granicus.if.org Git - postgresql/blob - src/backend/port/dynloader/linux.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * linux.c
   4  *        Dynamic Loader for Postgres for Linux, generated from those for
   5  *        Ultrix.
   6  *
   7  *        You need to install the dld library on your Linux system!
   8  *
   9  * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
  10  * Portions Copyright (c) 1994, Regents of the University of California
  11  *
  12  *
  13  * IDENTIFICATION
  14  *        src/backend/port/dynloader/linux.c
  15  *
  16  *-------------------------------------------------------------------------
  17  */
  18
  19 #include "postgres.h"
  20
  21 #ifdef HAVE_DLD_H
  22 #include <dld.h>
  23 #endif
  24
  25 #include "dynloader.h"
  26 #include "miscadmin.h"
  27
  28
  29 #ifndef HAVE_DLOPEN
  30
  31 void *
  32 pg_dlopen(char *filename)
  33 {
  34 #ifndef HAVE_DLD_H
  35         elog(ERROR, "dynamic load not supported");
  36         return NULL;
  37 #else
  38         static int      dl_initialized = 0;
  39
  40         /*
  41          * initializes the dynamic loader with the executable's pathname. (only
  42          * needs to do this the first time pg_dlopen is called.)
  43          */
  44         if (!dl_initialized)
  45         {
  46                 if (dld_init(dld_find_executable(my_exec_path)))
  47                         return NULL;
  48
  49                 /*
  50                  * if there are undefined symbols, we want dl to search from the
  51                  * following libraries also.
  52                  */
  53                 dl_initialized = 1;
  54         }
  55
  56         /*
  57          * link the file, then check for undefined symbols!
  58          */
  59         if (dld_link(filename))
  60                 return NULL;
  61
  62         /*
  63          * If undefined symbols: try to link with the C and math libraries! This
  64          * could be smarter, if the dynamic linker was able to handle shared libs!
  65          */
  66         if (dld_undefined_sym_count > 0)
  67         {
  68                 if (dld_link("/usr/lib/libc.a"))
  69                 {
  70                         elog(WARNING, "could not link C library");
  71                         return NULL;
  72                 }
  73                 if (dld_undefined_sym_count > 0)
  74                 {
  75                         if (dld_link("/usr/lib/libm.a"))
  76                         {
  77                                 elog(WARNING, "could not link math library");
  78                                 return NULL;
  79                         }
  80                         if (dld_undefined_sym_count > 0)
  81                         {
  82                                 int                     count = dld_undefined_sym_count;
  83                                 char      **list = dld_list_undefined_sym();
  84
  85                                 /* list the undefined symbols, if any */
  86                                 do
  87                                 {
  88                                         elog(WARNING, "\"%s\" is undefined", *list);
  89                                         list++;
  90                                         count--;
  91                                 } while (count > 0);
  92
  93                                 dld_unlink_by_file(filename, 1);
  94                                 return NULL;
  95                         }
  96                 }
  97         }
  98
  99         return (void *) strdup(filename);
 100 #endif
 101 }
 102
 103 PGFunction
 104 pg_dlsym(void *handle, char *funcname)
 105 {
 106 #ifndef HAVE_DLD_H
 107         return NULL;
 108 #else
 109         return (PGFunction) dld_get_func((funcname));
 110 #endif
 111 }
 112
 113 void
 114 pg_dlclose(void *handle)
 115 {
 116 #ifndef HAVE_DLD_H
 117 #else
 118         dld_unlink_by_file(handle, 1);
 119         free(handle);
 120 #endif
 121 }
 122
 123 char *
 124 pg_dlerror(void)
 125 {
 126 #ifndef HAVE_DLD_H
 127         return "dynaloader unsupported";
 128 #else
 129         return dld_strerror(dld_errno);
 130 #endif
 131 }
 132
 133 #endif                                                  /* !HAVE_DLOPEN */