1 /*
   2  * Copyright (c) 2003, 2019, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include <jni.h>
  26 #include <unistd.h>
  27 #include <fcntl.h>
  28 #include <string.h>
  29 #include <stdlib.h>
  30 #include <stddef.h>
  31 #include <elf.h>
  32 #include <link.h>
  33 #include "libproc_impl.h"
  34 #include "proc_service.h"
  35 #include "salibelf.h"
  36 #include "cds.h"
  37 
  38 // This file has the libproc implementation to read core files.
  39 // For live processes, refer to ps_proc.c. Portions of this is adapted
  40 // /modelled after Solaris libproc.so (in particular Pcore.c)
  41 
  42 //----------------------------------------------------------------------
  43 // ps_prochandle cleanup helper functions
  44 
  45 // close all file descriptors
  46 static void close_files(struct ps_prochandle* ph) {
  47   lib_info* lib = NULL;
  48 
  49   // close core file descriptor
  50   if (ph->core->core_fd >= 0)
  51     close(ph->core->core_fd);
  52 
  53   // close exec file descriptor
  54   if (ph->core->exec_fd >= 0)
  55     close(ph->core->exec_fd);
  56 
  57   // close interp file descriptor
  58   if (ph->core->interp_fd >= 0)
  59     close(ph->core->interp_fd);
  60 
  61   // close class share archive file
  62   if (ph->core->classes_jsa_fd >= 0)
  63     close(ph->core->classes_jsa_fd);
  64 
  65   // close all library file descriptors
  66   lib = ph->libs;
  67   while (lib) {
  68     int fd = lib->fd;
  69     if (fd >= 0 && fd != ph->core->exec_fd) {
  70       close(fd);
  71     }
  72     lib = lib->next;
  73   }
  74 }
  75 
  76 // clean all map_info stuff
  77 static void destroy_map_info(struct ps_prochandle* ph) {
  78   map_info* map = ph->core->maps;
  79   while (map) {
  80     map_info* next = map->next;
  81     free(map);
  82     map = next;
  83   }
  84 
  85   if (ph->core->map_array) {
  86     free(ph->core->map_array);
  87   }
  88 
  89   // Part of the class sharing workaround
  90   map = ph->core->class_share_maps;
  91   while (map) {
  92     map_info* next = map->next;
  93     free(map);
  94     map = next;
  95   }
  96 }
  97 
  98 // ps_prochandle operations
  99 static void core_release(struct ps_prochandle* ph) {
 100   if (ph->core) {
 101     close_files(ph);
 102     destroy_map_info(ph);
 103     free(ph->core);
 104   }
 105 }
 106 
 107 static map_info* allocate_init_map(int fd, off_t offset, uintptr_t vaddr, size_t memsz) {
 108   map_info* map;
 109   if ( (map = (map_info*) calloc(1, sizeof(map_info))) == NULL) {
 110     print_debug("can't allocate memory for map_info\n");
 111     return NULL;
 112   }
 113 
 114   // initialize map
 115   map->fd     = fd;
 116   map->offset = offset;
 117   map->vaddr  = vaddr;
 118   map->memsz  = memsz;
 119   return map;
 120 }
 121 
 122 // add map info with given fd, offset, vaddr and memsz
 123 static map_info* add_map_info(struct ps_prochandle* ph, int fd, off_t offset,
 124                              uintptr_t vaddr, size_t memsz) {
 125   map_info* map;
 126   if ((map = allocate_init_map(fd, offset, vaddr, memsz)) == NULL) {
 127     return NULL;
 128   }
 129 
 130   // add this to map list
 131   map->next  = ph->core->maps;
 132   ph->core->maps   = map;
 133   ph->core->num_maps++;
 134 
 135   return map;
 136 }
 137 
 138 // Part of the class sharing workaround
 139 static map_info* add_class_share_map_info(struct ps_prochandle* ph, off_t offset,
 140                              uintptr_t vaddr, size_t memsz) {
 141   map_info* map;
 142   if ((map = allocate_init_map(ph->core->classes_jsa_fd,
 143                                offset, vaddr, memsz)) == NULL) {
 144     return NULL;
 145   }
 146 
 147   map->next = ph->core->class_share_maps;
 148   ph->core->class_share_maps = map;
 149   return map;
 150 }
 151 
 152 // Return the map_info for the given virtual address.  We keep a sorted
 153 // array of pointers in ph->map_array, so we can binary search.
 154 static map_info* core_lookup(struct ps_prochandle *ph, uintptr_t addr) {
 155   int mid, lo = 0, hi = ph->core->num_maps - 1;
 156   map_info *mp;
 157 
 158   while (hi - lo > 1) {
 159     mid = (lo + hi) / 2;
 160     if (addr >= ph->core->map_array[mid]->vaddr) {
 161       lo = mid;
 162     } else {
 163       hi = mid;
 164     }
 165   }
 166 
 167   if (addr < ph->core->map_array[hi]->vaddr) {
 168     mp = ph->core->map_array[lo];
 169   } else {
 170     mp = ph->core->map_array[hi];
 171   }
 172 
 173   if (addr >= mp->vaddr && addr < mp->vaddr + mp->memsz) {
 174     return (mp);
 175   }
 176 
 177 
 178   // Part of the class sharing workaround
 179   // Unfortunately, we have no way of detecting -Xshare state.
 180   // Check out the share maps atlast, if we don't find anywhere.
