/**************************************************************************/
/*                                                                        */
/*                                 OCaml                                  */
/*                                                                        */
/*            Xavier Leroy, projet Cristal, INRIA Rocquencourt            */
/*                                                                        */
/*   Copyright 2001 Institut National de Recherche en Informatique et     */
/*     en Automatique.                                                    */
/*                                                                        */
/*   All rights reserved.  This file is distributed under the terms of    */
/*   the GNU Lesser General Public License version 2.1, with the          */
/*   special exception on linking described in the file LICENSE.          */
/*                                                                        */
/**************************************************************************/

#define CAML_INTERNALS

/* Unix-specific stuff */

#define _GNU_SOURCE
           /* Helps finding RTLD_DEFAULT in glibc */
           /* also secure_getenv */

#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include "caml/config.h"
#ifdef SUPPORT_DYNAMIC_LINKING
#ifdef __CYGWIN__
#include "flexdll.h"
#else
#include <dlfcn.h>
#endif
#endif
#ifdef HAS_UNISTD
#include <unistd.h>
#endif
#ifdef HAS_DIRENT
#include <dirent.h>
#else
#include <sys/dir.h>
#endif
#ifdef __APPLE__
#include <mach-o/dyld.h>
#endif
#include "caml/fail.h"
#include "caml/memory.h"
#include "caml/misc.h"
#include "caml/osdeps.h"
#include "caml/signals.h"
#include "caml/sys.h"
#include "caml/io.h"
#include "caml/alloc.h"

#ifndef S_ISREG
#define S_ISREG(mode) (((mode) & S_IFMT) == S_IFREG)
#endif

#ifndef EINTR
#define EINTR (-1)
#endif
#ifndef EAGAIN
#define EAGAIN (-1)
#endif
#ifndef EWOULDBLOCK
#define EWOULDBLOCK (-1)
#endif

int caml_read_fd(int fd, int flags, void * buf, int n)
{
  int retcode;
  caml_enter_blocking_section_no_pending();
  retcode = read(fd, buf, n);
  caml_leave_blocking_section();
  if (retcode == -1) {
    if (errno == EINTR) return Io_interrupted;
    else caml_sys_io_error(NO_ARG);
  }
  return retcode;
}

int caml_write_fd(int fd, int flags, void * buf, int n)
{
  int retcode;
 again:
  caml_enter_blocking_section_no_pending();
  retcode = write(fd, buf, n);
  caml_leave_blocking_section();
  if (retcode == -1) {
    if (errno == EINTR) return Io_interrupted;
    if ((errno == EAGAIN || errno == EWOULDBLOCK) && n > 1) {
      /* We couldn't do a partial write here, probably because
         n <= PIPE_BUF and POSIX says that writes of less than
         PIPE_BUF characters must be atomic.
         We first try again with a partial write of 1 character.
         If that fails too, we'll return an error code. */
      n = 1; goto again;
    }
  }
  if (retcode == -1) caml_sys_io_error(NO_ARG);
  CAMLassert (retcode > 0);
  return retcode;
}

caml_stat_string caml_decompose_path(struct ext_table * tbl, char * path)
{
  char * p, * q;
  size_t n;

  if (path == NULL) return NULL;
  p = caml_stat_strdup(path);
  q = p;
  while (1) {
    for (n = 0; q[n] != 0 && q[n] != ':'; n++) /*nothing*/;
    caml_ext_table_add(tbl, q);
    q = q + n;
    if (*q == 0) break;
    *q = 0;
    q += 1;
  }
  return p;
}

caml_stat_string caml_search_in_path(struct ext_table * path, const char * name)
{
  const char * p;
  char * dir, * fullname;
  int i;
  struct stat st;

  for (p = name; *p != 0; p++) {
    if (*p == '/') goto not_found;
  }
  for (i = 0; i < path->size; i++) {
    dir = path->contents[i];
    if (dir[0] == 0) dir = ".";  /* empty path component = current dir */
    fullname = caml_stat_strconcat(3, dir, "/", name);
    if (stat(fullname, &st) == 0 && S_ISREG(st.st_mode))
      return fullname;
    caml_stat_free(fullname);
  }
 not_found:
  return caml_stat_strdup(name);
}

