#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <stddef.h>
#include <string.h>
#include <unistd.h>
#include <stdint.h>
#include <elf.h>
#include <sys/mman.h>
#include <limits.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <errno.h>
#include <link.h>
#include <setjmp.h>
#include <pthread.h>
#include <ctype.h>
#include <dlfcn.h>
#include "pthread_impl.h"
#include "libc.h"
#include "dynlink.h"

static void error(const char*, ...);

#define MAXP2(a, b) (-(-(a) & -(b)))
#define ALIGN(x, y) ((x) + (y)-1 & -(y))

struct debug {
  int ver;
  void* head;
  void (*bp)(void);
  int state;
  void* base;
};

struct td_index {
  size_t args[2];
  struct td_index* next;
};

struct dso {
#if DL_FDPIC
  struct fdpic_loadmap* loadmap;
#else
  unsigned char* base;
#endif
  char* name;
  size_t* dynv;
  struct dso *next, *prev;

  Phdr* phdr;
  int phnum;
  size_t phentsize;
  int refcnt;
  Sym* syms;
  uint32_t* hashtab;
  uint32_t* ghashtab;
  int16_t* versym;
  char* strings;
  unsigned char* map;
  size_t map_len;
  dev_t dev;
  ino_t ino;
  signed char global;
  char relocated;
  char constructed;
  char kernel_mapped;
  struct dso **deps, *needed_by;
  char *rpath_orig, *rpath;
  struct tls_module tls;
  size_t tls_id;
  size_t relro_start, relro_end;
  void** new_dtv;
  unsigned char* new_tls;
  volatile int new_dtv_idx, new_tls_idx;
  struct td_index* td_index;
  struct dso* fini_next;
  char* shortname;
#if DL_FDPIC
  unsigned char* base;
#else
  struct fdpic_loadmap* loadmap;
#endif
  struct funcdesc {
    void* addr;
    size_t* got;
  } * funcdescs;
  size_t* got;
  char buf[];
};

struct symdef {
  Sym* sym;
  struct dso* dso;
};

int __init_tp(void*);
void __init_libc(char**, char*);
void* __copy_tls(unsigned char*);

__attribute__((__visibility__("hidden"))) const char* __libc_get_version(void);

static struct builtin_tls {
  char c;
  struct pthread pt;
  void* space[16];
} builtin_tls[1];
#define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt)

#define ADDEND_LIMIT 4096
static size_t *saved_addends, *apply_addends_to;

static struct dso ldso;
static struct dso *head, *tail, *fini_head;
static char *env_path, *sys_path;
static unsigned long long gencnt;
static int runtime;
static int ldd_mode;
static int ldso_fail;
static int noload;
static jmp_buf* rtld_fail;
static pthread_rwlock_t lock;
static struct debug debug;
static struct tls_module* tls_tail;
static size_t tls_cnt, tls_offset, tls_align = MIN_TLS_ALIGN;
static size_t static_tls_cnt;
static pthread_mutex_t init_fini_lock = {._m_type = PTHREAD_MUTEX_RECURSIVE};
static struct fdpic_loadmap* app_loadmap;
static struct fdpic_dummy_loadmap app_dummy_loadmap;

struct debug* _dl_debug_addr = &debug;

__attribute__((__visibility__("hidden"))) void (*const __init_array_start)(
    void) = 0,
  (*const __fini_array_start)(void) = 0;

__attribute__((__visibility__("hidden"))) extern void (*const __init_array_end)(
    void),
    (*const __fini_array_end)(void);

weak_alias(__init_array_start, __init_array_end);
weak_alias(__fini_array_start, __fini_array_end);

static int dl_strcmp(const char* l, const char* r) {
  for (; *l == *r && *l; l++, r++)
    ;
  return *(unsigned char*)l - *(unsigned char*)r;
}
#define strcmp(l, r) dl_strcmp(l, r)

/* Compute load address for a virtual address in a given dso. */
#if DL_FDPIC
static void* laddr(const struct dso* p, size_t v) {
  size_t j = 0;
  if (!p->loadmap)
    return p->base + v;
  for (j = 0; v - p->loadmap->segs[j].p_vaddr >= p->loadmap->segs[j].p_memsz;
       j++)
    ;
  return (void*)(v - p->loadmap->segs[j].p_vaddr + p->loadmap->segs[j].addr);
}
#define fpaddr(p, v) ((void (*)()) & (struct funcdesc){laddr(p, v), (p)->got})
#else
#define laddr(p, v) (void*)((p)->base + (v))
#define fpaddr(p, v) ((void (*)())laddr(p, v))
#endif

static void decode_vec(size_t* v, size_t* a, size_t cnt) {
  size_t i;
  for (i = 0; i < cnt; i++)
    a[i] = 0;
  for (; v[0]; v += 2)
    if (v[0] - 1 < cnt - 1) {
      a[0] |= 1UL << v[0];
      a[v[0]] = v[1];
    }
}

static int search_vec(size_t* v, size_t* r, size_t key) {
  for (; v[0] != key; v += 2)
    if (!v[0])
      return 0;
  *r = v[1];
  return 1;
}

static uint32_t sysv_hash(const char* s0) {
  const unsigned char* s = (void*)s0;
  uint_fast32_t h = 0;
  while (*s) {
    h = 16 * h + *s++;
    h ^= h >> 24 & 0xf0;
  }
  return h & 0xfffffff;
}

static uint32_t gnu_hash(const char* s0) {
  const unsigned char* s = (void*)s0;
  uint_fast32_t h = 5381;
  for (; *s; s++)
    h += h * 32 + *s;
  return h;
}

static Sym* sysv_lookup(const char* s, uint32_t h, struct dso* dso) {
  size_t i;
  Sym* syms = dso->syms;
  uint32_t* hashtab = dso->hashtab;
  char* strings = dso->strings;
  for (i = hashtab[2 + h % hashtab[0]]; i; i = hashtab[2 + hashtab[0] + i]) {
    if ((!dso->versym || dso->versym[i] >= 0) &&
        (!strcmp(s, strings + syms[i].st_name)))
      return syms + i;
  }
  return 0;
}

static Sym* gnu_lookup(uint32_t h1,
                       uint32_t* hashtab,
                       struct dso* dso,
                       const char* s) {
  uint32_t nbuckets = hashtab[0];
  uint32_t* buckets = hashtab + 4 + hashtab[2] * (sizeof(size_t) / 4);
  uint32_t i = buckets[h1 % nbuckets];

  if (!i)
    return 0;

  uint32_t* hashval = buckets + nbuckets + (i - hashtab[1]);

  for (h1 |= 1;; i++) {
    uint32_t h2 = *hashval++;
    if ((h1 == (h2 | 1)) && (!dso->versym || dso->versym[i] >= 0) &&
        !strcmp(s, dso->strings + dso->syms[i].st_name))
      return dso->syms + i;
    if (h2 & 1)
      break;
  }

  return 0;
}

static Sym* gnu_lookup_filtered(uint32_t h1,
                                uint32_t* hashtab,
                                struct dso* dso,
                                const char* s,
                                uint32_t fofs,
                                size_t fmask) {
  const size_t* bloomwords = (const void*)(hashtab + 4);
  size_t f = bloomwords[fofs & (hashtab[2] - 1)];
  if (!(f & fmask))
    return 0;

  f >>= (h1 >> hashtab[3]) % (8 * sizeof f);
  if (!(f & 1))
    return 0;

  return gnu_lookup(h1, hashtab, dso, s);
}

#define OK_TYPES                                                         \
  (1 << STT_NOTYPE | 1 << STT_OBJECT | 1 << STT_FUNC | 1 << STT_COMMON | \
   1 << STT_TLS)
#define OK_BINDS (1 << STB_GLOBAL | 1 << STB_WEAK | 1 << STB_GNU_UNIQUE)

#ifndef ARCH_SYM_REJECT_UND
#define ARCH_SYM_REJECT_UND(s) 0
#endif

static struct symdef find_sym(struct dso* dso, const char* s, int need_def) {
  uint32_t h = 0, gh, gho, *ght;
  size_t ghm = 0;
  struct symdef def = {0};
  for (; dso; dso = dso->next) {
    Sym* sym;
    if (!dso->global)
      continue;
    if ((ght = dso->ghashtab)) {
      if (!ghm) {
        gh = gnu_hash(s);
        int maskbits = 8 * sizeof ghm;
        gho = gh / maskbits;
        ghm = 1ul << gh % maskbits;
      }
      sym = gnu_lookup_filtered(gh, ght, dso, s, gho, ghm);
    } else {
      if (!h)
        h = sysv_hash(s);
      sym = sysv_lookup(s, h, dso);
    }
    if (!sym)
      continue;
    if (!sym->st_shndx)
      if (need_def || (sym->st_info & 0xf) == STT_TLS ||
          ARCH_SYM_REJECT_UND(sym))
        continue;
    if (!sym->st_value)
      if ((sym->st_info & 0xf) != STT_TLS)
        continue;
    if (!(1 << (sym->st_info & 0xf) & OK_TYPES))
      continue;
    if (!(1 << (sym->st_info >> 4) & OK_BINDS))
      continue;

    if (def.sym && sym->st_info >> 4 == STB_WEAK)
      continue;
    def.sym = sym;
    def.dso = dso;
    if (sym->st_info >> 4 == STB_GLOBAL)
      break;
  }
  return def;
}