 181   // This is done this way so to avoid reading share pages
 182   // ahead of other normal maps. For eg. with -Xshare:off we don't
 183   // want to prefer class sharing data to data from core.
 184   mp = ph->core->class_share_maps;
 185   if (mp) {
 186     print_debug("can't locate map_info at 0x%lx, trying class share maps\n", addr);
 187   }
 188   while (mp) {
 189     if (addr >= mp->vaddr && addr < mp->vaddr + mp->memsz) {
 190       print_debug("located map_info at 0x%lx from class share maps\n", addr);
 191       return (mp);
 192     }
 193     mp = mp->next;
 194   }
 195 
 196   print_debug("can't locate map_info at 0x%lx\n", addr);
 197   return (NULL);
 198 }
 199 
 200 //---------------------------------------------------------------
 201 // Part of the class sharing workaround:
 202 //
 203 // With class sharing, pages are mapped from classes.jsa file.
 204 // The read-only class sharing pages are mapped as MAP_SHARED,
 205 // PROT_READ pages. These pages are not dumped into core dump.
 206 // With this workaround, these pages are read from classes.jsa.
 207 
 208 static bool read_jboolean(struct ps_prochandle* ph, uintptr_t addr, jboolean* pvalue) {
 209   jboolean i;
 210   if (ps_pdread(ph, (psaddr_t) addr, &i, sizeof(i)) == PS_OK) {
 211     *pvalue = i;
 212     return true;
 213   } else {
 214     return false;
 215   }
 216 }
 217 
 218 static bool read_pointer(struct ps_prochandle* ph, uintptr_t addr, uintptr_t* pvalue) {
 219   uintptr_t uip;
 220   if (ps_pdread(ph, (psaddr_t) addr, (char *)&uip, sizeof(uip)) == PS_OK) {
 221     *pvalue = uip;
 222     return true;
 223   } else {
 224     return false;
 225   }
 226 }
 227 
 228 // used to read strings from debuggee
 229 static bool read_string(struct ps_prochandle* ph, uintptr_t addr, char* buf, size_t size) {
 230   size_t i = 0;
 231   char  c = ' ';
 232 
 233   while (c != '\0') {
 234     if (ps_pdread(ph, (psaddr_t) addr, &c, sizeof(char)) != PS_OK) {
 235       return false;
 236     }
 237     if (i < size - 1) {
 238       buf[i] = c;
 239     } else {
 240       // smaller buffer
 241       return false;
 242     }
 243     i++; addr++;
 244   }
 245 
 246   buf[i] = '\0';
 247   return true;
 248 }
 249 
 250 #define USE_SHARED_SPACES_SYM "UseSharedSpaces"
 251 // mangled name of Arguments::SharedArchivePath
 252 #define SHARED_ARCHIVE_PATH_SYM "_ZN9Arguments17SharedArchivePathE"
 253 #define LIBJVM_NAME "/libjvm.so"
 254 
 255 static bool init_classsharing_workaround(struct ps_prochandle* ph) {
 256   lib_info* lib = ph->libs;
 257   while (lib != NULL) {
 258     // we are iterating over shared objects from the core dump. look for
 259     // libjvm.so.
 260     const char *jvm_name = 0;
 261     if ((jvm_name = strstr(lib->name, LIBJVM_NAME)) != 0) {
 262       char classes_jsa[PATH_MAX];
 263       CDSFileMapHeaderBase header;
 264       int fd = -1;
 265       int m = 0;
 266       size_t n = 0;
 267       uintptr_t base = 0, useSharedSpacesAddr = 0;
 268       uintptr_t sharedArchivePathAddrAddr = 0, sharedArchivePathAddr = 0;
 269       jboolean useSharedSpaces = 0;
 270       map_info* mi = 0;
 271 
 272       memset(classes_jsa, 0, sizeof(classes_jsa));
 273       jvm_name = lib->name;
 274       useSharedSpacesAddr = lookup_symbol(ph, jvm_name, USE_SHARED_SPACES_SYM);
 275       if (useSharedSpacesAddr == 0) {
 276         print_debug("can't lookup 'UseSharedSpaces' flag\n");
 277         return false;
 278       }
 279 
 280       // Hotspot vm types are not exported to build this library. So
 281       // using equivalent type jboolean to read the value of
 282       // UseSharedSpaces which is same as hotspot type "bool".
