/* Unix SMB/Netbios implementation. Version 1.9. Shared memory functions Copyright (C) Erik Devriendt 1996 This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program 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 General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ #ifdef FAST_SHARE_MODES #include "includes.h" extern int DEBUGLEVEL; #define SHM_MAGIC 0x53484100 /* = "SHM" in hex */ #define SHM_VERSION 1 /* WARNING : offsets are used because mmap() does not guarantee that all processes have the shared memory mapped to the same address */ struct ShmHeader { int shm_magic; int shm_version; int total_size; /* in bytes */ BOOL consistent; shm_offset_t first_free_off; shm_offset_t userdef_off; /* a userdefined offset. can be used to store root of tree or list */ struct { /* a cell is a range of bytes of sizeof(struct ShmBlockDesc) size */ int cells_free; int cells_used; int cells_system; /* number of cells used as allocated block descriptors */ } statistics; }; #define SHM_NOT_FREE_OFF (-1) struct ShmBlockDesc { shm_offset_t next; /* offset of next block in the free list or SHM_NOT_FREE_OFF when block in use */ int size; /* user size in BlockDescSize units */ }; #define EOList_Addr (struct ShmBlockDesc *)( 0 ) #define EOList_Off (NULL_OFFSET) #define CellSize sizeof(struct ShmBlockDesc) /* HeaderSize aligned on 8 byte boundary */ #define AlignedHeaderSize ((sizeof(struct ShmHeader)+7) & ~7) static int shm_fd = -1; static pstring shm_processreg_name = ""; static struct ShmHeader *shm_header_p = (struct ShmHeader *)0; static int shm_times_locked = 0; static BOOL shm_register_process(char *processreg_file, pid_t pid, BOOL *other_processes) { int old_umask; int shm_processes_fd = -1; int nb_read; pid_t other_pid; int free_slot = -1; int erased_slot; old_umask = umask(0); shm_processes_fd = open(processreg_file, O_RDWR | O_CREAT, 0666); umask(old_umask); if ( shm_processes_fd < 0 ) { DEBUG(0,("ERROR shm_register_process : processreg_file open failed with code %d\n",errno)); return False; } *other_processes = False; while ((nb_read = read(shm_processes_fd, &other_pid, sizeof(other_pid))) > 0) { if(other_pid) { if(process_exists(other_pid)) *other_processes = True; else { /* erase old pid */ DEBUG(2,("shm_register_process : erasing stale record for pid %d\n",other_pid)); other_pid = (pid_t)0; erased_slot = lseek(shm_processes_fd, -sizeof(other_pid), SEEK_CUR); write(shm_processes_fd, &other_pid, sizeof(other_pid)); if(free_slot < 0) free_slot = erased_slot; } } else if(free_slot < 0) free_slot = lseek(shm_processes_fd, -sizeof(other_pid), SEEK_CUR); } if (nb_read < 0) { DEBUG(0,("ERROR shm_register_process : processreg_file read failed with code %d\n",errno)); close(shm_processes_fd); return False; } if(free_slot < 0) free_slot = lseek(shm_processes_fd, 0, SEEK_END); DEBUG(2,("shm_register_process : writing record for pid %d at offset %d\n",pid,free_slot)); lseek(shm_processes_fd, free_slot, SEEK_SET); if(write(shm_processes_fd, &pid, sizeof(pid)) < 0) { DEBUG(0,("ERROR shm_register_process : processreg_file write failed with code %d\n",errno)); close(shm_processes_fd); return False; } close(shm_processes_fd); return True; } static BOOL shm_unregister_process(char *processreg_file, pid_t pid#!/bin/sh # options '-D' and '-c cmd' are mutually exclusive # #-D Run in background. This requires '-o' option. #-c cmd Command 'cmd' will be run and staprun will # exit when it does. The '_stp_target' variable # will contain the pid for the command. staprun -c /bin/ls -D fake_module
generated by cgit (git 2.34.1) at 2025-08-23 14:19:37 +0000
