ADB(CP) XENIX System V ADB(CP)
Name
adb - Invokes a general-purpose debugger.
Syntax
adb [-w] [-p prompt ] [ objfil [ corefile ] ]
Description
adb is a general purpose debugging program. It may be used
to examine files and to provide a controlled environment for
the execution of XENIX programs.
objfil is normally an executable program file, preferably
containing a symbol table; if not then the symbolic features
of adb cannot be used although the file can still be
examined. The default for objfil is a.out. corefile is
assumed to be a core image file produced after executing
objfil; the default for corefile is core.
Requests to adb are read from the standard input and
responses are to the standard output. If the -w option is
present then both objfil and corefile are created if
necessary and opened for reading and writing so that files
can be modified using adb. The QUIT and INTERRUPT keys
cause adb to return to the next command. The -p option
defines the prompt string. It may be any combination of
characters. The default is an asterisk (*).
In general requests to adb are of the form:
[address] [, count] [command] [;]
If address is present then dot is set to address. Initially
dot is set to 0. For most commands count specifies how many
times the command will be executed. The default count is 1.
address is a special expression having the form:
[segment:]offset
where segment gives the address of a specific text or data
segment, and offset gives an offset from the beginning of
that segment. If segment is not given, the last segment
value given in a command is used.
The interpretation of an address depends on the context it
is used in. If a subprocess is being debugged then
addresses are interpreted in the usual way in the address
space of the subprocess. For further details of address
mapping see Addresses.
Expressions
. The value of dot.
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+ The value of dot incremented by the current
increment.
^ The value of dot decremented by the current
increment.
" The last address typed.
integer
An octal number if integer begins with a 0; a
hexadecimal number if preceded by # or 0x; otherwise
a decimal number.
integer.fraction
A 32-bit floating point number.
'cccc' The ASCII value of up to 4 characters. \ may be used
to escape a '.
< name The value of name, which is either a variable name or
a register name. adb maintains a number of variables
(see Variables) named by single letters or digits.
If name is a register name then the value of the
register is obtained from the system header in
corefile. The register names are ax bx cx dx di si
bp fl ip cs ds ss es sp. The name fl refers to the
status flags.
symbol A symbol is a sequence of upper or lower case
letters, underscores or digits, not starting with a
digit. The value of the symbol is taken from the
symbol table in objfil. An initial _ or ~ will be
prepended to symbol if needed.
_ symbol
In C, the `true name' of an external symbol begins
with _. It may be necessary to use this name to
disinguish it from internal or hidden variables of a
program.
(exp) The value of the expression exp.
Monadic operators
*exp The contents of the location addressed by exp.
-exp Integer negation.
~exp Bitwise complement.
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Dyadic operators
Dyadic operators are left-associative and are less binding
than monadic operators.
e1+e2 Integer addition.
e1-e2 Integer subtraction.
e1*e2 Integer multiplication.
e1%e2 Integer division.
e1&e2 Bitwise conjunction.
e1|e2 Bitwise disjunction.
e1^e2 Remainder after division of e1 by e2.
e1#e2 E1 rounded up to the next multiple of e2.
Commands
Most commands consist of a verb followed by a modifier or
list of modifiers. The following verbs are available. (The
commands `?' and `/' may be followed by `*'; see Addresses
for further details.)
?f Locations starting at address in objfil are printed
according to the format f.
/f Locations starting at address in corefile are printed
according to the format f.
=f The value of address itself is printed in the styles
indicated by the format f. (For i format `?' is
printed for the parts of the instruction that reference
subsequent words.)
A format consists of one or more characters that specify a
style of printing. Each format character may be preceded by
a decimal integer that is a repeat count for the format
character. While stepping through a format dot is
incremented temporarily by the amount given for each format
letter. If no format is given then the last format is used.
The format letters available are as follows:
o 2 Prints 2 bytes in octal. All octal numbers
output by adb are preceded by 0.
O 4 Prints 4 bytes in octal.
q 2 Prints in signed octal.
Q 4 Prints long signed octal.
d 2 Prints in decimal.
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D 4 Prints long decimal.
x 2 Prints 2 bytes in hexadecimal.
X 4 Prints 4 bytes in hexadecimal.
u 2 Prints as an unsigned decimal number.
U 4 Prints long unsigned decimal.
f 4 Prints the 32 bit value as a floating point
number.
F 8 Prints double floating point.
b 1 Prints the addressed byte in octal.
c 1 Prints the addressed character.
C 1 Prints the addressed character using the
following escape convention. Character
values 000 to 040 are printed as an at-sign
(@) followed by the corresponding character
in the octal range 0100 to 0140. The at-sign
character itself is printed as @@.
s n Prints the addressed characters until a zero
character is reached.
S n Prints a string using the at-sign (@) escape
convention. Here n is the length of the
string including its zero terminator.
Y 4 Prints 4 bytes in date format (see ctime(S)).
i n Prints as machine instructions. n is the
number of bytes occupied by the instruction.
This style of printing causes variables 1 and
2 to be set to the offset parts of the source
and destination respectively.
a 0 Prints the value of dot in symbolic form.
Symbols are checked to ensure that they have
an appropriate type as indicated below.
/ local or global data symbol
? local or global text symbol
= local or global absolute symbol
A 0 Prints the value of dot in absolute form.
p 2 Prints the addressed value in symbolic form
using the same rules for symbol lookup as a.
t 0 When preceded by an integer, tabs to the next
appropriate tab stop. For example, 8t moves
to the next 8-space tab stop.
r 0 Prints a space.
n 0 Prints a newline.