 283       if (read_jboolean(ph, useSharedSpacesAddr, &useSharedSpaces) != true) {
 284         print_debug("can't read the value of 'UseSharedSpaces' flag\n");
 285         return false;
 286       }
 287 
 288       if ((int)useSharedSpaces == 0) {
 289         print_debug("UseSharedSpaces is false, assuming -Xshare:off!\n");
 290         return true;
 291       }
 292 
 293       sharedArchivePathAddrAddr = lookup_symbol(ph, jvm_name, SHARED_ARCHIVE_PATH_SYM);
 294       if (sharedArchivePathAddrAddr == 0) {
 295         print_debug("can't lookup shared archive path symbol\n");
 296         return false;
 297       }
 298 
 299       if (read_pointer(ph, sharedArchivePathAddrAddr, &sharedArchivePathAddr) != true) {
 300         print_debug("can't read shared archive path pointer\n");
 301         return false;
 302       }
 303 
 304       if (read_string(ph, sharedArchivePathAddr, classes_jsa, sizeof(classes_jsa)) != true) {
 305         print_debug("can't read shared archive path value\n");
 306         return false;
 307       }
 308 
 309       print_debug("looking for %s\n", classes_jsa);
 310       // open the class sharing archive file
 311       fd = pathmap_open(classes_jsa);
 312       if (fd < 0) {
 313         print_debug("can't open %s!\n", classes_jsa);
 314         ph->core->classes_jsa_fd = -1;
 315         return false;
 316       } else {
 317         print_debug("opened %s\n", classes_jsa);
 318       }
 319 
 320       // read CDSFileMapHeaderBase from the file
 321       memset(&header, 0, sizeof(CDSFileMapHeaderBase));
 322       if ((n = read(fd, &header, sizeof(CDSFileMapHeaderBase)))
 323            != sizeof(CDSFileMapHeaderBase)) {
 324         print_debug("can't read shared archive file map header from %s\n", classes_jsa);
 325         close(fd);
 326         return false;
 327       }
 328 
 329       // check file magic
 330       if (header._magic != CDS_ARCHIVE_MAGIC) {
 331         print_debug("%s has bad shared archive file magic number 0x%x, expecting 0x%x\n",
 332                     classes_jsa, header._magic, CDS_ARCHIVE_MAGIC);
 333         close(fd);
 334         return false;
 335       }
 336 
 337       // check version
 338       if (header._version != CURRENT_CDS_ARCHIVE_VERSION) {
 339         print_debug("%s has wrong shared archive file version %d, expecting %d\n",
 340                      classes_jsa, header._version, CURRENT_CDS_ARCHIVE_VERSION);
 341         close(fd);
 342         return false;
 343       }
 344 
 345       ph->core->classes_jsa_fd = fd;
 346       // add read-only maps from classes.jsa to the list of maps
 347       for (m = 0; m < NUM_CDS_REGIONS; m++) {
 348         if (header._space[m]._read_only) {
 349           base = (uintptr_t) header._space[m]._addr._base;
 350           // no need to worry about the fractional pages at-the-end.
 351           // possible fractional pages are handled by core_read_data.
 352           add_class_share_map_info(ph, (off_t) header._space[m]._file_offset,
 353                                    base, (size_t) header._space[m]._used);
 354           print_debug("added a share archive map at 0x%lx\n", base);
 355         }
 356       }
 357       return true;
 358    }
 359    lib = lib->next;
 360   }
 361   return true;
 362 }
 363 
 364 
 365 //---------------------------------------------------------------------------
 366 // functions to handle map_info
 367 
 368 // Order mappings based on virtual address.  We use this function as the
 369 // callback for sorting the array of map_info pointers.
 370 static int core_cmp_mapping(const void *lhsp, const void *rhsp)
 371 {
 372   const map_info *lhs = *((const map_info **)lhsp);
 373   const map_info *rhs = *((const map_info **)rhsp);
 374 
 375   if (lhs->vaddr == rhs->vaddr) {
 376     return (0);
 377   }
 378 
 379   return (lhs->vaddr < rhs->vaddr ? -1 : 1);
 380 }
 381 
 382 // we sort map_info by starting virtual address so that we can do
 383 // binary search to read from an address.
 384 static bool sort_map_array(struct ps_prochandle* ph) {
 385   size_t num_maps = ph->core->num_maps;
 386   map_info* map = ph->core->maps;
 387   int i = 0;
 388 
 389   // allocate map_array
 390   map_info** array;
 391   if ( (array = (map_info**) malloc(sizeof(map_info*) * num_maps)) == NULL) {
 392     print_debug("can't allocate memory for map array\n");
 393     return false;
 394   }
 395 
 396   // add maps to array
 397   while (map) {
 398     array[i] = map;
 399     i++;
 400     map = map->next;
 401   }
 402 
 403   // sort is called twice. If this is second time, clear map array
 404   if (ph->core->map_array) {
 405     free(ph->core->map_array);
 406   }
 407 
 408   ph->core->map_array = array;
 409   // sort the map_info array by base virtual address.
 410   qsort(ph->core->map_array, ph->core->num_maps, sizeof (map_info*),
 411         core_cmp_mapping);
 412 
 413   // print map
 414   if (is_debug()) {
 415     int j = 0;
 416     print_debug("---- sorted virtual address map ----\n");
 417     for (j = 0; j < ph->core->num_maps; j++) {
 418       print_debug("base = 0x%lx\tsize = %zu\n", ph->core->map_array[j]->vaddr,
 419                   ph->core->map_array[j]->memsz);
 420     }
 421   }
 422 
 423   return true;
 424 }
 425 
 426 #ifndef MIN
 427 #define MIN(x, y) (((x) < (y))? (x): (y))
 428 #endif
 429 
 430 static bool core_read_data(struct ps_prochandle* ph, uintptr_t addr, char *buf, size_t size) {
 431    ssize_t resid = size;
 432    int page_size=sysconf(_SC_PAGE_SIZE);
 433    while (resid != 0) {
 434       map_info *mp = core_lookup(ph, addr);
 435       uintptr_t mapoff;
 436       ssize_t len, rem;
 437       off_t off;
 438       int fd;
 439 
 440       if (mp == NULL) {
 441          break;  /* No mapping for this address */
 442       }
 443 
 444       fd = mp->fd;
 445       mapoff = addr - mp->vaddr;
 446       len = MIN(resid, mp->memsz - mapoff);
 447       off = mp->offset + mapoff;
 448 
 449       if ((len = pread(fd, buf, len, off)) <= 0) {
 450          break;
 451       }
 452 
 453       resid -= len;
 454       addr += len;
 455       buf = (char *)buf + len;
 456 
 457       // mappings always start at page boundary. But, may end in fractional
 458       // page. fill zeros for possible fractional page at the end of a mapping.
