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boinc/lib/shmem.cpp

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// This file is part of BOINC.
// http://boinc.berkeley.edu
// Copyright (C) 2008 University of California
//
// BOINC 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 3 of the License, or (at your option) any later version.
//
// BOINC 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.
//
// You should have received a copy of the GNU Lesser General Public License
// along with BOINC. If not, see <http://www.gnu.org/licenses/>.
// interfaces for accessing shared memory segments
#if defined(_WIN32)
#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>
#include "error_numbers.h"
#include "shmem.h"
// MAP_FILE isn't defined on most operating systems, and even then, it
// is often defined just for the sake of compatibility. On those that
// don't define it, we will....
#ifndef MAP_FILE
#define MAP_FILE 0
#endif
#endif
#ifdef _USING_FCGI_
#include "boinc_fcgi.h"
using FCGI::fprintf;
#define perror FCGI::perror
#else
using std::fprintf;
using std::perror;
#endif
#ifdef _WIN32
HANDLE create_shmem(LPCTSTR seg_name, int size, void** pp, bool try_global) {
HANDLE hMap = NULL;
DWORD dwError = 0;
DWORD dwRes = 0;
PSID pEveryoneSID = NULL;
PACL pACL = NULL;
PSECURITY_DESCRIPTOR pSD = NULL;
EXPLICIT_ACCESS ea;
SID_IDENTIFIER_AUTHORITY SIDAuthWorld = SECURITY_WORLD_SID_AUTHORITY;
SECURITY_ATTRIBUTES sa;
OSVERSIONINFO osvi;
char global_seg_name[256];
// Win9X doesn't like any reference to a security descriptor.
// So if we detect that we are running on the Win9X platform pass
// a NULL value for it.
//
osvi.dwOSVersionInfoSize = sizeof(osvi);
GetVersionEx(&osvi);
if (osvi.dwPlatformId == VER_PLATFORM_WIN32_WINDOWS) {
hMap = CreateFileMapping(INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE, 0, size, seg_name);
dwError = GetLastError();
} else {
// Create a well-known SID for the Everyone group.
if(!AllocateAndInitializeSid(&SIDAuthWorld, 1,
SECURITY_WORLD_RID,
0, 0, 0, 0, 0, 0, 0,
&pEveryoneSID)
) {
fprintf(stderr, "AllocateAndInitializeSid Error %u\n", GetLastError());
goto Cleanup;
}
// Initialize an EXPLICIT_ACCESS structure for an ACE.
// The ACE will allow Everyone all access to the shared memory object.
ZeroMemory(&ea, sizeof(EXPLICIT_ACCESS));
ea.grfAccessPermissions = FILE_MAP_ALL_ACCESS;
ea.grfAccessMode = SET_ACCESS;
ea.grfInheritance= NO_INHERITANCE;
ea.Trustee.TrusteeForm = TRUSTEE_IS_SID;
ea.Trustee.TrusteeType = TRUSTEE_IS_WELL_KNOWN_GROUP;
ea.Trustee.ptstrName = (LPTSTR) pEveryoneSID;
// Create a new ACL that contains the new ACEs.
dwRes = SetEntriesInAcl(1, &ea, NULL, &pACL);
if (ERROR_SUCCESS != dwRes) {
fprintf(stderr, "SetEntriesInAcl Error %u\n", GetLastError());
goto Cleanup;
}
// Initialize a security descriptor.
pSD = (PSECURITY_DESCRIPTOR) LocalAlloc(LPTR, SECURITY_DESCRIPTOR_MIN_LENGTH);
if (NULL == pSD) {
fprintf(stderr, "LocalAlloc Error %u\n", GetLastError());
goto Cleanup;
}
if (!InitializeSecurityDescriptor(pSD, SECURITY_DESCRIPTOR_REVISION)) {
fprintf(stderr, "InitializeSecurityDescriptor Error %u\n", GetLastError());
goto Cleanup;
}
// Add the ACL to the security descriptor.
if (!SetSecurityDescriptorDacl(pSD,
TRUE, // bDaclPresent flag
pACL,
FALSE) // not a default DACL
) {
fprintf(stderr,
"SetSecurityDescriptorDacl Error %u\n", GetLastError()
);
goto Cleanup;
}
// Initialize a security attributes structure.
sa.nLength = sizeof (SECURITY_ATTRIBUTES);
sa.lpSecurityDescriptor = pSD;
sa.bInheritHandle = FALSE;
// Use the security attributes to set the security descriptor
// when you create a shared file mapping.