"..." 0 Prints the enclosed string.
^ Decrements dot by the current increment.
Nothing is printed.
+ Increments dot by 1. Nothing is printed.
- Decrements dot by 1. Nothing is printed.
newline
If the previous command temporarily incremented dot,
makes the increment permanent. Repeat the previous
command with a count of 1.
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[?/]l value mask
Words starting at dot are masked with mask and compared
with value until a match is found. If L is used then
the match is for
4 bytes at a time instead of 2. If no match is found
then dot is unchanged; otherwise dot is set to the
matched location. If mask is omitted then -1 is used.
[?/]w value ...
Writes the 2-byte value into the addressed location.
If the command is W, writes 4 bytes. Odd addresses are
not allowed when writing to the subprocess address
space.
[?/]m segnum fpos size
Sets new values for the given segment's file position
and size. If size is not given, then only the file
position is changed. The segnum must the segment
number of a segment already in the memory map (see
Addresses). If ? is given, a text segment is affected;
if / a data segment.
[?/]M segnum fpos size
Creates a new segment in the memory map. The segment
is given file position fpos and physical size size .
The segnum must not already exist in the memory map.
If ? is given, a text segment is created; if / a data
segment.
>name
dot is assigned to the variable or register named.
! A shell is called to read the rest of the line
following `!'.
$modifier
Miscellaneous commands. The available modifiers are:
<f Read commands from the file f and return.
>f Send output to the file f, which is created if it
does not exist.
r Print the general registers and the instruction
addressed by ip. Dot is set to ip.
f Print the floating registers in single or double
length.
b Print all breakpoints and their associated counts
and commands.
c C stack backtrace. If address is given then it is
taken as the address of the current frame (instead
of bp). If C is used then the names and (16 bit)
values of all automatic and static variables are
printed for each active function. If count is
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given then only the first count frames are
printed.
e The names and values of external variables are
printed.
w Set the page width for output to address (default
80).
s Set the limit for symbol matches to address
(default 255).
o Sets input and output default format to octal.
d Sets input and output default format to decimal.
x Sets input and output default format to
hexadecimal.
q Exit from adb.
v Print all non zero variables in octal.
m Print the address map.
:modifier
Manage a subprocess. Available modifiers are:
brc Set breakpoint at address. The breakpoint is
executed count-1 times before causing a stop.
Each time the breakpoint is encountered the
command c is executed. If this command sets dot
to zero then the breakpoint causes a stop.
dl Delete breakpoint at address.
r [arguments]
Run objfil as a subprocess. If address is given
explicitly then the program is entered at this
point; otherwise the program is entered at its
standard entry point. count specifies how many
breakpoints are to be ignored before stopping.
arguments to the subprocess may be supplied on the
same line as the command. An argument starting
with < or > causes the standard input or output to
be established for the command. All signals are
turned on on entry to the subprocess.
R [arguments]
Same as the r command except that arguments are
passed through a shell before being passed to to
the program. This means shell metacharacters can
be used in filenames.
cos The subprocess is continued and signal s is passed
to it, see signal(S). If address is given then
the subprocess is continued at this address. If
no signal is specified then the signal that caused
the subprocess to stop is sent. Breakpoint
skipping is the same as for r.
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ss As for co except that the subprocess is single
stepped count times. If there is no current
subprocess then objfil is run as a subprocess as
for r. In this case no signal can be sent; the
remainder of the line is treated as arguments to
the subprocess.
k The current subprocess, if any, is terminated.
Variables
adb provides a number of variables. Named variables are set
initially by adb but are not used subsequently. Numbered
variables are reserved for communication as follows.
0 The last value printed.
1 The last offset part of an instruction source.
2 The previous value of variable 1.
On entry the following are set from the system header in the
corefile. If corefile does not appear to be a core file
then these values are set from objfil:
b The base address of the data segment.
d The data segment size.
e The entry point.
m The execution type.
n The number of segments.
s The stack segment size.
t The text segment size.
Addresses
Addresses in adb refer to either a location in a file or in
actual memory. When there is no current process in memory,
adb addresses are computed as file locations, and requested
text and data are read from the objfil and corefile files.
When there is a process, such as after a :r command,
addresses are computed as actual memory locations.
All text and data segments in a program have associated
memory map entries. Each entry has a unique segment number.
In addition, each entry has the file position of that
segment's first byte, and the physical size of the segment
in the file. When a process is running, a segment's entry
has a virtual size which defines the size of the segment in
memory at the current time. This size can change during
execution.
When a address is given and no process is running, the file
location corresponding to the address is calculated as:
effective-file-address = file-position + offset
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If a process is running, the memory location is simply the
offset in the given segment. These addresses are valid if
and only if
0 <= offset <= size
where size is physical size for file locations and virtual
size for memory locations. Otherwise, the requested address
is not legal.
The initial setting of both mappings is suitable for normal
a.out and core files. If either file is not of the kind
expected then, for that file, file position is set to 0, and
size is set to the maximum file size. In this way, the
whole file can be examined with no address translation.
So that adb may be used on large files, all appropriate
values are kept as signed 32 bit integers.
Files
a.out
core
See Also
ptrace(S), a.out(F), core(F)
Diagnostics
The message ``adb'' appears when there is no current command
or format.
Comments about inaccessible files, syntax errors, abnormal
termination of commands, etc.
Exit status is 0, unless last command failed or returned
nonzero status.
Notes
A breakpoint set at the entry point is not effective on
initial entry to the program.
System calls cannot be single stepped.
Local variables whose names are the same as an external
variable may foul up the accessing of the external.
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