 459       rem = mp->memsz % page_size;
 460       if (rem > 0) {
 461          rem = page_size - rem;
 462          len = MIN(resid, rem);
 463          resid -= len;
 464          addr += len;
 465          // we are not assuming 'buf' to be zero initialized.
 466          memset(buf, 0, len);
 467          buf += len;
 468       }
 469    }
 470 
 471    if (resid) {
 472       print_debug("core read failed for %d byte(s) @ 0x%lx (%d more bytes)\n",
 473               size, addr, resid);
 474       return false;
 475    } else {
 476       return true;
 477    }
 478 }
 479 
 480 // null implementation for write
 481 static bool core_write_data(struct ps_prochandle* ph,
 482                              uintptr_t addr, const char *buf , size_t size) {
 483    return false;
 484 }
 485 
 486 static bool core_get_lwp_regs(struct ps_prochandle* ph, lwpid_t lwp_id,
 487                           struct user_regs_struct* regs) {
 488    // for core we have cached the lwp regs from NOTE section
 489    thread_info* thr = ph->threads;
 490    while (thr) {
 491      if (thr->lwp_id == lwp_id) {
 492        memcpy(regs, &thr->regs, sizeof(struct user_regs_struct));
 493        return true;
 494      }
 495      thr = thr->next;
 496    }
 497    return false;
 498 }
 499 
 500 static ps_prochandle_ops core_ops = {
 501    .release=  core_release,
 502    .p_pread=  core_read_data,
 503    .p_pwrite= core_write_data,
 504    .get_lwp_regs= core_get_lwp_regs
 505 };
 506 
 507 // read regs and create thread from NT_PRSTATUS entries from core file
 508 static bool core_handle_prstatus(struct ps_prochandle* ph, const char* buf, size_t nbytes) {
 509    // we have to read prstatus_t from buf
 510    // assert(nbytes == sizeof(prstaus_t), "size mismatch on prstatus_t");
 511    prstatus_t* prstat = (prstatus_t*) buf;
 512    thread_info* newthr;
 513    print_debug("got integer regset for lwp %d\n", prstat->pr_pid);
 514    if((newthr = add_thread_info(ph, prstat->pr_pid)) == NULL)
 515       return false;
 516 
 517    // copy regs
 518    memcpy(&newthr->regs, prstat->pr_reg, sizeof(struct user_regs_struct));
 519 
 520    if (is_debug()) {
 521       print_debug("integer regset\n");
 522 #ifdef i386
 523       // print the regset
 524       print_debug("\teax = 0x%x\n", newthr->regs.eax);
 525       print_debug("\tebx = 0x%x\n", newthr->regs.ebx);
 526       print_debug("\tecx = 0x%x\n", newthr->regs.ecx);
 527       print_debug("\tedx = 0x%x\n", newthr->regs.edx);
 528       print_debug("\tesp = 0x%x\n", newthr->regs.esp);
 529       print_debug("\tebp = 0x%x\n", newthr->regs.ebp);
 530       print_debug("\tesi = 0x%x\n", newthr->regs.esi);
 531       print_debug("\tedi = 0x%x\n", newthr->regs.edi);
 532       print_debug("\teip = 0x%x\n", newthr->regs.eip);
 533 #endif
 534 
 535 #if defined(amd64) || defined(x86_64)
 536       // print the regset
 537       print_debug("\tr15 = 0x%lx\n", newthr->regs.r15);
 538       print_debug("\tr14 = 0x%lx\n", newthr->regs.r14);
 539       print_debug("\tr13 = 0x%lx\n", newthr->regs.r13);
 540       print_debug("\tr12 = 0x%lx\n", newthr->regs.r12);
 541       print_debug("\trbp = 0x%lx\n", newthr->regs.rbp);
 542       print_debug("\trbx = 0x%lx\n", newthr->regs.rbx);
 543       print_debug("\tr11 = 0x%lx\n", newthr->regs.r11);
 544       print_debug("\tr10 = 0x%lx\n", newthr->regs.r10);
 545       print_debug("\tr9 = 0x%lx\n", newthr->regs.r9);
 546       print_debug("\tr8 = 0x%lx\n", newthr->regs.r8);
 547       print_debug("\trax = 0x%lx\n", newthr->regs.rax);
 548       print_debug("\trcx = 0x%lx\n", newthr->regs.rcx);
 549       print_debug("\trdx = 0x%lx\n", newthr->regs.rdx);
 550       print_debug("\trsi = 0x%lx\n", newthr->regs.rsi);
 551       print_debug("\trdi = 0x%lx\n", newthr->regs.rdi);
 552       print_debug("\torig_rax = 0x%lx\n", newthr->regs.orig_rax);
 553       print_debug("\trip = 0x%lx\n", newthr->regs.rip);
 554       print_debug("\tcs = 0x%lx\n", newthr->regs.cs);
 555       print_debug("\teflags = 0x%lx\n", newthr->regs.eflags);
 556       print_debug("\trsp = 0x%lx\n", newthr->regs.rsp);
 557       print_debug("\tss = 0x%lx\n", newthr->regs.ss);
 558       print_debug("\tfs_base = 0x%lx\n", newthr->regs.fs_base);
 559       print_debug("\tgs_base = 0x%lx\n", newthr->regs.gs_base);
 560       print_debug("\tds = 0x%lx\n", newthr->regs.ds);
 561       print_debug("\tes = 0x%lx\n", newthr->regs.es);
 562       print_debug("\tfs = 0x%lx\n", newthr->regs.fs);
 563       print_debug("\tgs = 0x%lx\n", newthr->regs.gs);
 564 #endif
 565    }
 566 
 567    return true;
 568 }
 569 
 570 #define ROUNDUP(x, y)  ((((x)+((y)-1))/(y))*(y))
 571 
 572 // read NT_PRSTATUS entries from core NOTE segment
 573 static bool core_handle_note(struct ps_prochandle* ph, ELF_PHDR* note_phdr) {
 574    char* buf = NULL;
 575    char* p = NULL;
 576    size_t size = note_phdr->p_filesz;
 577 
 578    // we are interested in just prstatus entries. we will ignore the rest.
