/* * (c) Copyright 1990-1996 OPEN SOFTWARE FOUNDATION, INC. * (c) Copyright 1990-1996 HEWLETT-PACKARD COMPANY * (c) Copyright 1990-1996 DIGITAL EQUIPMENT CORPORATION * (c) Copyright 1991, 1992 Siemens-Nixdorf Information Systems * To anyone who acknowledges that this file is provided "AS IS" without * any express or implied warranty: permission to use, copy, modify, and * distribute this file for any purpose is hereby granted without fee, * provided that the above copyright notices and this notice appears in * all source code copies, and that none of the names listed above be used * in advertising or publicity pertaining to distribution of the software * without specific, written prior permission. None of these organizations * makes any representations about the suitability of this software for * any purpose. */ /* * Header file for thread synchrounous I/O */ #ifndef CMA_THREAD_IO #define CMA_THREAD_IO /* * INCLUDE FILES */ #include <cma_config.h> #include <sys/select.h> #include <cma.h> #include <sys/types.h> #include <sys/time.h> #include <cma_init.h> #include <cma_errors.h> /* * CONSTANTS */ /* * Maximum number of files (ie, max_fd+1) */ #define cma__c_mx_file FD_SETSIZE /* * Number of bits per file descriptor bit mask (ie number of bytes * bits/byte) */ #define cma__c_nbpm NFDBITS /* * TYPE DEFINITIONS */ typedef enum CMA__T_IO_TYPE { cma__c_io_read = 0, cma__c_io_write = 1, cma__c_io_except = 2 } cma__t_io_type; #define cma__c_max_io_type 2 /* * From our local <sys/types.h>: * * typedef long fd_mask; * * typedef struct fd_set { * fd_mask fds_bits[howmany(FD_SETSIZE, NFDBITS)]; * } fd_set; * */ typedef fd_mask cma__t_mask; typedef fd_set cma__t_file_mask; /* * GLOBAL DATA */ /* * Maximum number of files (ie, max_fd+1) as determined by getdtablesize(). */ extern int cma__g_mx_file; /* * Number of submasks (ie "int" sized chunks) per file descriptor mask as * determined by getdtablesize(). */ extern int cma__g_nspm; /* * MACROS */ /* * Define a constant for the errno value which indicates that the requested * operation was not performed because it would block the process. */ # define cma__is_blocking(s) \ ((s == EAGAIN) || (s == EWOULDBLOCK) || (s == EINPROGRESS) || \ (s == EALREADY) || (s == EDEADLK)) /* * It is necessary to issue an I/O function, before calling cma__io_wait() * in the following cases: * * * This file descriptor has been set non-blocking by CMA * * This file descriptor has been set non-blocking by the user. */ #define cma__issue_io_call(fd) \ ( (cma__g_file[fd]->non_blocking) || \ (cma__g_file[fd]->user_fl.user_non_blocking) ) #define cma__set_user_nonblocking(flags) \ /* * Determine if the file is open */ /* * If the file gets closed while waiting for the mutex cma__g_file[rfd] * gets set to null. This results in a crash if NDEBUG is set to 0 * since cma__int_lock tries to dereference it to set the mutex ownership * after it gets the mutex. The following will still set the ownership * in cma__int_lock so we'll set it back to noone if cma__g_file is null * when we come back just in case it matters. It shouldn't since its no * longer in use but..... * Callers of this should recheck cma__g_file after the reservation to * make sure continueing makes sense. */ #define cma__fd_reserve(rfd) \ { \ cma__t_int_mutex *__mutex__; \ __mutex__ = cma__g_file[rfd]->mutex; \ cma__int_lock (__mutex__); \ if(cma__g_file[rfd] == (cma__t_file_obj *)cma_c_null_ptr) \ cma__int_unlock(__mutex__); \ } /* * Unreserve a file descriptor */ #define cma__fd_unreserve(ufd) cma__int_unlock (cma__g_file[ufd]->mutex) /* * AND together two select file descriptor masks */ #define cma__fdm_and(target,a,b) \ { \ int __i__ = cma__g_nspm; \ while (__i__--) \ (target)->fds_bits[__i__] = \ (a)->fds_bits[__i__] & (b)->fds_bits[__i__]; \ } /* * Clear a bit in a select file descriptor mask * * FD_CLR(n, p) := ((p)->fds_bits[(n)/NFDBITS] &= ~(1 << ((n) % NFDBITS))) */ #define cma__fdm_clr_bit(n,p) FD_CLR (n, p) /* * Copy the contents of one file descriptor mask into another. If the * destination operand is null, do nothing; if the source operand is null, * simply zero the destination. */ #define cma__fdm_copy(src,dst,nfds) { \ if (dst) \ if (src) { \ cma__t_mask *__s__ = (cma__t_mask *)(src); \ cma__t_mask *__d__ = (cma__t_mask *)(dst); \ int __i__; \ for (__i__ = 0; __i__ < (nfds); __i__ += cma__c_nbpm) \ *__d__++ = *__s__++; \ } \ else \ cma__fdm_zero (dst); \ } /* * To increment count for each bit set in fd - mask */ #define cma__fdm_count_bits(map,count) \ { \ int __i__ = cma__g_nspm; \ while (__i__--) { \ cma__t_mask __tm__; \ __tm__ = (map)->fds_bits[__i__]; \ while(__tm__) { \ (count)++; \ __tm__ &= ~(__tm__ & (-__tm__)); /* Assumes 2's comp */ \ } \ } \ } /* * Test if a bit is set in a select file descriptor mask * * FD_ISSET(n,p) := ((p)->fds_bits[(n)/NFDBITS] & (1 << ((n) % NFDBITS))) */ #define cma__fdm_is_set(n,p) FD_ISSET (n, p) /* * OR together two select file descriptor masks */ #define cma__fdm_or(target,a,b) \ { \ int __i__ = cma__g_nspm; \ while (__i__--) \ (target)->fds_bits[__i__] = \ (a)->fds_bits[__i__] | (b)->fds_bits[__i__]; \ } /* * Set a bit in a select file descriptor mask * * FD_SET(n,p) := ((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS))) */ #define cma__fdm_set_bit(n,p) FD_SET (n, p) /* * Clear a select file descriptor mask. */ #define cma__fdm_zero(n) \ cma__memset ((char *) n, 0, cma__g_nspm * sizeof(cma__t_mask)) /* * CMA "thread-synchronous" I/O read/write operations */ /* * Since all CMA "thread-synchronous" I/O (read or write) operations on * U*ix follow the exact same structure, the wrapper routines have been * condensed into a macro. * * The steps performed are as follows: * 1. Check that the file descriptor is a legitimate value. * 2. Check that the entry in the CMA file "database" which corresponds to * the file descriptor indicates that the "file" was "opened" by CMA. * 3. Reserve the file, to serialized access to files. This not only * simplifies things, but also defends against non-reentrancy. * 4. If the "file" is "set" for non-blocking I/O, check if we * have actually set the file non-blocking yet, and if not do so. * Then, issue the I/O operantion. * Success or failure is returned immediately, after unreserving the * file. If the error indicates that the operation would have caused * the process to block, continue to the next step. * 5. The I/O prolog adds this "file" to the global bit mask, which * represents all "files" which have threads waiting to perform I/O on * them, and causes the thread to block on the condition variable for * this "file". Periodically, a select is done on this global bit * mask, and the condition variables corresponding to "files" which * are ready for I/O are signaled, releasing those waiting threads to * perform their I/O. * 6. When the thread returns from the I/O prolog, it can (hopefully) * perform its operation without blocking the process. * 7. The I/O epilog clears the bit in the global mask and/or signals the * the next thread waiting for this "file", as appropriate. * 8. If the I/O failed, continue to loop. * 9. Finally, the "file" is unreserved, as we're done with it, and the * result of the operation is returned. * * * Note: currently, we believe that timeslicing which is based on the * virtual-time timer does not cause system calls to return EINTR. * Threfore, any EINTR returns are relayed directly to the caller. * On platforms which do not support a virtual-time timer, the code * should probably catch EINTR returns and restart the system call. */ /* * This macro is used for both read-type and write-type functions. * * Note: the second call to "func" may require being bracketed in a * cma__interrupt_disable/cma__interrupt_enable