525 lines
13 KiB
C
525 lines
13 KiB
C
/*--------------------------------------------------------------------
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* ps_status.c
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*
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* Routines to support changing the ps display of PostgreSQL backends
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* to contain some useful information. Mechanism differs wildly across
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* platforms.
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*
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* src/backend/utils/misc/ps_status.c
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*
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* Copyright (c) 2000-2024, PostgreSQL Global Development Group
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* various details abducted from various places
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*--------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include <unistd.h>
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#if defined(__darwin__)
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#include <crt_externs.h>
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#endif
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#include "libpq/libpq.h"
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#include "miscadmin.h"
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#include "pgstat.h"
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#include "utils/guc.h"
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#include "utils/ps_status.h"
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extern char **environ;
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/* GUC variable */
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bool update_process_title = DEFAULT_UPDATE_PROCESS_TITLE;
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/*
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* Alternative ways of updating ps display:
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*
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* PS_USE_SETPROCTITLE_FAST
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* use the function setproctitle_fast(const char *, ...)
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* (FreeBSD)
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* PS_USE_SETPROCTITLE
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* use the function setproctitle(const char *, ...)
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* (other BSDs)
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* PS_USE_CLOBBER_ARGV
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* write over the argv and environment area
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* (Linux and most SysV-like systems)
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* PS_USE_WIN32
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* push the string out as the name of a Windows event
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* PS_USE_NONE
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* don't update ps display
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* (This is the default, as it is safest.)
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*/
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#if defined(HAVE_SETPROCTITLE_FAST)
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#define PS_USE_SETPROCTITLE_FAST
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#elif defined(HAVE_SETPROCTITLE)
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#define PS_USE_SETPROCTITLE
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#elif defined(__linux__) || defined(__sun) || defined(__darwin__)
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#define PS_USE_CLOBBER_ARGV
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#elif defined(WIN32)
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#define PS_USE_WIN32
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#else
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#define PS_USE_NONE
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#endif
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/* Different systems want the buffer padded differently */
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#if defined(__linux__) || defined(__darwin__)
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#define PS_PADDING '\0'
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#else
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#define PS_PADDING ' '
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#endif
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#ifndef PS_USE_NONE
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#ifndef PS_USE_CLOBBER_ARGV
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/* all but one option need a buffer to write their ps line in */
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#define PS_BUFFER_SIZE 256
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static char ps_buffer[PS_BUFFER_SIZE];
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static const size_t ps_buffer_size = PS_BUFFER_SIZE;
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#else /* PS_USE_CLOBBER_ARGV */
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static char *ps_buffer; /* will point to argv area */
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static size_t ps_buffer_size; /* space determined at run time */
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static size_t last_status_len; /* use to minimize length of clobber */
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#endif /* PS_USE_CLOBBER_ARGV */
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static size_t ps_buffer_cur_len; /* nominal strlen(ps_buffer) */
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static size_t ps_buffer_fixed_size; /* size of the constant prefix */
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/*
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* Length of ps_buffer before the suffix was appended to the end, or 0 if we
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* didn't set a suffix.
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*/
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static size_t ps_buffer_nosuffix_len;
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static void flush_ps_display(void);
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#endif /* not PS_USE_NONE */
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/* save the original argv[] location here */
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static int save_argc;
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static char **save_argv;
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/*
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* Call this early in startup to save the original argc/argv values.
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* If needed, we make a copy of the original argv[] array to preserve it
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* from being clobbered by subsequent ps_display actions.
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*
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* (The original argv[] will not be overwritten by this routine, but may be
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* overwritten during init_ps_display. Also, the physical location of the
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* environment strings may be moved, so this should be called before any code
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* that might try to hang onto a getenv() result.)
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*
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* Note that in case of failure this cannot call elog() as that is not
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* initialized yet. We rely on write_stderr() instead.
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*/
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char **
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save_ps_display_args(int argc, char **argv)
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{
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save_argc = argc;
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save_argv = argv;
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#if defined(PS_USE_CLOBBER_ARGV)
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/*
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* If we're going to overwrite the argv area, count the available space.
