Mercurial > hg > octave-nkf > gnulib-hg

annotate lib/freadseek.c @ 12559:c2cbabec01dd

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
update nearly all FSF copyright year lists to include 2010 Use the same procedure as for 2009, outlined in http://thread.gmane.org/gmane.comp.lib.gnulib.bugs/20081
author Jim Meyering <meyering@redhat.com>
date Fri, 01 Jan 2010 10:31:12 +0100
parents e8d2c6fc33ad
children 6fa9f46e6153
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
9738
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
1 /* Skipping input from a FILE stream.
12559
c2cbabec01dd update nearly all FSF copyright year lists to include 2010
Jim Meyering <meyering@redhat.com>
parents: 12421
diff changeset
2 Copyright (C) 2007-2010 Free Software Foundation, Inc.
9738
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
3
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
4 This program is free software: you can redistribute it and/or modify
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
5 it under the terms of the GNU General Public License as published by
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
6 the Free Software Foundation; either version 3 of the License, or
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
7 (at your option) any later version.
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
8
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
9 This program is distributed in the hope that it will be useful,
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
12 GNU General Public License for more details.
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
13
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
14 You should have received a copy of the GNU General Public License
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
16
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
17 #include <config.h>
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
18
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
19 /* Specification. */
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
20 #include "freadseek.h"
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
21
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
22 #include <stdlib.h>
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
23 #include <unistd.h>
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
24
9826
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
25 #include "freadahead.h"
9819
9ccce8a9bf52 Pass test-freadseek on cygwin.
Eric Blake <ebb9@byu.net>
parents: 9738
diff changeset
26 #include "freadptr.h"
9738
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
27
9980
2c1ba629f5d5 New private include file lib/stdio-impl.h.
Bruno Haible <bruno@clisp.org>
parents: 9928
diff changeset
28 #include "stdio-impl.h"
2c1ba629f5d5 New private include file lib/stdio-impl.h.
Bruno Haible <bruno@clisp.org>
parents: 9928
diff changeset
29
9826
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
30 /* Increment the in-memory pointer. INCREMENT must be at most the buffer size
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
31 returned by freadptr().
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
32 This is very cheap (no system calls). */
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
33 static inline void
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
34 freadptrinc (FILE *fp, size_t increment)
9738
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
35 {
9826
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
36 /* Keep this code in sync with freadptr! */
10780
5c7a68d31801 Add support for Haiku.
Bruno Haible <bruno@clisp.org>
parents: 10404
diff changeset
37 #if defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */
9826
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
38 fp->_IO_read_ptr += increment;
9981
e3d6988a9347 Add tentative support for DragonFly BSD.
Bruno Haible <bruno@clisp.org>
parents: 9980
diff changeset
39 #elif defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */
e3d6988a9347 Add tentative support for DragonFly BSD.
Bruno Haible <bruno@clisp.org>
parents: 9980
diff changeset
40 fp_->_p += increment;
e3d6988a9347 Add tentative support for DragonFly BSD.
Bruno Haible <bruno@clisp.org>
parents: 9980
diff changeset
41 fp_->_r -= increment;
9881
e21211210418 Port the extended stdio functions to emx+gcc.
Bruno Haible <bruno@clisp.org>
parents: 9876
diff changeset
42 #elif defined __EMX__ /* emx+gcc */
e21211210418 Port the extended stdio functions to emx+gcc.
Bruno Haible <bruno@clisp.org>
parents: 9876
diff changeset
43 fp->_ptr += increment;
e21211210418 Port the extended stdio functions to emx+gcc.
Bruno Haible <bruno@clisp.org>
parents: 9876
diff changeset
44 fp->_rcount -= increment;
9876
057a5220dfd5 Add tentative support for OpenServer.
Bruno Haible <bruno@clisp.org>
parents: 9826
diff changeset
45 #elif defined _IOERR /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, mingw */
9826
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
46 fp_->_ptr += increment;
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
47 fp_->_cnt -= increment;
9738
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
48 #elif defined __UCLIBC__ /* uClibc */
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
49 # ifdef __STDIO_BUFFERS
9826
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
50 fp->__bufpos += increment;
9738
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
51 # else
9826
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
52 abort ();
9738
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
53 # endif
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
54 #elif defined __QNX__ /* QNX */
9826
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
55 fp->_Next += increment;
11236
d4475bf2a2bf Add tentative support for FreeMiNT.
Bruno Haible <bruno@clisp.org>
parents: 10780
diff changeset
56 #elif defined __MINT__ /* Atari FreeMiNT */
d4475bf2a2bf Add tentative support for FreeMiNT.
Bruno Haible <bruno@clisp.org>
parents: 10780
diff changeset
57 fp->__bufp += increment;
10404
4611578c5669 Add conditional code for SLOW_BUT_NO_HACKS.
Bruno Haible <bruno@clisp.org>
parents: 9981
diff changeset
58 #elif defined SLOW_BUT_NO_HACKS /* users can define this */
9738
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
59 #else
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
60 #error "Please port gnulib freadseek.c to your platform! Look at the definition of getc, getc_unlocked on your system, then report this to bug-gnulib."
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
61 #endif
9826
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
62 }
9738
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
63
9826
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
64 int
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
65 freadseek (FILE *fp, size_t offset)
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
66 {
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
67 size_t total_buffered;
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
68 int fd;
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
69
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
70 if (offset == 0)
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
71 return 0;
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
72
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
73 /* Seek over the already read and buffered input as quickly as possible,
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
74 without doing any system calls. */
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
75 total_buffered = freadahead (fp);
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
76 /* This loop is usually executed at most twice: once for ungetc buffer (if
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
77 present) and once for the main buffer. */
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
78 while (total_buffered > 0)
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
79 {
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
80 size_t buffered;
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
81
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
82 if (freadptr (fp, &buffered) != NULL && buffered > 0)
12421
e8d2c6fc33ad Use spaces for indentation, not tabs.
