mirror of
https://github.com/postgres/postgres.git
synced 2025-05-18 17:41:14 +03:00
285 lines
8.7 KiB
C
285 lines
8.7 KiB
C
/*-------------------------------------------------------------------------
|
|
*
|
|
* thread.c
|
|
*
|
|
* Prototypes and macros around system calls, used to help make
|
|
* threaded libraries reentrant and safe to use from threaded applications.
|
|
*
|
|
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
|
|
*
|
|
* $Id: thread.c,v 1.12.2.5 2004/03/23 02:04:33 momjian Exp $
|
|
*
|
|
*-------------------------------------------------------------------------
|
|
*/
|
|
|
|
#include "postgres.h"
|
|
|
|
#include <sys/types.h>
|
|
#include <errno.h>
|
|
#if defined(WIN32) && (defined(_MSC_VER) || defined(__BORLANDC__))
|
|
#undef ERROR
|
|
#else
|
|
#include <pwd.h>
|
|
#endif
|
|
#if defined(ENABLE_THREAD_SAFETY)
|
|
#include <pthread.h>
|
|
#endif
|
|
|
|
/*
|
|
* Threading sometimes requires specially-named versions of functions
|
|
* that return data in static buffers, like strerror_r() instead of
|
|
* strerror(). Other operating systems use pthread_setspecific()
|
|
* and pthread_getspecific() internally to allow standard library
|
|
* functions to return static data to threaded applications. And some
|
|
* operating systems have neither, meaning we have to do our own locking.
|
|
*
|
|
* Additional confusion exists because many operating systems that
|
|
* use pthread_setspecific/pthread_getspecific() also have *_r versions
|
|
* of standard library functions for compatibility with operating systems
|
|
* that require them. However, internally, these *_r functions merely
|
|
* call the thread-safe standard library functions.
|
|
*
|
|
* For example, BSD/OS 4.3 uses Bind 8.2.3 for getpwuid(). Internally,
|
|
* getpwuid() calls pthread_setspecific/pthread_getspecific() to return
|
|
* static data to the caller in a thread-safe manner. However, BSD/OS
|
|
* also has getpwuid_r(), which merely calls getpwuid() and shifts
|
|
* around the arguments to match the getpwuid_r() function declaration.
|
|
* Therefore, while BSD/OS has getpwuid_r(), it isn't required. It also
|
|
* doesn't have strerror_r(), so we can't fall back to only using *_r
|
|
* functions for threaded programs.
|
|
*
|
|
* The current setup is to try threading in this order:
|
|
*
|
|
* use non-*_r function names if they are all thread-safe
|
|
* (NEED_REENTRANT_FUNCS=no)
|
|
* use *_r functions if they exist (configure test)
|
|
* do our own locking and copying of non-threadsafe functions
|
|
*
|
|
* The disadvantage of the last option is not the thread overhead but
|
|
* the fact that all function calls are serialized, and with gethostbyname()
|
|
* requiring a DNS lookup, that could be slow.
|
|
*
|
|
* One thread-safe solution for gethostbyname() might be to use getaddrinfo().
|
|
*
|
|
* See src/tools/thread to see if your operating system has thread-safe
|
|
* non-*_r functions.
|
|
*/
|
|
|
|
|
|
/*
|
|
* Wrapper around strerror and strerror_r to use the former if it is
|
|
* available and also return a more useful value (the error string).
|
|
*/
|
|
char *
|
|
pqStrerror(int errnum, char *strerrbuf, size_t buflen)
|
|
{
|
|
#if defined(FRONTEND) && defined(ENABLE_THREAD_SAFETY) && defined(NEED_REENTRANT_FUNCS) && defined(HAVE_STRERROR_R)
|
|
/* reentrant strerror_r is available */
|
|
/* some early standards had strerror_r returning char * */
|
|
strerror_r(errnum, strerrbuf, buflen);
|
|
return strerrbuf;
|
|
|
|
#else
|
|
|
|
#if defined(FRONTEND) && defined(ENABLE_THREAD_SAFETY) && defined(NEED_REENTRANT_FUNCS) && !defined(HAVE_STRERROR_R)
|
|
static pthread_mutex_t strerror_lock = PTHREAD_MUTEX_INITIALIZER;
|
|
pthread_mutex_lock(&strerror_lock);
|
|
#endif
|
|
|
|
/* no strerror_r() available, just use strerror */
|
|
StrNCpy(strerrbuf, strerror(errnum), buflen);
|
|
|
|
#if defined(FRONTEND) && defined(ENABLE_THREAD_SAFETY) && defined(NEED_REENTRANT_FUNCS) && !defined(HAVE_STRERROR_R)
|
|
pthread_mutex_unlock(&strerror_lock);
|
|
#endif
|
|
|
|
return strerrbuf;
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* Wrapper around getpwuid() or getpwuid_r() to mimic POSIX getpwuid_r()
|
|
* behaviour, if it is not available or required.