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* Also move the environment to make additional room.
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*/
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{
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char *end_of_area = NULL;
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char **new_environ;
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int i;
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/*
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* check for contiguous argv strings
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*/
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for (i = 0; i < argc; i++)
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{
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if (i == 0 || end_of_area + 1 == argv[i])
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end_of_area = argv[i] + strlen(argv[i]);
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}
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if (end_of_area == NULL) /* probably can't happen? */
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{
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ps_buffer = NULL;
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ps_buffer_size = 0;
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return argv;
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}
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/*
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* check for contiguous environ strings following argv
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*/
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for (i = 0; environ[i] != NULL; i++)
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{
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if (end_of_area + 1 == environ[i])
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end_of_area = environ[i] + strlen(environ[i]);
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}
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ps_buffer = argv[0];
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last_status_len = ps_buffer_size = end_of_area - argv[0];
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/*
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* move the environment out of the way
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*/
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new_environ = (char **) malloc((i + 1) * sizeof(char *));
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if (!new_environ)
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{
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write_stderr("out of memory\n");
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exit(1);
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}
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for (i = 0; environ[i] != NULL; i++)
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{
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new_environ[i] = strdup(environ[i]);
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if (!new_environ[i])
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{
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write_stderr("out of memory\n");
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exit(1);
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}
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}
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new_environ[i] = NULL;
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environ = new_environ;
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}
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/*
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* If we're going to change the original argv[] then make a copy for
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* argument parsing purposes.
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*
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* (NB: do NOT think to remove the copying of argv[], even though
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* postmaster.c finishes looking at argv[] long before we ever consider
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* changing the ps display. On some platforms, getopt() keeps pointers
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* into the argv array, and will get horribly confused when it is
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* re-called to analyze a subprocess' argument string if the argv storage
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* has been clobbered meanwhile. Other platforms have other dependencies
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* on argv[].
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*/
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{
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char **new_argv;
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int i;
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new_argv = (char **) malloc((argc + 1) * sizeof(char *));
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if (!new_argv)
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{
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write_stderr("out of memory\n");
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exit(1);
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}
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for (i = 0; i < argc; i++)
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{
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new_argv[i] = strdup(argv[i]);
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if (!new_argv[i])
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{
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write_stderr("out of memory\n");
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exit(1);
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}
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}
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new_argv[argc] = NULL;
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#if defined(__darwin__)
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/*
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* macOS has a static copy of the argv pointer, which we may fix like
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* so:
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*/
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*_NSGetArgv() = new_argv;
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#endif
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argv = new_argv;
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}
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#endif /* PS_USE_CLOBBER_ARGV */
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return argv;
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}
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/*
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* Call this once during subprocess startup to set the identification
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* values.
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*
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* If fixed_part is NULL, a default will be obtained from MyBackendType.
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*
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* At this point, the original argv[] array may be overwritten.
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*/
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void
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init_ps_display(const char *fixed_part)
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{
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#ifndef PS_USE_NONE
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bool save_update_process_title;
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#endif
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Assert(fixed_part || MyBackendType);
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if (!fixed_part)
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fixed_part = GetBackendTypeDesc(MyBackendType);
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#ifndef PS_USE_NONE
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/* no ps display for stand-alone backend */
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if (!IsUnderPostmaster)
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return;
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/* no ps display if you didn't call save_ps_display_args() */
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if (!save_argv)
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return;
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#ifdef PS_USE_CLOBBER_ARGV
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/* If ps_buffer is a pointer, it might still be null */
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if (!ps_buffer)
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return;
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/* make extra argv slots point at end_of_area (a NUL) */
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for (int i = 1; i < save_argc; i++)
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save_argv[i] = ps_buffer + ps_buffer_size;
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#endif /* PS_USE_CLOBBER_ARGV */
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/*
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* Make fixed prefix of ps display.