__attribute__((__visibility__("hidden"))) ptrdiff_t __tlsdesc_static(),
    __tlsdesc_dynamic();

static void do_relocs(struct dso* dso,
                      size_t* rel,
                      size_t rel_size,
                      size_t stride) {
  unsigned char* base = dso->base;
  Sym* syms = dso->syms;
  char* strings = dso->strings;
  Sym* sym;
  const char* name;
  void* ctx;
  int type;
  int sym_index;
  struct symdef def;
  size_t* reloc_addr;
  size_t sym_val;
  size_t tls_val;
  size_t addend;
  int skip_relative = 0, reuse_addends = 0, save_slot = 0;

  if (dso == &ldso) {
    /* Only ldso's REL table needs addend saving/reuse. */
    if (rel == apply_addends_to)
      reuse_addends = 1;
    skip_relative = 1;
  }

  for (; rel_size; rel += stride, rel_size -= stride * sizeof(size_t)) {
    if (skip_relative && IS_RELATIVE(rel[1], dso->syms))
      continue;
    type = R_TYPE(rel[1]);
    if (type == REL_NONE)
      continue;
    sym_index = R_SYM(rel[1]);
    reloc_addr = laddr(dso, rel[0]);
    if (sym_index) {
      sym = syms + sym_index;
      name = strings + sym->st_name;
      ctx = type == REL_COPY ? head->next : head;
      def = (sym->st_info & 0xf) == STT_SECTION
                ? (struct symdef){.dso = dso, .sym = sym}
                : find_sym(ctx, name, type == REL_PLT);
      if (!def.sym &&
          (sym->st_shndx != SHN_UNDEF || sym->st_info >> 4 != STB_WEAK)) {
        error("Error relocating %s: %s: symbol not found", dso->name, name);
        if (runtime)
          longjmp(*rtld_fail, 1);
        continue;
      }
    } else {
      sym = 0;
      def.sym = 0;
      def.dso = dso;
    }

    if (stride > 2) {
      addend = rel[2];
    } else if (type == REL_GOT || type == REL_PLT || type == REL_COPY) {
      addend = 0;
    } else if (reuse_addends) {
      /* Save original addend in stage 2 where the dso
       * chain consists of just ldso; otherwise read back
       * saved addend since the inline one was clobbered. */
      if (head == &ldso)
        saved_addends[save_slot] = *reloc_addr;
      addend = saved_addends[save_slot++];
    } else {
      addend = *reloc_addr;
    }

    sym_val = def.sym ? (size_t)laddr(def.dso, def.sym->st_value) : 0;
    tls_val = def.sym ? def.sym->st_value : 0;

    switch (type) {
      case REL_NONE:
        break;
      case REL_OFFSET:
        addend -= (size_t)reloc_addr;
      case REL_SYMBOLIC:
      case REL_GOT:
      case REL_PLT:
        *reloc_addr = sym_val + addend;
        break;
      case REL_RELATIVE:
        *reloc_addr = (size_t)base + addend;
        break;
      case REL_SYM_OR_REL:
        if (sym)
          *reloc_addr = sym_val + addend;
        else
          *reloc_addr = (size_t)base + addend;
        break;
      case REL_COPY:
        memcpy(reloc_addr, (void*)sym_val, sym->st_size);
        break;
      case REL_OFFSET32:
        *(uint32_t*)reloc_addr = sym_val + addend - (size_t)reloc_addr;
        break;
      case REL_FUNCDESC:
        *reloc_addr =
            def.sym ? (size_t)(def.dso->funcdescs + (def.sym - def.dso->syms))
                    : 0;
        break;
      case REL_FUNCDESC_VAL:
        if ((sym->st_info & 0xf) == STT_SECTION)
          *reloc_addr += sym_val;
        else
          *reloc_addr = sym_val;
        reloc_addr[1] = def.sym ? (size_t)def.dso->got : 0;
        break;
      case REL_DTPMOD:
        *reloc_addr = def.dso->tls_id;
        break;
      case REL_DTPOFF:
        *reloc_addr = tls_val + addend - DTP_OFFSET;
        break;
#ifdef TLS_ABOVE_TP
      case REL_TPOFF:
        *reloc_addr = tls_val + def.dso->tls.offset + TPOFF_K + addend;
        break;
#else
      case REL_TPOFF:
        *reloc_addr = tls_val - def.dso->tls.offset + addend;
        break;
      case REL_TPOFF_NEG:
        *reloc_addr = def.dso->tls.offset - tls_val + addend;
        break;
#endif
      case REL_TLSDESC:
        if (stride < 3)
          addend = reloc_addr[1];
        if (runtime && def.dso->tls_id >= static_tls_cnt) {
          struct td_index* new = malloc(sizeof *new);
          if (!new) {
            error("Error relocating %s: cannot allocate TLSDESC for %s",
                  dso->name, sym ? name : "(local)");
            longjmp(*rtld_fail, 1);
          }
          new->next = dso->td_index;
          dso->td_index = new;
          new->args[0] = def.dso->tls_id;
          new->args[1] = tls_val + addend;
          reloc_addr[0] = (size_t)__tlsdesc_dynamic;
          reloc_addr[1] = (size_t) new;
        } else {
          reloc_addr[0] = (size_t)__tlsdesc_static;
#ifdef TLS_ABOVE_TP
          reloc_addr[1] = tls_val + def.dso->tls.offset + TPOFF_K + addend;
#else
          reloc_addr[1] = tls_val - def.dso->tls.offset + addend;
#endif
        }
        break;
      default:
        error("Error relocating %s: unsupported relocation type %d", dso->name,
              type);
        if (runtime)
          longjmp(*rtld_fail, 1);
        continue;
    }
  }
}

/* A huge hack: to make up for the wastefulness of shared libraries
 * needing at least a page of dirty memory even if they have no global
 * data, we reclaim the gaps at the beginning and end of writable maps
 * and "donate" them to the heap by setting up minimal malloc
 * structures and then freeing them. */

static void reclaim(struct dso* dso, size_t start, size_t end) {
  size_t *a, *z;
  if (start >= dso->relro_start && start < dso->relro_end)
    start = dso->relro_end;
  if (end >= dso->relro_start && end < dso->relro_end)
    end = dso->relro_start;
  start = start + 6 * sizeof(size_t) - 1 & -4 * sizeof(size_t);
  end = (end & -4 * sizeof(size_t)) - 2 * sizeof(size_t);
  if (start > end || end - start < 4 * sizeof(size_t))
    return;
  a = laddr(dso, start);
  z = laddr(dso, end);
  a[-2] = 1;
  a[-1] = z[0] = end - start + 2 * sizeof(size_t) | 1;
  z[1] = 1;
  free(a);
}

static void reclaim_gaps(struct dso* dso) {
  Phdr* ph = dso->phdr;
  size_t phcnt = dso->phnum;

  if (DL_FDPIC)
    return;  // FIXME
  for (; phcnt--; ph = (void*)((char*)ph + dso->phentsize)) {
    if (ph->p_type != PT_LOAD)
      continue;
    if ((ph->p_flags & (PF_R | PF_W)) != (PF_R | PF_W))
      continue;
    reclaim(dso, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
    reclaim(dso, ph->p_vaddr + ph->p_memsz,
            ph->p_vaddr + ph->p_memsz + PAGE_SIZE - 1 & -PAGE_SIZE);
  }
}

static void* mmap_fixed(void* p,
                        size_t n,
                        int prot,
                        int flags,
                        int fd,
                        off_t off) {
  static int no_map_fixed;
  char* q;
  if (!no_map_fixed) {
    q = mmap(p, n, prot, flags | MAP_FIXED, fd, off);
    if (!DL_NOMMU_SUPPORT || q != MAP_FAILED || errno != EINVAL)
      return q;
    no_map_fixed = 1;
  }
  /* Fallbacks for MAP_FIXED failure on NOMMU kernels. */
  if (flags & MAP_ANONYMOUS) {
    memset(p, 0, n);
    return p;
  }
  ssize_t r;
  if (lseek(fd, off, SEEK_SET) < 0)
    return MAP_FAILED;
  for (q = p; n; q += r, off += r, n -= r) {
    r = read(fd, q, n);
    if (r < 0 && errno != EINTR)
      return MAP_FAILED;
    if (!r) {
      memset(q, 0, n);
      break;
    }
  }
  return p;
}

