/*-------------------------------------------------------------------- * 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 #if defined(__darwin__) #include #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 */ #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 */ } /* * 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. */ void set_ps_display(const char *activity) { #ifndef PS_USE_NONE /* update_process_title=off disables updates */ if (!update_process_title) return; /* no ps display for stand-alone backend */ if (!IsUnderPostmaster) return; #ifdef PS_USE_CLOBBER_ARGV /* If ps_buffer is a pointer, it might still be null */ if (!ps_buffer) return; #endif /* Update ps_buffer to contain both fixed part and activity */ strlcpy(ps_buffer + ps_buffer_fixed_size, activity, ps_buffer_size - ps_buffer_fixed_size); ps_buffer_cur_len = strlen(ps_buffer); /* Transmit new setting to kernel, if necessary */ #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 }