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Annotation of cci/usr/src/man/man2/brk.2, revision 1.1.1.1

1.1       root        1: .TH BRK 2
                      2: .SH NAME
                      3: brk, sbrk \- change data segment space allocation
                      4: .SH SYNOPSIS
                      5: .B int brk (endds)
                      6: .br
                      7: .B char *endds;
                      8: .PP
                      9: .B  char *sbrk (incr)
                     10: .br
                     11: .B int incr;
                     12: .SH DESCRIPTION
                     13: .I Brk\^
                     14: and
                     15: .I sbrk\^
                     16: are used to change dynamically the amount of space allocated
                     17: for the calling process's data segment; see
                     18: .IR exec (2).
                     19: The change is made by resetting the process's break value and allocating
                     20: the appropriate amount of space.
                     21: The break value
                     22: is the address of the first location beyond the end of the data segment.
                     23: The amount of allocated space increases as the break value increases.
                     24: The newly allocated space is set to zero.
                     25: .PP
                     26: .I Brk\^
                     27: sets the break value to
                     28: .I endds\^
                     29: and changes the allocated space accordingly.
                     30: .PP
                     31: .I Sbrk\^
                     32: adds 
                     33: .I incr\^
                     34: bytes to the break value and changes the allocated space accordingly.
                     35: .I Incr\^
                     36: can be negative, in which case the amount of allocated space is decreased.
                     37: .PP
                     38: .I Brk\^
                     39: and
                     40: .I sbrk\^
                     41: will fail without making any change in the allocated space if one or more of
                     42: the following are true:
                     43: .IP
                     44: Such a change would result in more space being allocated
                     45: than is allowed by a system-imposed maximum (see
                     46: .IR ulimit (2)).
                     47: .SM
                     48: \%[ENOMEM]
                     49: .IP
                     50: Such a change would result in the break value being greater than or equal
                     51: to the start address of any attached shared memory segment (see
                     52: .IR shmop (2)).
                     53: .SH RETURN VALUE
                     54: Upon successful completion,
                     55: .I brk\^
                     56: returns a value of 0 and
                     57: .I sbrk\^
                     58: returns the old break value.
                     59: Otherwise, a value of \-1 is returned and
                     60: .I errno\^
                     61: is set to indicate the error.
                     62: .SH SEE ALSO
                     63: exec(2), shmop(2), ulimit(2).
                     64: .\"    @(#)brk.2       6.2 of 9/6/83

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