static void unmap_library(struct dso* dso) {
  if (dso->loadmap) {
    size_t i;
    for (i = 0; i < dso->loadmap->nsegs; i++) {
      if (!dso->loadmap->segs[i].p_memsz)
        continue;
      munmap((void*)dso->loadmap->segs[i].addr, dso->loadmap->segs[i].p_memsz);
    }
    free(dso->loadmap);
  } else if (dso->map && dso->map_len) {
    munmap(dso->map, dso->map_len);
  }
}

static void* map_library(int fd, struct dso* dso) {
  Ehdr buf[(896 + sizeof(Ehdr)) / sizeof(Ehdr)];
  void* allocated_buf = 0;
  size_t phsize;
  size_t addr_min = SIZE_MAX, addr_max = 0, map_len;
  size_t this_min, this_max;
  size_t nsegs = 0;
  off_t off_start;
  Ehdr* eh;
  Phdr *ph, *ph0;
  unsigned prot;
  unsigned char *map = MAP_FAILED, *base;
  size_t dyn = 0;
  size_t tls_image = 0;
  size_t i;

  ssize_t l = read(fd, buf, sizeof buf);
  eh = buf;
  if (l < 0)
    return 0;
  if (l < sizeof *eh || (eh->e_type != ET_DYN && eh->e_type != ET_EXEC))
    goto noexec;
  phsize = eh->e_phentsize * eh->e_phnum;
  if (phsize > sizeof buf - sizeof *eh) {
    allocated_buf = malloc(phsize);
    if (!allocated_buf)
      return 0;
    l = pread(fd, allocated_buf, phsize, eh->e_phoff);
    if (l < 0)
      goto error;
    if (l != phsize)
      goto noexec;
    ph = ph0 = allocated_buf;
  } else if (eh->e_phoff + phsize > l) {
    l = pread(fd, buf + 1, phsize, eh->e_phoff);
    if (l < 0)
      goto error;
    if (l != phsize)
      goto noexec;
    ph = ph0 = (void*)(buf + 1);
  } else {
    ph = ph0 = (void*)((char*)buf + eh->e_phoff);
  }
  for (i = eh->e_phnum; i; i--, ph = (void*)((char*)ph + eh->e_phentsize)) {
    if (ph->p_type == PT_DYNAMIC) {
      dyn = ph->p_vaddr;
    } else if (ph->p_type == PT_TLS) {
      tls_image = ph->p_vaddr;
      dso->tls.align = ph->p_align;
      dso->tls.len = ph->p_filesz;
      dso->tls.size = ph->p_memsz;
    } else if (ph->p_type == PT_GNU_RELRO) {
      dso->relro_start = ph->p_vaddr & -PAGE_SIZE;
      dso->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
    }
    if (ph->p_type != PT_LOAD)
      continue;
    nsegs++;
    if (ph->p_vaddr < addr_min) {
      addr_min = ph->p_vaddr;
      off_start = ph->p_offset;
      prot = (((ph->p_flags & PF_R) ? PROT_READ : 0) |
              ((ph->p_flags & PF_W) ? PROT_WRITE : 0) |
              ((ph->p_flags & PF_X) ? PROT_EXEC : 0));
    }
    if (ph->p_vaddr + ph->p_memsz > addr_max) {
      addr_max = ph->p_vaddr + ph->p_memsz;
    }
  }
  if (!dyn)
    goto noexec;
  if (DL_FDPIC && !(eh->e_flags & FDPIC_CONSTDISP_FLAG)) {
    dso->loadmap =
        calloc(1, sizeof *dso->loadmap + nsegs * sizeof *dso->loadmap->segs);
    if (!dso->loadmap)
      goto error;
    dso->loadmap->nsegs = nsegs;
    for (ph = ph0, i = 0; i < nsegs;
         ph = (void*)((char*)ph + eh->e_phentsize)) {
      if (ph->p_type != PT_LOAD)
        continue;
      prot = (((ph->p_flags & PF_R) ? PROT_READ : 0) |
              ((ph->p_flags & PF_W) ? PROT_WRITE : 0) |
              ((ph->p_flags & PF_X) ? PROT_EXEC : 0));
      map = mmap(0, ph->p_memsz + (ph->p_vaddr & PAGE_SIZE - 1), prot,
                 MAP_PRIVATE, fd, ph->p_offset & -PAGE_SIZE);
      if (map == MAP_FAILED) {
        unmap_library(dso);
        goto error;
      }
      dso->loadmap->segs[i].addr = (size_t)map + (ph->p_vaddr & PAGE_SIZE - 1);
      dso->loadmap->segs[i].p_vaddr = ph->p_vaddr;
      dso->loadmap->segs[i].p_memsz = ph->p_memsz;
      i++;
      if (prot & PROT_WRITE) {
        size_t brk = (ph->p_vaddr & PAGE_SIZE - 1) + ph->p_filesz;
        size_t pgbrk = brk + PAGE_SIZE - 1 & -PAGE_SIZE;
        size_t pgend =
            brk + ph->p_memsz - ph->p_filesz + PAGE_SIZE - 1 & -PAGE_SIZE;
        if (pgend > pgbrk &&
            mmap_fixed(map + pgbrk, pgend - pgbrk, prot,
                       MAP_PRIVATE | MAP_FIXED | MAP_ANONYMOUS, -1,
                       off_start) == MAP_FAILED)
          goto error;
        memset(map + brk, 0, pgbrk - brk);
      }
    }
    map = (void*)dso->loadmap->segs[0].addr;
    map_len = 0;
    goto done_mapping;
  }
  addr_max += PAGE_SIZE - 1;
  addr_max &= -PAGE_SIZE;
  addr_min &= -PAGE_SIZE;
  off_start &= -PAGE_SIZE;
  map_len = addr_max - addr_min + off_start;
  /* The first time, we map too much, possibly even more than
   * the length of the file. This is okay because we will not
   * use the invalid part; we just need to reserve the right
   * amount of virtual address space to map over later. */
  map = DL_NOMMU_SUPPORT
            ? mmap((void*)addr_min, map_len, PROT_READ | PROT_WRITE | PROT_EXEC,
                   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0)
            : mmap((void*)addr_min, map_len, prot, MAP_PRIVATE, fd, off_start);
  if (map == MAP_FAILED)
    goto error;
  dso->map = map;
  dso->map_len = map_len;
  /* If the loaded file is not relocatable and the requested address is
   * not available, then the load operation must fail. */
  if (eh->e_type != ET_DYN && addr_min && map != (void*)addr_min) {
    errno = EBUSY;
    goto error;
  }
  base = map - addr_min;
  dso->phdr = 0;
  dso->phnum = 0;
  for (ph = ph0, i = eh->e_phnum; i;
       i--, ph = (void*)((char*)ph + eh->e_phentsize)) {
    if (ph->p_type != PT_LOAD)
      continue;
    /* Check if the programs headers are in this load segment, and
     * if so, record the address for use by dl_iterate_phdr. */
    if (!dso->phdr && eh->e_phoff >= ph->p_offset &&
        eh->e_phoff + phsize <= ph->p_offset + ph->p_filesz) {
      dso->phdr = (void*)(base + ph->p_vaddr + (eh->e_phoff - ph->p_offset));
      dso->phnum = eh->e_phnum;
      dso->phentsize = eh->e_phentsize;
    }
    /* Reuse the existing mapping for the lowest-address LOAD */
    if ((ph->p_vaddr & -PAGE_SIZE) == addr_min && !DL_NOMMU_SUPPORT)
      continue;
    this_min = ph->p_vaddr & -PAGE_SIZE;
    this_max = ph->p_vaddr + ph->p_memsz + PAGE_SIZE - 1 & -PAGE_SIZE;
    off_start = ph->p_offset & -PAGE_SIZE;
    prot = (((ph->p_flags & PF_R) ? PROT_READ : 0) |
            ((ph->p_flags & PF_W) ? PROT_WRITE : 0) |
            ((ph->p_flags & PF_X) ? PROT_EXEC : 0));
    if (mmap_fixed(base + this_min, this_max - this_min, prot,
                   MAP_PRIVATE | MAP_FIXED, fd, off_start) == MAP_FAILED)
      goto error;
    if (ph->p_memsz > ph->p_filesz) {
      size_t brk = (size_t)base + ph->p_vaddr + ph->p_filesz;
      size_t pgbrk = brk + PAGE_SIZE - 1 & -PAGE_SIZE;
      memset((void*)brk, 0, pgbrk - brk & PAGE_SIZE - 1);
      if (pgbrk - (size_t)base < this_max &&
          mmap_fixed((void*)pgbrk, (size_t)base + this_max - pgbrk, prot,
                     MAP_PRIVATE | MAP_FIXED | MAP_ANONYMOUS, -1,
                     0) == MAP_FAILED)
        goto error;
    }
  }
  for (i = 0; ((size_t*)(base + dyn))[i]; i += 2)
    if (((size_t*)(base + dyn))[i] == DT_TEXTREL) {
      if (mprotect(map, map_len, PROT_READ | PROT_WRITE | PROT_EXEC) &&
          errno != ENOSYS)
        goto error;
      break;
    }
done_mapping:
  dso->base = base;
  dso->dynv = laddr(dso, dyn);
  if (dso->tls.size)
    dso->tls.image = laddr(dso, tls_image);
  if (!runtime)
    reclaim_gaps(dso);
  free(allocated_buf);
  return map;
noexec:
  errno = ENOEXEC;
error:
  if (map != MAP_FAILED)
    unmap_library(dso);
  free(allocated_buf);
  return 0;
}

