static int file_ram_open(const char *path,
const char *region_name,
bool readonly,
- bool *created,
- Error **errp)
+ bool *created)
{
char *filename;
char *sanitized_name;
for (;;) {
fd = open(path, readonly ? O_RDONLY : O_RDWR);
if (fd >= 0) {
+ /*
+ * open(O_RDONLY) won't fail with EISDIR. Check manually if we
+ * opened a directory and fail similarly to how we fail ENOENT
+ * in readonly mode. Note that mkstemp() would imply O_RDWR.
+ */
+ if (readonly) {
+ struct stat file_stat;
+
+ if (fstat(fd, &file_stat)) {
+ close(fd);
+ if (errno == EINTR) {
+ continue;
+ }
+ return -errno;
+ } else if (S_ISDIR(file_stat.st_mode)) {
+ close(fd);
+ return -EISDIR;
+ }
+ }
/* @path names an existing file, use it */
break;
}
if (errno == ENOENT) {
+ if (readonly) {
+ /* Refuse to create new, readonly files. */
+ return -ENOENT;
+ }
/* @path names a file that doesn't exist, create it */
fd = open(path, O_RDWR | O_CREAT | O_EXCL, 0644);
if (fd >= 0) {
g_free(filename);
}
if (errno != EEXIST && errno != EINTR) {
- error_setg_errno(errp, errno,
- "can't open backing store %s for guest RAM",
- path);
- return -1;
+ return -errno;
}
/*
* Try again on EINTR and EEXIST. The latter happens when
static void *file_ram_alloc(RAMBlock *block,
ram_addr_t memory,
int fd,
- bool readonly,
bool truncate,
off_t offset,
Error **errp)
perror("ftruncate");
}
- qemu_map_flags = readonly ? QEMU_MAP_READONLY : 0;
+ qemu_map_flags = (block->flags & RAM_READONLY) ? QEMU_MAP_READONLY : 0;
qemu_map_flags |= (block->flags & RAM_SHARED) ? QEMU_MAP_SHARED : 0;
qemu_map_flags |= (block->flags & RAM_PMEM) ? QEMU_MAP_SYNC : 0;
qemu_map_flags |= (block->flags & RAM_NORESERVE) ? QEMU_MAP_NORESERVE : 0;
#ifdef CONFIG_POSIX
RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr,
uint32_t ram_flags, int fd, off_t offset,
- bool readonly, Error **errp)
+ Error **errp)
{
RAMBlock *new_block;
Error *local_err = NULL;
/* Just support these ram flags by now. */
assert((ram_flags & ~(RAM_SHARED | RAM_PMEM | RAM_NORESERVE |
- RAM_PROTECTED | RAM_NAMED_FILE)) == 0);
+ RAM_PROTECTED | RAM_NAMED_FILE | RAM_READONLY |
+ RAM_READONLY_FD)) == 0);
if (xen_enabled()) {
error_setg(errp, "-mem-path not supported with Xen");
new_block->used_length = size;
new_block->max_length = size;
new_block->flags = ram_flags;
- new_block->host = file_ram_alloc(new_block, size, fd, readonly,
- !file_size, offset, errp);
+ new_block->host = file_ram_alloc(new_block, size, fd, !file_size, offset,
+ errp);
if (!new_block->host) {
g_free(new_block);
return NULL;
RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
uint32_t ram_flags, const char *mem_path,
- off_t offset, bool readonly, Error **errp)
+ off_t offset, Error **errp)
{
int fd;
bool created;
RAMBlock *block;
- fd = file_ram_open(mem_path, memory_region_name(mr), readonly, &created,
- errp);
+ fd = file_ram_open(mem_path, memory_region_name(mr),
+ !!(ram_flags & RAM_READONLY_FD), &created);
if (fd < 0) {
+ error_setg_errno(errp, -fd, "can't open backing store %s for guest RAM",
+ mem_path);
+ if (!(ram_flags & RAM_READONLY_FD) && !(ram_flags & RAM_SHARED) &&
+ fd == -EACCES) {
+ /*
+ * If we can open the file R/O (note: will never create a new file)
+ * and we are dealing with a private mapping, there are still ways
+ * to consume such files and get RAM instead of ROM.
+ */
+ fd = file_ram_open(mem_path, memory_region_name(mr), true,
+ &created);
+ if (fd < 0) {
+ return NULL;
+ }
+ assert(!created);
+ close(fd);
+ error_append_hint(errp, "Consider opening the backing store"
+ " read-only but still creating writable RAM using"
+ " '-object memory-backend-file,readonly=on,rom=off...'"
+ " (see \"VM templating\" documentation)\n");
+ }
return NULL;
}
- block = qemu_ram_alloc_from_fd(size, mr, ram_flags, fd, offset, readonly,
- errp);
+ block = qemu_ram_alloc_from_fd(size, mr, ram_flags, fd, offset, errp);
if (!block) {
if (created) {
unlink(mem_path);
ram_addr_t offset;
int flags;
void *area, *vaddr;
+ int prot;
RAMBLOCK_FOREACH(block) {
offset = addr - block->offset;
flags |= block->flags & RAM_SHARED ?
MAP_SHARED : MAP_PRIVATE;
flags |= block->flags & RAM_NORESERVE ? MAP_NORESERVE : 0;
+ prot = PROT_READ;
+ prot |= block->flags & RAM_READONLY ? 0 : PROT_WRITE;
if (block->fd >= 0) {
- area = mmap(vaddr, length, PROT_READ | PROT_WRITE,
- flags, block->fd, offset + block->fd_offset);
+ area = mmap(vaddr, length, prot, flags, block->fd,
+ offset + block->fd_offset);
} else {
flags |= MAP_ANONYMOUS;
- area = mmap(vaddr, length, PROT_READ | PROT_WRITE,
- flags, -1, 0);
+ area = mmap(vaddr, length, prot, flags, -1, 0);
}
if (area != vaddr) {
error_report("Could not remap addr: "
* so a userfault will trigger.
*/
#ifdef CONFIG_FALLOCATE_PUNCH_HOLE
+ /*
+ * fallocate() will fail with readonly files. Let's print a
+ * proper error message.
+ */
+ if (rb->flags & RAM_READONLY_FD) {
+ error_report("ram_block_discard_range: Discarding RAM"
+ " with readonly files is not supported");
+ goto err;
+
+ }
/*
* We'll discard data from the actual file, even though we only
* have a MAP_PRIVATE mapping, possibly messing with other
projects / thirdparty / qemu.git / blobdiff