1 /*
2 * Copyright 2019 Intel Corporation
3 * SPDX-License-Identifier: MIT
4 */
5
6 #include "os_file.h"
7 #include "detect_os.h"
8
9 #include <errno.h>
10 #include <fcntl.h>
11 #include <stdlib.h>
12 #include <sys/stat.h>
13
14 #if DETECT_OS_WINDOWS
15 #include <io.h>
16 #define open _open
17 #define fdopen _fdopen
18 #define O_CREAT _O_CREAT
19 #define O_EXCL _O_EXCL
20 #define O_WRONLY _O_WRONLY
21 #else
22 #include <unistd.h>
23 #ifndef F_DUPFD_CLOEXEC
24 #define F_DUPFD_CLOEXEC 1030
25 #endif
26 #endif
27
28
29 FILE *
os_file_create_unique(const char * filename,int filemode)30 os_file_create_unique(const char *filename, int filemode)
31 {
32 int fd = open(filename, O_CREAT | O_EXCL | O_WRONLY, filemode);
33 if (fd == -1)
34 return NULL;
35 return fdopen(fd, "w");
36 }
37
38
39 #if DETECT_OS_WINDOWS
40 int
os_dupfd_cloexec(int fd)41 os_dupfd_cloexec(int fd)
42 {
43 /*
44 * On Windows child processes don't inherit handles by default:
45 * https://devblogs.microsoft.com/oldnewthing/20111216-00/?p=8873
46 */
47 return dup(fd);
48 }
49 #else
50 int
os_dupfd_cloexec(int fd)51 os_dupfd_cloexec(int fd)
52 {
53 int minfd = 3;
54 int newfd = fcntl(fd, F_DUPFD_CLOEXEC, minfd);
55
56 if (newfd >= 0)
57 return newfd;
58
59 if (errno != EINVAL)
60 return -1;
61
62 newfd = fcntl(fd, F_DUPFD, minfd);
63
64 if (newfd < 0)
65 return -1;
66
67 long flags = fcntl(newfd, F_GETFD);
68 if (flags == -1) {
69 close(newfd);
70 return -1;
71 }
72
73 if (fcntl(newfd, F_SETFD, flags | FD_CLOEXEC) == -1) {
74 close(newfd);
75 return -1;
76 }
77
78 return newfd;
79 }
80 #endif
81
82 #include <fcntl.h>
83 #include <sys/stat.h>
84
85 #if DETECT_OS_WINDOWS
86 typedef ptrdiff_t ssize_t;
87 #endif
88
89 static ssize_t
readN(int fd,char * buf,size_t len)90 readN(int fd, char *buf, size_t len)
91 {
92 /* err was initially set to -ENODATA but in some BSD systems
93 * ENODATA is not defined and ENOATTR is used instead.
94 * As err is not returned by any function it can be initialized
95 * to -EFAULT that exists everywhere.
96 */
97 int err = -EFAULT;
98 size_t total = 0;
99 do {
100 ssize_t ret = read(fd, buf + total, len - total);
101
102 if (ret < 0)
103 ret = -errno;
104
105 if (ret == -EINTR || ret == -EAGAIN)
106 continue;
107
108 if (ret <= 0) {
109 err = ret;
110 break;
111 }
112
113 total += ret;
114 } while (total != len);
115
116 return total ? (ssize_t)total : err;
117 }
118
119 #ifndef O_BINARY
120 /* Unix makes no distinction between text and binary files. */
121 #define O_BINARY 0
122 #endif
123
124 char *
os_read_file(const char * filename,size_t * size)125 os_read_file(const char *filename, size_t *size)
126 {
127 /* Note that this also serves as a slight margin to avoid a 2x grow when
128 * the file is just a few bytes larger when we read it than when we
129 * fstat'ed it.
130 * The string's NULL terminator is also included in here.
131 */
132 size_t len = 64;
133
134 int fd = open(filename, O_RDONLY | O_BINARY);
135 if (fd == -1) {
136 /* errno set by open() */
137 return NULL;
138 }
139
140 /* Pre-allocate a buffer at least the size of the file if we can read
141 * that information.
142 */
143 struct stat stat;
144 if (fstat(fd, &stat) == 0)
145 len += stat.st_size;
146
147 char *buf = malloc(len);
148 if (!buf) {
149 close(fd);
150 errno = -ENOMEM;
151 return NULL;
152 }
153
154 ssize_t actually_read;
155 size_t offset = 0, remaining = len - 1;
156 while ((actually_read = readN(fd, buf + offset, remaining)) == (ssize_t)remaining) {
157 char *newbuf = realloc(buf, 2 * len);
158 if (!newbuf) {
159 free(buf);
160 close(fd);
161 errno = -ENOMEM;
162 return NULL;
163 }
164
165 buf = newbuf;
166 len *= 2;
167 offset += actually_read;
168 remaining = len - offset - 1;
169 }
170
171 close(fd);
172
173 if (actually_read > 0)
174 offset += actually_read;
175
176 /* Final resize to actual size */
177 len = offset + 1;
178 char *newbuf = realloc(buf, len);
179 if (!newbuf) {
180 free(buf);
181 errno = -ENOMEM;
182 return NULL;
183 }
184 buf = newbuf;
185
186 buf[offset] = '\0';
187
188 if (size)
189 *size = offset;
190
191 return buf;
192 }
193
194 #if DETECT_OS_LINUX
195
196 #include <sys/syscall.h>
197 #include <unistd.h>
198
199 /* copied from <linux/kcmp.h> */
200 #define KCMP_FILE 0
201
202 int
os_same_file_description(int fd1,int fd2)203 os_same_file_description(int fd1, int fd2)
204 {
205 pid_t pid = getpid();
206
207 /* Same file descriptor trivially implies same file description */
208 if (fd1 == fd2)
209 return 0;
210
211 return syscall(SYS_kcmp, pid, pid, KCMP_FILE, fd1, fd2);
212 }
213
214 #else
215
216 int
os_same_file_description(int fd1,int fd2)217 os_same_file_description(int fd1, int fd2)
218 {
219 /* Same file descriptor trivially implies same file description */
220 if (fd1 == fd2)
221 return 0;
222
223 /* Otherwise we can't tell */
224 return -1;
225 }
226
227 #endif
228