erased_slot = lseek(shm_processes_fd, -sizeof(other_pid), SEEK_CUR); if(write(shm_processes_fd, &other_pid, sizeof(other_pid)) < 0) { DEBUG(0,("ERROR shm_unregister_process : processreg_file write failed with code %d\n",errno)); close(shm_processes_fd); return False; } found = True; break; } } if (nb_read < 0) { DEBUG(0,("ERROR shm_unregister_process : processreg_file read failed with code %d\n",errno)); close(shm_processes_fd); return False; } if(!found) { DEBUG(0,("ERROR shm_unregister_process : couldn't find pid %d in file %s\n",pid,processreg_file)); close(shm_processes_fd); return False; } close(shm_processes_fd); return True; } static BOOL shm_validate_header(int size) { if( !shm_header_p ) { /* not mapped yet */ DEBUG(0,("ERROR shm_validate_header : shmem not mapped\n")); return False; } if(shm_header_p->shm_magic != SHM_MAGIC) { DEBUG(0,("ERROR shm_validate_header : bad magic\n")); return False; } if(shm_header_p->shm_version != SHM_VERSION) { DEBUG(0,("ERROR shm_validate_header : bad version %X\n",shm_header_p->shm_version)); return False; } if(shm_header_p->total_size != size) { DEBUG(0,("ERROR shm_validate_header : shmem size mismatch (old = %d, new = %d)\n",shm_header_p->total_size,size)); return False; } if(!shm_header_p->consistent) { DEBUG(0,("ERROR shm_validate_header : shmem not consistent\n")); return False; } return True; } static BOOL shm_initialize(int size) { struct ShmBlockDesc * first_free_block_p; DEBUG(2,("shm_initialize : initializing shmem file of size %d\n",size)); if( !shm_header_p ) { /* not mapped yet */ DEBUG(0,("ERROR shm_initialize : shmem not mapped\n")); return False; } shm_header_p->shm_magic = SHM_MAGIC; shm_header_p->shm_version = SHM_VERSION; shm_header_p->total_size = size; shm_header_p->first_free_off = AlignedHeaderSize; shm_header_p->userdef_off = NULL_OFFSET; first_free_block_p = (struct ShmBlockDesc *)shm_offset2addr(shm_header_p->first_free_off); first_free_block_p->next = EOList_Off; first_free_block_p->size = ( size - AlignedHeaderSize - CellSize ) / CellSize ; shm_header_p->statistics.cells_free = first_free_block_p->size; shm_header_p->statistics.cells_used = 0; shm_header_p->statistics.cells_system = 1; shm_header_p->consistent = True; return True; } static void shm_solve_neighbors(struct ShmBlockDesc *head_p ) { struct ShmBlockDesc *next_p; /* Check if head_p and head_p->next are neighbors and if so join them */ if ( head_p == EOList_Addr ) return ; if ( head_p->next == EOList_Off ) return ; next_p = (struct ShmBlockDesc *)shm_offset2addr(head_p->next); if ( ( head_p + head_p->size + 1 ) == next_p) { head_p->size += next_p->size +1 ; /* adapt size */ head_p->next = next_p->next ; /* link out */ shm_header_p->statistics.cells_free += 1; shm_header_p->statistics.cells_system -= 1; } } BOOL shm_open( char *file_name, int size) { int filesize; BOOL created_new = False; BOOL other_processes = True; int old_umask; DEBUG(2,("shm_open : using shmem file %s to be of size %d\n",file_name,size)); old_umask = umask(0); shm_fd = open(file_name, O_RDWR | O_CREAT, 0666); umask(old_umask); if ( shm_fd < 0 ) { DEBUG(0,("ERROR shm_open : open failed with code %d\n",errno)); return False; } if (!shm_lock()) { DEBUG(0,("ERROR shm_open : can't do shm_lock\n")); return False; } if( (filesize = lseek(shm_fd, 0, SEEK_END)) < 0) { DEBUG(0,("ERROR shm_open : lseek failed with code %d\n",errno)); shm_unlock(); close(shm_fd); return False; } /* return the file offset to 0 to save on later seeks */ lseek(shm_fd,0,SEEK_SET); if (filesize == 0) { /* we just created a new one */ created_new = True; } /* to find out if some other process is already mapping the file, we use a registration file containing the processids of the file mapping processes */ /* construct processreg file name */ strcpy(shm_processreg_name, file_name); strcat(shm_processreg_name, ".processes"); if (! shm_register_process(shm_processreg_name, getpid(), &other_processes)) { shm_unlock(); close(shm_fd); return False; } if (created_new || !other_processes) { /* we just created a new one, or are the first opener, lets set it size */ if( ftruncate(shm_fd, size) <0) { DEBUG(0,("ERROR shm_open : ftruncate failed with code %d\n",errno)); shm_unregister_process(shm_processreg_name, getpid()); shm_unlock(); close(shm_fd); return False; } /* paranoia */ lseek(shm_fd,0,SEEK_SET); filesize = size; } if (size != filesize ) { /* the existing