MACH-MAP(3) MACH-MAP(3)
NAME
allocmap, addseg, findseg, addrtoseg, addrtosegafter,
removeseg, freemap, get1, get2, get4, get8, put1, put2,
put4, put8, rget, rput, fpformat, locnone, locaddr,
locconst, locreg, locindir, loccmp, loceval, locfmt,
locsimplify, lget1, lget2, lget4, lget8, lput1, lput2,
lput4, lput8 - machine-independent access to address spaces
and register sets
SYNOPSIS
#include <u.h>
#include <libc.h>
#include <mach.h>
typedef struct Map Map;
typedef struct Seg Seg;
struct Seg
{
char *name;
char *file;
int fd;
ulong base;
ulong size;
ulong offset;
int (*rw)(Map*, Seg*, ulong, void*, uint, int);
};
struct Map
{
Seg *seg;
int nseg;
...
};
Map *allocmap(void)
int addseg(Map *map, Seg seg)
int findseg(Map *map, char *name, char *file)
int addrtoseg(Map *map, ulong addr, Seg *seg)
int addrtosegafter(Map *map, ulong addr, Seg *seg)
void removeseg(Map *map, int i)
void freemap(Map *map)
int get1(Map *map, ulong addr, uchar *a, uint n)
int get2(Map *map, ulong addr, u16int *u)
int get4(Map *map, ulong addr, u32int *u)
int get8(Map *map, ulong addr, u64int *u)
int put1(Map *map, ulong addr, uchar *a, uint n)
int put2(Map *map, ulong addr, u16int u)
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int put4(Map *map, ulong addr, u32int u)
int put8(Map *map, ulong addr, u64int u)
int rget(Regs *regs, char *reg, ulong *u)
int fpformat(Map *map, char *reg, char *a, uint n, char code);
int rput(Regs *regs, char *name, ulong u)
Loc locnone(void)
Loc locaddr(ulong addr)
Loc locconst(ulong con)
Loc locreg(char *reg)
Loc locindir(char *reg, long offset)
int loccmp(Loc *a, Loc *b)
int loceval(Map *map, Loc loc, ulong *addr)
int locfmt(Fmt *fmt)
int locsimplify(Map *map, Loc *regs, Loc loc, Loc *newloc)
int lget1(Map *map, Loc loc, uchar *a, uint n)
int lget2(Map *map, Loc loc, u16int *u)
int lget4(Map *map, Loc loc, u32int *u)
int lget8(Map *map, Loc loc, u64int *u)
int lput1(Map *map, Loc loc, uchar *a, uint n)
int lput2(Map *map, Loc loc, u16int u)
int lput4(Map *map, Loc loc, u32int u)
int lput8(Map *map, Loc loc, u64int u)
DESCRIPTION
These functions provide a processor-independent interface
for accessing executable files, core files, and running pro-
cesses via maps, data structures that provides access to an
address space and register set. The functions described in
mach-file(3) are typically used to construct these maps.
Related library functions described in mach-symbol(3) pro-
vide similar access to symbol tables.
Each map comprises an optional register set and one or more
segments, each associating a non-overlapping range of memory
addresses with a logical section of an executable file or of
a running process's address space. Other library functions
then use a map and the architecture-specific data structures
to provide a generic interface to the processor-dependent
data.
Each segment has a name (e.g., text or data) and may be
associated with a particular file. A segment represents a
range of accessible address space. Segments may be backed
an arbitary access function (if the rw pointer is non-nil),
or by the contents of an open file (using the fd file
descriptor). Each range has a starting address in the space
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(base) and an extent (size). In segments mapped by files,
the range begins at byte offset in the file. The rw func-
tion is most commonly used to provide access to executing
processes via ptrace(2) and to zeroed segments.
Allocmap creates an empty map; freemap frees a map.
Addseg adds the given segment to the map, resizing the map's
seg array if necessary. A negative return value indicates
an allocation error.
Findseg returns the index of the segment with the given name
(and, if file is non-nil, the given file), or -1 if no such
segment is found.
Addrtoseg returns the index of the segment containing for
the given address, or -1 if that address is not mapped.
Segments may have overlapping address ranges: addseg appends
segments to the end of the seg array in the map, and
addrtoseg searches the map backwards from the end, so the
most recently mapped segment wins.
Addrtosegafter returns the index of the segment containing
the lowest mapped address greater than addr.
Removeseg removes the segment at the given index.
Get1, get2, get4, and get8 retrieve the data stored at
address addr in the address space associated with map. Get1
retrieves n bytes of data beginning at addr into buf. Get2,
get4 and get8 retrieve 16-bit, 32-bit and 64-bit values
respectively, into the location pointed to by u. The value
is byte-swapped if the source byte order differs from that
of the current architecture. This implies that the value
returned by get2, get4, and get8 may not be the same as the
byte sequences returned by get1 when n is two, four or
eight; the former may be byte-swapped, the latter reflects
the byte order of the target architecture. These functions
return the number of bytes read or a -1 when there is an
error.
Put1, put2, put4, and put8 write to the address space asso-
ciated with map. The address is translated using the map
parameters and multi-byte quantities are byte-swapped, if
necessary, before they are written. Put1 transfers n bytes
stored at buf; put2, put4, and put8 write the 16-bit, 32-bit
or 64-bit quantity contained in val, respectively. The num-
ber of bytes transferred is returned. A -1 return value
indicates an error.
When representing core files or running programs, maps also
provide access to the register set. Rget and rput read or
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write the register named by reg. If the register is smaller
than a ulong, the high bits are ignored.
Fpformat converts the contents of a floating-point register
to a string. Buf is the address of a buffer of n bytes to
hold the resulting string. Code must be either `F' or `f',
selecting double or single precision, respectively. If code
is `F', the contents of the specified register and the fol-
lowing register are interpreted as a double-precision
floating-point number; this is meaningful only for architec-
tures that implement double-precision floats by combining
adjacent single-precision registers.
A location represents a place in an executing image capable
of storing a value. Note that locations are typically
passed by value rather than by reference.
Locnone returns an unreadable, unwritable location. Locaddr
returns a location representing the memory address addr.
Locreg returns a location representing the register reg.
Locindir returns an location representing the memory address
at offset added to the value of reg. Locconst returns an
imaginary unwritable location holding the constant con; such
locations are useful for passing specific constants to func-
tions expect locations, such as unwind (see mach-stack(3)).
Loccmp compares two locations, returning negative, zero, or
positive values if *a is less than, equal to, or greater
than *b, respectively. Register locations are ordered
before memory addresses, which are ordered before indirec-
tions.
Locfmt is a print(3)-verb that formats a Loc structure (not
a pointer to one).
Indirection locations are needed in some contexts (e.g.,
when using findlsym (see mach-symbol(3))), but bothersome in
most. Locsimplify rewrites indirections as absolute memory
addresses, by evaluating the register using the given map
and adding the offset.
The functions lget1, lget2, lget4, lget8, lput1, lput2,
lput4, and lput8 read and write the given locations, using
the get, put, rget, and rput function families as necessary.
SOURCE
/usr/local/plan9/src/libmach
SEE ALSO
mach(3), mach-file(3)
DIAGNOSTICS
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These routines set errstr.
BUGS
This man page needs to describe Regs and Regdesc and
coreregs.
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