Tor  0.4.5.0-alpha-dev
fdio.c
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1 /* Copyright (c) 2003-2004, Roger Dingledine
2  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
3  * Copyright (c) 2007-2020, The Tor Project, Inc. */
4 /* See LICENSE for licensing information */
5 
6 /**
7  * \file fdio.c
8  *
9  * \brief Low-level compatibility wrappers for fd-based IO.
10  **/
11 
12 #include "orconfig.h"
13 
14 #ifdef HAVE_UNISTD_H
15 #include <unistd.h>
16 #endif
17 #ifdef _WIN32
18 #include <windows.h>
19 #endif
20 #ifdef HAVE_SYS_TYPES_H
21 #include <sys/types.h>
22 #endif
23 
24 #include "lib/fdio/fdio.h"
25 #include "lib/cc/torint.h"
26 #include "lib/err/torerr.h"
27 
28 #include <stdlib.h>
29 #include <stdio.h>
30 
31 /* Some old versions of Unix didn't define constants for these values,
32  * and instead expect you to say 0, 1, or 2. */
33 
34 /** @cond */
35 #ifndef SEEK_SET
36 #define SEEK_SET 0
37 #endif
38 #ifndef SEEK_CUR
39 #define SEEK_CUR 1
40 #endif
41 #ifndef SEEK_END
42 #define SEEK_END 2
43 #endif
44 /** @endcond */
45 
46 /** Return the position of <b>fd</b> with respect to the start of the file. */
47 off_t
49 {
50 #ifdef _WIN32
51  return (off_t) _lseeki64(fd, 0, SEEK_CUR);
52 #else
53  return (off_t) lseek(fd, 0, SEEK_CUR);
54 #endif
55 }
56 
57 /** Move <b>fd</b> to the end of the file. Return -1 on error, 0 on success.
58  * If the file is a pipe, do nothing and succeed.
59  **/
60 int
62 {
63 #ifdef _WIN32
64  return _lseeki64(fd, 0, SEEK_END) < 0 ? -1 : 0;
65 #else
66  off_t rc = lseek(fd, 0, SEEK_END) < 0 ? -1 : 0;
67 #ifdef ESPIPE
68  /* If we get an error and ESPIPE, then it's a pipe or a socket of a fifo:
69  * no need to worry. */
70  if (rc < 0 && errno == ESPIPE)
71  rc = 0;
72 #endif /* defined(ESPIPE) */
73  return (rc < 0) ? -1 : 0;
74 #endif /* defined(_WIN32) */
75 }
76 
77 /** Move <b>fd</b> to position <b>pos</b> in the file. Return -1 on error, 0
78  * on success. */
79 int
80 tor_fd_setpos(int fd, off_t pos)
81 {
82 #ifdef _WIN32
83  return _lseeki64(fd, pos, SEEK_SET) < 0 ? -1 : 0;
84 #else
85  return lseek(fd, pos, SEEK_SET) < 0 ? -1 : 0;
86 #endif
87 }
88 
89 /** Replacement for ftruncate(fd, 0): move to the front of the file and remove
90  * all the rest of the file. Return -1 on error, 0 on success. */
91 int
93 {
94  /* Rumor has it that some versions of ftruncate do not move the file pointer.
95  */
96  if (tor_fd_setpos(fd, 0) < 0)
97  return -1;
98 
99 #ifdef _WIN32
100  return _chsize(fd, 0);
101 #else
102  return ftruncate(fd, 0);
103 #endif
104 }
105 
106 /** Minimal version of write_all, for use by logging. */
107 int
108 write_all_to_fd_minimal(int fd, const char *buf, size_t count)
109 {
110  size_t written = 0;
111  raw_assert(count < SSIZE_MAX);
112 
113  while (written < count) {
114  ssize_t result = write(fd, buf+written, count-written);
115  if (result<0)
116  return -1;
117  written += result;
118  }
119  return 0;
120 }
torint.h
Integer definitions used throughout Tor.
tor_ftruncate
int tor_ftruncate(int fd)
Definition: fdio.c:92
write_all_to_fd_minimal
int write_all_to_fd_minimal(int fd, const char *buf, size_t count)
Definition: fdio.c:108
fdio.h
Header for fdio.c.
tor_fd_seekend
int tor_fd_seekend(int fd)
Definition: fdio.c:61
tor_fd_setpos
int tor_fd_setpos(int fd, off_t pos)
Definition: fdio.c:80
torerr.h
Headers for torerr.c.
tor_fd_getpos
off_t tor_fd_getpos(int fd)
Definition: fdio.c:48