static int path_open(const char* name,
                     const char* s,
                     char* buf,
                     size_t buf_size) {
  size_t l;
  int fd;
  for (;;) {
    s += strspn(s, ":\n");
    l = strcspn(s, ":\n");
    if (l - 1 >= INT_MAX)
      return -1;
    if (snprintf(buf, buf_size, "%.*s/%s", (int)l, s, name) < buf_size) {
      if ((fd = open(buf, O_RDONLY | O_CLOEXEC)) >= 0)
        return fd;
      switch (errno) {
        case ENOENT:
        case ENOTDIR:
        case EACCES:
        case ENAMETOOLONG:
          break;
        default:
          /* Any negative value but -1 will inhibit
           * futher path search. */
          return -2;
      }
    }
    s += l;
  }
}

static int fixup_rpath(struct dso* p, char* buf, size_t buf_size) {
  size_t n, l;
  const char *s, *t, *origin;
  char* d;
  if (p->rpath || !p->rpath_orig)
    return 0;
  if (!strchr(p->rpath_orig, '$')) {
    p->rpath = p->rpath_orig;
    return 0;
  }
  n = 0;
  s = p->rpath_orig;
  while ((t = strchr(s, '$'))) {
    if (strncmp(t, "$ORIGIN", 7) && strncmp(t, "${ORIGIN}", 9))
      return 0;
    s = t + 1;
    n++;
  }
  if (n > SSIZE_MAX / PATH_MAX)
    return 0;

  if (p->kernel_mapped) {
    /* $ORIGIN searches cannot be performed for the main program
     * when it is suid/sgid/AT_SECURE. This is because the
     * pathname is under the control of the caller of execve.
     * For libraries, however, $ORIGIN can be processed safely
     * since the library's pathname came from a trusted source
     * (either system paths or a call to dlopen). */
    if (libc.secure)
      return 0;
    l = readlink("/proc/self/exe", buf, buf_size);
    if (l == -1)
      switch (errno) {
        case ENOENT:
        case ENOTDIR:
        case EACCES:
          break;
        default:
          return -1;
      }
    if (l >= buf_size)
      return 0;
    buf[l] = 0;
    origin = buf;
  } else {
    origin = p->name;
  }
  t = strrchr(origin, '/');
  l = t ? t - origin : 0;
  p->rpath = malloc(strlen(p->rpath_orig) + n * l + 1);
  if (!p->rpath)
    return -1;

  d = p->rpath;
  s = p->rpath_orig;
  while ((t = strchr(s, '$'))) {
    memcpy(d, s, t - s);
    d += t - s;
    memcpy(d, origin, l);
    d += l;
    /* It was determined previously that the '$' is followed
     * either by "ORIGIN" or "{ORIGIN}". */
    s = t + 7 + 2 * (t[1] == '{');
  }
  strcpy(d, s);
  return 0;
}

static void decode_dyn(struct dso* p) {
  size_t dyn[DYN_CNT];
  decode_vec(p->dynv, dyn, DYN_CNT);
  p->syms = laddr(p, dyn[DT_SYMTAB]);
  p->strings = laddr(p, dyn[DT_STRTAB]);
  if (dyn[0] & (1 << DT_HASH))
    p->hashtab = laddr(p, dyn[DT_HASH]);
  if (dyn[0] & (1 << DT_RPATH))
    p->rpath_orig = p->strings + dyn[DT_RPATH];
  if (dyn[0] & (1 << DT_RUNPATH))
    p->rpath_orig = p->strings + dyn[DT_RUNPATH];
  if (dyn[0] & (1 << DT_PLTGOT))
    p->got = laddr(p, dyn[DT_PLTGOT]);
  if (search_vec(p->dynv, dyn, DT_GNU_HASH))
    p->ghashtab = laddr(p, *dyn);
  if (search_vec(p->dynv, dyn, DT_VERSYM))
    p->versym = laddr(p, *dyn);
}

static size_t count_syms(struct dso* p) {
  if (p->hashtab)
    return p->hashtab[1];

  size_t nsym, i;
  uint32_t* buckets = p->ghashtab + 4 + (p->ghashtab[2] * sizeof(size_t) / 4);
  uint32_t* hashval;
  for (i = nsym = 0; i < p->ghashtab[0]; i++) {
    if (buckets[i] > nsym)
      nsym = buckets[i];
  }
  if (nsym) {
    hashval = buckets + p->ghashtab[0] + (nsym - p->ghashtab[1]);
    do
      nsym++;
    while (!(*hashval++ & 1));
  }
  return nsym;
}

static void* dl_mmap(size_t n) {
  void* p;
  int prot = PROT_READ | PROT_WRITE, flags = MAP_ANONYMOUS | MAP_PRIVATE;
#ifdef SYS_mmap2
  p = (void*)__syscall(SYS_mmap2, 0, n, prot, flags, -1, 0);
#else
  p = (void*)__syscall(SYS_mmap, 0, n, prot, flags, -1, 0);
#endif
  return p == MAP_FAILED ? 0 : p;
}

static void makefuncdescs(struct dso* p) {
  static int self_done;
  size_t nsym = count_syms(p);
  size_t i, size = nsym * sizeof(*p->funcdescs);

  if (!self_done) {
    p->funcdescs = dl_mmap(size);
    self_done = 1;
  } else {
    p->funcdescs = malloc(size);
  }
  if (!p->funcdescs) {
    if (!runtime)
      a_crash();
    error("Error allocating function descriptors for %s", p->name);
    longjmp(*rtld_fail, 1);
  }
  for (i = 0; i < nsym; i++) {
    if ((p->syms[i].st_info & 0xf) == STT_FUNC && p->syms[i].st_shndx) {
      p->funcdescs[i].addr = laddr(p, p->syms[i].st_value);
      p->funcdescs[i].got = p->got;
    } else {
      p->funcdescs[i].addr = 0;
      p->funcdescs[i].got = 0;
    }
  }
}

static struct dso* load_library(const char* name, struct dso* needed_by) {
  char buf[2 * NAME_MAX + 2];
  const char* pathname;
  unsigned char* map;
  struct dso *p, temp_dso = {0};
  int fd;
  struct stat st;
  size_t alloc_size;
  int n_th = 0;
  int is_self = 0;

  if (!*name) {
    errno = EINVAL;
    return 0;
  }

  /* Catch and block attempts to reload the implementation itself */
  if (name[0] == 'l' && name[1] == 'i' && name[2] == 'b') {
    static const char *rp, reserved[] = "c\0pthread\0rt\0m\0dl\0util\0xnet\0";
    char* z = strchr(name, '.');
    if (z) {
      size_t l = z - name;
      for (rp = reserved; *rp && strncmp(name + 3, rp, l - 3);
           rp += strlen(rp) + 1)
        ;
      if (*rp) {
        if (ldd_mode) {
          /* Track which names have been resolved
           * and only report each one once. */
          static unsigned reported;
          unsigned mask = 1U << (rp - reserved);
          if (!(reported & mask)) {
            reported |= mask;
            dprintf(1, "\t%s => %s (%p)\n", name, ldso.name, ldso.base);
          }
        }
        is_self = 1;
      }
    }
  }
  if (!strcmp(name, ldso.name))
    is_self = 1;
  if (is_self) {
    if (!ldso.prev) {
      tail->next = &ldso;
      ldso.prev = tail;
      tail = ldso.next ? ldso.next : &ldso;
    }
    return &ldso;
  }
  if (strchr(name, '/')) {
    pathname = name;
    fd = open(name, O_RDONLY | O_CLOEXEC);
  } else {
    /* Search for the name to see if it's already loaded */
    for (p = head->next; p; p = p->next) {
      if (p->shortname && !strcmp(p->shortname, name)) {
        p->refcnt++;
        return p;
      }
    }
    if (strlen(name) > NAME_MAX)
      return 0;
    fd = -1;
    if (env_path)
      fd = path_open(name, env_path, buf, sizeof buf);
    for (p = needed_by; fd == -1 && p; p = p->needed_by) {
      if (fixup_rpath(p, buf, sizeof buf) < 0)
        fd = -2; /* Inhibit further search. */
      if (p->rpath)
        fd = path_open(name, p->rpath, buf, sizeof buf);
    }
    if (fd == -1) {
      if (!sys_path) {
        char* prefix = 0;
        size_t prefix_len;
        if (ldso.name[0] == '/') {
          char *s, *t, *z;
          for (s = t = z = ldso.name; *s; s++)
            if (*s == '/')
              z = t, t = s;
          prefix_len = z - ldso.name;
          if (prefix_len < PATH_MAX)
            prefix = ldso.name;
        }
        if (!prefix) {
          prefix = "";
          prefix_len = 0;
        }
        char etc_ldso_path[prefix_len + 1 + sizeof "/etc/ld-musl-" LDSO_ARCH
                                                   ".path"];
        snprintf(etc_ldso_path, sizeof etc_ldso_path,
                 "%.*s/etc/ld-musl-" LDSO_ARCH ".path", (int)prefix_len,
                 prefix);
        FILE* f = fopen(etc_ldso_path, "rbe");
        if (f) {
          if (getdelim(&sys_path, (size_t[1]){0}, 0, f) <= 0) {
            free(sys_path);
            sys_path = "";
          }
          fclose(f);
        } else if (errno != ENOENT) {
          sys_path = "";
        }
      }
      if (!sys_path)
        sys_path = "/lib:/usr/local/lib:/usr/lib";
      fd = path_open(name, sys_path, buf, sizeof buf);
    }
    pathname = buf;
  }
  if (fd < 0)
    return 0;
  if (fstat(fd, &st) < 0) {
    close(fd);
    return 0;
  }
  for (p = head->next; p; p = p->next) {
    if (p->dev == st.st_dev && p->ino == st.st_ino) {
      /* If this library was previously loaded with a
       * pathname but a search found the same inode,
       * setup its shortname so it can be found by name. */
      if (!p->shortname && pathname != name)
        p->shortname = strrchr(p->name, '/') + 1;
      close(fd);
      p->refcnt++;
      return p;
    }
  }
  map = noload ? 0 : map_library(fd, &temp_dso);
  close(fd);
  if (!map)
    return 0;

