src/backend/port/qnx4/shm.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * shm.c
   4  *        System V Shared Memory Emulation
   5  *
   6  * Copyright (c) 1999, repas AEG Automation GmbH
   7  *
   8  *
   9  * IDENTIFICATION
  10  *        $Header: /cvsroot/pgsql/src/backend/port/qnx4/Attic/shm.c,v 1.4 2001/03/22 03:59:43 momjian Exp $
  11  *
  12  *-------------------------------------------------------------------------
  13  */
  14
  15 #include <errno.h>
  16 #include <fcntl.h>
  17 #include <stdlib.h>
  18 #include <unistd.h>
  19 #include <sys/mman.h>
  20 #include <sys/shm.h>
  21
  22
  23 #define MODE    0777
  24
  25 #define SHMMAX  1024
  26
  27
  28 struct shm_info
  29 {
  30         int                     shmid;
  31         key_t           key;
  32         size_t          size;
  33         void       *addr;
  34 };
  35
  36 static struct shm_info *ShmInfo;
  37
  38
  39 static int      shm_putinfo(struct shm_info * info);
  40 static int      shm_updinfo(int i, struct shm_info * info);
  41 static int      shm_getinfo(int shmid, struct shm_info * info);
  42 static int      shm_getinfobyaddr(const void *addr, struct shm_info * info);
  43
  44
  45 static int
  46 shm_putinfo(struct shm_info * info)
  47 {
  48         int                     i;
  49
  50         if (ShmInfo == NULL)
  51         {
  52                 ShmInfo = calloc(SHMMAX, sizeof(struct shm_info));
  53                 if (ShmInfo == NULL)
  54                         return -1;
  55                 /* initialize ShmInfo */
  56                 for (i = 0; i < SHMMAX; i++)
  57                         ShmInfo[i].shmid = -1;
  58         }
  59
  60         /* search first free element */
  61         i = 0;
  62         while (i < SHMMAX && ShmInfo[i].shmid != -1)
  63                 i++;
  64         if (i >= SHMMAX)
  65         {
  66                 errno = ENOSPC;
  67                 return -1;
  68         }
  69
  70         memcpy(&ShmInfo[i], info, sizeof(struct shm_info));
  71
  72         return i;
  73 }
  74
  75 static int
  76 shm_updinfo(int i, struct shm_info * info)
  77 {
  78         if (i >= SHMMAX)
  79                 return -1;
  80         if (ShmInfo == NULL)
  81                 return -1;
  82
  83         memcpy(&ShmInfo[i], info, sizeof(struct shm_info));
  84
  85         return i;
  86 }
  87
  88 static int
  89 shm_getinfo(int shmid, struct shm_info * info)
  90 {
  91         int                     i;
  92
  93         if (ShmInfo == NULL)
  94                 return -1;
  95
  96         /* search element */
  97         i = 0;
  98         while (i < SHMMAX && ShmInfo[i].shmid != shmid)
  99                 i++;
 100         if (i >= SHMMAX)
 101                 return -1;
 102
 103         memcpy(info, &ShmInfo[i], sizeof(struct shm_info));
 104
 105         return i;
 106 }
 107
 108 static int
 109 shm_getinfobyaddr(const void *addr, struct shm_info * info)
 110 {
 111         int                     i;
 112
 113         if (ShmInfo == (struct shm_info *) - 1)
 114                 return -1;
 115
 116         /* search element */
 117         i = 0;
 118         while (i < SHMMAX && ShmInfo[i].addr != addr)
 119                 i++;
 120         if (i >= SHMMAX)
 121                 return -1;
 122
 123         memcpy(info, &ShmInfo[i], sizeof(struct shm_info));
 124
 125         return i;
 126 }
 127
 128
 129 void *
 130 shmat(int shmid, const void *shmaddr, int shmflg)
 131 {
 132         struct shm_info info;
 133         int                     i;
 134
 135         i = shm_getinfo(shmid, &info);
 136         if (i == -1)
 137         {
 138                 errno = EACCES;
 139                 return (void *) -1;
 140         }
 141
 142         info.addr = mmap((void *) shmaddr, info.size,
 143                                          PROT_READ | PROT_WRITE, MAP_SHARED, shmid, 0);
 144         if (info.addr == MAP_FAILED)
 145                 return info.addr;
 146
 147         if (shm_updinfo(i, &info) == -1)
 148         {
 149                 errno = EACCES;
 150                 return (void *) -1;
 151         }
 152
 153         return info.addr;
 154 }
 155
 156 int
 157 shmdt(const void *addr)
 158 {
 159         struct shm_info info;
 160
 161         if (shm_getinfobyaddr(addr, &info) == -1)
 162         {
 163                 errno = EACCES;
 164                 return -1;
 165         }
 166
 167         return munmap((void *) addr, info.size);
 168 }
 169
 170 int
 171 shmctl(int shmid, int cmd, struct shmid_ds * buf)
 172 {
 173         struct shm_info info;
 174         char            name[NAME_MAX + 1];
 175
 176         if (cmd == IPC_RMID)
 177         {
 178                 if (shm_getinfo(shmid, &info) == -1)
 179                 {
 180                         errno = EACCES;
 181                         return -1;
 182                 }
 183                 return shm_unlink(itoa(info.key, name, 16));
 184         }
 185         if (cmd == IPC_STAT)
 186         {
 187
 188                 /*
 189                  * Can we support IPC_STAT?  We only need shm_nattch ... For now,
 190                  * punt and assume the shm seg does not exist.
 191                  */
 192                 errno = EINVAL;
 193                 return -1;
 194         }
 195         errno = EINVAL;
 196         return -1;
 197 }
 198
 199 int
 200 shmget(key_t key, size_t size, int flags)
 201 {
 202         char            name[NAME_MAX + 1];
 203         int                     oflag = 0;
 204         struct shm_info info;
 205
 206         if (flags & IPC_CREAT)
 207                 oflag |= O_CREAT;
 208         if (flags & IPC_EXCL)
 209                 oflag |= O_EXCL;
 210         if (flags & SHM_R)
 211         {
 212                 if (flags & SHM_W)
 213                         oflag |= O_RDWR;
 214                 else
 215                         oflag |= O_RDONLY;
 216         }
 217         info.shmid = shm_open(itoa(key, name, 16), oflag, MODE);
 218
 219         /* store shared memory information */
 220         if (info.shmid != -1)
 221         {
 222                 info.key = key;
 223                 info.size = size;
 224                 info.addr = NULL;
 225                 if (shm_putinfo(&info) == -1)
 226                         return -1;
 227         }
 228
 229         /* The size may only be set once. Ignore errors. */
 230         ltrunc(info.shmid, size, SEEK_SET);
 231
 232         return info.shmid;
 233 }