file has a different size and we are not the first opener. Since another process is still using it, we will use the file size */ DEBUG(0,("WARNING shm_open : filesize (%d) != expected size (%d), using filesize\n",filesize,size)); size = filesize; } shm_header_p = (struct ShmHeader *)mmap( NULL, size, PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, shm_fd, 0); /* WARNING, shm_header_p can be different for different processes mapping the same file ! */ if (shm_header_p == (struct ShmHeader *)(-1)) { DEBUG(0,("ERROR shm_open : mmap failed with code %d\n",errno)); shm_unregister_process(shm_processreg_name, getpid()); shm_unlock(); close(shm_fd); return False; } if (created_new || !other_processes) { shm_initialize(size); } else if (!shm_validate_header(size) ) { /* existing file is corrupt, samba admin should remove it by hand */ DEBUG(0,("ERROR shm_open : corrupt shared mem file, remove it manually\n")); munmap((caddr_t)shm_header_p, size); shm_unregister_process(shm_processreg_name, getpid()); shm_unlock(); close(shm_fd); return False; } shm_unlock(); return True; } BOOL shm_close( void ) { DEBUG(2,("shm_close\n")); if(shm_times_locked > 0) DEBUG(0,("WARNING shm_close : shmem was still locked %d times\n",shm_times_locked));; if ( munmap((caddr_t)shm_header_p, shm_header_p->total_size) < 0) { DEBUG(0,("ERROR shm_close : munmap failed with code %d\n",errno)); } shm_lock(); shm_unregister_process(shm_processreg_name, getpid()); shm_unlock(); close(shm_fd); shm_fd = -1; shm_processreg_name[0] = '\0'; shm_header_p = (struct ShmHeader *)0; shm_times_locked = 0; return True; } shm_offset_t shm_alloc(int size) { unsigned num_cells ; struct ShmBlockDesc *scanner_p; struct ShmBlockDesc *prev_p; struct ShmBlockDesc *new_p; shm_offset_t result_offset; if( !shm_header_p ) { /* not mapped yet */ DEBUG(0,("ERROR shm_alloc : shmem not mapped\n")); return NULL_OFFSET; } if( !shm_header_p->consistent) { DEBUG(0,("ERROR shm_alloc : shmem not consistent\n")); return NULL_OFFSET; } /* calculate the number of cells */ num_cells = (size + CellSize -1) / CellSize; /* set start of scan */ prev_p = (struct ShmBlockDesc *)shm_offset2addr(shm_header_p->first_free_off); scanner_p = prev_p ; /* scan the free list to find a matching free space */ while ( ( scanner_p != EOList_Addr ) && ( scanner_p->size < num_cells ) ) { prev_p = scanner_p; scanner_p = (struct ShmBlockDesc *)shm_offset2addr(scanner_p->next); } /* at this point scanner point to a block header or to the end of the list */ if ( scanner_p == EOList_Addr ) { DEBUG(0,("ERROR shm_alloc : alloc of %d bytes failed, no free space found\n",size)); return (NULL_OFFSET); } /* going to modify shared mem */ shm_header_p->consistent = False; /* if we found a good one : scanner == the good one */ if ( scanner_p->size <= num_cells + 2 ) { /* there is no use in making a new one, it will be too small anyway * we will link out scanner */ if ( prev_p == scanner_p ) { shm_header_p->first_free_off = scanner_p->next ; } else { prev_p->next = scanner_p->next ; } shm_header_p->statistics.cells_free -= scanner_p->size; shm_header_p->statistics.cells_used += scanner_p->size; } else { /* Make a new one */ new_p = scanner_p + 1 + num_cells; new_p->size = scanner_p->size - num_cells - 1; new_p->next = scanner_p->next; scanner_p->size = num_cells; scanner_p->next = shm_addr2offset(new_p); if ( prev_p != scanner_p ) { prev_p->next = shm_addr2offset(new_p) ; } else { shm_header_p->first_free_off = shm_addr2offset(new_p) ; } shm_header_p->statistics.cells_free -= num_cells+1; shm_header_p->statistics.cells_used += num_cells; shm_header_p->statistics.cells_system += 1; } result_offset = shm_addr2offset( &(scanner_p[1]) ); scanner_p->next = SHM_NOT_FREE_OFF ; /* end modification of shared mem */ shm_header_p->consistent = True; DEBUG(2,("shm_alloc : request for %d bytes, allocated %d bytes at offset %d\n",size,scanner_p->size*CellSize,result_offset )); return ( result_offset ); } BOOL shm_free(shm_offset_t offset) { struct