|
|
*/
|
|
#ifndef WIN32
|
|
int
|
|
pqGetpwuid(uid_t uid, struct passwd *resultbuf, char *buffer,
|
|
size_t buflen, struct passwd **result)
|
|
{
|
|
#if defined(FRONTEND) && defined(ENABLE_THREAD_SAFETY) && defined(NEED_REENTRANT_FUNCS) && defined(HAVE_GETPWUID_R)
|
|
|
|
#ifdef GETPWUID_R_5ARG
|
|
/* POSIX version */
|
|
getpwuid_r(uid, resultbuf, buffer, buflen, result);
|
|
#else
|
|
/*
|
|
* Early POSIX draft of getpwuid_r() returns 'struct passwd *'.
|
|
* getpwuid_r(uid, resultbuf, buffer, buflen)
|
|
*/
|
|
*result = getpwuid_r(uid, resultbuf, buffer, buflen);
|
|
#endif
|
|
#else
|
|
|
|
#if defined(FRONTEND) && defined(ENABLE_THREAD_SAFETY) && defined(NEED_REENTRANT_FUNCS) && !defined(HAVE_GETPWUID_R)
|
|
static pthread_mutex_t getpwuid_lock = PTHREAD_MUTEX_INITIALIZER;
|
|
pthread_mutex_lock(&getpwuid_lock);
|
|
#endif
|
|
|
|
/* no getpwuid_r() available, just use getpwuid() */
|
|
*result = getpwuid(uid);
|
|
|
|
#if defined(FRONTEND) && defined(ENABLE_THREAD_SAFETY) && defined(NEED_REENTRANT_FUNCS) && !defined(HAVE_GETPWUID_R)
|
|
|
|
/* Use 'buffer' memory for storage of strings used by struct passwd */
|
|
if (*result &&
|
|
strlen((*result)->pw_name) + 1 +
|
|
strlen((*result)->pw_passwd) + 1 +
|
|
strlen((*result)->pw_gecos) + 1 +
|
|
/* skip class if it exists */
|
|
strlen((*result)->pw_dir) + 1 +
|
|
strlen((*result)->pw_shell) + 1 <= buflen)
|
|
{
|
|
memcpy(resultbuf, *result, sizeof(struct passwd));
|
|
strcpy(buffer, (*result)->pw_name);
|
|
resultbuf->pw_name = buffer;
|
|
buffer += strlen(resultbuf->pw_name) + 1;
|
|
strcpy(buffer, (*result)->pw_passwd);
|
|
resultbuf->pw_passwd = buffer;
|
|
buffer += strlen(resultbuf->pw_passwd) + 1;
|
|
strcpy(buffer, (*result)->pw_gecos);
|
|
resultbuf->pw_gecos = buffer;
|
|
buffer += strlen(resultbuf->pw_gecos) + 1;
|
|
strcpy(buffer, (*result)->pw_dir);
|
|
resultbuf->pw_dir = buffer;
|
|
buffer += strlen(resultbuf->pw_dir) + 1;
|
|
strcpy(buffer, (*result)->pw_shell);
|
|
resultbuf->pw_shell = buffer;
|
|
buffer += strlen(resultbuf->pw_shell) + 1;
|
|
|
|
*result = resultbuf;
|
|
}
|
|
else
|
|
{
|
|
*result = NULL;
|
|
errno = ERANGE;
|
|
}
|
|
|
|
pthread_mutex_unlock(&getpwuid_lock);
|
|
#endif
|
|
#endif
|
|
return (*result == NULL) ? -1 : 0;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Wrapper around gethostbyname() or gethostbyname_r() to mimic
|
|
* POSIX gethostbyname_r() behaviour, if it is not available or required.
|
|
* This function is called _only_ by our getaddinfo() portability function.
