#include <string.h>
#include <sys/stat.h>
#include <sys/mman.h>
-#include <sys/param.h>
+#include <sys/vfs.h>
+#include <linux/magic.h>
#include <init.h>
#include <os.h>
-/* Modified by which_tmpdir, which is called during early boot */
-static char *default_tmpdir = "/tmp";
-
-/*
- * Modified when creating the physical memory file and when checking
- * the tmp filesystem for usability, both happening during early boot.
- */
+/* Set by make_tempfile() during early boot. */
static char *tempdir = NULL;
-static void __init find_tempdir(void)
+/* Check if dir is on tmpfs. Return 0 if yes, -1 if no or error. */
+static int __init check_tmpfs(const char *dir)
{
- const char *dirs[] = { "TMP", "TEMP", "TMPDIR", NULL };
- int i;
- char *dir = NULL;
-
- if (tempdir != NULL)
- /* We've already been called */
- return;
- for (i = 0; dirs[i]; i++) {
- dir = getenv(dirs[i]);
- if ((dir != NULL) && (*dir != '\0'))
- break;
- }
- if ((dir == NULL) || (*dir == '\0'))
- dir = default_tmpdir;
+ struct statfs st;
- tempdir = malloc(strlen(dir) + 2);
- if (tempdir == NULL) {
- fprintf(stderr, "Failed to malloc tempdir, "
- "errno = %d\n", errno);
- return;
- }
- strcpy(tempdir, dir);
- strcat(tempdir, "/");
-}
-
-/*
- * Remove bytes from the front of the buffer and refill it so that if there's a
- * partial string that we care about, it will be completed, and we can recognize
- * it.
- */
-static int pop(int fd, char *buf, size_t size, size_t npop)
-{
- ssize_t n;
- size_t len = strlen(&buf[npop]);
-
- memmove(buf, &buf[npop], len + 1);
- n = read(fd, &buf[len], size - len - 1);
- if (n < 0)
- return -errno;
-
- buf[len + n] = '\0';
- return 1;
-}
-
-/*
- * This will return 1, with the first character in buf being the
- * character following the next instance of c in the file. This will
- * read the file as needed. If there's an error, -errno is returned;
- * if the end of the file is reached, 0 is returned.
- */
-static int next(int fd, char *buf, size_t size, char c)
-{
- ssize_t n;
- char *ptr;
-
- while ((ptr = strchr(buf, c)) == NULL) {
- n = read(fd, buf, size - 1);
- if (n == 0)
- return 0;
- else if (n < 0)
- return -errno;
-
- buf[n] = '\0';
+ printf("Checking if %s is on tmpfs...", dir);
+ if (statfs(dir, &st) < 0) {
+ printf("%s\n", strerror(errno));
+ } else if (st.f_type != TMPFS_MAGIC) {
+ printf("no\n");
+ } else {
+ printf("OK\n");
+ return 0;
}
-
- return pop(fd, buf, size, ptr - buf + 1);
+ return -1;
}
/*
- * Decode an octal-escaped and space-terminated path of the form used by
- * /proc/mounts. May be used to decode a path in-place. "out" must be at least
- * as large as the input. The output is always null-terminated. "len" gets the
- * length of the output, excluding the trailing null. Returns 0 if a full path
- * was successfully decoded, otherwise an error.
+ * Choose the tempdir to use. We want something on tmpfs so that our memory is
+ * not subject to the host's vm.dirty_ratio. If a tempdir is specified in the
+ * environment, we use that even if it's not on tmpfs, but we warn the user.
+ * Otherwise, we try common tmpfs locations, and if no tmpfs directory is found
+ * then we fall back to /tmp.
