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"standby clone": cowardly refuse to clone into an active data directory

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By checking the PID file in the same way pg_ctl does, we can be pretty
much certain whether the target data directory contains an active
PostgreSQL instance.
This commit is contained in:
Ian Barwick
2018-02-07 23:27:45 +09:00
committed by Ian Barwick
parent 76cc11b786
commit 571e6b2783
3 changed files with 167 additions and 59 deletions
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162
dirutil.c
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@@ -21,6 +21,7 @@
#include <unistd.h>
#include <dirent.h>
#include <signal.h>
#include <sys/stat.h>
#include <errno.h>
#include <stdio.h>
@@ -38,31 +39,29 @@
static int unlink_dir_callback(const char *fpath, const struct stat *sb, int typeflag, struct FTW *ftwbuf);
/* PID can be negative if backend is standalone */
typedef long pgpid_t;
/*
* make sure the directory either doesn't exist or is empty
* we use this function to check the new data directory and
* the directories for tablespaces
* Check if a directory exists, and if so whether it is empty.
*
* This is the same check initdb does on the new PGDATA dir
*
* Returns 0 if nonexistent, 1 if exists and empty, 2 if not empty,
* or -1 if trouble accessing directory
* This function is used for checking both the data directory
* and tablespace directories.
*/
int
DataDirState
check_dir(char *path)
{
DIR *chkdir;
struct dirent *file;
int result = 1;
DIR *chkdir = NULL;
struct dirent *file = NULL;
int result = DIR_EMPTY;
errno = 0;
chkdir = opendir(path);
if (!chkdir)
return (errno == ENOENT) ? 0 : -1;
return (errno == ENOENT) ? DIR_NOENT : DIR_ERROR;
while ((file = readdir(chkdir)) != NULL)
{
@@ -74,25 +73,15 @@ check_dir(char *path)
}
else
{
result = 2; /* not empty */
result = DIR_NOT_EMPTY;
break;
}
}
#ifdef WIN32
/*
* This fix is in mingw cvs (runtime/mingwex/dirent.c rev 1.4), but not in
* released version
*/
if (GetLastError() == ERROR_NO_MORE_FILES)
errno = 0;
#endif
closedir(chkdir);
if (errno != 0)
return -1; /* some kind of I/O error? */
return DIR_ERROR; /* some kind of I/O error? */
return result;
}
@@ -107,12 +96,13 @@ create_dir(char *path)
if (mkdir_p(path, 0700) == 0)
return true;
log_error(_("unable to create directory \"%s\": %s"),
path, strerror(errno));
log_error(_("unable to create directory \"%s\""), path);
log_detail("%s", strerror(errno));
return false;
}
bool
set_dir_permissions(char *path)
{
@@ -147,26 +137,6 @@ mkdir_p(char *path, mode_t omode)
oumask = 0;
retval = 0;
#ifdef WIN32
/* skip network and drive specifiers for win32 */
if (strlen(p) >= 2)
{
if (p[0] == '/' && p[1] == '/')
{
/* network drive */
p = strstr(p + 2, "/");
if (p == NULL)
return 1;
}
else if (p[1] == ':' &&
((p[0] >= 'a' && p[0] <= 'z') ||
(p[0] >= 'A' && p[0] <= 'Z')))
{
/* local drive */
p += 2;
}
}
#endif
if (p[0] == '/') /* Skip leading '/'. */
++p;
@@ -243,15 +213,91 @@ is_pg_dir(char *path)
return false;
}
/*
* Attempt to determine if a PostgreSQL data directory is in use
* by reading the pidfile. This is the same mechanism used by
* "pg_ctl".
*
* This function will abort with appropriate log messages if a file error
* is encountered, as the user will need to address the situation before
* any further useful progress can be made.
*/
PgDirState
is_pg_running(char *path)
{
long pid;
FILE *pidf;
char pid_file[MAXPGPATH];
/* it's reasonable to assume the pidfile name will not change */
snprintf(pid_file, MAXPGPATH, "%s/postmaster.pid", path);
pidf = fopen(pid_file, "r");
if (pidf == NULL)
{
/*
* No PID file - PostgreSQL shouldn't be running. From 9.3 (the
* earliesty version we care about) removal of the PID file will
* cause the postmaster to shut down, so it's highly unlikely
* that PostgreSQL will still be running.
*/
if (errno == ENOENT)
{
return PG_DIR_NOT_RUNNING;
}
else
{
log_error(_("unable to open PostgreSQL PID file \"%s\""), pid_file);
log_detail("%s", strerror(errno));
exit(ERR_BAD_CONFIG);
}
}
/*
* In the unlikely event we're unable to extract a PID from the PID file,
* log a warning but assume we're not dealing with a running instance
* as PostgreSQL should have shut itself down in these cases anyway.
*/
if (fscanf(pidf, "%ld", &pid) != 1)
{
/* Is the file empty? */
if (ftell(pidf) == 0 && feof(pidf))
{
log_warning(_("PostgreSQL PID file \"%s\" is empty"), path);
}
else
{
log_warning(_("invalid data in PostgreSQL PID file \"%s\""), path);
}
return PG_DIR_NOT_RUNNING;
}
fclose(pidf);
if (pid == getpid())
return PG_DIR_NOT_RUNNING;
if (pid == getppid())
return PG_DIR_NOT_RUNNING;
if (kill(pid, 0) == 0)
return PG_DIR_RUNNING;
return PG_DIR_NOT_RUNNING;
}
bool
create_pg_dir(char *path, bool force)
{
/* Check this directory could be used as a PGDATA dir */
/* Check this directory can be used as a PGDATA dir */
switch (check_dir(path))
{
case 0:
/* dir not there, must create it */
case DIR_NOENT:
/* directory does not exist, attempt to create it */
log_info(_("creating directory \"%s\"..."), path);
if (!create_dir(path))
@@ -261,20 +307,20 @@ create_pg_dir(char *path, bool force)
return false;
}
break;
case 1:
/* Present but empty, fix permissions and use it */
log_info(_("checking and correcting permissions on existing directory %s"),
case DIR_EMPTY:
/* exists but empty, fix permissions and use it */
log_info(_("checking and correcting permissions on existing directory \"%s\""),
path);
if (!set_dir_permissions(path))
{
log_error(_("unable to change permissions of directory \"%s\":\n %s"),
path, strerror(errno));
log_error(_("unable to change permissions of directory \"%s\""), path);
log_detail("%s", strerror(errno));
return false;
}
break;
case 2:
/* Present and not empty */
case DIR_NOT_EMPTY:
/* exists but is not empty */
log_warning(_("directory \"%s\" exists but is not empty"),
path);
@@ -282,7 +328,7 @@ create_pg_dir(char *path, bool force)
{
if (force == true)
{
log_notice(_("deleting existing data directory \"%s\""), path);
log_notice(_("-F/--force provided - deleting existing data directory \"%s\""), path);
nftw(path, unlink_dir_callback, 64, FTW_DEPTH | FTW_PHYS);
return true;
}
@@ -300,7 +346,7 @@ create_pg_dir(char *path, bool force)
return false;
}
break;
default:
case DIR_ERROR:
log_error(_("could not access directory \"%s\": %s"),
path, strerror(errno));
return false;