3 ** Automatic prototype discovery:
4 *** Use debuginfo if available
5 Alternatively, use debuginfo to generate configure file.
6 *** Demangled identifiers contain partial prototypes themselves
7 ** Automatically update list of syscalls?
8 ** Update /etc/ltrace.conf
9 In particular, we could use a config directory, where packages
10 would install their ltrace config scripts. The config file could
11 be named after SONAME, and automatically read when corresponding
13 ** More operating systems (solaris?)
14 ** Get rid of EVENT_ARCH_SYSCALL and EVENT_ARCH_SYSRET
15 ** Implement displaced tracing
16 A technique used in GDB (and in uprobes, I believe), whereby the
17 instruction under breakpoint is moved somewhere else, and followed
18 by a jump back to original place. When the breakpoint hits, the IP
19 is moved to the displaced instruction, and the process is
20 continued. We avoid all the fuss with singlestepping and
22 ** Create different ltrace processes to trace different children
25 This would be useful for replacing the arg1, emt2 etc.
27 *** parameter pack improvements
28 The above format tweaks require that packs that expand to no types
29 at all be supported. If this works, then it should be relatively
30 painless to implement conditionals:
32 | void ptrace(REQ=enum(PTRACE_TRACEME=0,...),
33 | if[REQ==0](pack(),pack(pid_t, void*, void *)))
35 This is of course dangerously close to a programming language, and
36 I think ltrace should be careful to stay as simple as possible.
37 (We can hook into Lua, or TinyScheme, or some such if we want more
38 general scripting capabilities. Implementing something ad-hoc is
39 undesirable.) But the above can be nicely expressed by pattern
42 | void ptrace(REQ=enum[int](...)):
44 | [REQ==1 or REQ==2] => (pid_t, void*)
45 | [true] => (pid_t, void*, void*);
49 | int open(string, FLAGS=flags[int](O_RDONLY=00,...,O_CREAT=0100,...)):
50 | [(FLAGS & 0100) != 0] => (flags[int](S_IRWXU,...))
52 This would still require pretty complete expression evaluation.
53 _Including_ pointer dereferences and such. And e.g. in accept, we
56 | int accept(int, +struct(short, +array(hex(char), X-2))*, (X=uint)*);
58 Perhaps we should hook to something after all.
61 Some calls result in setting errno. Somehow mark those, and on
64 *** second conversions?
65 This definitely calls for some general scripting. The goal is to
66 have seconds in adjtimex calls show as e.g. 10s, 1m15s or some
69 *** format should take arguments like string does
70 Format should take value argument describing the value that should
71 be analyzed. The following overwriting rules would then apply:
73 | format | format(array(char, zero)*) |
74 | format(LENS) | X=LENS, format[X] |
76 The latter expanded form would be canonical.
78 This depends on named arguments and parameter pack improvements
79 (we need to be able to construct parameter packs that expand to
82 *** More fine-tuned control of right arguments
83 Combination of named arguments and some extensions could take care
86 | void func(X=hide(int*), long*, +pack(X)); |
88 This would show long* as input argument (i.e. the function could
89 mangle it), and later show the pre-fetched X. The "pack" syntax is
90 utterly undeveloped as of now. The general idea is to produce
91 arguments that expand to some mix of types and values. But maybe
92 all we need is something like
94 | void func(out int*, long*); |
96 ltrace would know that out/inout/in arguments are given in the
97 right order, but left pass should display in and inout arguments
98 only, and right pass then out and inout. + would be
99 backward-compatible syntactic sugar, expanded like so:
101 | void func(int*, int*, +long*, long*); |
102 | void func(in int*, in int*, out long*, out long*); |
104 But sometimes we may want to see a different type on the way in and
105 on the way out. E.g. in asprintf, what's interesting on the way in
106 is the address, but on the way out we want to see buffer contents.
107 Does something like the following make sense?
109 | void func(X=void*, long*, out string(X)); |
111 ** Support for functions that never return
112 This would be useful for __cxa_throw, presumably also for longjmp
113 (do we handle that at all?) and perhaps a handful of others.
115 ** Support flag fields
116 enum-like syntax, except disjunction of several values is assumed.
118 We currently can't define time_t on 32bit machines. That mean we
119 can't describe a range of time-related functions.
121 ** Support signed char, unsigned char, char
122 Also, don't format it as characted by default, string lens can do
123 it. Perhaps introduce byte and ubyte and leave 'char' as alias of
124 one of those with string lens applied by default.
126 ** Support fixed-width types
127 Really we should keep everything as {u,}int{8,16,32,64} internally,
128 and have long, short and others be translated to one of those
129 according to architecture rules. Maybe this could be achieved by a
130 per-arch config file with typedefs such as:
132 | typedef ulong = uint8_t |
134 ** Some more functions in vect might be made to take const*
135 Or even marked __attribute__((pure)).
138 ** After a clone(), syscalls may be seen as sysrets in s390 (see trace.c:syscall_p())