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postgres/src/backend/main/main.c
Tom Lane f13ea95f9e Change pg_ctl to detect server-ready by watching status in postmaster.pid. 
Traditionally, "pg_ctl start -w" has waited for the server to become
ready to accept connections by attempting a connection once per second.
That has the major problem that connection issues (for instance, a
kernel packet filter blocking traffic) can't be reliably told apart
from server startup issues, and the minor problem that if server startup
isn't quick, we accumulate "the database system is starting up" spam
in the server log.  We've hacked around many of the possible connection
issues, but it resulted in ugly and complicated code in pg_ctl.c.

In commit c61559ec3, I changed the probe rate to every tenth of a second.
That prompted Jeff Janes to complain that the log-spam problem had become
much worse.  In the ensuing discussion, Andres Freund pointed out that
we could dispense with connection attempts altogether if the postmaster
were changed to report its status in postmaster.pid, which "pg_ctl start"
already relies on being able to read.  This patch implements that, teaching
postmaster.c to report a status string into the pidfile at the same
state-change points already identified as being of interest for systemd
status reporting (cf commit 7d17e683f).  pg_ctl no longer needs to link
with libpq at all; all its functions now depend on reading server files.

In support of this, teach AddToDataDirLockFile() to allow addition of
postmaster.pid lines in not-necessarily-sequential order.  This is needed
on Windows where the SHMEM_KEY line will never be written at all.  We still
have the restriction that we don't want to truncate the pidfile; document
the reasons for that a bit better.

Also, fix the pg_ctl TAP tests so they'll notice if "start -w" mode
is broken --- before, they'd just wait out the sixty seconds until
the loop gives up, and then report success anyway.  (Yes, I found that
out the hard way.)

While at it, arrange for pg_ctl to not need to #include miscadmin.h;
as a rather low-level backend header, requiring that to be compilable
client-side is pretty dubious.  This requires moving the #define's
associated with the pidfile into a new header file, and moving
PG_BACKEND_VERSIONSTR someplace else.  For lack of a clearly better
"someplace else", I put it into port.h, beside the declaration of
find_other_exec(), since most users of that macro are passing the value to
find_other_exec().  (initdb still depends on miscadmin.h, but at least
pg_ctl and pg_upgrade no longer do.)

In passing, fix main.c so that PG_BACKEND_VERSIONSTR actually defines the
output of "postgres -V", which remarkably it had never done before.

Discussion: https://postgr.es/m/CAMkU=1xJW8e+CTotojOMBd-yzUvD0e_JZu2xHo=MnuZ4__m7Pg@mail.gmail.com
2017-06-28 17:31:32 -04:00