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*/
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#if defined(PS_USE_SETPROCTITLE) || defined(PS_USE_SETPROCTITLE_FAST)
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/*
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* apparently setproctitle() already adds a `progname:' prefix to the ps
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* line
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*/
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#define PROGRAM_NAME_PREFIX ""
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#else
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#define PROGRAM_NAME_PREFIX "postgres: "
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#endif
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if (*cluster_name == '\0')
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{
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snprintf(ps_buffer, ps_buffer_size,
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PROGRAM_NAME_PREFIX "%s ",
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fixed_part);
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}
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else
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{
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snprintf(ps_buffer, ps_buffer_size,
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PROGRAM_NAME_PREFIX "%s: %s ",
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cluster_name, fixed_part);
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}
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ps_buffer_cur_len = ps_buffer_fixed_size = strlen(ps_buffer);
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/*
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* On the first run, force the update.
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*/
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save_update_process_title = update_process_title;
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update_process_title = true;
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set_ps_display("");
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update_process_title = save_update_process_title;
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#endif /* not PS_USE_NONE */
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}
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#ifndef PS_USE_NONE
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/*
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* update_ps_display_precheck
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* Helper function to determine if updating the process title is
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* something that we need to do.
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*/
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static bool
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update_ps_display_precheck(void)
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{
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/* update_process_title=off disables updates */
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if (!update_process_title)
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return false;
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/* no ps display for stand-alone backend */
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if (!IsUnderPostmaster)
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return false;
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#ifdef PS_USE_CLOBBER_ARGV
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/* If ps_buffer is a pointer, it might still be null */
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if (!ps_buffer)
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return false;
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#endif
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return true;
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}
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#endif /* not PS_USE_NONE */
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/*
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* set_ps_display_suffix
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* Adjust the process title to append 'suffix' onto the end with a space
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* between it and the current process title.
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*/
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void
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set_ps_display_suffix(const char *suffix)
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{
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#ifndef PS_USE_NONE
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size_t len;
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/* first, check if we need to update the process title */
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if (!update_ps_display_precheck())
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return;
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/* if there's already a suffix, overwrite it */
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if (ps_buffer_nosuffix_len > 0)
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ps_buffer_cur_len = ps_buffer_nosuffix_len;
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else
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ps_buffer_nosuffix_len = ps_buffer_cur_len;
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len = strlen(suffix);
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/* check if we have enough space to append the suffix */
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if (ps_buffer_cur_len + len + 1 >= ps_buffer_size)
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{
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/* not enough space. Check the buffer isn't full already */
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if (ps_buffer_cur_len < ps_buffer_size - 1)
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{
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/* append a space before the suffix */
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ps_buffer[ps_buffer_cur_len++] = ' ';
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/* just add what we can and fill the ps_buffer */
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memcpy(ps_buffer + ps_buffer_cur_len, suffix,
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ps_buffer_size - ps_buffer_cur_len - 1);
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ps_buffer[ps_buffer_size - 1] = '\0';
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ps_buffer_cur_len = ps_buffer_size - 1;
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}
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}
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else
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{
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ps_buffer[ps_buffer_cur_len++] = ' ';
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memcpy(ps_buffer + ps_buffer_cur_len, suffix, len + 1);
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ps_buffer_cur_len = ps_buffer_cur_len + len;
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}
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Assert(strlen(ps_buffer) == ps_buffer_cur_len);
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/* and set the new title */
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flush_ps_display();
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#endif /* not PS_USE_NONE */
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}
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/*
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* set_ps_display_remove_suffix
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* Remove the process display suffix added by set_ps_display_suffix
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*/
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void
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set_ps_display_remove_suffix(void)
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{
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#ifndef PS_USE_NONE
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/* first, check if we need to update the process title */
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if (!update_ps_display_precheck())
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return;
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/* check we added a suffix */
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if (ps_buffer_nosuffix_len == 0)
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return; /* no suffix */
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/* remove the suffix from ps_buffer */
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ps_buffer[ps_buffer_nosuffix_len] = '\0';
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ps_buffer_cur_len = ps_buffer_nosuffix_len;
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ps_buffer_nosuffix_len = 0;
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Assert(ps_buffer_cur_len == strlen(ps_buffer));
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/* and set the new title */
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flush_ps_display();
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#endif /* not PS_USE_NONE */
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}
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/*
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* Call this to update the ps status display to a fixed prefix plus an
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* indication of what you're currently doing passed in the argument.