 579    // Advance the seek pointer to the start of the PT_NOTE data
 580    if (lseek(ph->core->core_fd, note_phdr->p_offset, SEEK_SET) == (off_t)-1) {
 581       print_debug("failed to lseek to PT_NOTE data\n");
 582       return false;
 583    }
 584 
 585    // Now process the PT_NOTE structures.  Each one is preceded by
 586    // an Elf{32/64}_Nhdr structure describing its type and size.
 587    if ( (buf = (char*) malloc(size)) == NULL) {
 588       print_debug("can't allocate memory for reading core notes\n");
 589       goto err;
 590    }
 591 
 592    // read notes into buffer
 593    if (read(ph->core->core_fd, buf, size) != size) {
 594       print_debug("failed to read notes, core file must have been truncated\n");
 595       goto err;
 596    }
 597 
 598    p = buf;
 599    while (p < buf + size) {
 600       ELF_NHDR* notep = (ELF_NHDR*) p;
 601       char* descdata  = p + sizeof(ELF_NHDR) + ROUNDUP(notep->n_namesz, 4);
 602       print_debug("Note header with n_type = %d and n_descsz = %u\n",
 603                                    notep->n_type, notep->n_descsz);
 604 
 605       if (notep->n_type == NT_PRSTATUS) {
 606         if (core_handle_prstatus(ph, descdata, notep->n_descsz) != true) {
 607           return false;
 608         }
 609       } else if (notep->n_type == NT_AUXV) {
 610         // Get first segment from entry point
 611         ELF_AUXV *auxv = (ELF_AUXV *)descdata;
 612         while (auxv->a_type != AT_NULL) {
 613           if (auxv->a_type == AT_ENTRY) {
 614             // Set entry point address to address of dynamic section.
 615             // We will adjust it in read_exec_segments().
 616             ph->core->dynamic_addr = auxv->a_un.a_val;
 617             break;
 618           }
 619           auxv++;
 620         }
 621       }
 622       p = descdata + ROUNDUP(notep->n_descsz, 4);
 623    }
 624 
 625    free(buf);
 626    return true;
 627 
 628 err:
 629    if (buf) free(buf);
 630    return false;
 631 }
 632 
 633 // read all segments from core file
 634 static bool read_core_segments(struct ps_prochandle* ph, ELF_EHDR* core_ehdr) {
 635    int i = 0;
 636    ELF_PHDR* phbuf = NULL;
 637    ELF_PHDR* core_php = NULL;
 638 
 639    if ((phbuf =  read_program_header_table(ph->core->core_fd, core_ehdr)) == NULL)
 640       return false;
 641 
 642    /*
 643     * Now iterate through the program headers in the core file.
 644     * We're interested in two types of Phdrs: PT_NOTE (which
 645     * contains a set of saved /proc structures), and PT_LOAD (which
 646     * represents a memory mapping from the process's address space).
 647     *
 648     * Difference b/w Solaris PT_NOTE and Linux/BSD PT_NOTE:
 649     *
 650     *     In Solaris there are two PT_NOTE segments the first PT_NOTE (if present)
 651     *     contains /proc structs in the pre-2.6 unstructured /proc format. the last
 652     *     PT_NOTE has data in new /proc format.
 653     *
 654     *     In Solaris, there is only one pstatus (process status). pstatus contains
 655     *     integer register set among other stuff. For each LWP, we have one lwpstatus
 656     *     entry that has integer regset for that LWP.
 657     *
 658     *     Linux threads are actually 'clone'd processes. To support core analysis
 659     *     of "multithreaded" process, Linux creates more than one pstatus (called
 660     *     "prstatus") entry in PT_NOTE. Each prstatus entry has integer regset for one
 661     *     "thread". Please refer to Linux kernel src file 'fs/binfmt_elf.c', in particular
 662     *     function "elf_core_dump".