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/*-------------------------------------------------------------------------
*
* main.c
* Stub main() routine for the postgres executable.
*
* This does some essential startup tasks for any incarnation of postgres
* (postmaster, standalone backend, standalone bootstrap process, or a
* separately exec'd child of a postmaster) and then dispatches to the
* proper FooMain() routine for the incarnation.
*
*
* Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/main/main.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <unistd.h>
#if defined(__NetBSD__)
#include <sys/param.h>
#endif
#if defined(_M_AMD64) && _MSC_VER == 1800
#include <math.h>
#include <versionhelpers.h>
#endif
#include "bootstrap/bootstrap.h"
#include "common/username.h"
#include "port/atomics.h"
#include "postmaster/postmaster.h"
#include "storage/s_lock.h"
#include "storage/spin.h"
#include "tcop/tcopprot.h"
#include "utils/help_config.h"
#include "utils/memutils.h"
#include "utils/pg_locale.h"
#include "utils/ps_status.h"
const char *progname;
static void startup_hacks(const char *progname);
static void init_locale(const char *categoryname, int category, const char *locale);
static void help(const char *progname);
static void check_root(const char *progname);
/*
* Any Postgres server process begins execution here.
*/
int
main(int argc, char *argv[])
{
bool do_check_root = true;
progname = get_progname(argv[0]);
/*
* Platform-specific startup hacks
*/
startup_hacks(progname);
/*
* Remember the physical location of the initially given argv[] array for
* possible use by ps display. On some platforms, the argv[] storage must
* be overwritten in order to set the process title for ps. In such cases
* save_ps_display_args makes and returns a new copy of the argv[] array.
*
* save_ps_display_args may also move the environment strings to make
* extra room. Therefore this should be done as early as possible during
* startup, to avoid entanglements with code that might save a getenv()
* result pointer.
*/
argv = save_ps_display_args(argc, argv);
/*
* If supported on the current platform, set up a handler to be called if
* the backend/postmaster crashes with a fatal signal or exception.
*/
#if defined(WIN32) && defined(HAVE_MINIDUMP_TYPE)
pgwin32_install_crashdump_handler();
#endif
/*
* Fire up essential subsystems: error and memory management
*
* Code after this point is allowed to use elog/ereport, though
* localization of messages may not work right away, and messages won't go
* anywhere but stderr until GUC settings get loaded.
*/
MemoryContextInit();
/*
* Set up locale information from environment. Note that LC_CTYPE and
* LC_COLLATE will be overridden later from pg_control if we are in an
* already-initialized database. We set them here so that they will be
* available to fill pg_control during initdb. LC_MESSAGES will get set
* later during GUC option processing, but we set it here to allow startup
* error messages to be localized.
*/
set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("postgres"));
#ifdef WIN32
/*
* Windows uses codepages rather than the environment, so we work around
* that by querying the environment explicitly first for LC_COLLATE and
* LC_CTYPE. We have to do this because initdb passes those values in the
* environment. If there is nothing there we fall back on the codepage.
*/
{
char *env_locale;
if ((env_locale = getenv("LC_COLLATE")) != NULL)
init_locale("LC_COLLATE", LC_COLLATE, env_locale);
else
init_locale("LC_COLLATE", LC_COLLATE, "");
if ((env_locale = getenv("LC_CTYPE")) != NULL)
init_locale("LC_CTYPE", LC_CTYPE, env_locale);
else
init_locale("LC_CTYPE", LC_CTYPE, "");
}
#else
init_locale("LC_COLLATE", LC_COLLATE, "");
init_locale("LC_CTYPE", LC_CTYPE, "");
#endif
#ifdef LC_MESSAGES
init_locale("LC_MESSAGES", LC_MESSAGES, "");
#endif
/*
* We keep these set to "C" always, except transiently in pg_locale.c; see
* that file for explanations.
*/
init_locale("LC_MONETARY", LC_MONETARY, "C");
init_locale("LC_NUMERIC", LC_NUMERIC, "C");
init_locale("LC_TIME", LC_TIME, "C");
/*
* Now that we have absorbed as much as we wish to from the locale
* environment, remove any LC_ALL setting, so that the environment
* variables installed by pg_perm_setlocale have force.
*/
unsetenv("LC_ALL");
check_strxfrm_bug();
/*
* Catch standard options before doing much else, in particular before we
