On Tue, Oct 09, 2012 at 11:20:48AM -0700, Ian Lance Taylor wrote:
> This patch to libbacktrace adds support for tracing through shared
> libraries. The libraries are found by calling dl_iterate_phdr, when it
> is available.
This functionality is definitely useful for meta-plugins like MELT
(since melt.so is dlopen-ing things)
>
> This patch has some preliminary support for tracing through libaries
> opened via dlopen, but there is no code for actually finding such
> libraries.
Perhaps you might use dladdr, on the few systems (notably GNU/Libc on Linux)
which have it?
>From man dlsym output:
int dladdr(void *addr, Dl_info *info);
The function dladdr() takes a function pointer and tries to resolve
name and file where it is located. Information is stored in the
Dl_info structure:
typedef struct {
const char *dli_fname; /* Pathname of shared object that
contains address */
void *dli_fbase; /* Address at which shared object
is loaded */
const char *dli_sname; /* Name of nearest symbol with address
lower than addr */
void *dli_saddr; /* Exact address of symbol named
in dli_sname */
} Dl_info;
If no symbol matching addr could be found, then dli_sname and dli_saddr
are set to NULL.
dladdr() returns 0 on error, and nonzero on success.
Or maybe I misunderstood libbacktrace and my comment is irrelevant. If it is
the case, sorry for the noise.
You could provide an extra API to register dlopen & dlclose to libbacktrace, if
that helps you
(of course, I would prefer avoiding that)
Cheers
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Basile STARYNKEVITCH http://starynkevitch.net/Basile/
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