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