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boinc/lib/shmem.C

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// Berkeley Open Infrastructure for Network Computing
// http://boinc.berkeley.edu
// Copyright (C) 2005 University of California
//
// This is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation;
// either version 2.1 of the License, or (at your option) any later version.
//
// This software is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
// See the GNU Lesser General Public License for more details.
//
// To view the GNU Lesser General Public License visit
// http://www.gnu.org/copyleft/lesser.html
// or write to the Free Software Foundation, Inc.,
// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
// interfaces for accessing shared memory segments
#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
#include "boinc_win.h"
#endif
#ifdef __EMX__
#define INCL_DOS
#define INCL_DOSERRORS
#include <os2.h>
extern "C" int debug_printf(const char *fmt, ...);
#endif
#ifndef _WIN32
#include "config.h"
#include <cstdio>
#include <cstring>
#include <sys/types.h>
#include <assert.h>
#if HAVE_SYS_IPC_H
#include <sys/ipc.h>
#endif
#if HAVE_SYS_SHM_H
#if __FreeBSD__
#include <sys/param.h>
#endif
#include <sys/shm.h>
#endif
#endif
#if(!defined (_WIN32) && !defined (__EMX__))
#include <fcntl.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/mman.h>
#endif
#include "error_numbers.h"
#include "shmem.h"
#ifdef _USING_FCGI_
#include "fcgi_stdio.h"
#endif
#ifdef _WIN32
HANDLE create_shmem(LPCTSTR seg_name, int size, void** pp, bool disable_mapview) {
SECURITY_ATTRIBUTES security;
HANDLE hMap;
DWORD dwError = 0;
security.nLength = sizeof(security);
security.lpSecurityDescriptor = NULL;
security.bInheritHandle = TRUE;
hMap = CreateFileMapping(INVALID_HANDLE_VALUE, &security, PAGE_READWRITE, 0, size, seg_name);
dwError = GetLastError();
if (disable_mapview && (NULL != hMap) && (ERROR_ALREADY_EXISTS == dwError)) {
CloseHandle(hMap);
hMap = NULL;
}
if (!disable_mapview && (NULL != hMap) && pp) {
*pp = MapViewOfFile( hMap, FILE_MAP_ALL_ACCESS, 0, 0, 0 );
}
return hMap;
}
HANDLE attach_shmem(LPCTSTR seg_name, void** pp) {
HANDLE hMap;
hMap = OpenFileMapping(FILE_MAP_ALL_ACCESS, FALSE, seg_name);
if (!hMap) return NULL;
if (pp) *pp = MapViewOfFile(hMap, FILE_MAP_ALL_ACCESS, 0, 0, 0);
return hMap;
}
int detach_shmem(HANDLE hMap, void* p) {
if (p) UnmapViewOfFile(p);
CloseHandle(hMap);
return 0;
}
#elif defined(__EMX__)
int create_shmem(key_t key, int size, void** pp) {
APIRET rc;
char buf[256];
sprintf(buf, "\\SHAREMEM\\BOINC\\%d", key);
//debug_printf( "create_shmem %s, %d, %p\n", buf, size, pp);
rc = DosAllocSharedMem(pp, (PSZ)buf, size, PAG_READ | PAG_WRITE | PAG_EXECUTE | PAG_COMMIT | OBJ_ANY);
if (rc == ERROR_ALREADY_EXISTS)
return attach_shmem( key, pp);
if (rc)
rc = DosAllocSharedMem(pp, (PSZ)buf, size, PAG_READ | PAG_WRITE | PAG_EXECUTE | PAG_COMMIT);
if (rc) {
//debug_printf( "DosAllocSharedMem %s failed, rc=%d\n", buf, rc);
return ERR_SHMGET;
}
//debug_printf( "create_shmem %p\n", *pp);
return 0;
}
int destroy_shmem(key_t key){
APIRET rc;
void* pp;
//debug_printf( "destroy_shmem %d\n", key);
attach_shmem( key, &pp);
rc = DosFreeMem(pp);
if (rc) {
//debug_printf( "DosFreeMem %d failed, rc=%d\n", key, rc);
return ERR_SHMCTL;
}
//debug_printf( "destroy_shmem %d done\n", key);
return 0;
}
int attach_shmem(key_t key, void** pp){
APIRET rc;
char buf[256];
sprintf(buf, "\\SHAREMEM\\BOINC\\%d", key);
//debug_printf( "attach_shmem %s, %p\n", buf, pp);
rc = DosGetNamedSharedMem(pp, (PSZ) buf, PAG_READ | PAG_WRITE);
if (rc) {
//debug_printf( "DosGetNamedSharedMem %s failed, rc=%d\n", buf, rc);
return ERR_SHMAT;
}
//debug_printf( "attach_shmem %p\n", *pp);
return 0;
}
int detach_shmem(void* p) {
/* dummy */
//debug_printf( "detach_shmem %p not supported\n", p);
return 0;
}
#else
// V6 mmap() shared memory for Unix/Linux/Mac
int create_shmem_mmap(char *path, size_t size, void** pp) {
int fd, retval;
struct stat sbuf;
// Return NULL pointer if create_shmem fails
*pp = 0;
if (size == 0) return ERR_SHMGET;
// NOTE: in principle it should be 0660, not 0666
// (i.e. Apache should belong to the same group as the
// project admin user, and should therefore be able to access the seg.
// However, this doesn't seem to work on some Linux systems.
// I don't have time to figure this out (31 July 07)
// it's a big headache for anyone it affects,
// and it's not a significant security issue.
