1 /*
2  * Copyright (C) 2008 The Android Open Source Project
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  *  * Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  *  * Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in
12  *    the documentation and/or other materials provided with the
13  *    distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19  * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 #undef _FORTIFY_SOURCE
30 
31 #include <errno.h>
32 #include <fcntl.h>
33 #include <stdarg.h>
34 #include <sys/resource.h>
35 #include <sys/types.h>
36 #include <sys/uio.h>
37 #include <sys/vfs.h>
38 #include <unistd.h>
39 
40 #if __LP64__
41 #error This code is only needed on 32-bit systems!
42 #endif
43 
44 // System calls we need.
45 extern "C" int __fcntl64(int, int, void*);
46 extern "C" int __llseek(int, unsigned long, unsigned long, off64_t*, int);
47 extern "C" int __preadv64(int, const struct iovec*, int, long, long);
48 extern "C" int __pwritev64(int, const struct iovec*, int, long, long);
49 
50 // For fcntl we use the fcntl64 system call to signal that we're using struct flock64.
fcntl(int fd,int cmd,...)51 int fcntl(int fd, int cmd, ...) {
52   va_list ap;
53 
54   va_start(ap, cmd);
55   void* arg = va_arg(ap, void*);
56   va_end(ap);
57 
58   return __fcntl64(fd, cmd, arg);
59 }
60 
61 // For lseek64 we need to use the llseek system call which splits the off64_t in two and
62 // returns the off64_t result via a pointer because 32-bit kernels can't return 64-bit results.
lseek64(int fd,off64_t off,int whence)63 off64_t lseek64(int fd, off64_t off, int whence) {
64   off64_t result;
65   unsigned long off_hi = static_cast<unsigned long>(off >> 32);
66   unsigned long off_lo = static_cast<unsigned long>(off);
67   if (__llseek(fd, off_hi, off_lo, &result, whence) < 0) {
68     return -1;
69   }
70   return result;
71 }
72 
73 // There is no pread for 32-bit off_t, so we need to widen and call pread64.
pread(int fd,void * buf,size_t byte_count,off_t offset)74 ssize_t pread(int fd, void* buf, size_t byte_count, off_t offset) {
75   return pread64(fd, buf, byte_count, static_cast<off64_t>(offset));
76 }
77 
78 // There is no pwrite for 32-bit off_t, so we need to widen and call pwrite64.
pwrite(int fd,const void * buf,size_t byte_count,off_t offset)79 ssize_t pwrite(int fd, const void* buf, size_t byte_count, off_t offset) {
80   return pwrite64(fd, buf, byte_count, static_cast<off64_t>(offset));
81 }
82 
83 // On LP32, there is no off_t preadv/pwritev, and even the 64-bit preadv/pwritev
84 // don't use off64_t (see SYSCALLS.TXT for more). Here, this means that we need
85 // to implement all four functions because the two system calls don't match any
86 // of the userspace functions. Unlike llseek, the pair is split lo-hi, not hi-lo.
preadv(int fd,const struct iovec * ios,int count,off_t offset)87 ssize_t preadv(int fd, const struct iovec* ios, int count, off_t offset) {
88   return __preadv64(fd, ios, count, offset, 0);
89 }
preadv64(int fd,const struct iovec * ios,int count,off64_t offset)90 ssize_t preadv64(int fd, const struct iovec* ios, int count, off64_t offset) {
91   return __preadv64(fd, ios, count, offset, offset >> 32);
92 }
pwritev(int fd,const struct iovec * ios,int count,off_t offset)93 ssize_t pwritev(int fd, const struct iovec* ios, int count, off_t offset) {
94   return __pwritev64(fd, ios, count, offset, 0);
95 }
pwritev64(int fd,const struct iovec * ios,int count,off64_t offset)96 ssize_t pwritev64(int fd, const struct iovec* ios, int count, off64_t offset) {
97   return __pwritev64(fd, ios, count, offset, offset >> 32);
98 }
99 
100 // There is no fallocate for 32-bit off_t, so we need to widen and call fallocate64.
fallocate(int fd,int mode,off_t offset,off_t length)101 int fallocate(int fd, int mode, off_t offset, off_t length) {
102   return fallocate64(fd, mode, static_cast<off64_t>(offset), static_cast<off64_t>(length));
103 }
104 
105 // There is no getrlimit64 system call, so we need to use prlimit64.
getrlimit64(int resource,rlimit64 * limits64)106 int getrlimit64(int resource, rlimit64* limits64) {
107   return prlimit64(0, resource, NULL, limits64);
108 }
109 
110 // There is no setrlimit64 system call, so we need to use prlimit64.
setrlimit64(int resource,const rlimit64 * limits64)111 int setrlimit64(int resource, const rlimit64* limits64) {
112   return prlimit64(0, resource, limits64, NULL);
113 }
114 
115 // There is no prlimit system call, so we need to use prlimit64.
prlimit(pid_t pid,int resource,const rlimit * n32,rlimit * o32)116 int prlimit(pid_t pid, int resource, const rlimit* n32, rlimit* o32) {
117   rlimit64 n64;
118   if (n32 != nullptr) {
119     n64.rlim_cur = (n32->rlim_cur == RLIM_INFINITY) ? RLIM64_INFINITY : n32->rlim_cur;
120     n64.rlim_max = (n32->rlim_max == RLIM_INFINITY) ? RLIM64_INFINITY : n32->rlim_max;
121   }
122 
123   rlimit64 o64;
124   int result = prlimit64(pid, resource,
125                          (n32 != nullptr) ? &n64 : nullptr,
126                          (o32 != nullptr) ? &o64 : nullptr);
127   if (result != -1 && o32 != nullptr) {
128     o32->rlim_cur = (o64.rlim_cur == RLIM64_INFINITY) ? RLIM_INFINITY : o64.rlim_cur;
129     o32->rlim_max = (o64.rlim_max == RLIM64_INFINITY) ? RLIM_INFINITY : o64.rlim_max;
130   }
131   return result;
132 }
133