45 lines
1.1 KiB
C
45 lines
1.1 KiB
C
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#include <lib.h>
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#define brk _brk
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#define sbrk _sbrk
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#include <unistd.h>
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extern char *_brksize;
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/* Both OSF/1 and SYSVR4 man pages specify that brk(2) returns int.
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* However, BSD4.3 specifies that brk() returns char*. POSIX omits
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* brk() on the grounds that it imposes a memory model on an architecture.
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* For this reason, brk() and sbrk() are not in the lib/posix directory.
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* On the other hand, they are so crucial to correct operation of so many
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* parts of the system, that we have chosen to hide the name brk using _brk,
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* as with system calls. In this way, if a user inadvertently defines a
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* procedure brk, MINIX may continue to work because the true call is _brk.
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*/
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PUBLIC int brk(addr)
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char *addr;
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{
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message m;
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if (addr != _brksize) {
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m.m1_p1 = addr;
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if (_syscall(MM, BRK, &m) < 0) return(-1);
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_brksize = m.m2_p1;
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}
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return(0);
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}
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PUBLIC char *sbrk(incr)
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int incr;
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{
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char *newsize, *oldsize;
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oldsize = _brksize;
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newsize = _brksize + incr;
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if ((incr > 0 && newsize < oldsize) || (incr < 0 && newsize > oldsize))
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return( (char *) -1);
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if (brk(newsize) == 0)
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return(oldsize);
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else
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return( (char *) -1);
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}
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