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Manual page for ADBGEN(8)

adbgen - generate adb script

SYNOPSIS

/usr/lib/adb/adbgen filename.adb ...

DESCRIPTION

adbgen makes it possible to write adb.1 scripts that do not contain hard-coded dependencies on structure member offsets. The input to adbgen is a file named filename.adb which contains adbgen header information, then a null line, then the name of a structure, and finally an adb script. adbgen only deals with one structure per file; all member names are assumed to be in this structure. The output of adbgen is an adb script in filename. adbgen operates by generating a C program which determines structure member offsets and sizes, which in turn generates the adb script.

The header lines, up to the null line, are copied verbatim into the generated C program. Typically these include C #include statements to include the header files containing the relevant structure declarations.

The adb script part may contain any valid adb commands (see adb.1 and may also contain adbgen requests, each enclosed in {}s. Request types are:

Print a structure member. The request form is {member,format}. member is a member name of the structure given earlier, and format is any valid adb format request. For example, to print the p_pid field of the proc structure as a decimal number, you would write {p_pid,d}.
Reference a structure member. The request form is {*member,base}. member is the member name whose value is desired, and base is an adb register name which contains the base address of the structure. For example, to get the p_pid field of the proc structure, you would get the proc structure address in an adb register, say <f, and write {*p_pid,<f}.
Tell adbgen that the offset is okay. The request form is {OFFSETOK}. This is useful after invoking another adb script which moves the adb dot.
Get the size of the structure. The request form is {SIZEOF}. adbgen replaces this request with the size of the structure. This is useful in incrementing a pointer to step through an array of structures.
Calculate an arbitrary C expression. The request form is {EXPR,expression}. adbgen replaces this request with the value of the expression. This is useful when more than one structure is involved in the script.
Get the offset to the end of the structure. The request form is {END}. This is useful at the end of the structure to get adb to align the dot for printing the next structure member.

adbgen keeps track of the movement of the adb dot and emits adb code to move forward or backward as necessary before printing any structure member in a script. adbgen's model of the behavior of adb's dot is simple: it is assumed that the first line of the script is of the form struct_address/adb text and that subsequent lines are of the form +/adb text. The adb dot then moves in a sane fashion. adbgen does not check the script to ensure that these limitations are met. adbgen also checks the size of the structure member against the size of the adb format code and warns you if they are not equal.

EXAMPLES

If there were an include file x.h which contained:

struct x {

char	*x_cp;
char	x_c;
int	x_i;

};

Then an adbgen file (call it script.adb) to print it would be:

#include "x.h"
x
./"x_cp"16t"x_c"8t"x_i"n{x_cp,X}{x_c,C}{x_i,D}

After running adbgen the output file script would contain:

: ./"x_cp"16t"x_c"8t"x_i"nXC+D

To invoke the script you would type:

: x$<script

FILES

/usr/lib/adb/*: adb scripts for debugging the kernel

BUGS

adb syntax is ugly; there should be a higher level interface for generating scripts.

Structure members which are bit fields cannot be handled because C will not give the address of a bit field. The address is needed to determine the offset.

DIAGNOSTICS

Warnings about structure member sizes not equal to adb format items and complaints about badly formatted requests. The C compiler complains if you reference a structure member that does not exist. It also complains about & before array names; these complaints may be ignored.