  /* Allocate storage for the new DSO. When there is TLS, this
   * storage must include a reservation for all pre-existing
   * threads to obtain copies of both the new TLS, and an
   * extended DTV capable of storing an additional slot for
   * the newly-loaded DSO. */
  alloc_size = sizeof *p + strlen(pathname) + 1;
  if (runtime && temp_dso.tls.image) {
    size_t per_th =
        temp_dso.tls.size + temp_dso.tls.align + sizeof(void*) * (tls_cnt + 3);
    n_th = libc.threads_minus_1 + 1;
    if (n_th > SSIZE_MAX / per_th)
      alloc_size = SIZE_MAX;
    else
      alloc_size += n_th * per_th;
  }
  p = calloc(1, alloc_size);
  if (!p) {
    unmap_library(&temp_dso);
    return 0;
  }
  memcpy(p, &temp_dso, sizeof temp_dso);
  decode_dyn(p);
  p->dev = st.st_dev;
  p->ino = st.st_ino;
  p->refcnt = 1;
  p->needed_by = needed_by;
  p->name = p->buf;
  strcpy(p->name, pathname);
  /* Add a shortname only if name arg was not an explicit pathname. */
  if (pathname != name)
    p->shortname = strrchr(p->name, '/') + 1;
  if (p->tls.image) {
    p->tls_id = ++tls_cnt;
    tls_align = MAXP2(tls_align, p->tls.align);
#ifdef TLS_ABOVE_TP
    p->tls.offset = tls_offset +
                    ((tls_align - 1) & -(tls_offset + (uintptr_t)p->tls.image));
    tls_offset += p->tls.size;
#else
    tls_offset += p->tls.size + p->tls.align - 1;
    tls_offset -= (tls_offset + (uintptr_t)p->tls.image) & (p->tls.align - 1);
    p->tls.offset = tls_offset;
#endif
    p->new_dtv =
        (void*)(-sizeof(size_t) &
                (uintptr_t)(p->name + strlen(p->name) + sizeof(size_t)));
    p->new_tls = (void*)(p->new_dtv + n_th * (tls_cnt + 1));
    if (tls_tail)
      tls_tail->next = &p->tls;
    else
      libc.tls_head = &p->tls;
    tls_tail = &p->tls;
  }

  tail->next = p;
  p->prev = tail;
  tail = p;

  if (DL_FDPIC)
    makefuncdescs(p);

  if (ldd_mode)
    dprintf(1, "\t%s => %s (%p)\n", name, pathname, p->base);

  return p;
}

static void load_deps(struct dso* p) {
  size_t i, ndeps = 0;
  struct dso ***deps = &p->deps, **tmp, *dep;
  for (; p; p = p->next) {
    for (i = 0; p->dynv[i]; i += 2) {
      if (p->dynv[i] != DT_NEEDED)
        continue;
      dep = load_library(p->strings + p->dynv[i + 1], p);
      if (!dep) {
        error("Error loading shared library %s: %m (needed by %s)",
              p->strings + p->dynv[i + 1], p->name);
        if (runtime)
          longjmp(*rtld_fail, 1);
        continue;
      }
      if (runtime) {
        tmp = realloc(*deps, sizeof(*tmp) * (ndeps + 2));
        if (!tmp)
          longjmp(*rtld_fail, 1);
        tmp[ndeps++] = dep;
        tmp[ndeps] = 0;
        *deps = tmp;
      }
    }
  }
}

static void load_preload(char* s) {
  int tmp;
  char* z;
  for (z = s; *z; s = z) {
    for (; *s && (isspace(*s) || *s == ':'); s++)
      ;
    for (z = s; *z && !isspace(*z) && *z != ':'; z++)
      ;
    tmp = *z;
    *z = 0;
    load_library(s, 0);
    *z = tmp;
  }
}

static void make_global(struct dso* p) {
  for (; p; p = p->next)
    p->global = 1;
}

static void do_mips_relocs(struct dso* p, size_t* got) {
  size_t i, j, rel[2];
  unsigned char* base = p->base;
  i = 0;
  search_vec(p->dynv, &i, DT_MIPS_LOCAL_GOTNO);
  if (p == &ldso) {
    got += i;
  } else {
    while (i--)
      *got++ += (size_t)base;
  }
  j = 0;
  search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
  i = 0;
  search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
  Sym* sym = p->syms + j;
  rel[0] = (unsigned char*)got - base;
  for (i -= j; i; i--, sym++, rel[0] += sizeof(size_t)) {
    rel[1] = (sym - p->syms) << 8 | R_MIPS_JUMP_SLOT;
    do_relocs(p, rel, sizeof rel, 2);
  }
}

static void reloc_all(struct dso* p) {
  size_t dyn[DYN_CNT];
  for (; p; p = p->next) {
    if (p->relocated)
      continue;
    decode_vec(p->dynv, dyn, DYN_CNT);
    if (NEED_MIPS_GOT_RELOCS)
      do_mips_relocs(p, laddr(p, dyn[DT_PLTGOT]));
    do_relocs(p, laddr(p, dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
              2 + (dyn[DT_PLTREL] == DT_RELA));
    do_relocs(p, laddr(p, dyn[DT_REL]), dyn[DT_RELSZ], 2);
    do_relocs(p, laddr(p, dyn[DT_RELA]), dyn[DT_RELASZ], 3);

    if (head != &ldso && p->relro_start != p->relro_end &&
        mprotect(laddr(p, p->relro_start), p->relro_end - p->relro_start,
                 PROT_READ) &&
        errno != ENOSYS) {
      error("Error relocating %s: RELRO protection failed: %m", p->name);
      if (runtime)
        longjmp(*rtld_fail, 1);
    }

    p->relocated = 1;
  }
}

static void kernel_mapped_dso(struct dso* p) {
  size_t min_addr = -1, max_addr = 0, cnt;
  Phdr* ph = p->phdr;
  for (cnt = p->phnum; cnt--; ph = (void*)((char*)ph + p->phentsize)) {
    if (ph->p_type == PT_DYNAMIC) {
      p->dynv = laddr(p, ph->p_vaddr);
    } else if (ph->p_type == PT_GNU_RELRO) {
      p->relro_start = ph->p_vaddr & -PAGE_SIZE;
      p->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
    }
    if (ph->p_type != PT_LOAD)
      continue;
    if (ph->p_vaddr < min_addr)
      min_addr = ph->p_vaddr;
    if (ph->p_vaddr + ph->p_memsz > max_addr)
      max_addr = ph->p_vaddr + ph->p_memsz;
  }
  min_addr &= -PAGE_SIZE;
  max_addr = (max_addr + PAGE_SIZE - 1) & -PAGE_SIZE;
  p->map = p->base + min_addr;
  p->map_len = max_addr - min_addr;
  p->kernel_mapped = 1;
}

void __libc_exit_fini() {
  struct dso* p;
  size_t dyn[DYN_CNT];
  for (p = fini_head; p; p = p->fini_next) {
    if (!p->constructed)
      continue;
    decode_vec(p->dynv, dyn, DYN_CNT);
    if (dyn[0] & (1 << DT_FINI_ARRAY)) {
      size_t n = dyn[DT_FINI_ARRAYSZ] / sizeof(size_t);
      size_t* fn = (size_t*)laddr(p, dyn[DT_FINI_ARRAY]) + n;
      while (n--)
        ((void (*)(void)) * --fn)();
    }
#ifndef NO_LEGACY_INITFINI
    if ((dyn[0] & (1 << DT_FINI)) && dyn[DT_FINI])
      fpaddr(p, dyn[DT_FINI])();
#endif
  }
}