ShmBlockDesc *header_p ; /* pointer to header of block to free */ struct ShmBlockDesc *scanner_p ; /* used to scan the list */ struct ShmBlockDesc *prev_p ; /* holds previous in the list */ if( !shm_header_p ) { /* not mapped yet */ DEBUG(0,("ERROR shm_free : shmem not mapped\n")); return False; } if( !shm_header_p->consistent) { DEBUG(0,("ERROR shm_free : shmem not consistent\n")); return False; } header_p = ( (struct ShmBlockDesc *)shm_offset2addr(offset) - 1); /* make pointer to header of block */ if (header_p->next != SHM_NOT_FREE_OFF) { DEBUG(0,("ERROR shm_free : bad offset (%d)\n",offset)); return False; } /* find a place in the free_list to put the header in */ /* set scanner and previous pointer to start of list */ prev_p = (struct ShmBlockDesc *)shm_offset2addr(shm_header_p->first_free_off); scanner_p = prev_p ; while ( ( scanner_p != EOList_Addr) && (scanner_p < header_p) ) /* while we didn't scan past its position */ { prev_p = scanner_p ; scanner_p = (struct ShmBlockDesc *)shm_offset2addr(scanner_p->next); } shm_header_p->consistent = False; DEBUG(2,("shm_free : freeing %d bytes at offset %d\n",header_p->size*CellSize,offset)); if ( scanner_p == prev_p ) { shm_header_p->statistics.cells_free += header_p->size; shm_header_p->statistics.cells_used -= header_p->size; /* we must free it at the beginning of the list */ shm_header_p->first_free_off = shm_addr2offset(header_p); /* set the free_list_pointer to this block_header */ /* scanner is the one that was first in the list */ header_p->next = shm_addr2offset(scanner_p); shm_solve_neighbors( header_p ); /* if neighbors then link them */ shm_header_p->consistent = True; return True; } else { shm_header_p->statistics.cells_free += header_p->size; shm_header_p->statistics.cells_used -= header_p->size; prev_p->next = shm_addr2offset(header_p); header_p->next = shm_addr2offset(scanner_p); shm_solve_neighbors(header_p) ; shm_solve_neighbors(prev_p) ; shm_header_p->consistent = True; return True; } } shm_offset_t shm_get_userdef_off(void) { if (!shm_header_p) return NULL_OFFSET; else return shm_header_p->userdef_off; } BOOL shm_set_userdef_off(shm_offset_t userdef_off) { if (!shm_header_p) return False; else shm_header_p->userdef_off = userdef_off; return True; } void * shm_offset2addr(shm_offset_t offset) { if (offset == NULL_OFFSET ) return (void *)(0); if (!shm_header_p) return (void *)(0); return (void *)((char *)shm_header_p + offset ); } shm_offset_t shm_addr2offset(void *addr) { if (!addr) return NULL_OFFSET; if (!shm_header_p) return NULL_OFFSET; return (shm_offset_t)((char *)addr - (char *)shm_header_p); } BOOL shm_lock(void) { if (shm_fd < 0) { DEBUG(0,("ERROR shm_lock : bad shm_fd (%d)\n",shm_fd)); return False; } shm_times_locked++; if(shm_times_locked > 1) { DEBUG(2,("shm_lock : locked %d times\n",shm_times_locked)); return True; } if (lockf(shm_fd, F_LOCK, 0) < 0) { DEBUG(0,("ERROR shm_lock : lockf failed with code %d\n",errno)); shm_times_locked--; return False; } return True; } BOOL shm_unlock(void) { if (shm_fd < 0) { DEBUG(0,("ERROR shm_unlock : bad shm_fd (%d)\n",shm_fd)); return False; } if(shm_times_locked == 0) { DEBUG(0,("ERROR shm_unlock : shmem not locked\n",shm_fd)); return False; } shm_times_locked--; if(shm_times_locked > 0) { DEBUG(2,("shm_unlock : still locked %d times\n",shm_times_locked)); return True; } if (lockf(shm_fd, F_ULOCK, 0) < 0) { DEBUG(0,("ERROR shm_unlock : lockf failed with code %d\n",errno)); shm_times_locked++; return False; } return True; } BOOL shm_get_usage(int *bytes_free, int *bytes_used, int *bytes_overhead) { if( !shm_header_p ) { /* not mapped yet */ DEBUG(0,("ERROR shm_free : shmem not mapped\n")); return False; } *bytes_free = shm_header_p->statistics.cells_free * CellSize; *bytes_used = shm_header_p->statistics.cells_used * CellSize; *bytes_overhead = shm_header_p->statistics.cells_system * CellSize + AlignedHeaderSize; return True; } #else /* FAST_SHARE_MODES */ int shmem_dummy_procedure(void) {return 0;} #endif