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95e6d268 MD |
1 | /* |
2 | * Copyright (C) 2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
3 | * | |
4 | * This library is free software; you can redistribute it and/or | |
5 | * modify it under the terms of the GNU Lesser General Public | |
6 | * License as published by the Free Software Foundation; version 2.1 of | |
7 | * the License. | |
8 | * | |
9 | * This library 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 GNU | |
12 | * Lesser General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU Lesser General Public | |
15 | * License along with this library; if not, write to the Free Software | |
16 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
17 | */ | |
18 | ||
19 | #define _GNU_SOURCE | |
20 | #define _LGPL_SOURCE | |
21 | #include <limits.h> | |
22 | #include <stdio.h> | |
23 | #include <sys/types.h> | |
24 | #include <unistd.h> | |
25 | #include <ust-fd.h> | |
26 | #include <dlfcn.h> | |
c668ba47 | 27 | #include <errno.h> |
95e6d268 MD |
28 | |
29 | #include <helper.h> | |
30 | #include "usterr-signal-safe.h" | |
31 | ||
c668ba47 | 32 | #define LTTNG_UST_DLSYM_FAILED_PTR 0x1 |
95e6d268 | 33 | |
c668ba47 MJ |
34 | static int (*__lttng_ust_fd_plibc_close)(int fd) = NULL; |
35 | static int (*__lttng_ust_fd_plibc_fclose)(FILE *stream) = NULL; | |
26be1417 MD |
36 | static int (*__lttng_ust_fd_plibc_close_range)(unsigned int first, |
37 | unsigned int last, int flags) = NULL; | |
c668ba47 MJ |
38 | |
39 | /* | |
40 | * Use dlsym to find the original libc close() symbol and store it in | |
41 | * __lttng_ust_fd_plibc_close. | |
42 | */ | |
95e6d268 | 43 | static |
c668ba47 | 44 | void *_lttng_ust_fd_init_plibc_close(void) |
95e6d268 | 45 | { |
c668ba47 | 46 | if (__lttng_ust_fd_plibc_close == NULL) { |
95e6d268 | 47 | __lttng_ust_fd_plibc_close = dlsym(RTLD_NEXT, "close"); |
c668ba47 MJ |
48 | |
49 | if (__lttng_ust_fd_plibc_close == NULL) { | |
50 | __lttng_ust_fd_plibc_close = (void *) LTTNG_UST_DLSYM_FAILED_PTR; | |
95e6d268 | 51 | fprintf(stderr, "%s\n", dlerror()); |
95e6d268 MD |
52 | } |
53 | } | |
c668ba47 MJ |
54 | |
55 | return __lttng_ust_fd_plibc_close; | |
95e6d268 MD |
56 | } |
57 | ||
c668ba47 MJ |
58 | /* |
59 | * Use dlsym to find the original libc fclose() symbol and store it in | |
60 | * __lttng_ust_fd_plibc_fclose. | |
61 | */ | |
52a20dc7 | 62 | static |
c668ba47 | 63 | void *_lttng_ust_fd_init_plibc_fclose(void) |
52a20dc7 | 64 | { |
c668ba47 | 65 | if (__lttng_ust_fd_plibc_fclose == NULL) { |
52a20dc7 | 66 | __lttng_ust_fd_plibc_fclose = dlsym(RTLD_NEXT, "fclose"); |
c668ba47 MJ |
67 | |
68 | if (__lttng_ust_fd_plibc_fclose == NULL) { | |
69 | __lttng_ust_fd_plibc_fclose = (void *) LTTNG_UST_DLSYM_FAILED_PTR; | |
52a20dc7 | 70 | fprintf(stderr, "%s\n", dlerror()); |
52a20dc7 MD |
71 | } |
72 | } | |
c668ba47 MJ |
73 | |
74 | return __lttng_ust_fd_plibc_fclose; | |
75 | } | |
76 | ||
26be1417 MD |
77 | /* |
78 | * Use dlsym to find the original libc close_range() symbol and store it | |
79 | * in __lttng_ust_fd_plibc_close_range. The close_range symbol only | |
80 | * appears in glibc 2.34, so it is considered optional. | |
81 | */ | |
82 | static | |
83 | void *_lttng_ust_fd_init_plibc_close_range(void) | |
84 | { | |
85 | if (__lttng_ust_fd_plibc_close_range == NULL) { | |
86 | __lttng_ust_fd_plibc_close_range = dlsym(RTLD_NEXT, "close_range"); | |
87 | ||
88 | if (__lttng_ust_fd_plibc_close_range == NULL) | |
89 | __lttng_ust_fd_plibc_close_range = (void *) LTTNG_UST_DLSYM_FAILED_PTR; | |
90 | } | |
91 | ||
92 | return __lttng_ust_fd_plibc_close_range; | |
93 | } | |
94 | ||
c668ba47 MJ |
95 | static |
96 | void _lttng_ust_fd_ctor(void) | |
97 | __attribute__((constructor)); | |
98 | static | |
99 | void _lttng_ust_fd_ctor(void) | |
100 | { | |
c668ba47 MJ |
101 | /* |
102 | * Initialize the function pointers to the original libc symbols in the | |
103 | * constructor since close() has to stay async-signal-safe and as such, | |
104 | * we can't call dlsym() in the override functions. | |
105 | */ | |
106 | (void) _lttng_ust_fd_init_plibc_close(); | |
107 | (void) _lttng_ust_fd_init_plibc_fclose(); | |