*/
-static int decode_path(const char *in, char *out, size_t *len)
+static char * __init choose_tempdir(void)
{
- char *first = out;
- int c;
+ static const char * const vars[] = {
+ "TMPDIR",
+ "TMP",
+ "TEMP",
+ NULL
+ };
+ static const char fallback_dir[] = "/tmp";
+ static const char * const tmpfs_dirs[] = {
+ "/dev/shm",
+ fallback_dir,
+ NULL
+ };
int i;
- int ret = -EINVAL;
- while (1) {
- switch (*in) {
- case '\0':
- goto out;
-
- case ' ':
- ret = 0;
- goto out;
-
- case '\\':
- in++;
- c = 0;
- for (i = 0; i < 3; i++) {
- if (*in < '0' || *in > '7')
- goto out;
- c = (c << 3) | (*in++ - '0');
- }
- *(unsigned char *)out++ = (unsigned char) c;
- break;
-
- default:
- *out++ = *in++;
- break;
+ const char *dir;
+
+ printf("Checking environment variables for a tempdir...");
+ for (i = 0; vars[i]; i++) {
+ dir = getenv(vars[i]);
+ if ((dir != NULL) && (*dir != '\0')) {
+ printf("%s\n", dir);
+ if (check_tmpfs(dir) >= 0)
+ goto done;
+ else
+ goto warn;
}
}
+ printf("none found\n");
-out:
- *out = '\0';
- *len = out - first;
- return ret;
-}
-
-/*
- * Computes the length of s when encoded with three-digit octal escape sequences
- * for the characters in chars.
- */
-static size_t octal_encoded_length(const char *s, const char *chars)
-{
- size_t len = strlen(s);
- while ((s = strpbrk(s, chars)) != NULL) {
- len += 3;
- s++;
- }
-
- return len;
-}
-
-enum {
- OUTCOME_NOTHING_MOUNTED,
- OUTCOME_TMPFS_MOUNT,
- OUTCOME_NON_TMPFS_MOUNT,
-};
-
-/* Read a line of /proc/mounts data looking for a tmpfs mount at "path". */
-static int read_mount(int fd, char *buf, size_t bufsize, const char *path,
- int *outcome)
-{
- int found;
- int match;
- char *space;
- size_t len;
-
- enum {
- MATCH_NONE,
- MATCH_EXACT,
- MATCH_PARENT,
- };
-
- found = next(fd, buf, bufsize, ' ');
- if (found != 1)
- return found;
-
- /*
- * If there's no following space in the buffer, then this path is
- * truncated, so it can't be the one we're looking for.
- */
- space = strchr(buf, ' ');
- if (space) {
- match = MATCH_NONE;
- if (!decode_path(buf, buf, &len)) {
- if (!strcmp(buf, path))
- match = MATCH_EXACT;
- else if (!strncmp(buf, path, len)
- && (path[len] == '/' || !strcmp(buf, "/")))
- match = MATCH_PARENT;
- }
-
- found = pop(fd, buf, bufsize, space - buf + 1);
- if (found != 1)
- return found;
-
- switch (match) {
- case MATCH_EXACT:
- if (!strncmp(buf, "tmpfs", strlen("tmpfs")))
- *outcome = OUTCOME_TMPFS_MOUNT;
- else
- *outcome = OUTCOME_NON_TMPFS_MOUNT;
- break;
-
- case MATCH_PARENT:
- /* This mount obscures any previous ones. */
- *outcome = OUTCOME_NOTHING_MOUNTED;
- break;
- }
+ for (i = 0; tmpfs_dirs[i]; i++) {
+ dir = tmpfs_dirs[i];
+ if (check_tmpfs(dir) >= 0)
+ goto done;
}
- return next(fd, buf, bufsize, '\n');
+ dir = fallback_dir;
+warn:
+ printf("Warning: tempdir %s is not on tmpfs\n", dir);
+done:
+ /* Make a copy since getenv results may not remain valid forever. */
+ return strdup(dir);
}
-/* which_tmpdir is called only during early boot */
-static int checked_tmpdir = 0;
-
/*
- * Look for a tmpfs mounted at /dev/shm. I couldn't find a cleaner
- * way to do this than to parse /proc/mounts. statfs will return the
- * same filesystem magic number and fs id for both /dev and /dev/shm
- * when they are both tmpfs, so you can't tell if they are different
- * filesystems. Also, there seems to be no other way of finding the
- * mount point of a filesystem from within it.
- *
- * If a /dev/shm tmpfs entry is found, then we switch to using it.
- * Otherwise, we stay with the default /tmp.
+ * Create an unlinked tempfile in a suitable tempdir. template must be the
+ * basename part of the template with a leading '/'.
