nfsd4: typo logical vs bitwise negate for want_mask
[linux-btrfs-devel.git] / arch / um / os-Linux / mem.c
blob62878cf1d33fb8efce33ff9572d080544207cf18
1 /*
2 * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3 * Licensed under the GPL
4 */
6 #include <stdio.h>
7 #include <stddef.h>
8 #include <stdlib.h>
9 #include <unistd.h>
10 #include <errno.h>
11 #include <fcntl.h>
12 #include <string.h>
13 #include <sys/stat.h>
14 #include <sys/mman.h>
15 #include <sys/param.h>
16 #include "init.h"
17 #include "kern_constants.h"
18 #include "os.h"
19 #include "user.h"
21 /* Modified by which_tmpdir, which is called during early boot */
22 static char *default_tmpdir = "/tmp";
25 * Modified when creating the physical memory file and when checking
26 * the tmp filesystem for usability, both happening during early boot.
28 static char *tempdir = NULL;
30 static void __init find_tempdir(void)
32 const char *dirs[] = { "TMP", "TEMP", "TMPDIR", NULL };
33 int i;
34 char *dir = NULL;
36 if (tempdir != NULL)
37 /* We've already been called */
38 return;
39 for (i = 0; dirs[i]; i++) {
40 dir = getenv(dirs[i]);
41 if ((dir != NULL) && (*dir != '\0'))
42 break;
44 if ((dir == NULL) || (*dir == '\0'))
45 dir = default_tmpdir;
47 tempdir = malloc(strlen(dir) + 2);
48 if (tempdir == NULL) {
49 fprintf(stderr, "Failed to malloc tempdir, "
50 "errno = %d\n", errno);
51 return;
53 strcpy(tempdir, dir);
54 strcat(tempdir, "/");
58 * This will return 1, with the first character in buf being the
59 * character following the next instance of c in the file. This will
60 * read the file as needed. If there's an error, -errno is returned;
61 * if the end of the file is reached, 0 is returned.
63 static int next(int fd, char *buf, size_t size, char c)
65 ssize_t n;
66 size_t len;
67 char *ptr;
69 while ((ptr = strchr(buf, c)) == NULL) {
70 n = read(fd, buf, size - 1);
71 if (n == 0)
72 return 0;
73 else if (n < 0)
74 return -errno;
76 buf[n] = '\0';
79 ptr++;
80 len = strlen(ptr);
81 memmove(buf, ptr, len + 1);
84 * Refill the buffer so that if there's a partial string that we care
85 * about, it will be completed, and we can recognize it.
87 n = read(fd, &buf[len], size - len - 1);
88 if (n < 0)
89 return -errno;
91 buf[len + n] = '\0';
92 return 1;
95 /* which_tmpdir is called only during early boot */
96 static int checked_tmpdir = 0;
99 * Look for a tmpfs mounted at /dev/shm. I couldn't find a cleaner
100 * way to do this than to parse /proc/mounts. statfs will return the
101 * same filesystem magic number and fs id for both /dev and /dev/shm
102 * when they are both tmpfs, so you can't tell if they are different
103 * filesystems. Also, there seems to be no other way of finding the
104 * mount point of a filesystem from within it.
106 * If a /dev/shm tmpfs entry is found, then we switch to using it.
107 * Otherwise, we stay with the default /tmp.
109 static void which_tmpdir(void)
111 int fd, found;
112 char buf[128] = { '\0' };
114 if (checked_tmpdir)
115 return;
117 checked_tmpdir = 1;
119 printf("Checking for tmpfs mount on /dev/shm...");
121 fd = open("/proc/mounts", O_RDONLY);
122 if (fd < 0) {
123 printf("failed to open /proc/mounts, errno = %d\n", errno);
124 return;
127 while (1) {
128 found = next(fd, buf, ARRAY_SIZE(buf), ' ');
129 if (found != 1)
130 break;
132 if (!strncmp(buf, "/dev/shm", strlen("/dev/shm")))
133 goto found;
135 found = next(fd, buf, ARRAY_SIZE(buf), '\n');
136 if (found != 1)
137 break;
140 err:
141 if (found == 0)
142 printf("nothing mounted on /dev/shm\n");
143 else if (found < 0)
144 printf("read returned errno %d\n", -found);
146 out:
147 close(fd);
149 return;
151 found:
152 found = next(fd, buf, ARRAY_SIZE(buf), ' ');
153 if (found != 1)
154 goto err;
156 if (strncmp(buf, "tmpfs", strlen("tmpfs"))) {
157 printf("not tmpfs\n");
158 goto out;
161 printf("OK\n");
162 default_tmpdir = "/dev/shm";
163 goto out;
166 static int __init make_tempfile(const char *template, char **out_tempname,
167 int do_unlink)
169 char *tempname;
170 int fd;
172 which_tmpdir();
173 tempname = malloc(MAXPATHLEN);
174 if (tempname == NULL)
175 return -1;
177 find_tempdir();
178 if ((tempdir == NULL) || (strlen(tempdir) >= MAXPATHLEN))
179 goto out;
181 if (template[0] != '/')
182 strcpy(tempname, tempdir);
183 else
184 tempname[0] = '\0';
185 strncat(tempname, template, MAXPATHLEN-1-strlen(tempname));
186 fd = mkstemp(tempname);
187 if (fd < 0) {
188 fprintf(stderr, "open - cannot create %s: %s\n", tempname,
189 strerror(errno));
190 goto out;
192 if (do_unlink && (unlink(tempname) < 0)) {
193 perror("unlink");
194 goto close;
196 if (out_tempname) {
197 *out_tempname = tempname;
198 } else
199 free(tempname);
200 return fd;
201 close:
202 close(fd);
203 out:
204 free(tempname);
205 return -1;
208 #define TEMPNAME_TEMPLATE "vm_file-XXXXXX"
210 static int __init create_tmp_file(unsigned long long len)
212 int fd, err;
213 char zero;
215 fd = make_tempfile(TEMPNAME_TEMPLATE, NULL, 1);
216 if (fd < 0)
217 exit(1);
219 err = fchmod(fd, 0777);
220 if (err < 0) {
221 perror("fchmod");
222 exit(1);
226 * Seek to len - 1 because writing a character there will
227 * increase the file size by one byte, to the desired length.
229 if (lseek64(fd, len - 1, SEEK_SET) < 0) {
230 perror("lseek64");
231 exit(1);
234 zero = 0;
236 err = write(fd, &zero, 1);
237 if (err != 1) {
238 perror("write");
239 exit(1);
242 return fd;
245 int __init create_mem_file(unsigned long long len)
247 int err, fd;
249 fd = create_tmp_file(len);
251 err = os_set_exec_close(fd);
252 if (err < 0) {
253 errno = -err;
254 perror("exec_close");
256 return fd;
260 void __init check_tmpexec(void)
262 void *addr;
263 int err, fd = create_tmp_file(UM_KERN_PAGE_SIZE);
265 addr = mmap(NULL, UM_KERN_PAGE_SIZE,
266 PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd, 0);
267 printf("Checking PROT_EXEC mmap in %s...",tempdir);
268 fflush(stdout);
269 if (addr == MAP_FAILED) {
270 err = errno;
271 perror("failed");
272 close(fd);
273 if (err == EPERM)
274 printf("%s must be not mounted noexec\n",tempdir);
275 exit(1);
277 printf("OK\n");
278 munmap(addr, UM_KERN_PAGE_SIZE);
280 close(fd);