Commit | Line | Data |
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95e6d268 | 1 | /* |
c0c0989a | 2 | * SPDX-License-Identifier: LGPL-2.1-only |
95e6d268 | 3 | * |
c0c0989a | 4 | * Copyright (C) 2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
95e6d268 MD |
5 | */ |
6 | ||
95e6d268 MD |
7 | #define _LGPL_SOURCE |
8 | #include <limits.h> | |
9 | #include <stdio.h> | |
10 | #include <sys/types.h> | |
11 | #include <unistd.h> | |
95e6d268 | 12 | #include <dlfcn.h> |
58048764 | 13 | #include <errno.h> |
95e6d268 | 14 | |
fca97dfd MJ |
15 | #include <lttng/ust-common.h> |
16 | ||
9d315d6d | 17 | #include "common/macros.h" |
fca97dfd | 18 | #include "common/ust-fd.h" |
95e6d268 | 19 | |
58048764 | 20 | #define LTTNG_UST_DLSYM_FAILED_PTR 0x1 |
95e6d268 | 21 | |
58048764 MJ |
22 | static int (*__lttng_ust_fd_plibc_close)(int fd) = NULL; |
23 | static int (*__lttng_ust_fd_plibc_fclose)(FILE *stream) = NULL; | |
4b01076f MD |
24 | static int (*__lttng_ust_fd_plibc_close_range)(unsigned int first, |
25 | unsigned int last, int flags) = NULL; | |
fca97dfd | 26 | |
58048764 MJ |
27 | /* |
28 | * Use dlsym to find the original libc close() symbol and store it in | |
29 | * __lttng_ust_fd_plibc_close. | |
30 | */ | |
95e6d268 | 31 | static |
58048764 | 32 | void *_lttng_ust_fd_init_plibc_close(void) |
95e6d268 | 33 | { |
58048764 | 34 | if (__lttng_ust_fd_plibc_close == NULL) { |
95e6d268 | 35 | __lttng_ust_fd_plibc_close = dlsym(RTLD_NEXT, "close"); |
58048764 MJ |
36 | |
37 | if (__lttng_ust_fd_plibc_close == NULL) { | |
38 | __lttng_ust_fd_plibc_close = (void *) LTTNG_UST_DLSYM_FAILED_PTR; | |
95e6d268 | 39 | fprintf(stderr, "%s\n", dlerror()); |
95e6d268 MD |
40 | } |
41 | } | |
58048764 MJ |
42 | |
43 | return __lttng_ust_fd_plibc_close; | |
95e6d268 MD |
44 | } |
45 | ||
58048764 MJ |
46 | /* |
47 | * Use dlsym to find the original libc fclose() symbol and store it in | |
48 | * __lttng_ust_fd_plibc_fclose. | |
49 | */ | |
52a20dc7 | 50 | static |
58048764 | 51 | void *_lttng_ust_fd_init_plibc_fclose(void) |
52a20dc7 | 52 | { |
58048764 | 53 | if (__lttng_ust_fd_plibc_fclose == NULL) { |
52a20dc7 | 54 | __lttng_ust_fd_plibc_fclose = dlsym(RTLD_NEXT, "fclose"); |
58048764 MJ |
55 | |
56 | if (__lttng_ust_fd_plibc_fclose == NULL) { | |
57 | __lttng_ust_fd_plibc_fclose = (void *) LTTNG_UST_DLSYM_FAILED_PTR; | |
52a20dc7 | 58 | fprintf(stderr, "%s\n", dlerror()); |
52a20dc7 MD |
59 | } |
60 | } | |
58048764 MJ |
61 | |
62 | return __lttng_ust_fd_plibc_fclose; | |
52a20dc7 MD |
63 | } |
64 | ||
4b01076f MD |
65 | /* |
66 | * Use dlsym to find the original libc close_range() symbol and store it | |
67 | * in __lttng_ust_fd_plibc_close_range. The close_range symbol only | |
68 | * appears in glibc 2.34, so it is considered optional. | |
69 | */ | |
70 | static | |
71 | void *_lttng_ust_fd_init_plibc_close_range(void) | |
72 | { | |
73 | if (__lttng_ust_fd_plibc_close_range == NULL) { | |
74 | __lttng_ust_fd_plibc_close_range = dlsym(RTLD_NEXT, "close_range"); | |
75 | ||
76 | if (__lttng_ust_fd_plibc_close_range == NULL) | |
77 | __lttng_ust_fd_plibc_close_range = (void *) LTTNG_UST_DLSYM_FAILED_PTR; | |
78 | } | |
79 | ||
80 | return __lttng_ust_fd_plibc_close_range; | |
81 | } | |
82 | ||
58048764 MJ |
83 | static |
84 | void _lttng_ust_fd_ctor(void) | |
85 | __attribute__((constructor)); | |
86 | static | |
87 | void _lttng_ust_fd_ctor(void) | |
88 | { | |
89 | lttng_ust_common_ctor(); | |
90 | ||
91 | /* | |
92 | * Initialize the function pointers to the original libc symbols in the | |
93 | * constructor since close() has to stay async-signal-safe and as such, | |
94 | * we can't call dlsym() in the override functions. | |
95 | */ | |
96 | (void) _lttng_ust_fd_init_plibc_close(); | |
97 | (void) _lttng_ust_fd_init_plibc_fclose(); | |
4b01076f | 98 | (void) _lttng_ust_fd_init_plibc_close_range(); |
58048764 MJ |
99 | } |
100 | ||
101 | /* | |
102 | * Override the libc close() symbol with our own, allowing applications to | |