//
fd = open(path, O_RDWR | O_CREAT, 0666);
if (fd < 0) return ERR_SHMGET;
retval = fstat(fd, &sbuf);
if (retval) return ERR_SHMGET;
if (sbuf.st_size < (long)size) {
// The following 2 lines extend the file and clear its new
// area to all zeros because they write beyond the old EOF.
// See the lseek man page for details.
lseek(fd, size-1, SEEK_SET);
write(fd, "\0", 1);
}
*pp = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, fd, 0);
// Now close the file. The kernel doesn<73>t use our file descriptor.
close(fd);
if (*pp == MAP_FAILED) {
*pp = 0;
return ERR_SHMGET;
}
return 0;
}
int destroy_shmem_mmap(key_t key){
return 0;
}
int attach_shmem_mmap(char *path, void** pp) {
int fd, retval;
struct stat sbuf;
// Return NULL pointer if attach_shmem fails
*pp = 0;
fd = open(path, O_RDWR);
if (fd < 0) return ERR_SHMGET;
retval = fstat(fd, &sbuf);
if (retval) return ERR_SHMGET;
if (sbuf.st_size == 0) return ERR_SHMGET;
*pp = mmap(NULL, sbuf.st_size, PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, fd, 0);
// Now close the file. The kernel doesn<73>t use our file descriptor.
close(fd);
if (*pp == MAP_FAILED) {
*pp = 0;
return ERR_SHMGET;
}
return 0;
}
int detach_shmem_mmap(void* p, size_t size) {
return munmap(p, size);
}
// Compatibility routines for Unix/Linux/Mac V5 applications
int create_shmem(key_t key, int size, gid_t gid, void** pp) {
int id;
// try 0666, then SHM_R|SHM_W
// seems like some platforms require one or the other
// (this may be superstition)
//
// NOTE: in principle it should be 0660, not 0666
// (i.e. Apache should belong to the same group as the
// project admin user, and should therefore be able to access the seg.
// However, this doesn't seem to work on some Linux systems.
// I don't have time to figure this out (31 July 07)
// it's a big headache for anyone it affects,
// and it's not a significant security issue.
//
id = shmget(key, size, IPC_CREAT|0666);
if (id < 0) {
id = shmget(key, size, IPC_CREAT|SHM_R|SHM_W);
}
if (id < 0) {
perror("shmget");
return ERR_SHMGET;
}
// set group ownership if requested
//
if (gid) {
int retval;
struct shmid_ds buf;
// Set the shmem segment's group ID
retval = shmctl(id, IPC_STAT, &buf);
if (retval) {
perror("shmget: shmctl STAT");
return ERR_SHMGET;
}
buf.shm_perm.gid = gid;
retval = shmctl(id, IPC_SET, &buf);
if (retval) {
perror("shmget: shmctl IPC_SET");
return ERR_SHMGET;
}
}
return attach_shmem(key, pp);
}
// Mark the shared memory segment so it will be released after
// the last attached process detaches or exits.
// On Mac OS X and some other systems, not doing this causes
// shared memory leaks if BOINC crashes or exits suddenly.
// On Mac OS X and some other systems, this command also
// prevents any more processes from attaching (by clearing
// the key in the shared memory structure), so BOINC does it
// only after we are completey done with the segment.
int destroy_shmem(key_t key){
struct shmid_ds buf;
int id, retval;
id = shmget(key, 0, 0);
if (id < 0) return 0; // assume it doesn't exist
retval = shmctl(id, IPC_STAT, &buf);
if (retval) {
perror("shmctl STAT");
return ERR_SHMCTL;
}
retval = shmctl(id, IPC_RMID, 0);
if (retval) {
perror("shmctl RMID");
return ERR_SHMCTL;
}
return 0;
}
int attach_shmem(key_t key, void** pp){
void* p;
int id;
id = shmget(key, 0, 0);
if (id < 0) {
perror("shmget");
return ERR_SHMGET;
}
p = shmat(id, 0, 0);
if ((long)p == -1) {
perror("shmat");
return ERR_SHMAT;
}
*pp = p;
return 0;
}
int detach_shmem(void* p) {
int retval;
retval = shmdt((char *)p);
return retval;
}
int print_shmem_info(key_t key) {
int id;
struct shmid_ds buf;
id = shmget(key, 0, 0);
if (id < 0) {
return ERR_SHMGET;
}
shmctl(id, IPC_STAT, &buf);
fprintf(
stderr, "shmem key: %x\t\tid: %d, size: %d, nattach: %d\n",
(unsigned int)key, id, (int)buf.shm_segsz, (int)buf.shm_nattch
);
return 0;
}
// For debugging shared memory logic
// For testing on Apple, Linux, UNIX systems with limited number
// of shared memory segments per process and / or system-wide
// Mac OS X has a default limit of 8 segments per process, 32 system-wide
// If
void stress_shmem(short reduce_by) {
int retval;
void * shmaddr[16];
key_t key[] = {
'BNC0', 'BNC1', 'BNC2', 'BNC3', 'BNC4', 'BNC5', 'BNC6', 'BNC7',
'BNC8', 'BNC9', 'BNCA', 'BNCB', 'BNCC', 'BNCD', 'BNCE', 'BNCF'
};
int i, id;
if (reduce_by > 16) reduce_by = 16;
// Tie up 5 of the 8 shared memory segments each process may have
for (i=0; i<reduce_by; i++) {
retval = create_shmem(key[i], 1024, 0, &shmaddr[i]);
id = shmget(key[i], 0, 0);
// Mark it for automatic destruction when BOINC exits
if (id >= 0) {
retval = shmctl(id, IPC_RMID, 0);
}
}
}
#endif // !defined(_WIN32) && !defined(__EMX__)
const char *BOINC_RCSID_f835f078de = "$Id$";
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