static void do_init_fini(struct dso* p) {
  size_t dyn[DYN_CNT];
  int need_locking = libc.threads_minus_1;
  /* Allow recursive calls that arise when a library calls
   * dlopen from one of its constructors, but block any
   * other threads until all ctors have finished. */
  if (need_locking)
    pthread_mutex_lock(&init_fini_lock);
  for (; p; p = p->prev) {
    if (p->constructed)
      continue;
    p->constructed = 1;
    decode_vec(p->dynv, dyn, DYN_CNT);
    if (dyn[0] & ((1 << DT_FINI) | (1 << DT_FINI_ARRAY))) {
      p->fini_next = fini_head;
      fini_head = p;
    }
#ifndef NO_LEGACY_INITFINI
    if ((dyn[0] & (1 << DT_INIT)) && dyn[DT_INIT])
      fpaddr(p, dyn[DT_INIT])();
#endif
    if (dyn[0] & (1 << DT_INIT_ARRAY)) {
      size_t n = dyn[DT_INIT_ARRAYSZ] / sizeof(size_t);
      size_t* fn = laddr(p, dyn[DT_INIT_ARRAY]);
      while (n--)
        ((void (*)(void)) * fn++)();
    }
    if (!need_locking && libc.threads_minus_1) {
      need_locking = 1;
      pthread_mutex_lock(&init_fini_lock);
    }
  }
  if (need_locking)
    pthread_mutex_unlock(&init_fini_lock);
}

void __libc_start_init(void) {
  do_init_fini(tail);
}

static void dl_debug_state(void) {}

weak_alias(dl_debug_state, _dl_debug_state);

void __init_tls(size_t* auxv) {}

__attribute__((__visibility__("hidden"))) void* __tls_get_new(size_t* v) {
  pthread_t self = __pthread_self();

  /* Block signals to make accessing new TLS async-signal-safe */
  sigset_t set;
  __block_all_sigs(&set);
  if (v[0] <= (size_t)self->dtv[0]) {
    __restore_sigs(&set);
    return (char*)self->dtv[v[0]] + v[1] + DTP_OFFSET;
  }

  /* This is safe without any locks held because, if the caller
   * is able to request the Nth entry of the DTV, the DSO list
   * must be valid at least that far out and it was synchronized
   * at program startup or by an already-completed call to dlopen. */
  struct dso* p;
  for (p = head; p->tls_id != v[0]; p = p->next)
    ;

  /* Get new DTV space from new DSO if needed */
  if (v[0] > (size_t)self->dtv[0]) {
    void** newdtv = p->new_dtv + (v[0] + 1) * a_fetch_add(&p->new_dtv_idx, 1);
    memcpy(newdtv, self->dtv, ((size_t)self->dtv[0] + 1) * sizeof(void*));
    newdtv[0] = (void*)v[0];
    self->dtv = self->dtv_copy = newdtv;
  }

  /* Get new TLS memory from all new DSOs up to the requested one */
  unsigned char* mem;
  for (p = head;; p = p->next) {
    if (!p->tls_id || self->dtv[p->tls_id])
      continue;
    mem = p->new_tls +
          (p->tls.size + p->tls.align) * a_fetch_add(&p->new_tls_idx, 1);
    mem += ((uintptr_t)p->tls.image - (uintptr_t)mem) & (p->tls.align - 1);
    self->dtv[p->tls_id] = mem;
    memcpy(mem, p->tls.image, p->tls.len);
    if (p->tls_id == v[0])
      break;
  }
  __restore_sigs(&set);
  return mem + v[1] + DTP_OFFSET;
}

static void update_tls_size() {
  libc.tls_cnt = tls_cnt;
  libc.tls_align = tls_align;
  libc.tls_size = ALIGN((1 + tls_cnt) * sizeof(void*) + tls_offset +
                            sizeof(struct pthread) + tls_align * 2,
                        tls_align);
}

/* Stage 1 of the dynamic linker is defined in dlstart.c. It calls the
 * following stage 2 and stage 3 functions via primitive symbolic lookup
 * since it does not have access to their addresses to begin with. */

/* Stage 2 of the dynamic linker is called after relative relocations
 * have been processed. It can make function calls to static functions
 * and access string literals and static data, but cannot use extern
 * symbols. Its job is to perform symbolic relocations on the dynamic
 * linker itself, but some of the relocations performed may need to be
 * replaced later due to copy relocations in the main program. */

__attribute__((__visibility__("hidden"))) void __dls2(unsigned char* base,
                                                      size_t* sp) {
  if (DL_FDPIC) {
    void* p1 = (void*)sp[-2];
    void* p2 = (void*)sp[-1];
    if (!p1) {
      size_t *auxv, aux[AUX_CNT];
      for (auxv = sp + 1 + *sp + 1; *auxv; auxv++)
        ;  // Pass
      auxv++;
      decode_vec(auxv, aux, AUX_CNT);
      if (aux[AT_BASE])
        ldso.base = (void*)aux[AT_BASE];
      else
        ldso.base = (void*)(aux[AT_PHDR] & -4096);
    }
    app_loadmap = p2 ? p1 : 0;
    ldso.loadmap = p2 ? p2 : p1;
    ldso.base = laddr(&ldso, 0);
  } else {
    ldso.base = base;
  }
  Ehdr* ehdr = (void*)ldso.base;
  ldso.name = ldso.shortname = "libc.so";
  ldso.global = 1;
  ldso.phnum = ehdr->e_phnum;
  ldso.phdr = laddr(&ldso, ehdr->e_phoff);
  ldso.phentsize = ehdr->e_phentsize;
  kernel_mapped_dso(&ldso);
  decode_dyn(&ldso);

  if (DL_FDPIC)
    makefuncdescs(&ldso);

  /* Prepare storage for to save clobbered REL addends so they
   * can be reused in stage 3. There should be very few. If
   * something goes wrong and there are a huge number, abort
   * instead of risking stack overflow. */
  size_t dyn[DYN_CNT];
  decode_vec(ldso.dynv, dyn, DYN_CNT);
  size_t* rel = laddr(&ldso, dyn[DT_REL]);
  size_t rel_size = dyn[DT_RELSZ];
  size_t symbolic_rel_cnt = 0;
  apply_addends_to = rel;
  for (; rel_size; rel += 2, rel_size -= 2 * sizeof(size_t))
    if (!IS_RELATIVE(rel[1], ldso.syms))
      symbolic_rel_cnt++;
  if (symbolic_rel_cnt >= ADDEND_LIMIT)
    a_crash();
  size_t addends[symbolic_rel_cnt + 1];
  saved_addends = addends;

  head = &ldso;
  reloc_all(&ldso);

  ldso.relocated = 0;

  /* Call dynamic linker stage-3, __dls3, looking it up
   * symbolically as a barrier against moving the address
   * load across the above relocation processing. */
  struct symdef dls3_def = find_sym(&ldso, "__dls3", 0);
  if (DL_FDPIC)
    ((stage3_func)&ldso.funcdescs[dls3_def.sym - ldso.syms])(sp);
  else
    ((stage3_func)laddr(&ldso, dls3_def.sym->st_value))(sp);
}

/* Stage 3 of the dynamic linker is called with the dynamic linker/libc
 * fully functional. Its job is to load (if not already loaded) and
 * process dependencies and relocations for the main application and
 * transfer control to its entry point. */

_Noreturn void __dls3(size_t* sp) {
  static struct dso app, vdso;
  size_t aux[AUX_CNT], *auxv;
  size_t i;
  char* env_preload = 0;
  size_t vdso_base;
  int argc = *sp;
  char** argv = (void*)(sp + 1);
  char** argv_orig = argv;
  char** envp = argv + argc + 1;

  /* Find aux vector just past environ[] and use it to initialize
   * global data that may be needed before we can make syscalls. */
  __environ = envp;
  for (i = argc + 1; argv[i]; i++)
    ;
  libc.auxv = auxv = (void*)(argv + i + 1);
  decode_vec(auxv, aux, AUX_CNT);
  __hwcap = aux[AT_HWCAP];
  libc.page_size = aux[AT_PAGESZ];
  libc.secure = ((aux[0] & 0x7800) != 0x7800 || aux[AT_UID] != aux[AT_EUID] ||
                 aux[AT_GID] != aux[AT_EGID] || aux[AT_SECURE]);

  /* Setup early thread pointer in builtin_tls for ldso/libc itself to
   * use during dynamic linking. If possible it will also serve as the
   * thread pointer at runtime. */
  libc.tls_size = sizeof builtin_tls;
  libc.tls_align = tls_align;
  if (__init_tp(__copy_tls((void*)builtin_tls)) < 0) {
    a_crash();
  }

