distr/util/safe_mem.c

   1 /* LINTLIBRARY */
   2
   3 #include <stdio.h>
   4 #include "util.h"
   5
   6 /*
   7  *  These are interface routines to be placed between a program and the
   8  *  system memory allocator.
   9  *
  10  *  It forces well-defined semantics for several 'borderline' cases:
  11  *
  12  *      malloc() of a 0 size object is guaranteed to return something
  13  *          which is not 0, and can safely be freed (but not dereferenced)
  14  *      free() accepts (silently) an 0 pointer
  15  *      realloc of a 0 pointer is allowed, and is equiv. to malloc()
  16  *      For the IBM/PC it forces no object > 64K; note that the size argument
  17  *          to malloc/realloc is a 'long' to catch this condition
  18  *
  19  *  The function pointer MMoutOfMemory() contains a vector to handle a
  20  *  'out-of-memory' error (which, by default, points at a simple wrap-up
  21  *  and exit routine).
  22  */
  23
  24 #ifdef __cplusplus
  25 extern "C" {
  26 #endif
  27
  28 extern char *MMalloc(long);
  29 extern void MMout_of_memory(long);
  30 extern char *MMrealloc(char *, long);
  31
  32 void (*MMoutOfMemory)(long) = MMout_of_memory;
  33
  34 #ifdef __cplusplus
  35 }
  36 #endif
  37
  38
  39 /* MMout_of_memory -- out of memory for lazy people, flush and exit */
  40 void
  41 MMout_of_memory(long size)
  42 {
  43     (void) fflush(stdout);
  44     (void) fprintf(stderr, "\nout of memory allocating %lu bytes\n",
  45                    (unsigned long) size);
  46     exit(1);
  47 }
  48
  49
  50 char *
  51 MMalloc(long size)
  52 {
  53     char *p;
  54
  55 #ifdef IBMPC
  56     if (size > 65000L) {
  57         if (MMoutOfMemory != (void (*)(long)) 0 ) (*MMoutOfMemory)(size);
  58         return NIL(char);
  59     }
  60 #endif
  61     if (size == 0) size = sizeof(long);
  62     if ((p = (char *) malloc((unsigned long) size)) == NIL(char)) {
  63         if (MMoutOfMemory != 0 ) (*MMoutOfMemory)(size);
  64         return NIL(char);
  65     }
  66     return p;
  67 }
  68
  69
  70 char *
  71 MMrealloc(char *obj, long size)
  72 {
  73     char *p;
  74
  75 #ifdef IBMPC
  76     if (size > 65000L) {
  77         if (MMoutOfMemory != 0 ) (*MMoutOfMemory)(size);
  78         return NIL(char);
  79     }
  80 #endif
  81     if (obj == NIL(char)) return MMalloc(size);
  82     if (size <= 0) size = sizeof(long);
  83     if ((p = (char *) realloc(obj, (unsigned long) size)) == NIL(char)) {
  84         if (MMoutOfMemory != 0 ) (*MMoutOfMemory)(size);
  85         return NIL(char);
  86     }
  87     return p;
  88 }
  89
  90
  91 void
  92 MMfree(char *obj)
  93 {
  94     if (obj != 0) {
  95         free(obj);
  96     }
  97 }