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	debugmalloc.c - 9base - revived minimalist port of Plan 9 userland to Unix
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	debugmalloc.c (3058B)
	---
	1 #include <u.h>
	2 #define NOPLAN9DEFINES
	3 #include <libc.h>
	4
	5 /*
	6 * The Unix libc routines cannot be trusted to do their own locking.
	7 * Sad but apparently true.
	8 */
	9 static Lock malloclock;
	10 static int mallocpid;
	11
	12 /*
	13 * The Unix mallocs don't do nearly enough error checking
	14 * for my tastes. We'll waste another 24 bytes per guy so that
	15 * we can. This is severely antisocial, since now free and p9free
	16 * are not interchangeable.
	17 */
	18 int debugmalloc;
	19
	20 #define Overhead (debugmalloc ? (6*sizeof(ulong)) : 0)
	21 #define MallocMagic 0xA110C09
	22 #define ReallocMagic 0xB110C09
	23 #define CallocMagic 0xC110C09
	24 #define FreeMagic 0xF533F533
	25 #define CheckMagic 0
	26 #define END "\x7F\x2E\x55\x23"
	27
	28 static void
	29 whoops(void *v)
	30 {
	31 fprint(2, "bad malloc block %p\n", v);
	32 abort();
	33 }
	34
	35 static void*
	36 mark(void *v, ulong pc, ulong n, ulong magic)
	37 {
	38 ulong *u;
	39 char *p;
	40
	41 if(!debugmalloc)
	42 return v;
	43
	44 if(v == nil)
	45 return nil;
	46
	47 if(magic == FreeMagic \|\| magic == CheckMagic){
	48 u = (ulong)((char)v-4*sizeof(ulong));
	49 if(u[0] != MallocMagic && u[0] != ReallocMagic && u[0] !…
	50 whoops(v);
	51 n = u[1];
	52 p = (char*)v+n;
	53 if(memcmp(p, END, 4) != 0)
	54 whoops(v);
	55 if(magic != CheckMagic){
	56 u[0] = FreeMagic;
	57 u[1] = u[2] = u[3] = pc;
	58 if(n > 16){
	59 u[4] = u[5] = u[6] = u[7] = pc;
	60 memset((char*)v+16, 0xFB, n-16);
	61 }
	62 }
	63 return u;
	64 }else{
	65 u = v;
	66 u[0] = magic;
	67 u[1] = n;
	68 u[2] = 0;
	69 u[3] = 0;
	70 if(magic == ReallocMagic)
	71 u[3] = pc;
	72 else
	73 u[2] = pc;
	74 p = (char*)(u+4)+n;
	75 memmove(p, END, 4);
	76 return u+4;
	77 }
	78 }
	79
	80 void
	81 setmalloctag(void *v, ulong t)
	82 {
	83 ulong *u;
	84
	85 if(!debugmalloc)
	86 return;
	87
	88 if(v == nil)
	89 return;
	90 u = mark(v, 0, 0, 0);
	91 u[2] = t;
	92 }
	93
	94 void
	95 setrealloctag(void *v, ulong t)
	96 {
	97 ulong *u;
	98
	99 if(!debugmalloc)
	100 return;
	101
	102 if(v == nil)
	103 return;
	104 u = mark(v, 0, 0, 0);
	105 u[3] = t;
	106 }
	107
	108 void*
	109 p9malloc(ulong n)
	110 {
	111 void *v;
	112 if(n == 0)
	113 n++;
	114 /fprint(2, "%s %d malloc\n", argv0, getpid()); /
	115 lock(&malloclock);
	116 mallocpid = getpid();
	117 v = malloc(n+Overhead);
	118 v = mark(v, getcallerpc(&n), n, MallocMagic);
	119 unlock(&malloclock);
	120 /fprint(2, "%s %d donemalloc\n", argv0, getpid()); /
	121 return v;
	122 }
	123
	124 void
	125 p9free(void *v)
	126 {
	127 if(v == nil)
	128 return;
	129
	130 /fprint(2, "%s %d free\n", argv0, getpid()); /
	131 lock(&malloclock);
	132 mallocpid = getpid();
	133 v = mark(v, getcallerpc(&v), 0, FreeMagic);
	134 free(v);
	135 unlock(&malloclock);
	136 /fprint(2, "%s %d donefree\n", argv0, getpid()); /
	137 }
	138
	139 void*
	140 p9calloc(ulong a, ulong b)
	141 {
	142 void *v;
	143
	144 /fprint(2, "%s %d calloc\n", argv0, getpid()); /
	145 lock(&malloclock);
	146 mallocpid = getpid();
	147 v = calloc(a*b+Overhead, 1);
	148 v = mark(v, getcallerpc(&a), a*b, CallocMagic);
	149 unlock(&malloclock);
	150 /fprint(2, "%s %d donecalloc\n", argv0, getpid()); /
	151 return v;
	152 }
	153
	154 void*
	155 p9realloc(void *v, ulong n)
	156 {
	157 /fprint(2, "%s %d realloc\n", argv0, getpid()); /
	158 lock(&malloclock);
	159 mallocpid = getpid();
	160 v = mark(v, getcallerpc(&v), 0, CheckMagic);
	161 v = realloc(v, n+Overhead);
	162 v = mark(v, getcallerpc(&v), n, ReallocMagic);
	163 unlock(&malloclock);
	164 /fprint(2, "%s %d donerealloc\n", argv0, getpid()); /
	165 return v;
	166 }