 663     */
 664 
 665     for (core_php = phbuf, i = 0; i < core_ehdr->e_phnum; i++) {
 666       switch (core_php->p_type) {
 667          case PT_NOTE:
 668             if (core_handle_note(ph, core_php) != true) {
 669               goto err;
 670             }
 671             break;
 672 
 673          case PT_LOAD: {
 674             if (core_php->p_filesz != 0) {
 675                if (add_map_info(ph, ph->core->core_fd, core_php->p_offset,
 676                   core_php->p_vaddr, core_php->p_filesz) == NULL) goto err;
 677             }
 678             break;
 679          }
 680       }
 681 
 682       core_php++;
 683    }
 684 
 685    free(phbuf);
 686    return true;
 687 err:
 688    free(phbuf);
 689    return false;
 690 }
 691 
 692 // read segments of a shared object
 693 static bool read_lib_segments(struct ps_prochandle* ph, int lib_fd, ELF_EHDR* lib_ehdr, uintptr_t lib_base) {
 694   int i = 0;
 695   ELF_PHDR* phbuf;
 696   ELF_PHDR* lib_php = NULL;
 697 
 698 #ifndef LIBC
 699 #error "LIBC not set"
 700 #endif
 701 
 702   int page_size = sysconf(_SC_PAGE_SIZE);
 703 
 704   if ((phbuf = read_program_header_table(lib_fd, lib_ehdr)) == NULL) {
 705     return false;
 706   }
 707 
 708   // we want to process only PT_LOAD segments that are not writable.
 709   // i.e., text segments. The read/write/exec (data) segments would
 710   // have been already added from core file segments.
 711   for (lib_php = phbuf, i = 0; i < lib_ehdr->e_phnum; i++) {
 712     if ((lib_php->p_type == PT_LOAD) && !(lib_php->p_flags & PF_W) && (lib_php->p_filesz != 0)) {
 713 
 714       uintptr_t target_vaddr = lib_php->p_vaddr + lib_base;
 715       map_info *existing_map = core_lookup(ph, target_vaddr);
 716 
 717       if (existing_map == NULL){
 718         if (add_map_info(ph, lib_fd, lib_php->p_offset,
 719                           target_vaddr, lib_php->p_memsz) == NULL) {
 720           goto err;
 721         }
 722       } else {
 723         // Coredump stores value of p_memsz elf field
 724         // rounded up to page boundary.
 725         if ((strcmp(LIBC, "musl")) &&
 726             (existing_map->memsz != page_size) &&
 727             (existing_map->fd != lib_fd) &&
 728             (ROUNDUP(existing_map->memsz, page_size) != ROUNDUP(lib_php->p_memsz, page_size))) {
 729 
 730           print_debug("address conflict @ 0x%lx (existing map size = %ld, size = %ld, flags = %d)\n",
 731                         target_vaddr, existing_map->memsz, lib_php->p_memsz, lib_php->p_flags);
 732           goto err;
 733         }
 734 
 735         /* replace PT_LOAD segment with library segment */
 736         print_debug("overwrote with new address mapping (memsz %ld -> %ld)\n",
 737                      existing_map->memsz, ROUNDUP(lib_php->p_memsz, page_size));
 738 
 739         existing_map->fd = lib_fd;
 740         existing_map->offset = lib_php->p_offset;
 741         existing_map->memsz = ROUNDUP(lib_php->p_memsz, page_size);
 742       }
 743     }
 744 
 745     lib_php++;
 746   }
 747 
 748   free(phbuf);
 749   return true;
 750 err:
 751   free(phbuf);
 752   return false;
 753 }
 754 
 755 // process segments from interpreter (ld.so or ld-linux.so)
 756 static bool read_interp_segments(struct ps_prochandle* ph) {
 757   ELF_EHDR interp_ehdr;
 758 
 759   if (read_elf_header(ph->core->interp_fd, &interp_ehdr) != true) {
 760     print_debug("interpreter is not a valid ELF file\n");
 761     return false;
 762   }
 763 
 764   if (read_lib_segments(ph, ph->core->interp_fd, &interp_ehdr, ph->core->ld_base_addr) != true) {
 765     print_debug("can't read segments of interpreter\n");
 766     return false;
 767   }
 768 
 769   return true;
 770 }
 771 
 772 // process segments of a a.out
 773 static bool read_exec_segments(struct ps_prochandle* ph, ELF_EHDR* exec_ehdr) {
 774   int i = 0;
 775   ELF_PHDR* phbuf = NULL;
 776   ELF_PHDR* exec_php = NULL;
 777 
 778   if ((phbuf = read_program_header_table(ph->core->exec_fd, exec_ehdr)) == NULL) {
 779     return false;
 780   }
 781 
 782   for (exec_php = phbuf, i = 0; i < exec_ehdr->e_phnum; i++) {
 783     switch (exec_php->p_type) {
 784 
 785       // add mappings for PT_LOAD segments
 786     case PT_LOAD: {
 787       // add only non-writable segments of non-zero filesz
 788       if (!(exec_php->p_flags & PF_W) && exec_php->p_filesz != 0) {
 789         if (add_map_info(ph, ph->core->exec_fd, exec_php->p_offset, exec_php->p_vaddr, exec_php->p_filesz) == NULL) goto err;
 790       }
 791       break;
 792     }
 793 
 794     // read the interpreter and it's segments
 795     case PT_INTERP: {
 796       char interp_name[BUF_SIZE + 1];
 797 
 798       // BUF_SIZE is PATH_MAX + NAME_MAX + 1.
 799       if (exec_php->p_filesz > BUF_SIZE) {
 800         goto err;
 801       }
 802       if (pread(ph->core->exec_fd, interp_name,
 803                 exec_php->p_filesz, exec_php->p_offset) != exec_php->p_filesz) {
 804         print_debug("Unable to read in the ELF interpreter\n");
 805         goto err;
 806       }
 807       interp_name[exec_php->p_filesz] = '\0';
 808       print_debug("ELF interpreter %s\n", interp_name);
 809       // read interpreter segments as well
 810       if ((ph->core->interp_fd = pathmap_open(interp_name)) < 0) {
 811         print_debug("can't open runtime loader\n");
 812         goto err;
 813       }
 814       break;
 815     }
 816 
 817     // from PT_DYNAMIC we want to read address of first link_map addr
 818     case PT_DYNAMIC: {
 819       if (exec_ehdr->e_type == ET_EXEC) {
 820         ph->core->dynamic_addr = exec_php->p_vaddr;
 821       } else { // ET_DYN
 822         // dynamic_addr has entry point of executable.