  /* Only trust user/env if kernel says we're not suid/sgid */
  if (!libc.secure) {
    env_path = getenv("LD_LIBRARY_PATH");
    env_preload = getenv("LD_PRELOAD");
  }

  /* If the main program was already loaded by the kernel,
   * AT_PHDR will point to some location other than the dynamic
   * linker's program headers. */
  if (aux[AT_PHDR] != (size_t)ldso.phdr) {
    size_t interp_off = 0;
    size_t tls_image = 0;
    /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
    Phdr* phdr = app.phdr = (void*)aux[AT_PHDR];
    app.phnum = aux[AT_PHNUM];
    app.phentsize = aux[AT_PHENT];
    for (i = aux[AT_PHNUM]; i;
         i--, phdr = (void*)((char*)phdr + aux[AT_PHENT])) {
      if (phdr->p_type == PT_PHDR)
        app.base = (void*)(aux[AT_PHDR] - phdr->p_vaddr);
      else if (phdr->p_type == PT_INTERP)
        interp_off = (size_t)phdr->p_vaddr;
      else if (phdr->p_type == PT_TLS) {
        tls_image = phdr->p_vaddr;
        app.tls.len = phdr->p_filesz;
        app.tls.size = phdr->p_memsz;
        app.tls.align = phdr->p_align;
      }
    }
    if (DL_FDPIC)
      app.loadmap = app_loadmap;
    if (app.tls.size)
      app.tls.image = laddr(&app, tls_image);
    if (interp_off)
      ldso.name = laddr(&app, interp_off);
    if ((aux[0] & (1UL << AT_EXECFN)) &&
        strncmp((char*)aux[AT_EXECFN], "/proc/", 6))
      app.name = (char*)aux[AT_EXECFN];
    else
      app.name = argv[0];
    kernel_mapped_dso(&app);
  } else {
    int fd;
    char* ldname = argv[0];
    size_t l = strlen(ldname);
    if (l >= 3 && !strcmp(ldname + l - 3, "ldd"))
      ldd_mode = 1;
    argv++;
    while (argv[0] && argv[0][0] == '-' && argv[0][1] == '-') {
      char* opt = argv[0] + 2;
      *argv++ = (void*)-1;
      if (!*opt) {
        break;
      } else if (!memcmp(opt, "list", 5)) {
        ldd_mode = 1;
      } else if (!memcmp(opt, "library-path", 12)) {
        if (opt[12] == '=')
          env_path = opt + 13;
        else if (opt[12])
          *argv = 0;
        else if (*argv)
          env_path = *argv++;
      } else if (!memcmp(opt, "preload", 7)) {
        if (opt[7] == '=')
          env_preload = opt + 8;
        else if (opt[7])
          *argv = 0;
        else if (*argv)
          env_preload = *argv++;
      } else {
        argv[0] = 0;
      }
    }
    argv[-1] = (void*)(argc - (argv - argv_orig));
    if (!argv[0]) {
      dprintf(2, "musl libc (" LDSO_ARCH
                 ")\n"
                 "Version %s\n"
                 "Dynamic Program Loader\n"
                 "Usage: %s [options] [--] pathname%s\n",
              __libc_get_version(), ldname, ldd_mode ? "" : " [args]");
      _exit(1);
    }
    fd = open(argv[0], O_RDONLY);
    if (fd < 0) {
      dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
      _exit(1);
    }
    runtime = 1;
    Ehdr* ehdr = (void*)map_library(fd, &app);
    if (!ehdr) {
      dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
      _exit(1);
    }
    runtime = 0;
    close(fd);
    ldso.name = ldname;
    app.name = argv[0];
    aux[AT_ENTRY] = (size_t)laddr(&app, ehdr->e_entry);
    /* Find the name that would have been used for the dynamic
     * linker had ldd not taken its place. */
    if (ldd_mode) {
      for (i = 0; i < app.phnum; i++) {
        if (app.phdr[i].p_type == PT_INTERP)
          ldso.name = laddr(&app, app.phdr[i].p_vaddr);
      }
      dprintf(1, "\t%s (%p)\n", ldso.name, ldso.base);
    }
  }
  if (app.tls.size) {
    libc.tls_head = tls_tail = &app.tls;
    app.tls_id = tls_cnt = 1;
#ifdef TLS_ABOVE_TP
    app.tls.offset = 0;
    tls_offset = app.tls.size + (-((uintptr_t)app.tls.image + app.tls.size) &
                                 (app.tls.align - 1));
#else
    tls_offset = app.tls.offset =
        app.tls.size +
        (-((uintptr_t)app.tls.image + app.tls.size) & (app.tls.align - 1));
#endif
    tls_align = MAXP2(tls_align, app.tls.align);
  }
  app.global = 1;
  decode_dyn(&app);
  if (DL_FDPIC) {
    makefuncdescs(&app);
    if (!app.loadmap) {
      app.loadmap = (void*)&app_dummy_loadmap;
      app.loadmap->nsegs = 1;
      app.loadmap->segs[0].addr = (size_t)app.map;
      app.loadmap->segs[0].p_vaddr = (size_t)app.map - (size_t)app.base;
      app.loadmap->segs[0].p_memsz = app.map_len;
    }
    argv[-3] = (void*)app.loadmap;
  }

  /* Attach to vdso, if provided by the kernel */
  if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR)) {
    Ehdr* ehdr = (void*)vdso_base;
    Phdr* phdr = vdso.phdr = (void*)(vdso_base + ehdr->e_phoff);
    vdso.phnum = ehdr->e_phnum;
    vdso.phentsize = ehdr->e_phentsize;
    for (i = ehdr->e_phnum; i;
         i--, phdr = (void*)((char*)phdr + ehdr->e_phentsize)) {
      if (phdr->p_type == PT_DYNAMIC)
        vdso.dynv = (void*)(vdso_base + phdr->p_offset);
      if (phdr->p_type == PT_LOAD)
        vdso.base = (void*)(vdso_base - phdr->p_vaddr + phdr->p_offset);
    }
    vdso.name = "";
    vdso.shortname = "linux-gate.so.1";
    vdso.global = 1;
    vdso.relocated = 1;
    decode_dyn(&vdso);
    vdso.prev = &ldso;
    ldso.next = &vdso;
  }

  /* Initial dso chain consists only of the app. */
  head = tail = &app;

  /* Donate unused parts of app and library mapping to malloc */
  reclaim_gaps(&app);
  reclaim_gaps(&ldso);

  /* Load preload/needed libraries, add their symbols to the global
   * namespace, and perform all remaining relocations. */
  if (env_preload)
    load_preload(env_preload);
  load_deps(&app);
  make_global(&app);

  for (i = 0; app.dynv[i]; i += 2) {
    if (!DT_DEBUG_INDIRECT && app.dynv[i] == DT_DEBUG)
      app.dynv[i + 1] = (size_t)&debug;
    if (DT_DEBUG_INDIRECT && app.dynv[i] == DT_DEBUG_INDIRECT) {
      size_t* ptr = (size_t*)app.dynv[i + 1];
      *ptr = (size_t)&debug;
    }
  }

  /* The main program must be relocated LAST since it may contin
   * copy relocations which depend on libraries' relocations. */
  reloc_all(app.next);
  reloc_all(&app);

  update_tls_size();
  if (libc.tls_size > sizeof builtin_tls || tls_align > MIN_TLS_ALIGN) {
    void* initial_tls = calloc(libc.tls_size, 1);
    if (!initial_tls) {
      dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
              argv[0], libc.tls_size);
      _exit(127);
    }
    if (__init_tp(__copy_tls(initial_tls)) < 0) {
      a_crash();
    }
  } else {
    size_t tmp_tls_size = libc.tls_size;
    pthread_t self = __pthread_self();
    /* Temporarily set the tls size to the full size of
     * builtin_tls so that __copy_tls will use the same layout
     * as it did for before. Then check, just to be safe. */
    libc.tls_size = sizeof builtin_tls;
    if (__copy_tls((void*)builtin_tls) != self)
      a_crash();
    libc.tls_size = tmp_tls_size;
  }
  static_tls_cnt = tls_cnt;

  if (ldso_fail)
    _exit(127);
  if (ldd_mode)
    _exit(0);

  /* Switch to runtime mode: any further failures in the dynamic
   * linker are a reportable failure rather than a fatal startup
   * error. */
  runtime = 1;

  debug.ver = 1;
  debug.bp = dl_debug_state;
  debug.head = head;
  debug.base = ldso.base;
  debug.state = 0;
  _dl_debug_state();

  errno = 0;

