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-rw-r--r--source3/locking/locking.c246
-rw-r--r--source3/locking/shmem.c722
2 files changed, 967 insertions, 1 deletions
diff --git a/source3/locking/locking.c b/source3/locking/locking.c
index 8f76ce43da..60428f2e98 100644
--- a/source3/locking/locking.c
+++ b/source3/locking/locking.c
@@ -17,6 +17,11 @@
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.
+
+ Revision History:
+
+ 12 aug 96: Erik.Devriendt@te6.siemens.be
+ added support for shared memory implementation of share mode locking
*/
#include "includes.h"
@@ -226,6 +231,34 @@ BOOL do_unlock(int fnum,int cnum,uint32 count,uint32 offset,int *eclass,uint32 *
return True; /* Did unlock */
}
+#ifdef FAST_SHARE_MODES
+/*******************************************************************
+ initialize the shared memory for share_mode management
+ ******************************************************************/
+BOOL start_share_mode_mgmt(void)
+{
+ pstring shmem_file_name;
+
+ strcpy(shmem_file_name,lp_lockdir());
+ trim_string(shmem_file_name,"","/");
+ if (!*shmem_file_name) return(False);
+ strcat(shmem_file_name, "/SHARE_MEM_FILE");
+ return shm_open(shmem_file_name, SHMEM_SIZE);
+}
+
+
+/*******************************************************************
+ deinitialize the shared memory for share_mode management
+ ******************************************************************/
+BOOL stop_share_mode_mgmt(void)
+{
+ return shm_close();
+}
+
+#else
+
+/* SHARE MODE LOCKS USING SLOW DESCRIPTION FILES */
+
/*******************************************************************
name a share file
******************************************************************/
@@ -251,6 +284,7 @@ static BOOL share_name_fnum(int fnum,char *name)
return(share_name(Files[fnum].cnum,&st,name));
}
+#endif
/*******************************************************************
get the share mode of a file using the fnum
@@ -278,6 +312,78 @@ get the share mode of a file
********************************************************************/
int get_share_mode(int cnum,struct stat *sbuf,int *pid)
{
+#ifdef FAST_SHARE_MODES
+ share_mode_record *scanner_p;
+ share_mode_record *prev_p;
+ int ret;
+ BOOL found = False;
+
+ *pid = 0;
+
+ if(!shm_lock()) return (0);
+
+ scanner_p = (share_mode_record *)shm_offset2addr(shm_get_userdef_off());
+ prev_p = scanner_p;
+ while(scanner_p)
+ {
+ if( (scanner_p->st_dev == sbuf->st_dev) && (scanner_p->st_ino == sbuf->st_ino) )
+ {
+ found = True;
+ break;
+ }
+ else
+ {
+ prev_p = scanner_p ;
+ scanner_p = (share_mode_record *)shm_offset2addr(scanner_p->next_offset);
+ }
+ }
+
+ if(!found)
+ {
+ shm_unlock();
+ return (0);
+ }
+
+ if(scanner_p->locking_version != LOCKING_VERSION)
+ {
+ DEBUG(2,("Deleting old share mode record due to old locking version %d",scanner_p->locking_version));
+ if(prev_p == scanner_p)
+ shm_set_userdef_off(scanner_p->next_offset);
+ else
+ prev_p->next_offset = scanner_p->next_offset;
+ shm_free(shm_addr2offset(scanner_p));
+ *pid = 0;
+
+ shm_unlock();
+ return (0);
+ }
+
+ *pid = scanner_p->pid;
+ ret = scanner_p->share_mode;
+
+ if (*pid && !process_exists(*pid))
+ {
+ ret = 0;
+ *pid = 0;
+ }
+
+ if (! *pid)
+ {
+ if(prev_p == scanner_p)
+ shm_set_userdef_off(scanner_p->next_offset);
+ else
+ prev_p->next_offset = scanner_p->next_offset;
+ shm_free(shm_addr2offset(scanner_p));
+ }
+
+ if (*pid)
+ DEBUG(5,("Read share mode record mode 0x%X pid=%d\n",ret,*pid));
+
+ if(!shm_unlock()) return (0);
+
+ return(ret);
+
+#else
pstring fname;
int fd2;
char buf[16];
@@ -319,6 +425,7 @@ int get_share_mode(int cnum,struct stat *sbuf,int *pid)
DEBUG(5,("Read share file %s mode 0x%X pid=%d\n",fname,ret,*pid));
return(ret);
+#endif
}
@@ -327,6 +434,67 @@ del the share mode of a file, if we set it last
********************************************************************/
void del_share_mode(int fnum)
{
+#ifdef FAST_SHARE_MODES
+ struct stat st;
+ time_t t=0;
+ int pid=0;
+ BOOL del = False;
+ share_mode_record *scanner_p;
+ share_mode_record *prev_p;
+ BOOL found = False;
+
+
+
+ if (fstat(Files[fnum].fd,&st) != 0) return;
+
+ if (!shm_lock()) return;
+
+ scanner_p = (share_mode_record *)shm_offset2addr(shm_get_userdef_off());
+ prev_p = scanner_p;
+ while(scanner_p)
+ {
