2 * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3 * Licensed under the GPL
15 #include <sys/param.h>
17 #include "kern_constants.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 };
37 /* We've already been called */
39 for (i = 0; dirs[i]; i++) {
40 dir = getenv(dirs[i]);
41 if ((dir != NULL) && (*dir != '\0'))
44 if ((dir == NULL) || (*dir == '\0'))
47 tempdir = malloc(strlen(dir) + 2);
48 if (tempdir == NULL) {
49 fprintf(stderr, "Failed to malloc tempdir, "
50 "errno = %d\n", errno);
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)
69 while ((ptr = strchr(buf, c)) == NULL) {
70 n = read(fd, buf, size - 1);
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);
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)
112 char buf[128] = { '\0' };
119 printf("Checking for tmpfs mount on /dev/shm...");
121 fd = open("/proc/mounts", O_RDONLY);
123 printf("failed to open /proc/mounts, errno = %d\n", errno);
128 found = next(fd, buf, ARRAY_SIZE(buf), ' ');
132 if (!strncmp(buf, "/dev/shm", strlen("/dev/shm")))
135 found = next(fd, buf, ARRAY_SIZE(buf), '\n');
142 printf("nothing mounted on /dev/shm\n");
144 printf("read returned errno %d\n", -found);
152 found = next(fd, buf, ARRAY_SIZE(buf), ' ');
156 if (strncmp(buf, "tmpfs", strlen("tmpfs"))) {
157 printf("not tmpfs\n");
162 default_tmpdir = "/dev/shm";
166 static int __init make_tempfile(const char *template, char **out_tempname,
173 tempname = malloc(MAXPATHLEN);
174 if (tempname == NULL)
178 if ((tempdir == NULL) || (strlen(tempdir) >= MAXPATHLEN))
181 if (template[0] != '/')
182 strcpy(tempname, tempdir);
185 strncat(tempname, template, MAXPATHLEN-1-strlen(tempname));
186 fd = mkstemp(tempname);
188 fprintf(stderr, "open - cannot create %s: %s\n", tempname,
192 if (do_unlink && (unlink(tempname) < 0)) {
197 *out_tempname = tempname;
206 #define TEMPNAME_TEMPLATE "vm_file-XXXXXX"
208 static int __init create_tmp_file(unsigned long long len)
213 fd = make_tempfile(TEMPNAME_TEMPLATE, NULL, 1);
217 err = fchmod(fd, 0777);
224 * Seek to len - 1 because writing a character there will
225 * increase the file size by one byte, to the desired length.
227 if (lseek64(fd, len - 1, SEEK_SET) < 0) {
234 err = write(fd, &zero, 1);
243 int __init create_mem_file(unsigned long long len)
247 fd = create_tmp_file(len);
249 err = os_set_exec_close(fd);
252 perror("exec_close");
258 void __init check_tmpexec(void)
261 int err, fd = create_tmp_file(UM_KERN_PAGE_SIZE);
263 addr = mmap(NULL, UM_KERN_PAGE_SIZE,
264 PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd, 0);
265 printf("Checking PROT_EXEC mmap in %s...",tempdir);
267 if (addr == MAP_FAILED) {
272 printf("%s must be not mounted noexec\n",tempdir);
276 munmap(addr, UM_KERN_PAGE_SIZE);