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.TH SEGBRK 2
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.SH NAME
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segbrk \- change memory allocation
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.SH SYNOPSIS
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.B #include <u.h>
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.br
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.B #include <libc.h>
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.PP
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.ta \w'\fLvoid* 'u
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.B
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void*	segbrk(void *saddr, void *addr)
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.PP
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.SH DESCRIPTION
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.I Segbrk
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sets the system's idea of the lowest unused location of a segment
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to
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.I addr
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rounded up to the next multiple of a page size, typically 4096 bytes.
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The segment is identified by
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.I saddr
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which may be any valid address within the segment.
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.PP
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A call to
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.I segbrk
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with a zero
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.I addr
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argument returns the address
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of the top of bss.
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.PP
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The system will prevent segments from overlapping and will not allow the
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length of the
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text, data, or stack segment to be altered.
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.SH SOURCE
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.B /sys/src/libc/9syscall
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.SH SEE ALSO
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.IR brk (2),
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.IR segattach (2),
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.IR segflush (2)
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.br
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.BR /proc/*/segment
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.SH DIAGNOSTICS
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Sets
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.IR errstr .
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.I Segbrk
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returns
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.B (void*)-1
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on error.
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.SH BUGS
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.I Segbrk
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is not fully defined or implemented.
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In particular,
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it cannot always return the top of bss
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when called with a zero
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.I addr
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argument.
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The
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.I segbrk
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system call may go away or be re-implemented
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to give more general segment control,
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subsuming the functions of
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.IR brk (2),
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.IR segflush (2)
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and
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.I segfree
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in
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.IR segattach (2).