189 lines
8.3 KiB
C
189 lines
8.3 KiB
C
/* This header file provides the reentrancy. */
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/* The reentrant system calls here serve two purposes:
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1) Provide reentrant versions of the system calls the ANSI C library
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requires.
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2) Provide these system calls in a namespace clean way.
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It is intended that *all* system calls that the ANSI C library needs
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be declared here. It documents them all in one place. All library access
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to the system is via some form of these functions.
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The target may provide the needed syscalls by any of the following:
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1) Define the reentrant versions of the syscalls directly.
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(eg: _open_r, _close_r, etc.). Please keep the namespace clean.
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When you do this, set "syscall_dir" to "syscalls" and add
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-DREENTRANT_SYSCALLS_PROVIDED to newlib_cflags in configure.host.
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2) Define namespace clean versions of the system calls by prefixing
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them with '_' (eg: _open, _close, etc.). Technically, there won't be
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true reentrancy at the syscall level, but the library will be namespace
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clean.
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When you do this, set "syscall_dir" to "syscalls" in configure.host.
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3) Define or otherwise provide the regular versions of the syscalls
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(eg: open, close, etc.). The library won't be reentrant nor namespace
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clean, but at least it will work.
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When you do this, add -DMISSING_SYSCALL_NAMES to newlib_cflags in
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configure.host.
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4) Define or otherwise provide the regular versions of the syscalls,
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and do not supply functional interfaces for any of the reentrant
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calls. With this method, the reentrant syscalls are redefined to
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directly call the regular system call without the reentrancy argument.
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When you do this, specify both -DREENTRANT_SYSCALLS_PROVIDED and
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-DMISSING_SYSCALL_NAMES via newlib_cflags in configure.host and do
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not specify "syscall_dir".
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Stubs of the reentrant versions of the syscalls exist in the libc/reent
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source directory and are provided if REENTRANT_SYSCALLS_PROVIDED isn't
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defined. These stubs call the native system calls: _open, _close, etc.
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if MISSING_SYSCALL_NAMES is *not* defined, otherwise they call the
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non-underscored versions: open, close, etc. when MISSING_SYSCALL_NAMES
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*is* defined.
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By default, newlib functions call the reentrant syscalls internally,
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passing a reentrancy structure as an argument. This reentrancy structure
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contains data that is thread-specific. For example, the errno value is
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kept in the reentrancy structure. If multiple threads exist, each will
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keep a separate errno value which is intuitive since the application flow
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cannot check for failure reliably otherwise.
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The reentrant syscalls are either provided by the platform, by the
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libc/reent stubs, or in the case of both MISSING_SYSCALL_NAMES and
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REENTRANT_SYSCALLS_PROVIDED being defined, the calls are redefined to
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simply call the regular syscalls with no reentrancy struct argument.
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A single-threaded application does not need to worry about the reentrancy
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structure. It is used internally.
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A multi-threaded application needs either to manually manage reentrancy
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structures or use dynamic reentrancy.
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Manually managing reentrancy structures entails calling special reentrant
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versions of newlib functions that have an additional reentrancy argument.
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For example, _printf_r. By convention, the first argument is the
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reentrancy structure. By default, the normal version of the function
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uses the default reentrancy structure: _REENT. The reentrancy structure
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is passed internally, eventually to the reentrant syscalls themselves.
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How the structures are stored and accessed in this model is up to the
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application.
