ext/kgio/tryopen.c

   1 #include <ruby.h>
   2 #ifdef HAVE_RUBY_IO_H
   3 #  include <ruby/io.h>
   4 #else
   5 #  include <rubyio.h>
   6 #endif
   7
   8 #ifdef HAVE_RUBY_ST_H
   9 #  include <ruby/st.h>
  10 #else
  11 #  include <st.h>
  12 #endif
  13
  14 #include <sys/types.h>
  15 #include <sys/stat.h>
  16 #include <fcntl.h>
  17 #include "set_file_path.h"
  18 #include "ancient_ruby.h"
  19
  20 static ID id_for_fd, id_to_path, id_path;
  21 static st_table *errno2sym;
  22
  23 struct open_args {
  24         const char *pathname;
  25         int flags;
  26         mode_t mode;
  27 };
  28
  29 #ifndef HAVE_RB_CLOEXEC_OPEN
  30 #  define rb_cloexec_open(p,f,m) open((p),(f),(m))
  31 #endif
  32
  33 static VALUE nogvl_open(void *ptr)
  34 {
  35         struct open_args *o = ptr;
  36
  37         return (VALUE)rb_cloexec_open(o->pathname, o->flags, o->mode);
  38 }
  39
  40 #ifndef HAVE_RB_THREAD_BLOCKING_REGION
  41 #  define RUBY_UBF_IO ((void *)(-1))
  42 #  include "rubysig.h"
  43 typedef void rb_unblock_function_t(void *);
  44 typedef VALUE rb_blocking_function_t(void *);
  45 static VALUE rb_thread_blocking_region(
  46         rb_blocking_function_t *fn, void *data1,
  47         rb_unblock_function_t *ubf, void *data2)
  48 {
  49         VALUE rv;
  50
  51         TRAP_BEG; /* for FIFO */
  52         rv = fn(data1);
  53         TRAP_END;
  54
  55         return rv;
  56 }
  57 #endif /* ! HAVE_RB_THREAD_BLOCKING_REGION */
  58
  59 /*
  60  * call-seq:
  61  *
  62  *      Kgio::File.tryopen(filename, [, mode [, perm]]) -> Kgio::File or Symbol
  63  *
  64  * Returns a Kgio::File object on a successful open.  +filename+ is a
  65  * path to any file on the filesystem.  If specified, +mode+ is a bitmask
  66  * of flags (see IO.sysopen) and +perm+ should be an octal number.
  67  *
  68  * This does not raise errors for most failures, but installs returns a
  69  * Ruby symbol for the constant in the Errno::* namespace.
  70  *
  71  * Common error symbols are:
  72  *
  73  * - :ENOENT
  74  * - :EACCES
  75  *
  76  * See your open(2) manpage for more information on open(2) errors.
  77  */
  78 static VALUE s_tryopen(int argc, VALUE *argv, VALUE klass)
  79 {
  80         int fd;
  81         VALUE pathname, flags, mode;
  82         struct open_args o;
  83         int retried = 0;
  84         VALUE rv;
  85
  86         rb_scan_args(argc, argv, "12", &pathname, &flags, &mode);
  87         if (rb_respond_to(pathname, id_to_path))
  88                 pathname = rb_funcall(pathname, id_to_path, 0);
  89         o.pathname = StringValueCStr(pathname);
  90
  91         switch (TYPE(flags)) {
  92         case T_NIL: o.flags = O_RDONLY; break;
  93         case T_FIXNUM: o.flags = FIX2INT(flags); break;
  94         case T_BIGNUM: o.flags = NUM2INT(flags); break;
  95         default: rb_raise(rb_eArgError, "flags must be an Integer");
  96         }
  97         switch (TYPE(mode)) {
  98         case T_NIL: o.mode = 0666; break;
  99         case T_FIXNUM: o.mode = FIX2INT(mode); break;
 100         case T_BIGNUM: o.mode = NUM2INT(mode); break;
 101         default: rb_raise(rb_eArgError, "mode must be an Integer");
 102         }
 103
 104 retry:
 105         fd = (int)rb_thread_blocking_region(nogvl_open, &o, RUBY_UBF_IO, 0);
 106         if (fd == -1) {
 107                 if (errno == EMFILE || errno == ENFILE || errno == ENOMEM) {
 108                         rb_gc();
 109                         if (retried)
 110                                 rb_sys_fail(o.pathname);
 111                         retried = 1;
 112                         goto retry;
 113                 }
 114                 if (fd == -1) {
 115                         int saved_errno = errno;
 116
 117                         if (!st_lookup(errno2sym, (st_data_t)errno, &rv)) {
 118                                 errno = saved_errno;
 119                                 rb_sys_fail(o.pathname);
 120                         }
 121                         return rv;
 122                 }
 123         }
 124         rv = rb_funcall(klass, id_for_fd, 1, INT2FIX(fd));
 125         set_file_path(rv, pathname);
 126         return rv;
 127 }
 128
 129 void init_kgio_tryopen(void)
 130 {
 131         VALUE mKgio = rb_define_module("Kgio");
 132         VALUE mPipeMethods = rb_const_get(mKgio, rb_intern("PipeMethods"));
 133         VALUE cFile;
 134         VALUE tmp;
 135         VALUE *ptr;
 136         long len;
 137
 138         id_path = rb_intern("path");
 139         id_for_fd = rb_intern("for_fd");
 140         id_to_path = rb_intern("to_path");
 141
 142         /*
 143          * Document-class: Kgio::File
 144          *
 145          * This subclass of the core File class adds the "tryopen" singleton
 146          * method for opening files.  A single "tryopen" and check for the
 147          * return value may be used to avoid unnecessary stat(2) syscalls
 148          * or File.open exceptions when checking for the existence of a file
 149          * and opening it.
 150          */
 151         cFile = rb_define_class_under(mKgio, "File", rb_cFile);
 152         rb_define_singleton_method(cFile, "tryopen", s_tryopen, -1);
 153         rb_include_module(cFile, mPipeMethods);
 154
 155         if (!rb_funcall(cFile, rb_intern("method_defined?"), 1,
 156                         ID2SYM(id_to_path)))
 157                 rb_define_alias(cFile, "to_path", "path");
 158
 159         errno2sym = st_init_numtable();
 160         tmp = rb_funcall(rb_mErrno, rb_intern("constants"), 0);
 161         ptr = RARRAY_PTR(tmp);
 162         len = RARRAY_LEN(tmp);
 163         for (; --len >= 0; ptr++) {
 164                 VALUE error;
 165                 ID const_id;
 166
 167                 switch (TYPE(*ptr)) {
 168                 case T_SYMBOL: const_id = SYM2ID(*ptr); break;
 169                 case T_STRING: const_id = rb_intern(RSTRING_PTR(*ptr)); break;
 170                 default: rb_bug("constant not a symbol or string");
 171                 }
 172
 173                 error = rb_const_get(rb_mErrno, const_id);
 174                 if ((TYPE(error) != T_CLASS) ||
 175                     !rb_const_defined(error, rb_intern("Errno")))
 176                         continue;
 177
 178                 error = rb_const_get(error, rb_intern("Errno"));
 179                 switch (TYPE(error)) {
 180                 case T_FIXNUM:
 181                 case T_BIGNUM:
 182                         st_insert(errno2sym, (st_data_t)NUM2INT(error),
 183                                   ID2SYM(const_id));
 184                 }
 185         }
 186 }