DYNODUMP
--------
Dynodump, not to be confused with DinoTurd (as seen in Jurassic Park),
is a shared object that provides one function:
int dynodump(char *new_file);
dynodump(), called from a running program will write a new executable
in new_file a la unexec() in GNU Emacs. The difference lies in the
relocations.
dynodump() will create an image with any relocations (which were
performed by the run-time dynamic linker) undone. This allows the new
image to be run in a different environment. There is, however, one
potentially major caveat. If a symbol reference gets updated during
the running of the calling program, its updated value will be lost.
An example (with additional blank lines for legibility):
$ cat lib.c
char _foo[] = "hello";
char _bar[] = "world";
$ cc -G -o lib.so lib.c
$ cat prog.c
extern char _foo, _bar;
int beenhere = 0;
char * foo = &_foo;
char * bar = &_bar;
int
main(void)
{
(void) printf("%d: foo = %x\n", beenhere, foo);
(void) printf("%d: bar = %x, ", beenhere, bar);
if (!beenhere) {
beenhere = 1;
bar++;
dynodump("newfile");
}
(void) printf("%x\n", bar);
}
$ cc -o prog prog.c -R. lib.so dynodump.so
$ ./prog
0: foo = ef7503cc
0: bar = ef7503d2, ef7503d3
$ ./newfile
1: foo = ef7503cc
1: bar = ef7503d2, ef7503d2
Notice that in the run of newfile, bar points at "world" instead of
the perhaps expected "orld".
Dynodump supports sparc, intel, and power pc architectures.
Dynodump is buildable with GNU make and gcc. If it works for you
with these tools, let me know.
Questions:
dynodump() was developed by Rod.Evans@Eng.Sun.COM and
Georg.Nikodym@Canada.Sun.COM. If you have questions, feel free to ask
them but be aware that Rod, "don't know jack about emacs."
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.