pair, but we'll * wait and see if this is necessary. */ #define cma__ts_func(func,fd,arglist,type,post_process) { \ cma_t_integer __res__; \ cma_t_boolean __done__ = cma_c_false; \ if ((fd < 0) || (fd >= cma__g_mx_file)) return (cma__set_errno (EBADF), -1); \ if (!cma__is_open(fd)) return (cma__set_errno (EBADF), -1); \ cma__fd_reserve (fd); \ if (!cma__is_open(fd)) return (cma__set_errno (EBADF), -1); \ if (cma__issue_io_call(fd)) {\ if ((!cma__g_file[fd]->set_non_blocking) && \ (cma__g_file[fd]->non_blocking == cma_c_true)) \ cma__set_nonblocking(fd); \ cma__interrupt_disable (0); \ TRY { \ __res__ = func arglist; \ } \ CATCH_ALL { \ cma__interrupt_enable (0); \ cma__fd_unreserve (fd); \ RERAISE; \ } \ ENDTRY \ cma__interrupt_enable (0); \ if ((__res__ != -1) \ || (!cma__is_blocking (errno)) \ || (cma__g_file[fd]->user_fl.user_non_blocking)) \ __done__ = cma_c_true; \ } \ if (__done__) { \ cma__fd_unreserve (fd); \ } \ else { \ TRY { \ cma__io_prolog (type, fd); \ while (!__done__) { \ cma__io_wait (type, fd); \ __res__ = func arglist; \ if ((__res__ != -1) \ || (!cma__is_blocking (errno)) \ || (cma__g_file[fd]->user_fl.user_non_blocking)) \ __done__ = cma_c_true; \ } \ } \ FINALLY { \ cma__io_epilog (type, fd); \ cma__fd_unreserve (fd); \ } \ ENDTRY \ } \ if (__res__ != -1) post_process; \ return __res__; \ } /* * Since most CMA "thread-synchronous" I/O ("open"-type) operations on * U*ix follow the exact same structure, the wrapper routines have been * condensed into a macro. * * The steps performed are as follows: * 1. Issue the open function. * 2. If the value returned indicates an error, return it to the caller. * 3. If the file descriptor returned is larger than what we think is the * maximum value (ie if it is too big for our database) then bugcheck. * 4. "Open" the "file" in the CMA file database. * 5. Return the file descriptor value to the caller. * * FIX-ME: for the time being, if the I/O operation returns EINTR, we * simply return it to the caller; eventually, we should catch this * and "do the right thing" (if we can figure out what that is). */ /* * This macro is used for all "open"-type functions which return a single file * desciptor by immediate value. */ #define cma__ts_open(func,arglist,post_process) { \ int __fd__; \ TRY { \ cma__int_init (); \ cma__int_lock (cma__g_io_data_mutex); \ __fd__ = func arglist; \ cma__int_unlock (cma__g_io_data_mutex); \ if (__fd__ >= 0 && __fd__ < cma__g_mx_file) \ post_process; \ } \ CATCH_ALL \ { \ cma__set_errno (EBADF); \ __fd__ = -1; \ } \ ENDTRY \ if (__fd__ >= cma__g_mx_file) \ cma__bugcheck ("cma__ts_open: fd is too large"); \ return __fd__; \ } /* * This macro is used for all "open"-type functions which return a pair of file * desciptors by reference parameter. */ #define cma__ts_open2(func,fdpair,arglist,post_process) { \ int __res__; \ TRY { \ cma__int_init (); \ cma__int_lock (cma__g_io_data_mutex); \ __res__ = func arglist; \ cma__int_unlock (cma__g_io_data_mutex); \ if (__res__ >= 0 && fdpair[0] < cma__g_mx_file \ && fdpair[1] < cma__g_mx_file) \ post_process; \ } \ CATCH_ALL \ { \ cma__set_errno (EBADF); \ __res__ = -1; \ } \ ENDTRY \ if ((fdpair[0] >= cma__g_mx_file) || (fdpair[1] >= cma__g_mx_file)) \ cma__bugcheck ("cma__ts_open2: one of fd's is too large"); \ return __res__; \ } /* * INTERNAL INTERFACES */ extern void cma__close_general (int); extern void cma__init_thread_io (void); extern cma_t_boolean cma__io_available (cma__t_io_type,int,struct timeval *); extern void cma__io_epilog (cma__t_io_type,int); extern void cma__io_prolog (cma__t_io_type,int); extern void cma__io_wait (cma__t_io_type,int); extern void cma__open_general (int); extern void cma__reinit_thread_io (int); extern void cma__set_nonblocking (int); extern void cma__set_user_nonblock_flags (int,int); extern cma_t_boolean cma__is_open (int fd); #endif