*/
-static void which_tmpdir(void)
+static int __init make_tempfile(const char *template)
{
+ char *tempname;
int fd;
- int found;
- int outcome;
- char *path;
- char *buf;
- size_t bufsize;
- if (checked_tmpdir)
- return;
-
- checked_tmpdir = 1;
-
- printf("Checking for tmpfs mount on /dev/shm...");
-
- path = realpath("/dev/shm", NULL);
- if (!path) {
- printf("failed to check real path, errno = %d\n", errno);
- return;
- }
- printf("%s...", path);
-
- /*
- * The buffer needs to be able to fit the full octal-escaped path, a
- * space, and a trailing null in order to successfully decode it.
- */
- bufsize = octal_encoded_length(path, " \t\n\\") + 2;
-
- if (bufsize < 128)
- bufsize = 128;
-
- buf = malloc(bufsize);
- if (!buf) {
- printf("malloc failed, errno = %d\n", errno);
- goto out;
- }
- buf[0] = '\0';
-
- fd = open("/proc/mounts", O_RDONLY);
- if (fd < 0) {
- printf("failed to open /proc/mounts, errno = %d\n", errno);
- goto out1;
- }
-
- outcome = OUTCOME_NOTHING_MOUNTED;
- while (1) {
- found = read_mount(fd, buf, bufsize, path, &outcome);
- if (found != 1)
- break;
- }
-
- if (found < 0) {
- printf("read returned errno %d\n", -found);
- } else {
- switch (outcome) {
- case OUTCOME_TMPFS_MOUNT:
- printf("OK\n");
- default_tmpdir = "/dev/shm";
- break;
-
- case OUTCOME_NON_TMPFS_MOUNT:
- printf("not tmpfs\n");
- break;
-
- default:
- printf("nothing mounted on /dev/shm\n");
- break;
+ if (tempdir == NULL) {
+ tempdir = choose_tempdir();
+ if (tempdir == NULL) {
+ fprintf(stderr, "Failed to choose tempdir: %s\n",
+ strerror(errno));
+ return -1;
}
}
- close(fd);
-out1:
- free(buf);
-out:
- free(path);
-}
-
-static int __init make_tempfile(const char *template, char **out_tempname,
- int do_unlink)
-{
- char *tempname;
- int fd;
-
- which_tmpdir();
- tempname = malloc(MAXPATHLEN);
+ tempname = malloc(strlen(tempdir) + strlen(template) + 1);
if (tempname == NULL)
return -1;
- find_tempdir();
- if ((tempdir == NULL) || (strlen(tempdir) >= MAXPATHLEN))
- goto out;
-
- if (template[0] != '/')
- strcpy(tempname, tempdir);
- else
- tempname[0] = '\0';
- strncat(tempname, template, MAXPATHLEN-1-strlen(tempname));
+ strcpy(tempname, tempdir);
+ strcat(tempname, template);
fd = mkstemp(tempname);
if (fd < 0) {
fprintf(stderr, "open - cannot create %s: %s\n", tempname,
strerror(errno));
goto out;
}
- if (do_unlink && (unlink(tempname) < 0)) {
+ if (unlink(tempname) < 0) {
perror("unlink");
goto close;
}
- if (out_tempname) {
- *out_tempname = tempname;
- } else
- free(tempname);
+ free(tempname);
return fd;
close:
close(fd);
return -1;
}
-#define TEMPNAME_TEMPLATE "vm_file-XXXXXX"
+#define TEMPNAME_TEMPLATE "/vm_file-XXXXXX"
static int __init create_tmp_file(unsigned long long len)
{
int fd, err;
char zero;
- fd = make_tempfile(TEMPNAME_TEMPLATE, NULL, 1);
+ fd = make_tempfile(TEMPNAME_TEMPLATE);
if (fd < 0)
exit(1);
return fd;
}
-
void __init check_tmpexec(void)
{
void *addr;
addr = mmap(NULL, UM_KERN_PAGE_SIZE,
PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd, 0);
- printf("Checking PROT_EXEC mmap in %s...",tempdir);
- fflush(stdout);
+ printf("Checking PROT_EXEC mmap in %s...", tempdir);
if (addr == MAP_FAILED) {
err = errno;
- perror("failed");
+ printf("%s\n", strerror(err));
close(fd);
if (err == EPERM)
- printf("%s must be not mounted noexec\n",tempdir);
+ printf("%s must be not mounted noexec\n", tempdir);
exit(1);
}
printf("OK\n");
projects / GitHub / MotorolaMobilityLLC / kernel-slsi.git / commitdiff