|
|
*/
|
|
#ifndef HAVE_GETADDRINFO
|
|
int
|
|
pqGethostbyname(const char *name,
|
|
struct hostent *resultbuf,
|
|
char *buffer, size_t buflen,
|
|
struct hostent **result,
|
|
int *herrno)
|
|
{
|
|
#if defined(FRONTEND) && defined(ENABLE_THREAD_SAFETY) && defined(NEED_REENTRANT_FUNCS) && defined(HAVE_GETHOSTBYNAME_R)
|
|
/*
|
|
* broken (well early POSIX draft) gethostbyname_r() which returns
|
|
* 'struct hostent *'
|
|
*/
|
|
*result = gethostbyname_r(name, resultbuf, buffer, buflen, herrno);
|
|
return (*result == NULL) ? -1 : 0;
|
|
|
|
#else
|
|
|
|
#if defined(FRONTEND) && defined(ENABLE_THREAD_SAFETY) && defined(NEED_REENTRANT_FUNCS) && !defined(HAVE_GETHOSTBYNAME_R)
|
|
static pthread_mutex_t gethostbyname_lock = PTHREAD_MUTEX_INITIALIZER;
|
|
pthread_mutex_lock(&gethostbyname_lock);
|
|
#endif
|
|
|
|
/* no gethostbyname_r(), just use gethostbyname() */
|
|
*result = gethostbyname(name);
|
|
|
|
#if defined(FRONTEND) && defined(ENABLE_THREAD_SAFETY) && defined(NEED_REENTRANT_FUNCS) && !defined(HAVE_GETHOSTBYNAME_R)
|
|
|
|
/*
|
|
* Use 'buffer' memory for storage of structures used by struct hostent.
|
|
* The layout is:
|
|
*
|
|
* addr pointers
|
|
* alias pointers
|
|
* addr structures
|
|
* alias structures
|
|
* name
|
|
*/
|
|
if (*result)
|
|
{
|
|
int i, pointers = 2 /* for nulls */, len = 0;
|
|
char **pbuffer;
|
|
|
|
for (i = 0; (*result)->h_addr_list[i]; i++, pointers++)
|
|
len += (*result)->h_length;
|
|
for (i = 0; (*result)->h_aliases[i]; i++, pointers++)
|
|
len += (*result)->h_length;
|
|
|
|
if (pointers * sizeof(char *) + MAXALIGN(len) + strlen((*result)->h_name) + 1 <= buflen)
|
|
{
|
|
memcpy(resultbuf, *result, sizeof(struct hostent));
|
|
|
|
pbuffer = (char **)buffer;
|
|
resultbuf->h_addr_list = pbuffer;
|
|
buffer += pointers * sizeof(char *);
|
|
|
|
for (i = 0; (*result)->h_addr_list[i]; i++, pbuffer++)
|
|
{
|
|
memcpy(buffer, (*result)->h_addr_list[i], (*result)->h_length);
|
|
resultbuf->h_addr_list[i] = buffer;
|
|
buffer += (*result)->h_length;
|
|
}
|
|
resultbuf->h_addr_list[i] = NULL;
|
|
pbuffer++;
|
|
|
|
resultbuf->h_aliases = pbuffer;
|
|
|
|
for (i = 0; (*result)->h_aliases[i]; i++, pbuffer++)
|
|
{
|
|
memcpy(buffer, (*result)->h_aliases[i], (*result)->h_length);
|
|
resultbuf->h_aliases[i] = buffer;
|
|
buffer += (*result)->h_length;
|
|
}
|
|
resultbuf->h_aliases[i] = NULL;
|
|
pbuffer++;
|
|
|
|
/* Place at end for cleaner alignment */
|
|
buffer = MAXALIGN(buffer);
|
|
strcpy(buffer, (*result)->h_name);
|
|
resultbuf->h_name = buffer;
|
|
buffer += strlen(resultbuf->h_name) + 1;
|
|
|
|
*result = resultbuf;
|
|
}
|
|
else
|
|
{
|
|
*result = NULL;
|
|
errno = ERANGE;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
if (*result != NULL)
|
|
*herrno = h_errno;
|
|
|
|
#if defined(FRONTEND) && defined(ENABLE_THREAD_SAFETY) && defined(NEED_REENTRANT_FUNCS) && !defined(HAVE_GETHOSTBYNAME_R)
|
|
pthread_mutex_unlock(&gethostbyname_lock);
|
|
#endif
|
|
|
|
if (*result != NULL)
|
|
return 0;
|
|
else
|
|
return -1;
|
|
#endif
|
|
}
|
|
#endif
|