dladdr(3C)

NAME
     dladdr - Translates address to symbolic information

SYNOPSIS
     cc [flags ...] [file ...]

     #include <dlfcn.h>
     int dladdr(void *address, Dl_info *dlip);

DESCRIPTION
     dladdr() determines if the specified address is located within one of
     the mapped objects (either the executable or a DSO) that make up the
     current application address space.  If the address is within an
     object, the symbol table available to the run-time linker (rld(1)) 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 structure must be preallocated by the user.  The structure
     members are filled in by dladdr() based on the specified address.  The
     Dl_info structure contains at least the following members:

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

     The members are defined as follows:

     dli_fname      Contains a pointer to the file name of the containing
                    object.

     dli_fbase      Contains the base address (in memory) of the containing
                    object.

     dli_sname      Contains a pointer to the nearest symbol name.  This
                    symbol either has the same address or is the nearest
                    symbol with a lower address.

     dli_saddr      Contains the actual address of the above symbol.

     The following nonstandard field is in Dl_info:

     dli_version    This is filled in with zero by dladdr().

NOTES
     If no symbol is found to describe the specified address, but the
     address is within a mapped-in object, the dli_sname and dli_saddr
     members are set to 0 by dladdr().

     The memory pointed to by dli_fname and dli_sname is within the mapped
     object. If the object is closed with dlclose(), the pointers become
     invalid.

     If the call is attempted on a system that does not have the supporting
     functionality, the following message will be emitted to /dev/tty by
     default, and the application will be terminated with a non-zero exit
     code:

          Fatal Error: _rld_new_interface: bad operation: 14

     Applications that might be executed on IRIX releases with very old rld
     should first attempt the call in a separate small process.  All IRIX
     6.5 releases and later, and all IRIX 6.2 releases and later with the
     applicable rld patch, have the interface and will not receive the
     error.  Define the environment variable _RLD_ARGS as the following to
     direct the rld message to disk, if its appearance on /dev/tty might be
     an annoyance:

          -log /tmp/rldmessage

     <dlfcn.h> does not contain a prototype for dladdr or definition of
     Dl_info.  The #include <dlfcn.h>  in the SYNOPSIS line is traditional,
     but contains no dladdr prototype and no IRIX library contains an
     implementation.  Write your own declaration based on the code below.

     The following code is dependent on internal interfaces that are not
     part of the IRIX compatibility guarantee; however, there is no future
     intention to change this interface, so on a practical level, the code
     below is safe to use on IRIX.

          #include <rld_interface.h>
          #ifndef _RLD_INTERFACE_DLFCN_H_DLADDR
          #define _RLD_INTERFACE_DLFCN_H_DLADDR
          typedef struct Dl_info {
              const char * dli_fname;
              void       * dli_fbase;
              const char * dli_sname;
              void       * dli_saddr;
              int          dli_version;
              int          dli_reserved1;
              long         dli_reserved[4];
          } Dl_info;
          #endif
          #define _RLD_DLADDR             14
          int dladdr(void *address, Dl_info *dl);

          int dladdr(void *address, Dl_info *dl)
          {
                  void *v;
                  v = _rld_new_interface(_RLD_DLADDR,address,dl);
                  return (int)v;
          }

DIAGNOSTICS
     The function returns zero if the address cannot be associated with a
     mapped-in object.  In such a case, the Dl_info fields are not touched.

     The function returns non-zero if it can be associated with a mapped-in
     object, and the Dl_info fields are updated.

SEE ALSO
     rld(1)
     dlopen(3C), dlclose(3C), dlsym(3C), sgidlopen_version(3C),
     sgidlopen_verison(3C)
     dso(5)