#ifdef __CYGWIN__

/* Cygwin needs special treatment because of the implicit ".exe" at the
   end of executable file names */

static int cygwin_file_exists(const char * name)
{
  int fd, ret;
  struct stat st;
  /* Cannot use stat() here because it adds ".exe" implicitly */
  fd = open(name, O_RDONLY);
  if (fd == -1) return 0;
  ret = fstat(fd, &st);
  close(fd);
  return ret == 0 && S_ISREG(st.st_mode);
}

static caml_stat_string cygwin_search_exe_in_path(struct ext_table * path,
                                                  const char * name)
{
  const char * p;
  char * dir, * fullname;
  int i;

  for (p = name; *p != 0; p++) {
    if (*p == '/' || *p == '\\') goto not_found;
  }
  for (i = 0; i < path->size; i++) {
    dir = path->contents[i];
    if (dir[0] == 0) dir = ".";  /* empty path component = current dir */
    fullname = caml_stat_strconcat(3, dir, "/", name);
    if (cygwin_file_exists(fullname)) return fullname;
    caml_stat_free(fullname);
    fullname = caml_stat_strconcat(4, dir, "/", name, ".exe");
    if (cygwin_file_exists(fullname)) return fullname;
    caml_stat_free(fullname);
  }
 not_found:
  if (cygwin_file_exists(name)) return caml_stat_strdup(name);
  fullname = caml_stat_strconcat(2, name, ".exe");
  if (cygwin_file_exists(fullname)) return fullname;
  caml_stat_free(fullname);
  return caml_stat_strdup(name);
}

#endif

caml_stat_string caml_search_exe_in_path(const char * name)
{
  struct ext_table path;
  char * tofree;
  caml_stat_string res;

  caml_ext_table_init(&path, 8);
  tofree = caml_decompose_path(&path, getenv("PATH"));
#ifndef __CYGWIN__
  res = caml_search_in_path(&path, name);
#else
  res = cygwin_search_exe_in_path(&path, name);
#endif
  caml_stat_free(tofree);
  caml_ext_table_free(&path, 0);
  return res;
}

caml_stat_string caml_search_dll_in_path(struct ext_table * path,
                                         const char * name)
{
  caml_stat_string dllname;
  caml_stat_string res;

  dllname = caml_stat_strconcat(2, name, ".so");
  res = caml_search_in_path(path, dllname);
  caml_stat_free(dllname);
  return res;
}

#ifdef SUPPORT_DYNAMIC_LINKING
#ifdef __CYGWIN__
/* Use flexdll */

void * caml_dlopen(char * libname, int for_execution, int global)
{
  int flags = (global ? FLEXDLL_RTLD_GLOBAL : 0);
  if (!for_execution) flags |= FLEXDLL_RTLD_NOEXEC;
  return flexdll_dlopen(libname, flags);
}

void caml_dlclose(void * handle)
{
  flexdll_dlclose(handle);
}

void * caml_dlsym(void * handle, const char * name)
{
  return flexdll_dlsym(handle, name);
}

void * caml_globalsym(const char * name)
{
  return flexdll_dlsym(flexdll_dlopen(NULL,0), name);
}

char * caml_dlerror(void)
{
  return flexdll_dlerror();
}

#else
/* Use normal dlopen */

#ifndef RTLD_GLOBAL
#define RTLD_GLOBAL 0
#endif
#ifndef RTLD_LOCAL
#define RTLD_LOCAL 0
#endif

void * caml_dlopen(char * libname, int for_execution, int global)
{
  return dlopen(libname, RTLD_NOW | (global ? RTLD_GLOBAL : RTLD_LOCAL));
  /* Could use RTLD_LAZY if for_execution == 0, but needs testing */
}