+ if( (scanner_p->st_dev == st.st_dev) && (scanner_p->st_ino == st.st_ino) )
+ {
+ found = True;
+ break;
+ }
+ else
+ {
+ prev_p = scanner_p ;
+ scanner_p = (share_mode_record *)shm_offset2addr(scanner_p->next_offset);
+ }
+ }
+
+ if(!found)
+ {
+ shm_unlock();
+ return;
+ }
+
+ t = scanner_p->time;
+ pid = scanner_p->pid;
+
+ if( (scanner_p->locking_version != LOCKING_VERSION) || !pid || !process_exists(pid))
+ del = True;
+
+ if (!del && t == Files[fnum].open_time && pid==(int)getpid())
+ del = True;
+
+ if (del)
+ {
+ DEBUG(2,("Deleting share mode record\n"));
+ if(prev_p == scanner_p)
+ shm_set_userdef_off(scanner_p->next_offset);
+ else
+ prev_p->next_offset = scanner_p->next_offset;
+ shm_free(shm_addr2offset(scanner_p));
+
+ }
+
+ shm_unlock();
+ return;
+
+#else
pstring fname;
int fd2;
char buf[16];
@@ -363,6 +531,7 @@ void del_share_mode(int fnum)
strcpy(share_del_pending,fname);
}
}
+#endif
}
@@ -371,6 +540,36 @@ set the share mode of a file
********************************************************************/
BOOL set_share_mode(int fnum,int mode)
{
+#ifdef FAST_SHARE_MODES
+ int pid = (int)getpid();
+ struct stat st;
+ shm_offset_t new_off;
+ share_mode_record *new_p;
+
+
+ if (fstat(Files[fnum].fd,&st) != 0) return(False);
+
+ if (!shm_lock()) return (False);
+ new_off = shm_alloc(sizeof(share_mode_record) + strlen(Files[fnum].name) );
+ if (new_off == NULL_OFFSET) return (False);
+ new_p = (share_mode_record *)shm_offset2addr(new_off);
+ new_p->locking_version = LOCKING_VERSION;
+ new_p->share_mode = mode;
+ new_p->time = Files[fnum].open_time;
+ new_p->pid = pid;
+ new_p->st_dev = st.st_dev;
+ new_p->st_ino = st.st_ino;
+ strcpy(new_p->file_name,Files[fnum].name);
+ new_p->next_offset = shm_get_userdef_off();
+ shm_set_userdef_off(new_off);
+
+
+ DEBUG(3,("Created share record for %s with mode 0x%X pid=%d\n",Files[fnum].name,mode,pid));
+
+ if (!shm_unlock()) return (False);
+ return(True);
+
+#else
pstring fname;
int fd2;
char buf[16];
@@ -406,14 +605,58 @@ BOOL set_share_mode(int fnum,int mode)
DEBUG(3,("Created share file %s with mode 0x%X pid=%d\n",fname,mode,pid));
return(True);
+#endif
}
/*******************************************************************
cleanup any stale share files
********************************************************************/
-void clean_share_files(void)
+void clean_share_modes(void)
{
+#ifdef USE_SHMEM
+ share_mode_record *scanner_p;
+ share_mode_record *prev_p;
+ int pid;
+
+ if (!shm_lock()) return;
+
+ scanner_p = (share_mode_record *)shm_offset2addr(shm_get_userdef_off());
+ prev_p = scanner_p;
+ while(scanner_p)
+ {
+ pid = scanner_p->pid;
+
+ if( (scanner_p->locking_version != LOCKING_VERSION) || !process_exists(pid))
+ {
+ DEBUG(2,("Deleting stale share mode record"));
+ if(prev_p == scanner_p)
+ {
+ shm_set_userdef_off(scanner_p->next_offset);
+ shm_free(shm_addr2offset(scanner_p));
+ scanner_p = (share_mode_record *)shm_offset2addr(shm_get_userdef_off());
+ prev_p = scanner_p;
+ }
+ else
+ {
+ prev_p->next_offset = scanner_p->next_offset;
+ shm_free(shm_addr2offset(scanner_p));
+ scanner_p = (share_mode_record *)shm_offset2addr(prev_p->next_offset);
+ }
+
+ }
+ else
+ {
+ prev_p = scanner_p ;
+ scanner_p = (share_mode_record *)shm_offset2addr(scanner_p->next_offset);
+ }
+ }
+
+
+ shm_unlock();
+ return;
+
+#else
char *lockdir = lp_lockdir();
void *dir;
char *s;
@@ -457,4 +700,5 @@ void clean_share_files(void)
}
closedir(dir);
+#endif
}
diff --git a/source3/locking/shmem.c b/source3/locking/shmem.c
new file mode 100644
index 0000000000..3a308d07ba
--- /dev/null
+++ b/source3/locking/shmem.c
@@ -0,0 +1,722 @@
+/*
+ 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)
+{
+ int old_umask;
+ int shm_processes_fd = -1;
+ int nb_read;
+ pid_t other_pid;
+ int erased_slot;
+ BOOL found = False;
+
+
+ old_umask = umask(0);
+ shm_processes_fd = open(processreg_file, O_RDWR);
+ umask(old_umask);
+ if ( shm_processes_fd < 0 )
+ {
+ DEBUG(0,("ERROR shm_unregister_process : processreg_file open failed with code %d\n",errno));
+ return False;
+ }
+
+ while ((nb_read = read(shm_processes_fd, &other_pid, sizeof(other_pid))) > 0)
+ {
+ if(other_pid == pid)
+ {
+ /* erase pid */
+ DEBUG(2,("shm_unregister_process : erasing record for pid %d\n",other_pid));
+ other_pid = (pid_t)0;
+ 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