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*
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* 'len' must be the same as strlen(activity)
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*/
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void
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set_ps_display_with_len(const char *activity, size_t len)
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{
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Assert(strlen(activity) == len);
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#ifndef PS_USE_NONE
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/* first, check if we need to update the process title */
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if (!update_ps_display_precheck())
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return;
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/* wipe out any suffix when the title is completely changed */
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ps_buffer_nosuffix_len = 0;
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/* Update ps_buffer to contain both fixed part and activity */
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if (ps_buffer_fixed_size + len >= ps_buffer_size)
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{
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/* handle the case where ps_buffer doesn't have enough space */
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memcpy(ps_buffer + ps_buffer_fixed_size, activity,
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ps_buffer_size - ps_buffer_fixed_size - 1);
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ps_buffer[ps_buffer_size - 1] = '\0';
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ps_buffer_cur_len = ps_buffer_size - 1;
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}
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else
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{
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memcpy(ps_buffer + ps_buffer_fixed_size, activity, len + 1);
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ps_buffer_cur_len = ps_buffer_fixed_size + len;
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}
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Assert(strlen(ps_buffer) == ps_buffer_cur_len);
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/* Transmit new setting to kernel, if necessary */
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flush_ps_display();
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#endif /* not PS_USE_NONE */
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}
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#ifndef PS_USE_NONE
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static void
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flush_ps_display(void)
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{
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#ifdef PS_USE_SETPROCTITLE
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setproctitle("%s", ps_buffer);
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#elif defined(PS_USE_SETPROCTITLE_FAST)
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setproctitle_fast("%s", ps_buffer);
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#endif
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#ifdef PS_USE_CLOBBER_ARGV
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/* pad unused memory; need only clobber remainder of old status string */
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if (last_status_len > ps_buffer_cur_len)
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MemSet(ps_buffer + ps_buffer_cur_len, PS_PADDING,
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last_status_len - ps_buffer_cur_len);
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last_status_len = ps_buffer_cur_len;
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#endif /* PS_USE_CLOBBER_ARGV */
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#ifdef PS_USE_WIN32
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{
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/*
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* Win32 does not support showing any changed arguments. To make it at
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* all possible to track which backend is doing what, we create a
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* named object that can be viewed with for example Process Explorer.
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*/
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static HANDLE ident_handle = INVALID_HANDLE_VALUE;
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char name[PS_BUFFER_SIZE + 32];
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if (ident_handle != INVALID_HANDLE_VALUE)
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CloseHandle(ident_handle);
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sprintf(name, "pgident(%d): %s", MyProcPid, ps_buffer);
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ident_handle = CreateEvent(NULL, TRUE, FALSE, name);
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}
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#endif /* PS_USE_WIN32 */
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}
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#endif /* not PS_USE_NONE */
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/*
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* Returns what's currently in the ps display, in case someone needs
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* it. Note that only the activity part is returned. On some platforms
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* the string will not be null-terminated, so return the effective
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* length into *displen.
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*/
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const char *
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get_ps_display(int *displen)
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{
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#ifdef PS_USE_CLOBBER_ARGV
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/* If ps_buffer is a pointer, it might still be null */
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if (!ps_buffer)
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{
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*displen = 0;
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return "";
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}
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#endif
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#ifndef PS_USE_NONE
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*displen = (int) (ps_buffer_cur_len - ps_buffer_fixed_size);
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return ps_buffer + ps_buffer_fixed_size;
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#else
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*displen = 0;
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return "";
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#endif
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}
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