  CRTJMP((void*)aux[AT_ENTRY], argv - 1);
  for (;;)
    ;
}

void* dlopen(const char* file, int mode) {
  struct dso* volatile p, *orig_tail, *next;
  struct tls_module* orig_tls_tail;
  size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
  size_t i;
  int cs;
  jmp_buf jb;

  if (!file)
    return head;

  pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
  pthread_rwlock_wrlock(&lock);
  __inhibit_ptc();

  p = 0;
  orig_tls_tail = tls_tail;
  orig_tls_cnt = tls_cnt;
  orig_tls_offset = tls_offset;
  orig_tls_align = tls_align;
  orig_tail = tail;
  noload = mode & RTLD_NOLOAD;

  rtld_fail = &jb;
  if (setjmp(*rtld_fail)) {
    /* Clean up anything new that was (partially) loaded */
    if (p && p->deps)
      for (i = 0; p->deps[i]; i++)
        if (p->deps[i]->global < 0)
          p->deps[i]->global = 0;
    for (p = orig_tail->next; p; p = next) {
      next = p->next;
      while (p->td_index) {
        void* tmp = p->td_index->next;
        free(p->td_index);
        p->td_index = tmp;
      }
      free(p->funcdescs);
      if (p->rpath != p->rpath_orig)
        free(p->rpath);
      free(p->deps);
      unmap_library(p);
      free(p);
    }
    if (!orig_tls_tail)
      libc.tls_head = 0;
    tls_tail = orig_tls_tail;
    tls_cnt = orig_tls_cnt;
    tls_offset = orig_tls_offset;
    tls_align = orig_tls_align;
    tail = orig_tail;
    tail->next = 0;
    p = 0;
    goto end;
  } else
    p = load_library(file, head);

  if (!p) {
    error(noload ? "Library %s is not already loaded"
                 : "Error loading shared library %s: %m",
          file);
    goto end;
  }

  /* First load handling */
  if (!p->deps) {
    load_deps(p);
    if (p->deps)
      for (i = 0; p->deps[i]; i++)
        if (!p->deps[i]->global)
          p->deps[i]->global = -1;
    if (!p->global)
      p->global = -1;
    reloc_all(p);
    if (p->deps)
      for (i = 0; p->deps[i]; i++)
        if (p->deps[i]->global < 0)
          p->deps[i]->global = 0;
    if (p->global < 0)
      p->global = 0;
  }

  if (mode & RTLD_GLOBAL) {
    if (p->deps)
      for (i = 0; p->deps[i]; i++)
        p->deps[i]->global = 1;
    p->global = 1;
  }

  update_tls_size();
  _dl_debug_state();
  orig_tail = tail;
end:
  __release_ptc();
  if (p)
    gencnt++;
  pthread_rwlock_unlock(&lock);
  if (p)
    do_init_fini(orig_tail);
  pthread_setcancelstate(cs, 0);
  return p;
}

__attribute__((__visibility__("hidden"))) int __dl_invalid_handle(void* h) {
  struct dso* p;
  for (p = head; p; p = p->next)
    if (h == p)
      return 0;
  error("Invalid library handle %p", (void*)h);
  return 1;
}

static void* addr2dso(size_t a) {
  struct dso* p;
  size_t i;
  if (DL_FDPIC)
    for (p = head; p; p = p->next) {
      i = count_syms(p);
      if (a - (size_t)p->funcdescs < i * sizeof(*p->funcdescs))
        return p;
    }
  for (p = head; p; p = p->next) {
    if (DL_FDPIC && p->loadmap) {
      for (i = 0; i < p->loadmap->nsegs; i++) {
        if (a - p->loadmap->segs[i].p_vaddr < p->loadmap->segs[i].p_memsz)
          return p;
      }
    } else {
      if (a - (size_t)p->map < p->map_len)
        return p;
    }
  }
  return 0;
}

void* __tls_get_addr(size_t*);

static void* do_dlsym(struct dso* p, const char* s, void* ra) {
  size_t i;
  uint32_t h = 0, gh = 0, *ght;
  Sym* sym;
  if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
    if (p == RTLD_DEFAULT) {
      p = head;
    } else if (p == RTLD_NEXT) {
      p = addr2dso((size_t)ra);
      if (!p)
        p = head;
      p = p->next;
    }
    struct symdef def = find_sym(p, s, 0);
    if (!def.sym)
      goto failed;
    if ((def.sym->st_info & 0xf) == STT_TLS)
      return __tls_get_addr((size_t[]){def.dso->tls_id, def.sym->st_value});
    if (DL_FDPIC && (def.sym->st_info & 0xf) == STT_FUNC)
      return def.dso->funcdescs + (def.sym - def.dso->syms);
    return laddr(def.dso, def.sym->st_value);
  }
  if (__dl_invalid_handle(p))
    return 0;
  if ((ght = p->ghashtab)) {
    gh = gnu_hash(s);
    sym = gnu_lookup(gh, ght, p, s);
  } else {
    h = sysv_hash(s);
    sym = sysv_lookup(s, h, p);
  }
  if (sym && (sym->st_info & 0xf) == STT_TLS)
    return __tls_get_addr((size_t[]){p->tls_id, sym->st_value});
  if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info & 0xf) == STT_FUNC)
    return p->funcdescs + (sym - p->syms);
  if (sym && sym->st_value && (1 << (sym->st_info & 0xf) & OK_TYPES))
    return laddr(p, sym->st_value);
  if (p->deps)
    for (i = 0; p->deps[i]; i++) {
      if ((ght = p->deps[i]->ghashtab)) {
        if (!gh)
          gh = gnu_hash(s);
        sym = gnu_lookup(gh, ght, p->deps[i], s);
      } else {
        if (!h)
          h = sysv_hash(s);
        sym = sysv_lookup(s, h, p->deps[i]);
      }
      if (sym && (sym->st_info & 0xf) == STT_TLS)
        return __tls_get_addr((size_t[]){p->deps[i]->tls_id, sym->st_value});
      if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info & 0xf) == STT_FUNC)
        return p->deps[i]->funcdescs + (sym - p->deps[i]->syms);
      if (sym && sym->st_value && (1 << (sym->st_info & 0xf) & OK_TYPES))
        return laddr(p->deps[i], sym->st_value);
    }
failed:
  error("Symbol not found: %s", s);
  return 0;
}

int dladdr(const void* addr, Dl_info* info) {
  struct dso* p;
  Sym *sym, *bestsym;
  uint32_t nsym;
  char* strings;
  void* best = 0;

  pthread_rwlock_rdlock(&lock);
  p = addr2dso((size_t)addr);
  pthread_rwlock_unlock(&lock);

  if (!p)
    return 0;

  sym = p->syms;
  strings = p->strings;
  nsym = count_syms(p);

  if (DL_FDPIC) {
    size_t idx = ((size_t)addr - (size_t)p->funcdescs) / sizeof(*p->funcdescs);
    if (idx < nsym && (sym[idx].st_info & 0xf) == STT_FUNC) {
      best = p->funcdescs + idx;
      bestsym = sym + idx;
    }
  }

  if (!best)
    for (; nsym; nsym--, sym++) {
      if (sym->st_value && (1 << (sym->st_info & 0xf) & OK_TYPES) &&
          (1 << (sym->st_info >> 4) & OK_BINDS)) {
        void* symaddr = laddr(p, sym->st_value);
        if (symaddr > addr || symaddr < best)
          continue;
        best = symaddr;
        bestsym = sym;
        if (addr == symaddr)
          break;
      }
    }

  if (!best)
    return 0;

  if (DL_FDPIC && (bestsym->st_info & 0xf) == STT_FUNC)
    best = p->funcdescs + (bestsym - p->syms);

  info->dli_fname = p->name;
  info->dli_fbase = p->base;
  info->dli_sname = strings + bestsym->st_name;
  info->dli_saddr = best;

  return 1;
}

__attribute__((__visibility__("hidden"))) void* __dlsym(void* restrict p,
                                                        const char* restrict s,
                                                        void* restrict ra) {
  void* res;
  pthread_rwlock_rdlock(&lock);
  res = do_dlsym(p, s, ra);
  pthread_rwlock_unlock(&lock);
  return res;
}

int dl_iterate_phdr(int (*callback)(struct dl_phdr_info* info,
                                    size_t size,
                                    void* data),
                    void* data) {
  struct dso* current;
  struct dl_phdr_info info;
  int ret = 0;
  for (current = head; current;) {
    info.dlpi_addr = (uintptr_t)current->base;
    info.dlpi_name = current->name;
    info.dlpi_phdr = current->phdr;
    info.dlpi_phnum = current->phnum;
    info.dlpi_adds = gencnt;
    info.dlpi_subs = 0;
    info.dlpi_tls_modid = current->tls_id;
    info.dlpi_tls_data = current->tls.image;

    ret = (callback)(&info, sizeof(info), data);

    if (ret != 0)
      break;

    pthread_rwlock_rdlock(&lock);
    current = current->next;
    pthread_rwlock_unlock(&lock);
  }
  return ret;
}

__attribute__((__visibility__("hidden"))) void __dl_vseterr(const char*,
                                                            va_list);

static void error(const char* fmt, ...) {
  va_list ap;
  va_start(ap, fmt);
  if (!runtime) {
    vdprintf(2, fmt, ap);
    dprintf(2, "\n");
    ldso_fail = 1;
    va_end(ap);
    return;
  }
  __dl_vseterr(fmt, ap);
  va_end(ap);
}