libio/iopopen.c

   1 /* Copyright (C) 1993-2017 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Written by Per Bothner <bothner@cygnus.com>.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.
  18
  19    As a special exception, if you link the code in this file with
  20    files compiled with a GNU compiler to produce an executable,
  21    that does not cause the resulting executable to be covered by
  22    the GNU Lesser General Public License.  This exception does not
  23    however invalidate any other reasons why the executable file
  24    might be covered by the GNU Lesser General Public License.
  25    This exception applies to code released by its copyright holders
  26    in files containing the exception.  */
  27
  28 #ifndef _POSIX_SOURCE
  29 # define _POSIX_SOURCE
  30 #endif
  31 #include "libioP.h"
  32 #include <fcntl.h>
  33 #include <signal.h>
  34 #include <unistd.h>
  35 #include <stdlib.h>
  36 #ifdef _LIBC
  37 # include <shlib-compat.h>
  38 # include <not-cancel.h>
  39 #endif
  40 #include <sys/types.h>
  41 #include <sys/wait.h>
  42 #include <kernel-features.h>
  43
  44 #ifndef _IO_fork
  45 #ifdef _LIBC
  46 #define _IO_fork __fork
  47 #else
  48 #define _IO_fork fork /* defined in libiberty, if needed */
  49 #endif
  50 extern _IO_pid_t _IO_fork (void) __THROW;
  51 #endif
  52
  53 #ifndef _IO_dup2
  54 #ifdef _LIBC
  55 #define _IO_dup2 __dup2
  56 #else
  57 #define _IO_dup2 dup2
  58 #endif
  59 extern int _IO_dup2 (int fd, int fd2) __THROW;
  60 #endif
  61
  62 #ifndef _IO_waitpid
  63 #ifdef _LIBC
  64 #define _IO_waitpid waitpid_not_cancel
  65 #else
  66 #define _IO_waitpid waitpid
  67 #endif
  68 #endif
  69
  70 #ifndef _IO_execl
  71 #define _IO_execl execl
  72 #endif
  73 #ifndef _IO__exit
  74 #define _IO__exit _exit
  75 #endif
  76
  77 #ifndef _IO_close
  78 #ifdef _LIBC
  79 #define _IO_close close_not_cancel
  80 #else
  81 #define _IO_close close
  82 #endif
  83 #endif
  84
  85 struct _IO_proc_file
  86 {
  87   struct _IO_FILE_plus file;
  88   /* Following fields must match those in class procbuf (procbuf.h) */
  89   _IO_pid_t pid;
  90   struct _IO_proc_file *next;
  91 };
  92 typedef struct _IO_proc_file _IO_proc_file;
  93
  94 static const struct _IO_jump_t _IO_proc_jumps;
  95
  96 static struct _IO_proc_file *proc_file_chain;
  97
  98 #ifdef _IO_MTSAFE_IO
  99 static _IO_lock_t proc_file_chain_lock = _IO_lock_initializer;
 100
 101 static void
 102 unlock (void *not_used)
 103 {
 104   _IO_lock_unlock (proc_file_chain_lock);
 105 }
 106 #endif
 107
 108 _IO_FILE *
 109 _IO_new_proc_open (_IO_FILE *fp, const char *command, const char *mode)
 110 {
 111   int read_or_write;
 112   int parent_end, child_end;
 113   int pipe_fds[2];
 114   _IO_pid_t child_pid;
 115
 116   int do_read = 0;
 117   int do_write = 0;
 118   int do_cloexec = 0;
 119   while (*mode != '\0')
 120     switch (*mode++)
 121       {
 122       case 'r':
 123         do_read = 1;
 124         break;
 125       case 'w':
 126         do_write = 1;
 127         break;
 128       case 'e':
 129         do_cloexec = 1;
 130         break;
 131       default:
 132       errout:
 133         __set_errno (EINVAL);
 134         return NULL;
 135       }
 136
 137   if ((do_read ^ do_write) == 0)
 138     goto errout;
 139
 140   if (_IO_file_is_open (fp))
 141     return NULL;
 142
 143 #ifdef O_CLOEXEC
 144 # ifndef __ASSUME_PIPE2
 145   if (__have_pipe2 >= 0)
 146 # endif
 147     {
 148       int r = __pipe2 (pipe_fds, O_CLOEXEC);
 149 # ifndef __ASSUME_PIPE2
