifndef PS_USE_NONE
+
+#ifndef PS_USE_CLOBBER_ARGV
+/* all but one option need a buffer to write their ps line in */
+#define PS_BUFFER_SIZE 256
+static char ps_buffer[PS_BUFFER_SIZE];
+static const size_t ps_buffer_size = PS_BUFFER_SIZE;
+#else							/* PS_USE_CLOBBER_ARGV */
+static char *ps_buffer;			/* will point to argv area */
+static size_t ps_buffer_size;	/* space determined at run time */
+static size_t last_status_len;	/* use to minimize length of clobber */
+#endif							/* PS_USE_CLOBBER_ARGV */
+
+static size_t ps_buffer_cur_len;	/* nominal strlen(ps_buffer) */
+
+static size_t ps_buffer_fixed_size; /* size of the constant prefix */
+
+/*
+ * Length of ps_buffer before the suffix was appended to the end, or 0 if we
+ * didn't set a suffix.
+ */
+static size_t ps_buffer_nosuffix_len;
+
+static void flush_ps_display(void);
+
+#endif							/* not PS_USE_NONE */
+
+/* save the original argv[] location here */
+static int	save_argc;
+static char **save_argv;
+
+
+/*
+ * Call this early in startup to save the original argc/argv values.
+ * If needed, we make a copy of the original argv[] array to preserve it
+ * from being clobbered by subsequent ps_display actions.
+ *
+ * (The original argv[] will not be overwritten by this routine, but may be
+ * overwritten during init_ps_display.  Also, the physical location of the
+ * environment strings may be moved, so this should be called before any code
+ * that might try to hang onto a getenv() result.)
+ *
+ * Note that in case of failure this cannot call elog() as that is not
+ * initialized yet.  We rely on write_stderr() instead.
+ */
+char	  **
+save_ps_display_args(int argc, char **argv)
+{
+	save_argc = argc;
+	save_argv = argv;
+
+#if defined(PS_USE_CLOBBER_ARGV)
+
+	/*
+	 * If we're going to overwrite the argv area, count the available space.
+	 * Also move the environment to make additional room.
+	 */
+	{
+		char	   *end_of_area = NULL;
+		char	  **new_environ;
+		int			i;
+
+		/*
+		 * check for contiguous argv strings
+		 */
+		for (i = 0; i < argc; i++)
+		{
+			if (i == 0 || end_of_area + 1 == argv[i])
+				end_of_area = argv[i] + strlen(argv[i]);
+		}
+
+		if (end_of_area == NULL)	/* probably can't happen? */
+		{
+			ps_buffer = NULL;
+			ps_buffer_size = 0;
+			return argv;
+		}
+
+		/*
+		 * check for contiguous environ strings following argv
+		 */
+		for (i = 0; environ[i] != NULL; i++)
+		{
+			if (end_of_area + 1 == environ[i])
+				end_of_area = environ[i] + strlen(environ[i]);
+		}
+
+		ps_buffer = argv[0];
+		last_status_len = ps_buffer_size = end_of_area - argv[0];
+
+		/*
+		 * move the environment out of the way
+		 */
+		new_environ = (char **) malloc((i + 1) * sizeof(char *));
+		if (!new_environ)
+		{
+			write_stderr("out of memory\n");
+			exit(1);
+		}
+		for (i = 0; environ[i] != NULL; i++)
+		{
+			new_environ[i] = strdup(environ[i]);
+			if (!new_environ[i])
+			{
+				write_stderr("out of memory\n");
+				exit(1);
+			}
+		}
+		new_environ[i] = NULL;
+		environ = new_environ;
+	}
+
+	/*
+	 * If we're going to change the original argv[] then make a copy for
+	 * argument parsing purposes.
+	 *
+	 * (NB: do NOT think to remove the copying of argv[], even though
+	 * postmaster.c finishes looking at argv[] long before we ever consider
+	 * changing the ps display.  On some platforms, getopt() keeps pointers
+	 * into the argv array, and will get horribly confused when it is
+	 * re-called to analyze a subprocess' argument string if the argv storage
+	 * has been clobbered meanwhile.  Other platforms have other dependencies
+	 * on argv[].
+	 */
+	{
+		char	  **new_argv;
+		int			i;
+
+		new_argv = (char **) malloc((argc + 1) * sizeof(char *));
+		if (!new_argv)
+		{
+			write_stderr("out of memory\n");
+			exit(1);
+		}
+		for (i = 0; i < argc; i++)
+		{
+			new_argv[i] = strdup(argv[i]);
+			if (!new_argv[i])
+			{
+				write_stderr("out of memory\n");
+				exit(1);
+			}
+		}
+		new_argv[argc] = NULL;
+
+#if defined(__darwin__)
+
+		/*
+		 * macOS has a static copy of the argv pointer, which we may fix like
+		 * so:
+		 */
+		*_NSGetArgv() = new_argv;
+#endif
+
+		argv = new_argv;
+	}
+#endif							/* PS_USE_CLOBBER_ARGV */
+
+	return argv;
+}
+
+/*
+ * Call this once during subprocess startup to set the identification
+ * values.