void caml_dlclose(void * handle)
{
  dlclose(handle);
}

void * caml_dlsym(void * handle, const char * name)
{
  return dlsym(handle, name);
}

void * caml_globalsym(const char * name)
{
#ifdef RTLD_DEFAULT
  return caml_dlsym(RTLD_DEFAULT, name);
#else
  return NULL;
#endif
}

char * caml_dlerror(void)
{
  return (char*) dlerror();
}

#endif
#else

void * caml_dlopen(char * libname, int for_execution, int global)
{
  return NULL;
}

void caml_dlclose(void * handle)
{
}

void * caml_dlsym(void * handle, const char * name)
{
  return NULL;
}

void * caml_globalsym(const char * name)
{
  return NULL;
}

char * caml_dlerror(void)
{
  return "dynamic loading not supported on this platform";
}

#endif

/* Add to [contents] the (short) names of the files contained in
   the directory named [dirname].  No entries are added for [.] and [..].
   Return 0 on success, -1 on error; set errno in the case of error. */

CAMLexport int caml_read_directory(char * dirname, struct ext_table * contents)
{
  DIR * d;
#ifdef HAS_DIRENT
  struct dirent * e;
#else
  struct direct * e;
#endif

  d = opendir(dirname);
  if (d == NULL) return -1;
  while (1) {
    e = readdir(d);
    if (e == NULL) break;
    if (strcmp(e->d_name, ".") == 0 || strcmp(e->d_name, "..") == 0) continue;
    caml_ext_table_add(contents, caml_stat_strdup(e->d_name));
  }
  closedir(d);
  return 0;
}

/* Recover executable name from /proc/self/exe if possible */

char * caml_executable_name(void)
{
#if defined(__linux__)
  int namelen, retcode;
  char * name;
  struct stat st;

  /* lstat("/proc/self/exe") returns st_size == 0 so we cannot use it
     to determine the size of the buffer.  Instead, we guess and adjust. */
  namelen = 256;
  while (1) {
    name = caml_stat_alloc(namelen);
    retcode = readlink("/proc/self/exe", name, namelen);
    if (retcode == -1) { caml_stat_free(name); return NULL; }
    if (retcode < namelen) break;
    caml_stat_free(name);
    if (namelen >= 1024*1024) return NULL; /* avoid runaway and overflow */
    namelen *= 2;
  }
  /* readlink() does not zero-terminate its result.
     There is room for a final zero since retcode < namelen. */
  name[retcode] = 0;
  /* Make sure that the contents of /proc/self/exe is a regular file.
     (Old Linux kernels return an inode number instead.) */
  if (stat(name, &st) == -1 || ! S_ISREG(st.st_mode)) {
    caml_stat_free(name); return NULL;
  }
  return name;

#elif defined(__APPLE__)
  unsigned int namelen;
  char * name;

  namelen = 256;
  name = caml_stat_alloc(namelen);
  if (_NSGetExecutablePath(name, &namelen) == 0) return name;
  caml_stat_free(name);
  /* Buffer is too small, but namelen now contains the size needed */
  name = caml_stat_alloc(namelen);
  if (_NSGetExecutablePath(name, &namelen) == 0) return name;
  caml_stat_free(name);
  return NULL;

#else
  return NULL;

#endif
}

char *caml_secure_getenv (char const *var)
{
#ifdef HAS_SECURE_GETENV
  return secure_getenv (var);
#elif defined (HAS___SECURE_GETENV)
  return __secure_getenv (var);
#elif defined(HAS_ISSETUGID)
  if (!issetugid ())
    return getenv(var);
  else
    return NULL;
#else
  if (geteuid () == getuid () && getegid () == getgid ())
    return getenv(var);
  else
    return NULL;
#endif
}

int caml_num_rows_fd(int fd)
{
#ifdef TIOCGWINSZ
  struct winsize w;
  w.ws_row = -1;
  if (ioctl(fd, TIOCGWINSZ, &w) == 0)
    return w.ws_row;
  else
    return -1;
#else
  return -1;
#endif
}