PTHREAD_GETSPECIFIC(3) BSD Library Functions Manual PTHREAD_GETSPECIFIC(3)
NAME
pthread_getspecific -- thread-specific data value
LIBRARY
POSIX Threads Library (libpthread, -lpthread)
SYNOPSIS
#include <pthread.h>
void *
pthread_getspecific(pthread_key_t key);
int
pthread_setspecific(pthread_key_t key, const void *value);
DESCRIPTION
The pthread_getspecific() function returns the value currently bound to the specified key on behalf of the calling thread. Conversely, the
pthread_setspecific() function associates a thread-specific value with a key obtained via a previous call to pthread_key_create(3). Differ-
ent threads have different values bound to each key. These values are typically pointers to blocks of dynamically allocated memory that have
been reserved for use by the calling thread.
Undefined behavior may follow if either function is called with a key value not obtained from pthread_key_create(3), or if the call is made
after key has been deleted with pthread_key_delete(3). It is possible to call either function from a thread-specific data destructor func-
tion. Note however that this is not well defined for the pthread_setspecific() function; lost storage or infinite loops may occur.
RETURN VALUES
The pthread_getspecific() function will return the thread-specific data value associated with the given key. If no thread-specific data
value is associated with key, then the value NULL is returned. If successful, the pthread_setspecific() function will return zero. Other-
wise an error number will be returned to indicate the error.
ERRORS
No errors are defined for either function.
SEE ALSO
pthread_key_create(3)
STANDARDS
These functions conform to IEEE Std 1003.1-2001 (``POSIX.1'').
BSD
July 9, 2010 BSD