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189 lines
8.6 KiB
189 lines
8.6 KiB
/* 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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#include <machine/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 _PARAMS ((struct _reent *, int)); |
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extern int _execve_r _PARAMS ((struct _reent *, const char *, char *const *, char *const *)); |
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extern int _fcntl_r _PARAMS ((struct _reent *, int, int, int)); |
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extern int _fork_r _PARAMS ((struct _reent *)); |
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extern int _fstat_r _PARAMS ((struct _reent *, int, struct stat *)); |
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extern int _getpid_r _PARAMS ((struct _reent *)); |
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extern int _isatty_r _PARAMS ((struct _reent *, int)); |
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extern int _kill_r _PARAMS ((struct _reent *, int, int)); |
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extern int _link_r _PARAMS ((struct _reent *, const char *, const char *)); |
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extern _off_t _lseek_r _PARAMS ((struct _reent *, int, _off_t, int)); |
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extern int _mkdir_r _PARAMS ((struct _reent *, const char *, int)); |
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extern int _open_r _PARAMS ((struct _reent *, const char *, int, int)); |
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extern _ssize_t _read_r _PARAMS ((struct _reent *, int, void *, size_t)); |
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extern int _rename_r _PARAMS ((struct _reent *, const char *, const char *)); |
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extern void *_sbrk_r _PARAMS ((struct _reent *, ptrdiff_t)); |
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extern int _stat_r _PARAMS ((struct _reent *, const char *, struct stat *)); |
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extern _CLOCK_T_ _times_r _PARAMS ((struct _reent *, struct tms *)); |
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extern int _unlink_r _PARAMS ((struct _reent *, const char *)); |
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extern int _wait_r _PARAMS ((struct _reent *, int *)); |
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extern _ssize_t _write_r _PARAMS ((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 _PARAMS ((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 _PARAMS ((struct _reent *, int, _off64_t, int)); |
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extern int _fstat64_r _PARAMS ((struct _reent *, int, struct stat64 *)); |
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extern int _open64_r _PARAMS ((struct _reent *, const char *, int, int)); |
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extern int _stat64_r _PARAMS ((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 (_COMPILING_NEWLIB) |
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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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