+ *
+ * If fixed_part is NULL, a default will be obtained from MyBackendType.
+ *
+ * At this point, the original argv[] array may be overwritten.
+ */
+void
+init_ps_display(const char *fixed_part)
+{
+#ifndef PS_USE_NONE
+	bool		save_update_process_title;
+#endif
+
+	Assert(fixed_part || MyBackendType);
+	if (!fixed_part)
+		fixed_part = GetBackendTypeDesc(MyBackendType);
+
+#ifndef PS_USE_NONE
+	/* no ps display for stand-alone backend */
+	if (!IsUnderPostmaster)
+		return;
+
+	/* no ps display if you didn't call save_ps_display_args() */
+	if (!save_argv)
+		return;
+
+#ifdef PS_USE_CLOBBER_ARGV
+	/* If ps_buffer is a pointer, it might still be null */
+	if (!ps_buffer)
+		return;
+
+	/* 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;
+#endif							/* PS_USE_CLOBBER_ARGV */
+
+	/*
+	 * Make fixed prefix of ps display.
+	 */
+
+#if defined(PS_USE_SETPROCTITLE) || defined(PS_USE_SETPROCTITLE_FAST)
+
+	/*
+	 * apparently setproctitle() already adds a `progname:' prefix to the ps
+	 * line
+	 */
+#define PROGRAM_NAME_PREFIX ""
+#else
+#define PROGRAM_NAME_PREFIX "postgres: "
+#endif
+
+	if (*cluster_name == '\0')
+	{
+		snprintf(ps_buffer, ps_buffer_size,
+				 PROGRAM_NAME_PREFIX "%s ",
+				 fixed_part);
+	}
+	else
+	{
+		snprintf(ps_buffer, ps_buffer_size,
+				 PROGRAM_NAME_PREFIX "%s: %s ",
+				 cluster_name, fixed_part);
+	}
+
+	ps_buffer_cur_len = ps_buffer_fixed_size = strlen(ps_buffer);
+
+	/*
+	 * On the first run, force the update.
+	 */
+	save_update_process_title = update_process_title;
+	update_process_title = true;
+	set_ps_display("");
+	update_process_title = save_update_process_title;
+#endif							/* not PS_USE_NONE */
+}
+
+#ifndef PS_USE_NONE
+/*
+ * update_ps_display_precheck
+ *		Helper function to determine if updating the process title is
+ *		something that we need to do.
+ */
+static bool
+update_ps_display_precheck(void)
+{
+	/* update_process_title=off disables updates */
+	if (!update_process_title)
+		return false;
+
+	/* no ps display for stand-alone backend */
+	if (!IsUnderPostmaster)
+		return false;
+
+#ifdef PS_USE_CLOBBER_ARGV
+	/* If ps_buffer is a pointer, it might still be null */
+	if (!ps_buffer)
+		return false;
+#endif
+
+	return true;
+}
+#endif							/* not PS_USE_NONE */
+
+/*
+ * set_ps_display_suffix
+ *		Adjust the process title to append 'suffix' onto the end with a space
+ *		between it and the current process title.
+ */
+void
+set_ps_display_suffix(const char *suffix)
+{
+#ifndef PS_USE_NONE
+	size_t		len;
+
+	/* first, check if we need to update the process title */
+	if (!update_ps_display_precheck())
+		return;
+
+	/* if there's already a suffix, overwrite it */
+	if (ps_buffer_nosuffix_len > 0)
+		ps_buffer_cur_len = ps_buffer_nosuffix_len;
+	else
+		ps_buffer_nosuffix_len = ps_buffer_cur_len;
+
+	len = strlen(suffix);
+
+	/* check if we have enough space to append the suffix */
+	if (ps_buffer_cur_len + len + 1 >= ps_buffer_size)
+	{
+		/* not enough space.  Check the buffer isn't full already */
+		if (ps_buffer_cur_len < ps_buffer_size - 1)
+		{
+			/* append a space before the suffix */
+			ps_buffer[ps_buffer_cur_len++] = ' ';
+
+			/* just add what we can and fill the ps_buffer */
+			memcpy(ps_buffer + ps_buffer_cur_len, suffix,
+				   ps_buffer_size - ps_buffer_cur_len - 1);
+			ps_buffer[ps_buffer_size - 1] = '\0';
+			ps_buffer_cur_len = ps_buffer_size - 1;
+		}
+	}
+	else
+	{
+		ps_buffer[ps_buffer_cur_len++] = ' ';
+		memcpy(ps_buffer + ps_buffer_cur_len, suffix, len + 1);
+		ps_buffer_cur_len = ps_buffer_cur_len + len;
+	}
+
+	Assert(strlen(ps_buffer) == ps_buffer_cur_len);
+
+	/* and set the new title */
+	flush_ps_display();
+#endif							/* not PS_USE_NONE */
+}
+
+/*
+ * set_ps_display_remove_suffix
+ *		Remove the process display suffix added by set_ps_display_suffix
+ */
+void
+set_ps_display_remove_suffix(void)
+{
+#ifndef PS_USE_NONE
+	/* first, check if we need to update the process title */
+	if (!update_ps_display_precheck())
+		return;
+
+	/* check we added a suffix */
+	if (ps_buffer_nosuffix_len == 0)
+		return;					/* no suffix */
+
+	/* remove the suffix from ps_buffer */
+	ps_buffer[ps_buffer_nosuffix_len] = '\0';
+	ps_buffer_cur_len = ps_buffer_nosuffix_len;
+	ps_buffer_nosuffix_len = 0;
+
+	Assert(ps_buffer_cur_len == strlen(ps_buffer));
+
+	/* and set the new title */
+	flush_ps_display();
+#endif							/* not PS_USE_NONE */
+}
+
+/*
+ * Call this to update the ps status display to a fixed prefix plus an
+ * indication of what you're currently doing passed in the argument.
