NAME

getc_unlocked, getchar_unlocked, putc_unlocked, putchar_unlocked - stdio with explicit client locking

 SYNOPSIS

#include <stdio.h>

int getc_unlocked(FILE *stream);
int getchar_unlocked(void);
int putc_unlocked(int c, FILE *stream);
int putchar_unlocked(int c);

 DESCRIPTION

Versions of the functions getc(), getchar(), putc(), and putchar() respectively named getc_unlocked(), getchar_unlocked(), putc_unlocked(), and putchar_unlocked() are provided which are functionally identical to the original versions with the exception that they are not required to be implemented in a thread-safe manner. They may only safely be used within a scope protected by flockfile() (or ftrylockfile()) and funlockfile(). These functions may safely be used in a multi-threaded program if and only if they are called while the invoking thread owns the ( FILE *) object, as is the case after a successful call of the flockfile() or ftrylockfile() functions.

 RETURN VALUE

See getc(), getchar(), putc(), and putchar().

 ERRORS

No errors are defined.

 EXAMPLES

None.

 APPLICATION USAGE

Because they may be implemented as macros, getc_unlocked() and putc_unlocked() may treat incorrectly a stream argument with side effects. In particular, getc_unlocked(*f++) and putc_unlocked(*f++) will not necessarily work as expected. Therefore, use of these functions should be preceded by the appropriate "#undef getc_unlocked" or "#undef putc_unlocked" statement in such situations.

 FUTURE DIRECTIONS

None.

 SEE ALSO

getc(), getchar(), putc(), putchar(), <stdio.h>.

DERIVATION

Derived from the POSIX Threads Extension (1003.1c-1995)