 823         // Thus we should substract it.
 824         ph->core->dynamic_addr += exec_php->p_vaddr - exec_ehdr->e_entry;
 825       }
 826       print_debug("address of _DYNAMIC is 0x%lx\n", ph->core->dynamic_addr);
 827       break;
 828     }
 829 
 830     } // switch
 831     exec_php++;
 832   } // for
 833 
 834   free(phbuf);
 835   return true;
 836  err:
 837   free(phbuf);
 838   return false;
 839 }
 840 
 841 
 842 #define FIRST_LINK_MAP_OFFSET offsetof(struct r_debug,  r_map)
 843 #define LD_BASE_OFFSET        offsetof(struct r_debug,  r_ldbase)
 844 #define LINK_MAP_ADDR_OFFSET  offsetof(struct link_map, l_addr)
 845 #define LINK_MAP_NAME_OFFSET  offsetof(struct link_map, l_name)
 846 #define LINK_MAP_NEXT_OFFSET  offsetof(struct link_map, l_next)
 847 
 848 // read shared library info from runtime linker's data structures.
 849 // This work is done by librtlb_db in Solaris
 850 static bool read_shared_lib_info(struct ps_prochandle* ph) {
 851   uintptr_t addr = ph->core->dynamic_addr;
 852   uintptr_t debug_base;
 853   uintptr_t first_link_map_addr;
 854   uintptr_t ld_base_addr;
 855   uintptr_t link_map_addr;
 856   uintptr_t lib_base_diff;
 857   uintptr_t lib_base;
 858   uintptr_t lib_name_addr;
 859   char lib_name[BUF_SIZE];
 860   ELF_DYN dyn;
 861   ELF_EHDR elf_ehdr;
 862   int lib_fd;
 863 
 864   // _DYNAMIC has information of the form
 865   //         [tag] [data] [tag] [data] .....
 866   // Both tag and data are pointer sized.
 867   // We look for dynamic info with DT_DEBUG. This has shared object info.
 868   // refer to struct r_debug in link.h
 869 
 870   dyn.d_tag = DT_NULL;
 871   while (dyn.d_tag != DT_DEBUG) {
 872     if (ps_pdread(ph, (psaddr_t) addr, &dyn, sizeof(ELF_DYN)) != PS_OK) {
 873       print_debug("can't read debug info from _DYNAMIC\n");
 874       return false;
 875     }
 876     addr += sizeof(ELF_DYN);
 877   }
 878 
 879   // we have got Dyn entry with DT_DEBUG
 880   debug_base = dyn.d_un.d_ptr;
 881   // at debug_base we have struct r_debug. This has first link map in r_map field
 882   if (ps_pdread(ph, (psaddr_t) debug_base + FIRST_LINK_MAP_OFFSET,
 883                  &first_link_map_addr, sizeof(uintptr_t)) != PS_OK) {
 884     print_debug("can't read first link map address\n");
 885     return false;
 886   }
 887 
 888   // read ld_base address from struct r_debug
 889   if (ps_pdread(ph, (psaddr_t) debug_base + LD_BASE_OFFSET, &ld_base_addr,
 890                  sizeof(uintptr_t)) != PS_OK) {
 891     print_debug("can't read ld base address\n");
 892     return false;
 893   }
 894   ph->core->ld_base_addr = ld_base_addr;
 895 
 896   print_debug("interpreter base address is 0x%lx\n", ld_base_addr);
 897 
 898   // now read segments from interp (i.e ld.so or ld-linux.so or ld-elf.so)
 899   if (read_interp_segments(ph) != true) {
 900       return false;
 901   }
 902 
 903   // after adding interpreter (ld.so) mappings sort again
 904   if (sort_map_array(ph) != true) {
 905     return false;
 906   }
 907 
 908    print_debug("first link map is at 0x%lx\n", first_link_map_addr);
 909 
 910    link_map_addr = first_link_map_addr;
 911    while (link_map_addr != 0) {
 912       // read library base address of the .so. Note that even though <sys/link.h> calls
 913       // link_map->l_addr as "base address",  this is * not * really base virtual
 914       // address of the shared object. This is actually the difference b/w the virtual
 915       // address mentioned in shared object and the actual virtual base where runtime
 916       // linker loaded it. We use "base diff" in read_lib_segments call below.
 917 
 918       if (ps_pdread(ph, (psaddr_t) link_map_addr + LINK_MAP_ADDR_OFFSET,
 919                    &lib_base_diff, sizeof(uintptr_t)) != PS_OK) {
 920          print_debug("can't read shared object base address diff\n");
 921          return false;
 922       }
 923 
 924       // read address of the name
 925       if (ps_pdread(ph, (psaddr_t) link_map_addr + LINK_MAP_NAME_OFFSET,
 926                     &lib_name_addr, sizeof(uintptr_t)) != PS_OK) {
 927          print_debug("can't read address of shared object name\n");
 928          return false;
 929       }
 930 
 931       // read name of the shared object
 932       lib_name[0] = '\0';
 933       if (lib_name_addr != 0 &&
 934           read_string(ph, (uintptr_t) lib_name_addr, lib_name, sizeof(lib_name)) != true) {
 935          print_debug("can't read shared object name\n");
 936          // don't let failure to read the name stop opening the file.  If something is really wrong
 937          // it will fail later.