Bruno Haible <bruno@clisp.org>
parents: 12255
diff changeset
83 {
e8d2c6fc33ad Use spaces for indentation, not tabs.
Bruno Haible <bruno@clisp.org>
parents: 12255
diff changeset
84 size_t increment = (buffered < offset ? buffered : offset);
9826
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
85
12421
e8d2c6fc33ad Use spaces for indentation, not tabs.
Bruno Haible <bruno@clisp.org>
parents: 12255
diff changeset
86 freadptrinc (fp, increment);
e8d2c6fc33ad Use spaces for indentation, not tabs.
Bruno Haible <bruno@clisp.org>
parents: 12255
diff changeset
87 offset -= increment;
e8d2c6fc33ad Use spaces for indentation, not tabs.
Bruno Haible <bruno@clisp.org>
parents: 12255
diff changeset
88 if (offset == 0)
e8d2c6fc33ad Use spaces for indentation, not tabs.
Bruno Haible <bruno@clisp.org>
parents: 12255
diff changeset
89 return 0;
e8d2c6fc33ad Use spaces for indentation, not tabs.
Bruno Haible <bruno@clisp.org>
parents: 12255
diff changeset
90 total_buffered -= increment;
e8d2c6fc33ad Use spaces for indentation, not tabs.
Bruno Haible <bruno@clisp.org>
parents: 12255
diff changeset
91 if (total_buffered == 0)
e8d2c6fc33ad Use spaces for indentation, not tabs.
Bruno Haible <bruno@clisp.org>
parents: 12255
diff changeset
92 break;
e8d2c6fc33ad Use spaces for indentation, not tabs.
Bruno Haible <bruno@clisp.org>
parents: 12255
diff changeset
93 }
9826
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
94 /* Read one byte. If we were reading from the ungetc buffer, this
12421
e8d2c6fc33ad Use spaces for indentation, not tabs.
Bruno Haible <bruno@clisp.org>
parents: 12255
diff changeset
95 switches the stream back to the main buffer. */
9826
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
96 if (fgetc (fp) == EOF)
12421
e8d2c6fc33ad Use spaces for indentation, not tabs.
Bruno Haible <bruno@clisp.org>
parents: 12255
diff changeset
97 goto eof;
9826
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
98 offset--;
9738
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
99 if (offset == 0)
12421
e8d2c6fc33ad Use spaces for indentation, not tabs.
Bruno Haible <bruno@clisp.org>
parents: 12255
diff changeset
100 return 0;
9826
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
101 total_buffered--;
9738
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
102 }
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
103
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
104 /* Test whether the stream is seekable or not. */
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
105 fd = fileno (fp);
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
106 if (fd >= 0 && lseek (fd, 0, SEEK_CUR) >= 0)
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
107 {
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
108 /* FP refers to a regular file. fseek is most efficient in this case. */
12255
83ddd76ac091 fflush, freadseek: use fseeko, not fseek
Eric Blake <ebb9@byu.net>
parents: 11236
diff changeset
109 return fseeko (fp, offset, SEEK_CUR);
9738
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
110 }
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
111 else
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
112 {
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
113 /* FP is a non-seekable stream, possibly not even referring to a file
12421
e8d2c6fc33ad Use spaces for indentation, not tabs.
Bruno Haible <bruno@clisp.org>
parents: 12255
diff changeset
114 descriptor. Read OFFSET bytes explicitly and discard them. */
9738
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
115 char buf[4096];
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
116
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
117 do
12421
e8d2c6fc33ad Use spaces for indentation, not tabs.
Bruno Haible <bruno@clisp.org>
parents: 12255
diff changeset
118 {
e8d2c6fc33ad Use spaces for indentation, not tabs.
Bruno Haible <bruno@clisp.org>
parents: 12255
diff changeset
119 size_t count = (sizeof (buf) < offset ? sizeof (buf) : offset);
e8d2c6fc33ad Use spaces for indentation, not tabs.
Bruno Haible <bruno@clisp.org>
parents: 12255
diff changeset
120 if (fread (buf, 1, count, fp) < count)
e8d2c6fc33ad Use spaces for indentation, not tabs.
Bruno Haible <bruno@clisp.org>
parents: 12255
diff changeset
121 goto eof;
e8d2c6fc33ad Use spaces for indentation, not tabs.
Bruno Haible <bruno@clisp.org>
parents: 12255
diff changeset
122 offset -= count;
e8d2c6fc33ad Use spaces for indentation, not tabs.
Bruno Haible <bruno@clisp.org>
parents: 12255
diff changeset
123 }
9738
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
124 while (offset > 0);
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
125
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
126 return 0;
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
127 }
9826
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
128
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
129 eof:
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
130 /* EOF, or error before or while reading. */
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
131 if (ferror (fp))
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
132 return EOF;
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
133 else
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
134 /* Encountered EOF. */
c421fead68d3 Improve freadseek's efficiency after ungetc.
Bruno Haible <bruno@clisp.org>
parents: 9825
diff changeset
135 return 0;
9738
923434ebe936 New module 'freadseek'.
Bruno Haible <bruno@clisp.org>
parents:
diff changeset
136 }