1 /* fsusage.c -- return space usage of mounted file systems
2
3 Copyright (C) 1991-1992, 1996, 1998-1999, 2002-2006, 2009-2023 Free Software
4 Foundation, Inc.
5
6 This file is free software: you can redistribute it and/or modify
7 it under the terms of the GNU Lesser General Public License as
8 published by the Free Software Foundation, either version 3 of the
9 License, or (at your option) any later version.
10
11 This file is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public License
17 along with this program. If not, see <https://www.gnu.org/licenses/>. */
18
19 #include <config.h>
20
21 #include "fsusage.h"
22
23 #include <limits.h>
24 #include <sys/types.h>
25
26 #if STAT_STATVFS || STAT_STATVFS64 /* POSIX 1003.1-2001 (and later) with XSI */
27 # include <sys/statvfs.h>
28 #else
29 /* Don't include backward-compatibility files unless they're needed.
30 Eventually we'd like to remove all this cruft. */
31 # include <fcntl.h>
32 # include <unistd.h>
33 # include <sys/stat.h>
34 #if HAVE_SYS_PARAM_H
35 # include <sys/param.h>
36 #endif
37 #if HAVE_SYS_MOUNT_H
38 # include <sys/mount.h>
39 #endif
40 #if HAVE_SYS_VFS_H
41 # include <sys/vfs.h>
42 #endif
43 # if HAVE_SYS_FS_S5PARAM_H /* Fujitsu UXP/V */
44 # include <sys/fs/s5param.h>
45 # endif
46 # if HAVE_SYS_STATFS_H
47 # include <sys/statfs.h>
48 # endif
49 #endif
50
51 /* Many space usage primitives use all 1 bits to denote a value that is
52 not applicable or unknown. Propagate this information by returning
53 a uintmax_t value that is all 1 bits if X is all 1 bits, even if X
54 is unsigned and narrower than uintmax_t. */
55 #define PROPAGATE_ALL_ONES(x) \
56 ((sizeof (x) < sizeof (uintmax_t) \
57 && (~ (x) == (sizeof (x) < sizeof (int) \
58 ? - (1 << (sizeof (x) * CHAR_BIT)) \
59 : 0))) \
60 ? UINTMAX_MAX : (uintmax_t) (x))
61
62 /* Extract the top bit of X as an uintmax_t value. */
63 #define EXTRACT_TOP_BIT(x) ((x) \
64 & ((uintmax_t) 1 << (sizeof (x) * CHAR_BIT - 1)))
65
66 /* If a value is negative, many space usage primitives store it into an
67 integer variable by assignment, even if the variable's type is unsigned.
68 So, if a space usage variable X's top bit is set, convert X to the
69 uintmax_t value V such that (- (uintmax_t) V) is the negative of
70 the original value. If X's top bit is clear, just yield X.
71 Use PROPAGATE_TOP_BIT if the original value might be negative;
72 otherwise, use PROPAGATE_ALL_ONES. */
73 #define PROPAGATE_TOP_BIT(x) ((x) | ~ (EXTRACT_TOP_BIT (x) - 1))
74
75 #ifdef STAT_STATVFS
76 /* Return true if statvfs works. This is false for statvfs on systems
77 with GNU libc on Linux kernels before 2.6.36, which stats all
78 preceding entries in /proc/mounts; that makes df hang if even one
79 of the corresponding file systems is hard-mounted but not available. */
80 # if ! (__linux__ && (__GLIBC__ || __UCLIBC__))
81 /* The FRSIZE fallback is not required in this case. */
82 # undef STAT_STATFS2_FRSIZE
83 static int statvfs_works (void) { return 1; }
84 # else
85 # include <string.h> /* for strverscmp */
86 # include <sys/utsname.h>
87 # include <sys/statfs.h>
88 # define STAT_STATFS2_BSIZE 1
89
90 static int
91 statvfs_works (void)
92 {
93 static int statvfs_works_cache = -1;
94 struct utsname name;
95 if (statvfs_works_cache < 0)
96 statvfs_works_cache = (uname (&name) == 0
97 && 0 <= strverscmp (name.release, "2.6.36"));
98 return statvfs_works_cache;
99 }
100 # endif
101 #endif
102
103
104 /* Fill in the fields of FSP with information about space usage for
105 the file system on which FILE resides.
106 DISK is the device on which FILE is mounted, for space-getting
107 methods that need to know it.
