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409 lines
8.1 KiB
409 lines
8.1 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) |
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*/ |
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <dirent.h> |
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#include <errno.h> |
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#include <fcntl.h> |
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#include <signal.h> |
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#include <string.h> |
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#include <unistd.h> |
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#include <sys/stat.h> |
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#include <init.h> |
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#include <os.h> |
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#define UML_DIR "~/.uml/" |
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#define UMID_LEN 64 |
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/* Changed by set_umid, which is run early in boot */ |
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static char umid[UMID_LEN] = { 0 }; |
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/* Changed by set_uml_dir and make_uml_dir, which are run early in boot */ |
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static char *uml_dir = UML_DIR; |
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static int __init make_uml_dir(void) |
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{ |
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char dir[512] = { '\0' }; |
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int len, err; |
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if (*uml_dir == '~') { |
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char *home = getenv("HOME"); |
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err = -ENOENT; |
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if (home == NULL) { |
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printk(UM_KERN_ERR |
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"%s: no value in environment for $HOME\n", |
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__func__); |
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goto err; |
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} |
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strlcpy(dir, home, sizeof(dir)); |
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uml_dir++; |
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} |
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strlcat(dir, uml_dir, sizeof(dir)); |
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len = strlen(dir); |
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if (len > 0 && dir[len - 1] != '/') |
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strlcat(dir, "/", sizeof(dir)); |
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err = -ENOMEM; |
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uml_dir = malloc(strlen(dir) + 1); |
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if (uml_dir == NULL) { |
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printk(UM_KERN_ERR "%s : malloc failed, errno = %d\n", |
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__func__, errno); |
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goto err; |
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} |
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strcpy(uml_dir, dir); |
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if ((mkdir(uml_dir, 0777) < 0) && (errno != EEXIST)) { |
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printk(UM_KERN_ERR "Failed to mkdir '%s': %s\n", |
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uml_dir, strerror(errno)); |
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err = -errno; |
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goto err_free; |
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} |
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return 0; |
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err_free: |
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free(uml_dir); |
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err: |
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uml_dir = NULL; |
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return err; |
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} |
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/* |
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* Unlinks the files contained in @dir and then removes @dir. |
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* Doesn't handle directory trees, so it's not like rm -rf, but almost such. We |
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* ignore ENOENT errors for anything (they happen, strangely enough - possibly |
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* due to races between multiple dying UML threads). |
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*/ |
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static int remove_files_and_dir(char *dir) |
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{ |
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DIR *directory; |
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struct dirent *ent; |
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int len; |
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char file[256]; |
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int ret; |
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directory = opendir(dir); |
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if (directory == NULL) { |
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if (errno != ENOENT) |
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return -errno; |
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else |
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return 0; |
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} |
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while ((ent = readdir(directory)) != NULL) { |
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if (!strcmp(ent->d_name, ".") || !strcmp(ent->d_name, "..")) |
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continue; |
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len = strlen(dir) + strlen("/") + strlen(ent->d_name) + 1; |
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if (len > sizeof(file)) { |
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ret = -E2BIG; |
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goto out; |
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} |
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sprintf(file, "%s/%s", dir, ent->d_name); |
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if (unlink(file) < 0 && errno != ENOENT) { |
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ret = -errno; |
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goto out; |
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} |
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} |
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if (rmdir(dir) < 0 && errno != ENOENT) { |
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ret = -errno; |
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goto out; |
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} |
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ret = 0; |
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out: |
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closedir(directory); |
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return ret; |
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} |
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/* |
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* This says that there isn't already a user of the specified directory even if |
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* there are errors during the checking. This is because if these errors |
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* happen, the directory is unusable by the pre-existing UML, so we might as |
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* well take it over. This could happen either by |
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* the existing UML somehow corrupting its umid directory |
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* something other than UML sticking stuff in the directory |
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* this boot racing with a shutdown of the other UML |
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* In any of these cases, the directory isn't useful for anything else. |
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* |
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* Boolean return: 1 if in use, 0 otherwise. |
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*/ |
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static inline int is_umdir_used(char *dir) |
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{ |
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char pid[sizeof("nnnnnnnnn")], *end, *file; |
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int dead, fd, p, n, err; |
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size_t filelen = strlen(dir) + sizeof("/pid") + 1; |
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file = malloc(filelen); |
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if (!file) |
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return -ENOMEM; |
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snprintf(file, filelen, "%s/pid", dir); |
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dead = 0; |
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fd = open(file, O_RDONLY); |
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if (fd < 0) { |
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fd = -errno; |
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if (fd != -ENOENT) { |
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printk(UM_KERN_ERR "is_umdir_used : couldn't open pid " |
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"file '%s', err = %d\n", file, -fd); |
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} |
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goto out; |
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} |
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err = 0; |
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n = read(fd, pid, sizeof(pid)); |
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if (n < 0) { |
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printk(UM_KERN_ERR "is_umdir_used : couldn't read pid file " |
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"'%s', err = %d\n", file, errno); |
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goto out_close; |
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} else if (n == 0) { |
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printk(UM_KERN_ERR "is_umdir_used : couldn't read pid file " |
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"'%s', 0-byte read\n", file); |
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goto out_close; |
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} |
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p = strtoul(pid, &end, 0); |
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if (end == pid) { |
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printk(UM_KERN_ERR "is_umdir_used : couldn't parse pid file " |
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"'%s', errno = %d\n", file, errno); |
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goto out_close; |
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} |
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if ((kill(p, 0) == 0) || (errno != ESRCH)) { |
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printk(UM_KERN_ERR "umid \"%s\" is already in use by pid %d\n", |
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umid, p); |
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return 1; |
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} |
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out_close: |
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close(fd); |
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out: |
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free(file); |
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return 0; |
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} |
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/* |
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* Try to remove the directory @dir unless it's in use. |
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* Precondition: @dir exists. |