+ *
+ * 'len' must be the same as strlen(activity)
+ */
+void
+set_ps_display_with_len(const char *activity, size_t len)
+{
+	Assert(strlen(activity) == len);
+
+#ifndef PS_USE_NONE
+	/* first, check if we need to update the process title */
+	if (!update_ps_display_precheck())
+		return;
+
+	/* wipe out any suffix when the title is completely changed */
+	ps_buffer_nosuffix_len = 0;
+
+	/* Update ps_buffer to contain both fixed part and activity */
+	if (ps_buffer_fixed_size + len >= ps_buffer_size)
+	{
+		/* handle the case where ps_buffer doesn't have enough space */
+		memcpy(ps_buffer + ps_buffer_fixed_size, activity,
+			   ps_buffer_size - ps_buffer_fixed_size - 1);
+		ps_buffer[ps_buffer_size - 1] = '\0';
+		ps_buffer_cur_len = ps_buffer_size - 1;
+	}
+	else
+	{
+		memcpy(ps_buffer + ps_buffer_fixed_size, activity, len + 1);
+		ps_buffer_cur_len = ps_buffer_fixed_size + len;
+	}
+	Assert(strlen(ps_buffer) == ps_buffer_cur_len);
+
+	/* Transmit new setting to kernel, if necessary */
+	flush_ps_display();
+#endif							/* not PS_USE_NONE */
+}
+
+#ifndef PS_USE_NONE
+static void
+flush_ps_display(void)
+{
+#ifdef PS_USE_SETPROCTITLE
+	setproctitle("%s", ps_buffer);
+#elif defined(PS_USE_SETPROCTITLE_FAST)
+	setproctitle_fast("%s", ps_buffer);
+#endif
+
+#ifdef PS_USE_CLOBBER_ARGV
+	/* pad unused memory; need only clobber remainder of old status string */
+	if (last_status_len > ps_buffer_cur_len)
+		MemSet(ps_buffer + ps_buffer_cur_len, PS_PADDING,
+			   last_status_len - ps_buffer_cur_len);
+	last_status_len = ps_buffer_cur_len;
+#endif							/* PS_USE_CLOBBER_ARGV */
+
+#ifdef PS_USE_WIN32
+	{
+		/*
+		 * Win32 does not support showing any changed arguments. To make it at
+		 * all possible to track which backend is doing what, we create a
+		 * named object that can be viewed with for example Process Explorer.
+		 */
+		static HANDLE ident_handle = INVALID_HANDLE_VALUE;
+		char		name[PS_BUFFER_SIZE + 32];
+
+		if (ident_handle != INVALID_HANDLE_VALUE)
+			CloseHandle(ident_handle);
+
+		sprintf(name, "pgident(%d): %s", MyProcPid, ps_buffer);
+
+		ident_handle = CreateEvent(NULL, TRUE, FALSE, name);
+	}
+#endif							/* PS_USE_WIN32 */
+}
+#endif							/* not PS_USE_NONE */
+
+/*
+ * Returns what's currently in the ps display, in case someone needs
+ * it.  Note that only the activity part is returned.  On some platforms
+ * the string will not be null-terminated, so return the effective
+ * length into *displen.
+ */
+const char *
+get_ps_display(int *displen)
+{
+#ifdef PS_USE_CLOBBER_ARGV
+	/* If ps_buffer is a pointer, it might still be null */
+	if (!ps_buffer)
+	{
+		*displen = 0;
+		return "";
+	}
+#endif
+
+#ifndef PS_USE_NONE
+	*displen = (int) (ps_buffer_cur_len - ps_buffer_fixed_size);
+
+	return ps_buffer + ps_buffer_fixed_size;
+#else
+	*displen = 0;
+	return "";
+#endif
+}