* insist on not being root.
*/
if (argc > 1)
{
if (strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-?") == 0)
{
help(progname);
exit(0);
}
if (strcmp(argv[1], "--version") == 0 || strcmp(argv[1], "-V") == 0)
{
fputs(PG_BACKEND_VERSIONSTR, stdout);
exit(0);
}
/*
* In addition to the above, we allow "--describe-config" and "-C var"
* to be called by root. This is reasonably safe since these are
* read-only activities. The -C case is important because pg_ctl may
* try to invoke it while still holding administrator privileges on
* Windows. Note that while -C can normally be in any argv position,
* if you want to bypass the root check you must put it first. This
* reduces the risk that we might misinterpret some other mode's -C
* switch as being the postmaster/postgres one.
*/
if (strcmp(argv[1], "--describe-config") == 0)
do_check_root = false;
else if (argc > 2 && strcmp(argv[1], "-C") == 0)
do_check_root = false;
}
/*
* Make sure we are not running as root, unless it's safe for the selected
* option.
*/
if (do_check_root)
check_root(progname);
/*
* Dispatch to one of various subprograms depending on first argument.
*/
#ifdef EXEC_BACKEND
if (argc > 1 && strncmp(argv[1], "--fork", 6) == 0)
SubPostmasterMain(argc, argv); /* does not return */
#endif
#ifdef WIN32
/*
* Start our win32 signal implementation
*
* SubPostmasterMain() will do this for itself, but the remaining modes
* need it here
*/
pgwin32_signal_initialize();
#endif
if (argc > 1 && strcmp(argv[1], "--boot") == 0)
AuxiliaryProcessMain(argc, argv); /* does not return */
else if (argc > 1 && strcmp(argv[1], "--describe-config") == 0)
GucInfoMain(); /* does not return */
else if (argc > 1 && strcmp(argv[1], "--single") == 0)
PostgresMain(argc, argv,
NULL, /* no dbname */
strdup(get_user_name_or_exit(progname))); /* does not return */
else
PostmasterMain(argc, argv); /* does not return */
abort(); /* should not get here */
}
/*
* Place platform-specific startup hacks here. This is the right
* place to put code that must be executed early in the launch of any new
* server process. Note that this code will NOT be executed when a backend
* or sub-bootstrap process is forked, unless we are in a fork/exec
* environment (ie EXEC_BACKEND is defined).
*
* XXX The need for code here is proof that the platform in question
* is too brain-dead to provide a standard C execution environment
* without help. Avoid adding more here, if you can.
*/
static void
startup_hacks(const char *progname)
{
/*
* Windows-specific execution environment hacking.
*/
#ifdef WIN32
{
WSADATA wsaData;
int err;
/* Make output streams unbuffered by default */
setvbuf(stdout, NULL, _IONBF, 0);
setvbuf(stderr, NULL, _IONBF, 0);
/* Prepare Winsock */
err = WSAStartup(MAKEWORD(2, 2), &wsaData);
if (err != 0)
{
write_stderr("%s: WSAStartup failed: %d\n",
progname, err);
exit(1);
}
/* In case of general protection fault, don't show GUI popup box */
SetErrorMode(SEM_FAILCRITICALERRORS | SEM_NOGPFAULTERRORBOX);
#if defined(_M_AMD64) && _MSC_VER == 1800
/*----------
* Avoid crashing in certain floating-point operations if we were
* compiled for x64 with MS Visual Studio 2013 and are running on
* Windows prior to 7/2008R2 SP1 on an AVX2-capable CPU.
*
* Ref: https://connect.microsoft.com/VisualStudio/feedback/details/811093/visual-studio-2013-rtm-c-x64-code-generation-bug-for-avx2-instructions
*----------
*/
if (!IsWindows7SP1OrGreater())
{
_set_FMA3_enable(0);
}
#endif /* defined(_M_AMD64) && _MSC_VER == 1800 */
}
#endif /* WIN32 */
/*
* Initialize dummy_spinlock, in case we are on a platform where we have
* to use the fallback implementation of pg_memory_barrier().
*/
SpinLockInit(&dummy_spinlock);
}
/*
* Make the initial permanent setting for a locale category. If that fails,
* perhaps due to LC_foo=invalid in the environment, use locale C. If even
* that fails, perhaps due to out-of-memory, the entire startup fails with it.
* When this returns, we are guaranteed to have a setting for the given
* category's environment variable.
*/
static void
init_locale(const char *categoryname, int category, const char *locale)
{
if (pg_perm_setlocale(category, locale) == NULL &&
pg_perm_setlocale(category, "C") == NULL)
elog(FATAL, "could not adopt \"%s\" locale nor C locale for %s",
locale, categoryname);
}
/*
* Help display should match the options accepted by PostmasterMain()