26be1417 | 108 | (void) _lttng_ust_fd_init_plibc_close_range(); |
52a20dc7 MD |
109 | } |
110 | ||
c668ba47 MJ |
111 | /* |
112 | * Override the libc close() symbol with our own, allowing applications to | |
113 | * close arbitrary file descriptors. If the fd is owned by lttng-ust, return | |
114 | * -1, errno=EBADF instead of closing it. | |
115 | * | |
116 | * If dlsym failed to find the original libc close() symbol, return -1, | |
117 | * errno=ENOSYS. | |
118 | * | |
119 | * There is a short window before the library constructor has executed where | |
120 | * this wrapper could call dlsym() and thus not be async-signal-safe. | |
121 | */ | |
95e6d268 MD |
122 | int close(int fd) |
123 | { | |
c668ba47 MJ |
124 | /* |
125 | * We can't retry dlsym here since close is async-signal-safe. | |
126 | */ | |
127 | if (_lttng_ust_fd_init_plibc_close() == (void *) LTTNG_UST_DLSYM_FAILED_PTR) { | |
128 | errno = ENOSYS; | |
129 | return -1; | |
130 | } | |
131 | ||
132 | return lttng_ust_safe_close_fd(fd, __lttng_ust_fd_plibc_close); | |
95e6d268 MD |
133 | } |
134 | ||
52a20dc7 | 135 | /* |
c668ba47 MJ |
136 | * Override the libc fclose() symbol with our own, allowing applications to |
137 | * close arbitrary streams. If the fd is owned by lttng-ust, return -1, | |
138 | * errno=EBADF instead of closing it. | |
139 | * | |
140 | * If dlsym failed to find the original libc close() symbol, return -1, | |
141 | * errno=ENOSYS. | |
142 | * | |
143 | * There is a short window before the library constructor has executed where | |
144 | * this wrapper could call dlsym() and thus not be async-signal-safe. | |
145 | * | |
146 | * Note: fcloseall() is not an issue because it closes only the streams it | |
147 | * knows about, which differs from the problems caused by gnulib | |
148 | * close_stdout(), which does an explicit fclose(stdout). | |
52a20dc7 MD |
149 | */ |
150 | int fclose(FILE *stream) | |
151 | { | |
c668ba47 MJ |
152 | if (_lttng_ust_fd_init_plibc_fclose() == (void *) LTTNG_UST_DLSYM_FAILED_PTR) { |
153 | errno = ENOSYS; | |
154 | return -1; | |
155 | } | |
156 | ||
157 | return lttng_ust_safe_fclose_stream(stream, | |
158 | __lttng_ust_fd_plibc_fclose); | |
52a20dc7 MD |
159 | } |
160 | ||
26be1417 MD |
161 | /* |
162 | * Override the libc close_range() symbol with our own, allowing | |
163 | * applications to close arbitrary file descriptors. If the fd is owned | |
164 | * by lttng-ust, return -1, errno=EBADF instead of closing it. | |
165 | * | |
166 | * If dlsym failed to find the original libc close_range() symbol, | |
167 | * return -1, errno=ENOSYS. | |
168 | * | |
169 | * There is a short window before the library constructor has executed where | |
170 | * this wrapper could call dlsym() and thus not be async-signal-safe. | |
171 | */ | |
172 | int close_range(unsigned int first, unsigned int last, int flags) | |
173 | { | |
174 | /* | |
175 | * We can't retry dlsym here since close is async-signal-safe. | |
176 | */ | |
177 | if (_lttng_ust_fd_init_plibc_close_range() == (void *) LTTNG_UST_DLSYM_FAILED_PTR) { | |
178 | errno = ENOSYS; | |
179 | return -1; | |
180 | } | |
181 | ||
182 | return lttng_ust_safe_close_range_fd(first, last, flags, __lttng_ust_fd_plibc_close_range); | |
183 | } | |
184 | ||
95e6d268 MD |
185 | #if defined(__sun__) || defined(__FreeBSD__) |
186 | /* Solaris and FreeBSD. */ | |
187 | void closefrom(int lowfd) | |
188 | { | |
c668ba47 MJ |
189 | if (_lttng_ust_fd_init_plibc_close() == (void *) LTTNG_UST_DLSYM_FAILED_PTR) { |
190 | return; | |
191 | } | |
192 | ||
193 | (void) lttng_ust_safe_closefrom_fd(lowfd, __lttng_ust_fd_plibc_close); | |
95e6d268 MD |
194 | } |
195 | #elif defined(__NetBSD__) || defined(__OpenBSD__) | |
196 | /* NetBSD and OpenBSD. */ | |
197 | int closefrom(int lowfd) | |
198 | { | |
c668ba47 MJ |
199 | if (_lttng_ust_fd_init_plibc_close() == (void *) LTTNG_UST_DLSYM_FAILED_PTR) { |
200 | errno = ENOSYS; | |
201 | return -1; | |
202 | } | |
203 | ||
204 | return lttng_ust_safe_closefrom_fd(lowfd, __lttng_ust_fd_plibc_close); | |
95e6d268 MD |
205 | } |
206 | #else | |
207 | /* As far as we know, this OS does not implement closefrom. */ | |
208 | #endif |