 150       if (__have_pipe2 == 0)
 151         __have_pipe2 = r != -1 || errno != ENOSYS ? 1 : -1;
 152
 153       if (__have_pipe2 > 0)
 154 # endif
 155         if (r < 0)
 156           return NULL;
 157     }
 158 #endif
 159 #ifndef __ASSUME_PIPE2
 160 # ifdef O_CLOEXEC
 161   if (__have_pipe2 < 0)
 162 # endif
 163     if (__pipe (pipe_fds) < 0)
 164       return NULL;
 165 #endif
 166
 167   if (do_read)
 168     {
 169       parent_end = pipe_fds[0];
 170       child_end = pipe_fds[1];
 171       read_or_write = _IO_NO_WRITES;
 172     }
 173   else
 174     {
 175       parent_end = pipe_fds[1];
 176       child_end = pipe_fds[0];
 177       read_or_write = _IO_NO_READS;
 178     }
 179
 180   ((_IO_proc_file *) fp)->pid = child_pid = _IO_fork ();
 181   if (child_pid == 0)
 182     {
 183       int child_std_end = do_read ? 1 : 0;
 184       struct _IO_proc_file *p;
 185
 186 #ifndef __ASSUME_PIPE2
 187       /* If we have pipe2 the descriptor is marked for close-on-exec.  */
 188       _IO_close (parent_end);
 189 #endif
 190       if (child_end != child_std_end)
 191         {
 192           _IO_dup2 (child_end, child_std_end);
 193 #ifndef __ASSUME_PIPE2
 194           _IO_close (child_end);
 195 #endif
 196         }
 197 #ifdef O_CLOEXEC
 198       else
 199         {
 200           /* The descriptor is already the one we will use.  But it must
 201              not be marked close-on-exec.  Undo the effects.  */
 202 # ifndef __ASSUME_PIPE2
 203           if (__have_pipe2 > 0)
 204 # endif
 205             __fcntl (child_end, F_SETFD, 0);
 206         }
 207 #endif
 208       /* POSIX.2:  "popen() shall ensure that any streams from previous
 209          popen() calls that remain open in the parent process are closed
 210          in the new child process." */
 211       for (p = proc_file_chain; p; p = p->next)
 212         {
 213           int fd = _IO_fileno ((_IO_FILE *) p);
 214
 215           /* If any stream from previous popen() calls has fileno
 216              child_std_end, it has been already closed by the dup2 syscall
 217              above.  */
 218           if (fd != child_std_end)
 219             _IO_close (fd);
 220         }
 221
 222       _IO_execl ("/bin/sh", "sh", "-c", command, (char *) 0);
 223       _IO__exit (127);
 224     }
 225   _IO_close (child_end);
 226   if (child_pid < 0)
 227     {
 228       _IO_close (parent_end);
 229       return NULL;
 230     }
 231
 232   if (do_cloexec)
 233     {
 234 #ifndef __ASSUME_PIPE2
 235 # ifdef O_CLOEXEC
 236       if (__have_pipe2 < 0)
 237 # endif
 238         __fcntl (parent_end, F_SETFD, FD_CLOEXEC);
 239 #endif
 240     }
 241   else
 242     {
 243 #ifdef O_CLOEXEC
 244       /* Undo the effects of the pipe2 call which set the
 245          close-on-exec flag.  */
 246 # ifndef __ASSUME_PIPE2
 247       if (__have_pipe2 > 0)
 248 # endif
 249         __fcntl (parent_end, F_SETFD, 0);
 250 #endif
 251     }
 252
 253   _IO_fileno (fp) = parent_end;
 254
 255   /* Link into proc_file_chain. */
 256 #ifdef _IO_MTSAFE_IO
 257   _IO_cleanup_region_start_noarg (unlock);
 258   _IO_lock_lock (proc_file_chain_lock);
 259 #endif
 260   ((_IO_proc_file *) fp)->next = proc_file_chain;
 261   proc_file_chain = (_IO_proc_file *) fp;
 262 #ifdef _IO_MTSAFE_IO
 263   _IO_lock_unlock (proc_file_chain_lock);
 264   _IO_cleanup_region_end (0);
 265 #endif
 266
 267   _IO_mask_flags (fp, read_or_write, _IO_NO_READS|_IO_NO_WRITES);
 268   return fp;
 269 }
 270
 271 _IO_FILE *
 272 _IO_new_popen (const char *command, const char *mode)
