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/*-------------------------------------------------------------------------
*
* 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 1.6 2003/09/05 17:43:40 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
/*
* 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.
*
* 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 assume either all standard functions are
* thread-safe (NEED_REENTRANT_FUNC_NAMES=no), or the operating system
* requires reentrant function names (NEED_REENTRANT_FUNC_NAMES=yes).
* Compile and run src/tools/test_thread_funcs.c to see if your operating
* system requires reentrant function names.
*/
/*
* 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(USE_THREADS) && defined(NEED_REENTRANT_FUNC_NAMES)
/* reentrant strerror_r is available */
/* some early standards had strerror_r returning char * */
strerror_r(errnum, strerrbuf, buflen);
return (strerrbuf);
#else
/* no strerror_r() available, just use strerror */
return strerror(errnum);
#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(USE_THREADS) && defined(NEED_REENTRANT_FUNC_NAMES)
/*
* Early POSIX draft of getpwuid_r() returns 'struct passwd *'.
* getpwuid_r(uid, resultbuf, buffer, buflen)
* Do we need to support it? bjm 2003-08-14
*/
/* POSIX version */
getpwuid_r(uid, resultbuf, buffer, buflen, result);
#else
/* no getpwuid_r() available, just use getpwuid() */
*result = getpwuid(uid);
#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.
*/
int
pqGethostbyname(const char *name,
struct hostent *resbuf,
char *buf, size_t buflen,
struct hostent **result,
int *herrno)
{
#if defined(USE_THREADS) && defined(NEED_REENTRANT_FUNC_NAMES)
/*
* broken (well early POSIX draft) gethostbyname_r() which returns
* 'struct hostent *'
*/
*result = gethostbyname_r(name, resbuf, buf, buflen, herrno);
return (*result == NULL) ? -1 : 0;
#else
/* no gethostbyname_r(), just use gethostbyname() */
*result = gethostbyname(name);
if (*result != NULL)
return 0;
else
{
*herrno = h_errno;
return -1;
}
#endif
}
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