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Copyright 1989 AT&T
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dladdr, dladdr1 - translate address to symbolic information

#include <dlfcn.h>

int dladdr(void *address, Dl_info_t *dlip);

int dladdr1(void *address, Dl_info_t *dlip, void **info, int flags);

The dladdr() and dladdr1() functions determine if the specified address is located within one of the mapped objects that make up the current applications address space. An address is deemed to fall within a mapped object when it is between the base address, and the _end address of that object. See NOTES. If a mapped object fits this criteria, the symbol table made available to the runtime linker is searched to locate the nearest symbol to the specified address. The nearest symbol is one that has a value less than or equal to the required address.

The Dl_info_t structure must be preallocated by the user. The structure members are filled in by dladdr(), based on the specified address. The Dl_info_t structure includes the following members:

 const char *dli_fname;
 void *dli_fbase;
 const char *dli_sname;
 void *dli_saddr;

The Dl_info_t members provide the following information. dli_fname

dli_fbase dli_sname dli_saddr

The dladdr1() function provides for addition information to be returned as specified by the flags argument: RTLD_DL_SYMENT

RTLD_DL_LINKMAP If the specified address cannot be matched to a mapped object, a 0 is returned. Otherwise, a non-zero return is made and the associated Dl_info_t elements are filled. The dladdr() and dladdr1() functions are one of a family of functions that give the user direct access to the dynamic linking facilities. These facilities are available to dynamically-linked processes only. See Linker and Libraries Guide. See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE ATTRIBUTE VALUE

MT-Level MT-Safe

ld (1), dlclose (3C), dldump (3C), dlerror (3C), dlopen (3C), dlsym (3C), attributes (7)

Linker and Libraries Guide

The Dl_info_t pointer elements point to addresses within the mapped objects. These pointers can become invalid if objects are removed prior to these elements use. See dlclose(3C).

If no symbol is found to describe the specified address, both the dli_sname and dli_saddr members are set to 0.

If the address specified exists within a mapped object in the range between the base address and the address of the first global symbol in the object, the reserved local symbol _START_ is returned. This symbol acts as a label representing the start of the mapped object. As a label, this symbol has no size. The dli_saddr member is set to the base address of the associated object. The dli_sname member is set to the symbol name _START_. If the flag argument is set to RTLD_DL_SYMENT, symbol information for _START_ is returned.

If an object is acting as a filter, care should be taken when interpreting the address of any symbol obtained using a handle to this object. For example, using dlsym(3C) to obtain the symbol _end for this object, results in returning the address of the symbol _end within the filtee, not the filter. For more information on filters see the Linker and Libraries Guide.