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* Returns 0 for success, < 0 for failure in removal or if the directory is in |
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* use. |
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*/ |
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static int umdir_take_if_dead(char *dir) |
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{ |
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int ret; |
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if (is_umdir_used(dir)) |
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return -EEXIST; |
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ret = remove_files_and_dir(dir); |
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if (ret) { |
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printk(UM_KERN_ERR "is_umdir_used - remove_files_and_dir " |
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"failed with err = %d\n", ret); |
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} |
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return ret; |
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} |
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static void __init create_pid_file(void) |
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{ |
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char pid[sizeof("nnnnnnnnn")], *file; |
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int fd, n; |
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n = strlen(uml_dir) + UMID_LEN + sizeof("/pid"); |
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file = malloc(n); |
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if (!file) |
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return; |
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if (umid_file_name("pid", file, n)) |
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goto out; |
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fd = open(file, O_RDWR | O_CREAT | O_EXCL, 0644); |
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if (fd < 0) { |
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printk(UM_KERN_ERR "Open of machine pid file \"%s\" failed: " |
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"%s\n", file, strerror(errno)); |
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goto out; |
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} |
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snprintf(pid, sizeof(pid), "%d\n", getpid()); |
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n = write(fd, pid, strlen(pid)); |
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if (n != strlen(pid)) |
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printk(UM_KERN_ERR "Write of pid file failed - err = %d\n", |
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errno); |
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close(fd); |
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out: |
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free(file); |
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} |
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int __init set_umid(char *name) |
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{ |
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if (strlen(name) > UMID_LEN - 1) |
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return -E2BIG; |
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strlcpy(umid, name, sizeof(umid)); |
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return 0; |
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} |
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/* Changed in make_umid, which is called during early boot */ |
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static int umid_setup = 0; |
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static int __init make_umid(void) |
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{ |
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int fd, err; |
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char tmp[256]; |
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if (umid_setup) |
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return 0; |
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make_uml_dir(); |
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if (*umid == '\0') { |
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strlcpy(tmp, uml_dir, sizeof(tmp)); |
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strlcat(tmp, "XXXXXX", sizeof(tmp)); |
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fd = mkstemp(tmp); |
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if (fd < 0) { |
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printk(UM_KERN_ERR "make_umid - mkstemp(%s) failed: " |
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"%s\n", tmp, strerror(errno)); |
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err = -errno; |
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goto err; |
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} |
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close(fd); |
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set_umid(&tmp[strlen(uml_dir)]); |
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/* |
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* There's a nice tiny little race between this unlink and |
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* the mkdir below. It'd be nice if there were a mkstemp |
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* for directories. |
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*/ |
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if (unlink(tmp)) { |
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err = -errno; |
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goto err; |
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} |
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} |
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snprintf(tmp, sizeof(tmp), "%s%s", uml_dir, umid); |
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err = mkdir(tmp, 0777); |
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if (err < 0) { |
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err = -errno; |
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if (err != -EEXIST) |
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goto err; |
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if (umdir_take_if_dead(tmp) < 0) |
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goto err; |
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err = mkdir(tmp, 0777); |
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} |
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if (err) { |
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err = -errno; |
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printk(UM_KERN_ERR "Failed to create '%s' - err = %d\n", umid, |
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errno); |
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goto err; |
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} |
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umid_setup = 1; |
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create_pid_file(); |
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err = 0; |
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err: |
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return err; |
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} |
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static int __init make_umid_init(void) |
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{ |
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if (!make_umid()) |
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return 0; |
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/* |
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* If initializing with the given umid failed, then try again with |
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* a random one. |
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*/ |
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printk(UM_KERN_ERR "Failed to initialize umid \"%s\", trying with a " |
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"random umid\n", umid); |
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*umid = '\0'; |
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make_umid(); |
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return 0; |
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} |
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__initcall(make_umid_init); |
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int __init umid_file_name(char *name, char *buf, int len) |
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{ |
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int n, err; |
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err = make_umid(); |
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if (err) |
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return err; |
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n = snprintf(buf, len, "%s%s/%s", uml_dir, umid, name); |
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if (n >= len) { |
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printk(UM_KERN_ERR "umid_file_name : buffer too short\n"); |
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return -E2BIG; |
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} |
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return 0; |
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} |
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char *get_umid(void) |
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{ |
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return umid; |
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} |
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static int __init set_uml_dir(char *name, int *add) |
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{ |
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if (*name == '\0') { |
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os_warn("uml_dir can't be an empty string\n"); |
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return 0; |
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} |
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if (name[strlen(name) - 1] == '/') { |
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uml_dir = name; |
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return 0; |
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} |
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uml_dir = malloc(strlen(name) + 2); |
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if (uml_dir == NULL) { |
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os_warn("Failed to malloc uml_dir - error = %d\n", errno); |
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/* |
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* Return 0 here because do_initcalls doesn't look at |
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* the return value. |
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*/ |
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return 0; |
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} |
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sprintf(uml_dir, "%s/", name); |
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return 0; |
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} |
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__uml_setup("uml_dir=", set_uml_dir, |
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"uml_dir=<directory>\n" |
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" The location to place the pid and umid files.\n\n" |
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); |
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static void remove_umid_dir(void) |
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{ |
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char *dir, err; |
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dir = malloc(strlen(uml_dir) + UMID_LEN + 1); |
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if (!dir) |
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return; |
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sprintf(dir, "%s%s", uml_dir, umid); |
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err = remove_files_and_dir(dir); |
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if (err) |
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os_warn("%s - remove_files_and_dir failed with err = %d\n", |
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__func__, err); |
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free(dir); |
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} |
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__uml_exitcall(remove_umid_dir);
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