// Try using 'Global' so that it can cross terminal server sessions
// The 'Global' prefix must be included in the shared memory
// name if the shared memory segment is going to cross
// terminal server session boundaries.
//
if (try_global) {
snprintf(global_seg_name, sizeof(global_seg_name), "Global\\%s", seg_name);
hMap = CreateFileMapping(
INVALID_HANDLE_VALUE, &sa, PAGE_READWRITE, 0,
size, global_seg_name
);
dwError = GetLastError();
if (!hMap && (ERROR_ACCESS_DENIED == dwError)) {
// Couldn't use the 'Global' tag, so try the original name.
try_global = false;
}
}
if (!try_global) {
hMap = CreateFileMapping(
INVALID_HANDLE_VALUE, &sa, PAGE_READWRITE, 0, size, seg_name
);
dwError = GetLastError();
}
}
if (hMap) {
if (GetLastError() == ERROR_ALREADY_EXISTS) {
CloseHandle(hMap);
hMap = NULL;
} else {
*pp = MapViewOfFile( hMap, FILE_MAP_ALL_ACCESS, 0, 0, 0 );
}
}
Cleanup:
if (osvi.dwPlatformId != VER_PLATFORM_WIN32_WINDOWS) {
if (pEveryoneSID)
FreeSid(pEveryoneSID);
if (pACL)
LocalFree(pACL);
if (pSD)
LocalFree(pSD);
}
return hMap;
}
HANDLE attach_shmem(LPCTSTR seg_name, void** pp) {
HANDLE hMap;
char global_seg_name[256];
// The 'Global' prefix must be included in the shared memory
// name if the shared memory segment is going to cross
// terminal server session boundaries.
//
snprintf(global_seg_name, sizeof(global_seg_name), "Global\\%s", seg_name);
// Try using 'Global' so that it can cross terminal server sessions
//
hMap = OpenFileMapping(FILE_MAP_ALL_ACCESS, FALSE, global_seg_name);
if (!hMap) {
// Couldn't use the 'Global' tag, so just attempt to use the original
// name.
//
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];
snprintf(buf, sizeof(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];
snprintf(buf, sizeof(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(const 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) {
close(fd);
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);
if (1 != write(fd, "\0", 1)) {
close(fd);
return ERR_SHMGET;
}
}
*pp = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, fd, 0);
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(const 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) {
close(fd);
return ERR_SHMGET;
}
if (sbuf.st_size == 0) {
close(fd);
return ERR_SHMGET;
}
*pp = mmap(NULL, sbuf.st_size, PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, fd, 0);
close(fd);
if (*pp == MAP_FAILED) {
*pp = 0;
return ERR_SHMGET;
}
return 0;
}
int detach_shmem_mmap(void* p, size_t size) {
return munmap((char *)p, size);
}
#if HAVE_SYS_SHM_H && !defined(ANDROID)
// 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");
fprintf(stderr, "shmem size: %d\n", size);
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 completely 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 in attach_shmem");
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;
}
#else // HAVE_SYS_SHM_H
// Platforms that don't have sys/shm.h will need stubs,
// or alternate implementations
int create_shmem(key_t, int size, gid_t gid, void**) {
perror("create_shmem: not supported on this platform");
return ERR_SHMGET;
}
int attach_shmem(key_t, void**) {
perror("attach_shmem: not supported on this platform");
return ERR_SHMGET;
}
int detach_shmem(void*) {
perror("detach_shmem: not supported on this platform");
return ERR_SHMGET;
}
int destroy_shmem(key_t) {
perror("destroy_shmem: not supported on this platform");
return ERR_SHMCTL;
}
#endif // !HAVE_SYS_SHM_H
#endif // !defined(_WIN32) && !defined(__EMX__)
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