* and PostgresMain().
*
* XXX On Windows, non-ASCII localizations of these messages only display
* correctly if the console output code page covers the necessary characters.
* Messages emitted in write_console() do not exhibit this problem.
*/
static void
help(const char *progname)
{
printf(_("%s is the PostgreSQL server.\n\n"), progname);
printf(_("Usage:\n %s [OPTION]...\n\n"), progname);
printf(_("Options:\n"));
printf(_(" -B NBUFFERS number of shared buffers\n"));
printf(_(" -c NAME=VALUE set run-time parameter\n"));
printf(_(" -C NAME print value of run-time parameter, then exit\n"));
printf(_(" -d 1-5 debugging level\n"));
printf(_(" -D DATADIR database directory\n"));
printf(_(" -e use European date input format (DMY)\n"));
printf(_(" -F turn fsync off\n"));
printf(_(" -h HOSTNAME host name or IP address to listen on\n"));
printf(_(" -i enable TCP/IP connections\n"));
printf(_(" -k DIRECTORY Unix-domain socket location\n"));
#ifdef USE_SSL
printf(_(" -l enable SSL connections\n"));
#endif
printf(_(" -N MAX-CONNECT maximum number of allowed connections\n"));
printf(_(" -o OPTIONS pass \"OPTIONS\" to each server process (obsolete)\n"));
printf(_(" -p PORT port number to listen on\n"));
printf(_(" -s show statistics after each query\n"));
printf(_(" -S WORK-MEM set amount of memory for sorts (in kB)\n"));
printf(_(" -V, --version output version information, then exit\n"));
printf(_(" --NAME=VALUE set run-time parameter\n"));
printf(_(" --describe-config describe configuration parameters, then exit\n"));
printf(_(" -?, --help show this help, then exit\n"));
printf(_("\nDeveloper options:\n"));
printf(_(" -f s|i|n|m|h forbid use of some plan types\n"));
printf(_(" -n do not reinitialize shared memory after abnormal exit\n"));
printf(_(" -O allow system table structure changes\n"));
printf(_(" -P disable system indexes\n"));
printf(_(" -t pa|pl|ex show timings after each query\n"));
printf(_(" -T send SIGSTOP to all backend processes if one dies\n"));
printf(_(" -W NUM wait NUM seconds to allow attach from a debugger\n"));
printf(_("\nOptions for single-user mode:\n"));
printf(_(" --single selects single-user mode (must be first argument)\n"));
printf(_(" DBNAME database name (defaults to user name)\n"));
printf(_(" -d 0-5 override debugging level\n"));
printf(_(" -E echo statement before execution\n"));
printf(_(" -j do not use newline as interactive query delimiter\n"));
printf(_(" -r FILENAME send stdout and stderr to given file\n"));
printf(_("\nOptions for bootstrapping mode:\n"));
printf(_(" --boot selects bootstrapping mode (must be first argument)\n"));
printf(_(" DBNAME database name (mandatory argument in bootstrapping mode)\n"));
printf(_(" -r FILENAME send stdout and stderr to given file\n"));
printf(_(" -x NUM internal use\n"));
printf(_("\nPlease read the documentation for the complete list of run-time\n"
"configuration settings and how to set them on the command line or in\n"
"the configuration file.\n\n"
"Report bugs to <pgsql-bugs@postgresql.org>.\n"));
}
static void
check_root(const char *progname)
{
#ifndef WIN32
if (geteuid() == 0)
{
write_stderr("\"root\" execution of the PostgreSQL server is not permitted.\n"
"The server must be started under an unprivileged user ID to prevent\n"
"possible system security compromise. See the documentation for\n"
"more information on how to properly start the server.\n");
exit(1);
}
/*
* Also make sure that real and effective uids are the same. Executing as
* a setuid program from a root shell is a security hole, since on many
* platforms a nefarious subroutine could setuid back to root if real uid
* is root. (Since nobody actually uses postgres as a setuid program,
* trying to actively fix this situation seems more trouble than it's
* worth; we'll just expend the effort to check for it.)
*/
if (getuid() != geteuid())
{
write_stderr("%s: real and effective user IDs must match\n",
progname);
exit(1);
}
#else /* WIN32 */
if (pgwin32_is_admin())
{
write_stderr("Execution of PostgreSQL by a user with administrative permissions is not\n"
"permitted.\n"
"The server must be started under an unprivileged user ID to prevent\n"
"possible system security compromises. See the documentation for\n"
"more information on how to properly start the server.\n");
exit(1);
}
#endif /* WIN32 */
}
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