 938       }
 939 
 940       if (lib_name[0] != '\0') {
 941          // ignore empty lib names
 942          lib_fd = pathmap_open(lib_name);
 943 
 944          if (lib_fd < 0) {
 945             print_debug("can't open shared object %s\n", lib_name);
 946             // continue with other libraries...
 947          } else {
 948             if (read_elf_header(lib_fd, &elf_ehdr)) {
 949                lib_base = lib_base_diff + find_base_address(lib_fd, &elf_ehdr);
 950                print_debug("reading library %s @ 0x%lx [ 0x%lx ]\n",
 951                            lib_name, lib_base, lib_base_diff);
 952                // while adding library mappings we need to use "base difference".
 953                if (! read_lib_segments(ph, lib_fd, &elf_ehdr, lib_base_diff)) {
 954                   print_debug("can't read shared object's segments\n");
 955                   close(lib_fd);
 956                   return false;
 957                }
 958                add_lib_info_fd(ph, lib_name, lib_fd, lib_base);
 959                // Map info is added for the library (lib_name) so
 960                // we need to re-sort it before calling the p_pdread.
 961                if (sort_map_array(ph) != true)
 962                   return false;
 963             } else {
 964                print_debug("can't read ELF header for shared object %s\n", lib_name);
 965                close(lib_fd);
 966                // continue with other libraries...
 967             }
 968          }
 969       }
 970 
 971     // read next link_map address
 972     if (ps_pdread(ph, (psaddr_t) link_map_addr + LINK_MAP_NEXT_OFFSET,
 973                    &link_map_addr, sizeof(uintptr_t)) != PS_OK) {
 974       print_debug("can't read next link in link_map\n");
 975       return false;
 976     }
 977   }
 978 
 979   return true;
 980 }
 981 
 982 // the one and only one exposed stuff from this file
 983 JNIEXPORT struct ps_prochandle* JNICALL
 984 Pgrab_core(const char* exec_file, const char* core_file) {
 985   ELF_EHDR core_ehdr;
 986   ELF_EHDR exec_ehdr;
 987   ELF_EHDR lib_ehdr;
 988 
 989   struct ps_prochandle* ph = (struct ps_prochandle*) calloc(1, sizeof(struct ps_prochandle));
 990   if (ph == NULL) {
 991     print_debug("can't allocate ps_prochandle\n");
 992     return NULL;
 993   }
 994 
 995   if ((ph->core = (struct core_data*) calloc(1, sizeof(struct core_data))) == NULL) {
 996     free(ph);
 997     print_debug("can't allocate ps_prochandle\n");
 998     return NULL;
 999   }
1000 
1001   // initialize ph
1002   ph->ops = &core_ops;
1003   ph->core->core_fd   = -1;
1004   ph->core->exec_fd   = -1;
1005   ph->core->interp_fd = -1;
1006 
1007   // open the core file
1008   if ((ph->core->core_fd = open(core_file, O_RDONLY)) < 0) {
1009     print_debug("can't open core file\n");
1010     goto err;
1011   }
1012 
1013   // read core file ELF header
1014   if (read_elf_header(ph->core->core_fd, &core_ehdr) != true || core_ehdr.e_type != ET_CORE) {
1015     print_debug("core file is not a valid ELF ET_CORE file\n");
1016     goto err;
1017   }
1018 
1019   if ((ph->core->exec_fd = open(exec_file, O_RDONLY)) < 0) {
1020     print_debug("can't open executable file\n");
1021     goto err;
1022   }
1023 
1024   if (read_elf_header(ph->core->exec_fd, &exec_ehdr) != true ||
1025       ((exec_ehdr.e_type != ET_EXEC) && (exec_ehdr.e_type != ET_DYN))) {
1026     print_debug("executable file is not a valid ELF file\n");
1027     goto err;
1028   }
1029 
1030   // process core file segments
1031   if (read_core_segments(ph, &core_ehdr) != true) {
1032     goto err;
1033   }
1034 
1035   // process exec file segments
1036   if (read_exec_segments(ph, &exec_ehdr) != true) {
1037     goto err;
1038   }
1039 
1040   // exec file is also treated like a shared object for symbol search
1041   if (add_lib_info_fd(ph, exec_file, ph->core->exec_fd,
1042                       (uintptr_t)0 + find_base_address(ph->core->exec_fd, &exec_ehdr)) == NULL) {
1043     goto err;
1044   }
1045 
1046   // allocate and sort maps into map_array, we need to do this
1047   // here because read_shared_lib_info needs to read from debuggee
1048   // address space
1049   if (sort_map_array(ph) != true) {
1050     goto err;
1051   }
1052 
1053   if (read_shared_lib_info(ph) != true) {
1054     goto err;
1055   }
1056 
1057   // sort again because we have added more mappings from shared objects
1058   if (sort_map_array(ph) != true) {
1059     goto err;
1060   }
1061 
1062   if (init_classsharing_workaround(ph) != true) {
1063     goto err;
1064   }
1065 
1066   return ph;
1067 
1068 err:
1069   Prelease(ph);
1070   return NULL;
1071 }