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Diffstat (limited to 'gl/ftello.c')
-rw-r--r-- | gl/ftello.c | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/gl/ftello.c b/gl/ftello.c new file mode 100644 index 0000000..14184e5 --- /dev/null +++ b/gl/ftello.c | |||
@@ -0,0 +1,157 @@ | |||
1 | /* An ftello() function that works around platform bugs. | ||
2 | Copyright (C) 2007, 2009-2023 Free Software Foundation, Inc. | ||
3 | |||
4 | This file is free software: you can redistribute it and/or modify | ||
5 | it under the terms of the GNU Lesser General Public License as | ||
6 | published by the Free Software Foundation; either version 2.1 of the | ||
7 | License, or (at your option) any later version. | ||
8 | |||
9 | This file is distributed in the hope that it will be useful, | ||
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
12 | GNU Lesser General Public License for more details. | ||
13 | |||
14 | You should have received a copy of the GNU Lesser General Public License | ||
15 | along with this program. If not, see <https://www.gnu.org/licenses/>. */ | ||
16 | |||
17 | #include <config.h> | ||
18 | |||
19 | /* Specification. */ | ||
20 | #include <stdio.h> | ||
21 | |||
22 | #include <errno.h> | ||
23 | #include "intprops.h" | ||
24 | |||
25 | /* Get lseek. */ | ||
26 | #include <unistd.h> | ||
27 | |||
28 | #include "stdio-impl.h" | ||
29 | |||
30 | off_t | ||
31 | ftello (FILE *fp) | ||
32 | #undef ftello | ||
33 | #if !HAVE_FTELLO | ||
34 | # undef ftell | ||
35 | # define ftello ftell | ||
36 | #endif | ||
37 | #if _GL_WINDOWS_64_BIT_OFF_T | ||
38 | # undef ftello | ||
39 | # if HAVE__FTELLI64 /* msvc, mingw64 */ | ||
40 | # define ftello _ftelli64 | ||
41 | # else /* mingw */ | ||
42 | # define ftello ftello64 | ||
43 | # endif | ||
44 | #endif | ||
45 | { | ||
46 | #if FTELLO_BROKEN_AFTER_UNGETC /* macOS >= 10.15 */ | ||
47 | /* The system's ftello() is completely broken, because it calls __sflush, | ||
48 | which makes side effects on the stream. */ | ||
49 | |||
50 | /* Handle non-seekable files first. */ | ||
51 | if (fp->_file < 0 || fp->_seek == NULL) | ||
52 | { | ||
53 | errno = ESPIPE; | ||
54 | return -1; | ||
55 | } | ||
56 | |||
57 | /* Determine the current offset, ignoring buffered and pushed-back bytes. */ | ||
58 | off_t pos; | ||
59 | |||
60 | if (fp->_flags & __SOFF) | ||
61 | pos = fp->_offset; | ||
62 | else | ||
63 | { | ||
64 | pos = fp->_seek (fp->_cookie, 0, SEEK_CUR); | ||
65 | if (pos < 0) | ||
66 | return -1; | ||
67 | if (fp->_flags & __SOPT) | ||
68 | { | ||
69 | fp->_offset = pos; | ||
70 | fp->_flags |= __SOFF; | ||
71 | } | ||
72 | } | ||
73 | |||
74 | if (fp->_flags & __SRD) | ||
75 | { | ||
76 | /* Now consider buffered and pushed-back bytes from ungetc. */ | ||
77 | if (fp->_ub._base != NULL) | ||
78 | /* Considering the buffered bytes, we are at position | ||
79 | pos - fp->_ur. | ||
80 | Considering also the pushed-back bytes, we are at position | ||
81 | pos - fp->_ur - fp->_r. */ | ||
82 | pos = pos - fp->_ur - fp->_r; | ||
83 | else | ||
84 | /* Considering the buffered bytes, we are at position | ||
85 | pos - fp->_r. */ | ||
86 | pos = pos - fp->_r; | ||
87 | if (pos < 0) | ||
88 | { | ||
89 | errno = EIO; | ||
90 | return -1; | ||
91 | } | ||
92 | } | ||
93 | else if ((fp->_flags & __SWR) && fp->_p != NULL) | ||
94 | { | ||
95 | /* Consider the buffered bytes. */ | ||
96 | off_t buffered = fp->_p - fp->_bf._base; | ||
97 | |||
98 | /* Compute pos + buffered, with overflow check. */ | ||
99 | off_t sum; | ||
100 | if (! INT_ADD_OK (pos, buffered, &sum)) | ||
101 | { | ||
102 | errno = EOVERFLOW; | ||
103 | return -1; | ||
104 | } | ||
105 | pos = sum; | ||
106 | } | ||
107 | |||
108 | return pos; | ||
109 | |||
110 | #else | ||
111 | |||
112 | # if LSEEK_PIPE_BROKEN | ||
113 | /* mingw gives bogus answers rather than failure on non-seekable files. */ | ||
114 | if (lseek (fileno (fp), 0, SEEK_CUR) == -1) | ||
115 | return -1; | ||
116 | # endif | ||
117 | |||
118 | # if FTELLO_BROKEN_AFTER_SWITCHING_FROM_READ_TO_WRITE /* Solaris */ | ||
119 | /* The Solaris stdio leaves the _IOREAD flag set after reading from a file | ||
120 | reaches EOF and the program then starts writing to the file. ftello | ||
121 | gets confused by this. */ | ||
122 | if (fp_->_flag & _IOWRT) | ||
123 | { | ||
124 | off_t pos; | ||
125 | |||
126 | /* Call ftello nevertheless, for the side effects that it does on fp. */ | ||
127 | ftello (fp); | ||
128 | |||
129 | /* Compute the file position ourselves. */ | ||
130 | pos = lseek (fileno (fp), (off_t) 0, SEEK_CUR); | ||
131 | if (pos >= 0) | ||
132 | { | ||
133 | if ((fp_->_flag & _IONBF) == 0 && fp_->_base != NULL) | ||
134 | pos += fp_->_ptr - fp_->_base; | ||
135 | } | ||
136 | return pos; | ||
137 | } | ||
138 | # endif | ||
139 | |||
140 | # if defined __SL64 && defined __SCLE /* Cygwin */ | ||
141 | if ((fp->_flags & __SL64) == 0) | ||
142 | { | ||
143 | /* Cygwin 1.5.0 through 1.5.24 failed to open stdin in 64-bit | ||
144 | mode; but has an ftello that requires 64-bit mode. */ | ||
145 | FILE *tmp = fopen ("/dev/null", "r"); | ||
146 | if (!tmp) | ||
147 | return -1; | ||
148 | fp->_flags |= __SL64; | ||
149 | fp->_seek64 = tmp->_seek64; | ||
150 | fclose (tmp); | ||
151 | } | ||
152 | # endif | ||
153 | |||
154 | return ftello (fp); | ||
155 | |||
156 | #endif | ||
157 | } | ||