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Dynamic reentrancy is specified by the __DYNAMIC_REENT__ flag. This
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flag denotes setting up a macro to replace _REENT with a function call
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to __getreent(). This function needs to be implemented by the platform
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and it is meant to return the reentrancy structure for the current
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thread. When the regular C functions (e.g. printf) go to call internal
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routines with the default _REENT structure, they end up calling with
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the reentrancy structure for the thread. Thus, application code does not
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need to call the _r routines nor worry about reentrancy structures. */
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/* WARNING: All identifiers here must begin with an underscore. This file is
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included by stdio.h and others and we therefore must only use identifiers
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in the namespace allotted to us. */
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#ifndef _REENT_H_
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#ifdef __cplusplus
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extern "C" {
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#endif
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#define _REENT_H_
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#include <sys/reent.h>
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#include <sys/_types.h>
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#define __need_size_t
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#define __need_ptrdiff_t
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#include <stddef.h>
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/* FIXME: not namespace clean */
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struct stat;
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struct tms;
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struct timeval;
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struct timezone;
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#if defined(REENTRANT_SYSCALLS_PROVIDED) && defined(MISSING_SYSCALL_NAMES)
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#define _close_r(__reent, __fd) close(__fd)
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#define _execve_r(__reent, __f, __arg, __env) execve(__f, __arg, __env)
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#define _fcntl_r(__reent, __fd, __cmd, __arg) fcntl(__fd, __cmd, __arg)
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#define _fork_r(__reent) fork()
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#define _fstat_r(__reent, __fdes, __stat) fstat(__fdes, __stat)
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#define _getpid_r(__reent) getpid()
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#define _isatty_r(__reent, __desc) isatty(__desc)
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#define _kill_r(__reent, __pid, __signal) kill(__pid, __signal)
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#define _link_r(__reent, __oldpath, __newpath) link(__oldpath, __newpath)
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#define _lseek_r(__reent, __fdes, __off, __w) lseek(__fdes, __off, __w)
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#define _mkdir_r(__reent, __path, __m) mkdir(__path, __m)
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#define _open_r(__reent, __path, __flag, __m) open(__path, __flag, __m)
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#define _read_r(__reent, __fd, __buff, __cnt) read(__fd, __buff, __cnt)
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#define _rename_r(__reent, __old, __new) rename(__old, __new)
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#define _sbrk_r(__reent, __incr) sbrk(__incr)
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#define _stat_r(__reent, __path, __buff) stat(__path, __buff)
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#define _times_r(__reent, __time) times(__time)
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#define _unlink_r(__reent, __path) unlink(__path)
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#define _wait_r(__reent, __status) wait(__status)
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#define _write_r(__reent, __fd, __buff, __cnt) write(__fd, __buff, __cnt)
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#define _gettimeofday_r(__reent, __tp, __tzp) gettimeofday(__tp, __tzp)
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#ifdef __LARGE64_FILES
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#define _lseek64_r(__reent, __fd, __off, __w) lseek64(__fd, __off, __w)
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#define _fstat64_r(__reent, __fd, __buff) fstat64(__fd, __buff)
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#define _open64_r(__reent, __path, __flag, __m) open64(__path, __flag, __m)
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#endif
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#else
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/* Reentrant versions of system calls. */
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extern int _close_r (struct _reent *, int);
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extern int _execve_r (struct _reent *, const char *, char *const *, char *const *);
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extern int _fcntl_r (struct _reent *, int, int, int);
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extern int _fork_r (struct _reent *);
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extern int _fstat_r (struct _reent *, int, struct stat *);
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extern int _getpid_r (struct _reent *);
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extern int _isatty_r (struct _reent *, int);
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extern int _kill_r (struct _reent *, int, int);
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extern int _link_r (struct _reent *, const char *, const char *);
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extern _off_t _lseek_r (struct _reent *, int, _off_t, int);
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extern int _mkdir_r (struct _reent *, const char *, int);
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extern int _open_r (struct _reent *, const char *, int, int);
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extern _ssize_t _read_r (struct _reent *, int, void *, size_t);
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extern int _rename_r (struct _reent *, const char *, const char *);
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extern void *_sbrk_r (struct _reent *, ptrdiff_t);
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extern int _stat_r (struct _reent *, const char *, struct stat *);
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extern _CLOCK_T_ _times_r (struct _reent *, struct tms *);
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extern int _unlink_r (struct _reent *, const char *);
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extern int _wait_r (struct _reent *, int *);
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extern _ssize_t _write_r (struct _reent *, int, const void *, size_t);
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/* This one is not guaranteed to be available on all targets. */
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extern int _gettimeofday_r (struct _reent *, struct timeval *__tp, void *__tzp);
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#ifdef __LARGE64_FILES
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#if defined(__CYGWIN__)
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#define stat64 stat
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#endif
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struct stat64;
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extern _off64_t _lseek64_r (struct _reent *, int, _off64_t, int);
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extern int _fstat64_r (struct _reent *, int, struct stat64 *);
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extern int _open64_r (struct _reent *, const char *, int, int);
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extern int _stat64_r (struct _reent *, const char *, struct stat64 *);
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/* Don't pollute namespace if not building newlib. */
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#if defined (__CYGWIN__) && !defined (_LIBC)
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#undef stat64
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#endif
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#endif
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#endif
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#ifdef __cplusplus
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}
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#endif
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#endif /* _REENT_H_ */
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