 273 {
 274   struct locked_FILE
 275   {
 276     struct _IO_proc_file fpx;
 277 #ifdef _IO_MTSAFE_IO
 278     _IO_lock_t lock;
 279 #endif
 280   } *new_f;
 281   _IO_FILE *fp;
 282
 283   new_f = (struct locked_FILE *) malloc (sizeof (struct locked_FILE));
 284   if (new_f == NULL)
 285     return NULL;
 286 #ifdef _IO_MTSAFE_IO
 287   new_f->fpx.file.file._lock = &new_f->lock;
 288 #endif
 289   fp = &new_f->fpx.file.file;
 290   _IO_init_internal (fp, 0);
 291   _IO_JUMPS (&new_f->fpx.file) = &_IO_proc_jumps;
 292   _IO_new_file_init_internal (&new_f->fpx.file);
 293 #if  !_IO_UNIFIED_JUMPTABLES
 294   new_f->fpx.file.vtable = NULL;
 295 #endif
 296   if (_IO_new_proc_open (fp, command, mode) != NULL)
 297     return (_IO_FILE *) &new_f->fpx.file;
 298   _IO_un_link (&new_f->fpx.file);
 299   free (new_f);
 300   return NULL;
 301 }
 302
 303 int
 304 _IO_new_proc_close (_IO_FILE *fp)
 305 {
 306   /* This is not name-space clean. FIXME! */
 307   int wstatus;
 308   _IO_proc_file **ptr = &proc_file_chain;
 309   _IO_pid_t wait_pid;
 310   int status = -1;
 311
 312   /* Unlink from proc_file_chain. */
 313 #ifdef _IO_MTSAFE_IO
 314   _IO_cleanup_region_start_noarg (unlock);
 315   _IO_lock_lock (proc_file_chain_lock);
 316 #endif
 317   for ( ; *ptr != NULL; ptr = &(*ptr)->next)
 318     {
 319       if (*ptr == (_IO_proc_file *) fp)
 320         {
 321           *ptr = (*ptr)->next;
 322           status = 0;
 323           break;
 324         }
 325     }
 326 #ifdef _IO_MTSAFE_IO
 327   _IO_lock_unlock (proc_file_chain_lock);
 328   _IO_cleanup_region_end (0);
 329 #endif
 330
 331   if (status < 0 || _IO_close (_IO_fileno(fp)) < 0)
 332     return -1;
 333   /* POSIX.2 Rationale:  "Some historical implementations either block
 334      or ignore the signals SIGINT, SIGQUIT, and SIGHUP while waiting
 335      for the child process to terminate.  Since this behavior is not
 336      described in POSIX.2, such implementations are not conforming." */
 337   do
 338     {
 339       wait_pid = _IO_waitpid (((_IO_proc_file *) fp)->pid, &wstatus, 0);
 340     }
 341   while (wait_pid == -1 && errno == EINTR);
 342   if (wait_pid == -1)
 343     return -1;
 344   return wstatus;
 345 }
 346
 347 static const struct _IO_jump_t _IO_proc_jumps libio_vtable = {
 348   JUMP_INIT_DUMMY,
 349   JUMP_INIT(finish, _IO_new_file_finish),
 350   JUMP_INIT(overflow, _IO_new_file_overflow),
 351   JUMP_INIT(underflow, _IO_new_file_underflow),
 352   JUMP_INIT(uflow, _IO_default_uflow),
 353   JUMP_INIT(pbackfail, _IO_default_pbackfail),
 354   JUMP_INIT(xsputn, _IO_new_file_xsputn),
 355   JUMP_INIT(xsgetn, _IO_default_xsgetn),
 356   JUMP_INIT(seekoff, _IO_new_file_seekoff),
 357   JUMP_INIT(seekpos, _IO_default_seekpos),
 358   JUMP_INIT(setbuf, _IO_new_file_setbuf),
 359   JUMP_INIT(sync, _IO_new_file_sync),
 360   JUMP_INIT(doallocate, _IO_file_doallocate),
 361   JUMP_INIT(read, _IO_file_read),
 362   JUMP_INIT(write, _IO_new_file_write),
 363   JUMP_INIT(seek, _IO_file_seek),
 364   JUMP_INIT(close, _IO_new_proc_close),
 365   JUMP_INIT(stat, _IO_file_stat),
 366   JUMP_INIT(showmanyc, _IO_default_showmanyc),
 367   JUMP_INIT(imbue, _IO_default_imbue)
 368 };
 369
 370 strong_alias (_IO_new_popen, __new_popen)
 371 versioned_symbol (libc, _IO_new_popen, _IO_popen, GLIBC_2_1);
 372 versioned_symbol (libc, __new_popen, popen, GLIBC_2_1);
 373 versioned_symbol (libc, _IO_new_proc_open, _IO_proc_open, GLIBC_2_1);
 374 versioned_symbol (libc, _IO_new_proc_close, _IO_proc_close, GLIBC_2_1);