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    The following form allows you to view linux man pages.

    Command:

    dl_iterate_phdr

    
    
    

    SYNOPSIS

           #define _GNU_SOURCE         /* See feature_test_macros(7) */
           #include <link.h>
    
           int dl_iterate_phdr(
                     int (*callback) (struct dl_phdr_info *info,
                                      size_t size, void *data,
                     void *data;
    
    
    

    DESCRIPTION

           The  dl_iterate_phdr() function allows an application to inquire at run
           time to find out which shared objects it has loaded.
    
           The dl_iterate_phdr() function walks through the list  of  an  applica-
           tion's  shared  objects  and  calls the function callback once for each
           object, until either all shared objects have been processed or callback
           returns a nonzero value.
    
           Each  call  to  callback  receives  three  arguments:  info, which is a
           pointer to a structure containing information about the shared  object;
           size,  which is the size of the structure pointed to by info; and data,
           which is a copy of whatever value was passed by the calling program  as
           the second argument (also named data) in the call to dl_iterate_phdr().
    
           The info argument is a structure of the following type:
    
               struct dl_phdr_info {
                   ElfW(Addr)        dlpi_addr;  /* Base address of object */
                   const char       *dlpi_name;  /* (Null-terminated) name of
                                                    object */
                   const ElfW(Phdr) *dlpi_phdr;  /* Pointer to array of
                                                    ELF program headers
                                                    for this object */
                   ElfW(Half)        dlpi_phnum; /* # of items in dlpi_phdr */
               };
    
           (The ElfW() macro definition turns its argument into the name of an ELF
           data  type  suitable  for the hardware architecture.  For example, on a
           32-bit platform, ElfW(Addr) yields the data type name Elf32_Addr.  Fur-
           ther  information  on  these  types  can  be  found  in the <elf.h> and
           <link.h> header files.)
    
           The dlpi_addr field indicates the base address  of  the  shared  object
           (i.e.,  the difference between the virtual memory address of the shared
           object and the offset of that object in the  file  from  which  it  was
           loaded).   The  dlpi_name  field is a null-terminated string giving the
           pathname from which the shared object was loaded.
    
           To understand the meaning of the dlpi_phdr and  dlpi_phnum  fields,  we
           need to be aware that an ELF shared object consists of a number of seg-
           ments, each of which has a corresponding program header describing  the
           segment.   The  dlpi_phdr field is a pointer to an array of the program
               } Elf32_Phdr;
    
           Note that we can calculate the location of a particular program header,
           x, in virtual memory using the formula:
    
             addr == info->dlpi_addr + info->dlpi_phdr[x].p_vaddr;
    
    
    

    RETURN VALUE

           The dl_iterate_phdr() function returns whatever value was  returned  by
           the last call to callback.
    
    
    

    VERSIONS

           dl_iterate_phdr() has been supported in glibc since version 2.2.4.
    
    
    

    CONFORMING TO

           The  dl_iterate_phdr() function is Linux-specific and should be avoided
           in portable applications.
    
    
    

    EXAMPLE

           The following program displays  a  list  of  pathnames  of  the  shared
           objects  it  has loaded.  For each shared object, the program lists the
           virtual addresses at which the object's ELF segments are loaded.
    
           #define _GNU_SOURCE
           #include <link.h>
           #include <stdlib.h>
           #include <stdio.h>
    
           static int
           callback(struct dl_phdr_info *info, size_t size, void *data)
           {
               int j;
    
               printf("name=%s (%d segments)\n", info->dlpi_name,
                   info->dlpi_phnum);
    
               for (j = 0; j < info->dlpi_phnum; j++)
                    printf("\t\t header %2d: address=%10p\n", j,
                        (void *) (info->dlpi_addr + info->dlpi_phdr[j].p_vaddr));
               return 0;
           }
    
           int
           main(int argc, char *argv[])
           {
               dl_iterate_phdr(callback, NULL);
    
               exit(EXIT_SUCCESS);
           }
    
    
    

    SEE ALSO

           ldd(1), objdump(1), readelf(1), dlopen(3), elf(5), ld.so(8)
    
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