103 | * close arbitrary file descriptors. If the fd is owned by lttng-ust, return | |
104 | * -1, errno=EBADF instead of closing it. | |
105 | * | |
106 | * If dlsym failed to find the original libc close() symbol, return -1, | |
107 | * errno=ENOSYS. | |
108 | * | |
109 | * There is a short window before the library constructor has executed where | |
110 | * this wrapper could call dlsym() and thus not be async-signal-safe. | |
111 | */ | |
95e6d268 MD |
112 | int close(int fd) |
113 | { | |
58048764 MJ |
114 | /* |
115 | * We can't retry dlsym here since close is async-signal-safe. | |
116 | */ | |
117 | if (_lttng_ust_fd_init_plibc_close() == (void *) LTTNG_UST_DLSYM_FAILED_PTR) { | |
118 | errno = ENOSYS; | |
119 | return -1; | |
120 | } | |
121 | ||
122 | return lttng_ust_safe_close_fd(fd, __lttng_ust_fd_plibc_close); | |
95e6d268 MD |
123 | } |
124 | ||
52a20dc7 | 125 | /* |
58048764 MJ |
126 | * Override the libc fclose() symbol with our own, allowing applications to |
127 | * close arbitrary streams. If the fd is owned by lttng-ust, return -1, | |
128 | * errno=EBADF instead of closing it. | |
129 | * | |
130 | * If dlsym failed to find the original libc close() symbol, return -1, | |
131 | * errno=ENOSYS. | |
132 | * | |
133 | * There is a short window before the library constructor has executed where | |
134 | * this wrapper could call dlsym() and thus not be async-signal-safe. | |
135 | * | |
136 | * Note: fcloseall() is not an issue because it closes only the streams it | |
137 | * knows about, which differs from the problems caused by gnulib | |
138 | * close_stdout(), which does an explicit fclose(stdout). | |
52a20dc7 MD |
139 | */ |
140 | int fclose(FILE *stream) | |
141 | { | |
58048764 MJ |
142 | if (_lttng_ust_fd_init_plibc_fclose() == (void *) LTTNG_UST_DLSYM_FAILED_PTR) { |
143 | errno = ENOSYS; | |
144 | return -1; | |
145 | } | |
146 | ||
147 | return lttng_ust_safe_fclose_stream(stream, | |
148 | __lttng_ust_fd_plibc_fclose); | |
52a20dc7 MD |
149 | } |
150 | ||
4b01076f MD |
151 | /* |
152 | * Override the libc close_range() symbol with our own, allowing | |
153 | * applications to close arbitrary file descriptors. If the fd is owned | |
154 | * by lttng-ust, return -1, errno=EBADF instead of closing it. | |
155 | * | |
156 | * If dlsym failed to find the original libc close_range() symbol, | |
157 | * return -1, errno=ENOSYS. | |
158 | * | |
159 | * There is a short window before the library constructor has executed where | |
160 | * this wrapper could call dlsym() and thus not be async-signal-safe. | |
161 | */ | |
162 | int close_range(unsigned int first, unsigned int last, int flags) | |
163 | { | |
164 | /* | |
165 | * We can't retry dlsym here since close is async-signal-safe. | |
166 | */ | |
167 | if (_lttng_ust_fd_init_plibc_close_range() == (void *) LTTNG_UST_DLSYM_FAILED_PTR) { | |
168 | errno = ENOSYS; | |
169 | return -1; | |
170 | } | |
171 | ||
172 | return lttng_ust_safe_close_range_fd(first, last, flags, __lttng_ust_fd_plibc_close_range); | |
173 | } | |
174 | ||
95e6d268 MD |
175 | #if defined(__sun__) || defined(__FreeBSD__) |
176 | /* Solaris and FreeBSD. */ | |
177 | void closefrom(int lowfd) | |
178 | { | |
58048764 MJ |
179 | if (_lttng_ust_fd_init_plibc_close() == (void *) LTTNG_UST_DLSYM_FAILED_PTR) { |
180 | return; | |
181 | } | |
182 | ||
23366626 | 183 | (void) lttng_ust_safe_closefrom_fd(lowfd, __lttng_ust_fd_plibc_close); |
95e6d268 MD |
184 | } |
185 | #elif defined(__NetBSD__) || defined(__OpenBSD__) | |
186 | /* NetBSD and OpenBSD. */ | |
187 | int closefrom(int lowfd) | |
188 | { | |
58048764 MJ |
189 | if (_lttng_ust_fd_init_plibc_close() == (void *) LTTNG_UST_DLSYM_FAILED_PTR) { |
190 | errno = ENOSYS; | |
191 | return -1; | |
192 | } | |
193 | ||
23366626 | 194 | return lttng_ust_safe_closefrom_fd(lowfd, __lttng_ust_fd_plibc_close); |
95e6d268 MD |
195 | } |
196 | #else | |
197 | /* As far as we know, this OS does not implement closefrom. */ | |
198 | #endif |