108 Return 0 if successful, -1 if not. When returning -1, ensure that
109 ERRNO is either a system error value, or zero if DISK is NULL
110 on a system that requires a non-NULL value. */
111 int
112 get_fs_usage (char const *file, char const *disk, struct fs_usage *fsp)
113 {
114 #ifdef STAT_STATVFS /* POSIX, except pre-2.6.36 glibc/Linux */
115
116 if (statvfs_works ())
117 {
118 struct statvfs vfsd;
119
120 if (statvfs (file, &vfsd) < 0)
121 return -1;
122
123 /* f_frsize isn't guaranteed to be supported. */
124 fsp->fsu_blocksize = (vfsd.f_frsize
125 ? PROPAGATE_ALL_ONES (vfsd.f_frsize)
126 : PROPAGATE_ALL_ONES (vfsd.f_bsize));
127
128 fsp->fsu_blocks = PROPAGATE_ALL_ONES (vfsd.f_blocks);
129 fsp->fsu_bfree = PROPAGATE_ALL_ONES (vfsd.f_bfree);
130 fsp->fsu_bavail = PROPAGATE_TOP_BIT (vfsd.f_bavail);
131 fsp->fsu_bavail_top_bit_set = EXTRACT_TOP_BIT (vfsd.f_bavail) != 0;
132 fsp->fsu_files = PROPAGATE_ALL_ONES (vfsd.f_files);
133 fsp->fsu_ffree = PROPAGATE_ALL_ONES (vfsd.f_ffree);
134 return 0;
135 }
136
137 #endif
138
139 #if defined STAT_STATVFS64 /* AIX */
140
141 struct statvfs64 fsd;
142
143 if (statvfs64 (file, &fsd) < 0)
144 return -1;
145
146 /* f_frsize isn't guaranteed to be supported. */
147 fsp->fsu_blocksize = (fsd.f_frsize
148 ? PROPAGATE_ALL_ONES (fsd.f_frsize)
149 : PROPAGATE_ALL_ONES (fsd.f_bsize));
150
151 #elif defined STAT_STATFS3_OSF1 /* OSF/1 */
152
153 struct statfs fsd;
154
155 if (statfs (file, &fsd, sizeof (struct statfs)) != 0)
156 return -1;
157
158 fsp->fsu_blocksize = PROPAGATE_ALL_ONES (fsd.f_fsize);
159
160 #elif defined STAT_STATFS2_FRSIZE /* 2.6 < glibc/Linux < 2.6.36 */
161
162 struct statfs fsd;
163
164 if (statfs (file, &fsd) < 0)
165 return -1;
166
167 fsp->fsu_blocksize = PROPAGATE_ALL_ONES (fsd.f_frsize);
168
169 #elif defined STAT_STATFS2_BSIZE /* glibc/Linux < 2.6, 4.3BSD, SunOS 4, \
170 Mac OS X < 10.4, FreeBSD < 5.0, \
171 NetBSD < 3.0, OpenBSD < 4.4 */
172
173 struct statfs fsd;
174
175 if (statfs (file, &fsd) < 0)
176 return -1;
177
178 fsp->fsu_blocksize = PROPAGATE_ALL_ONES (fsd.f_bsize);
179
180 # ifdef STATFS_TRUNCATES_BLOCK_COUNTS
181
182 /* In SunOS 4.1.2, 4.1.3, and 4.1.3_U1, the block counts in the
183 struct statfs are truncated to 2GB. These conditions detect that
184 truncation, presumably without botching the 4.1.1 case, in which
185 the values are not truncated. The correct counts are stored in
186 undocumented spare fields. */
187 if (fsd.f_blocks == 0x7fffffff / fsd.f_bsize && fsd.f_spare[0] > 0)
188 {
189 fsd.f_blocks = fsd.f_spare[0];
190 fsd.f_bfree = fsd.f_spare[1];
191 fsd.f_bavail = fsd.f_spare[2];
192 }
193 # endif /* STATFS_TRUNCATES_BLOCK_COUNTS */
194
195 #elif defined STAT_STATFS2_FSIZE /* 4.4BSD and older NetBSD */
196
197 struct statfs fsd;
198
199 if (statfs (file, &fsd) < 0)
200 return -1;
201
202 fsp->fsu_blocksize = PROPAGATE_ALL_ONES (fsd.f_fsize);
203
204 #elif defined STAT_STATFS4 /* SVR3, old Irix */
205
206 struct statfs fsd;
207
208 if (statfs (file, &fsd, sizeof fsd, 0) < 0)
209 return -1;
210
211 /* Empirically, the block counts on most SVR3 and SVR3-derived
212 systems seem to always be in terms of 512-byte blocks,
213 no matter what value f_bsize has. */
214 fsp->fsu_blocksize = 512;
215
216 #endif
217
218 #if (defined STAT_STATVFS64 || defined STAT_STATFS3_OSF1 \
219 || defined STAT_STATFS2_FRSIZE || defined STAT_STATFS2_BSIZE \
220 || defined STAT_STATFS2_FSIZE || defined STAT_STATFS4)
221
222 fsp->fsu_blocks = PROPAGATE_ALL_ONES (fsd.f_blocks);
223 fsp->fsu_bfree = PROPAGATE_ALL_ONES (fsd.f_bfree);
224 fsp->fsu_bavail = PROPAGATE_TOP_BIT (fsd.f_bavail);
225 fsp->fsu_bavail_top_bit_set = EXTRACT_TOP_BIT (fsd.f_bavail) != 0;
226 fsp->fsu_files = PROPAGATE_ALL_ONES (fsd.f_files);
227 fsp->fsu_ffree = PROPAGATE_ALL_ONES (fsd.f_ffree);
228
229 #endif
230
231 (void) disk; /* avoid argument-unused warning */
232 return 0;
233 }