From: Eric Biggers Date: Tue, 27 Dec 2016 23:24:55 +0000 (-0600) Subject: unix_capture.c: support capturing extended attributes X-Git-Tag: v1.11.0~29 X-Git-Url: https://wimlib.net/git/?p=wimlib;a=commitdiff_plain;h=1b80c9fa453d64763b3247311db6ada6f4bdf36b unix_capture.c: support capturing extended attributes --- diff --git a/src/unix_capture.c b/src/unix_capture.c index 1c207cb8..d869f258 100644 --- a/src/unix_capture.c +++ b/src/unix_capture.c @@ -30,6 +30,10 @@ #include #include /* for PATH_MAX */ #include +#include +#ifdef HAVE_SYS_XATTR_H +# include +#endif #include #include "wimlib/blob_table.h" @@ -39,6 +43,7 @@ #include "wimlib/scan.h" #include "wimlib/timestamp.h" #include "wimlib/unix_data.h" +#include "wimlib/xattr.h" #ifdef HAVE_FDOPENDIR # define my_fdopendir(dirfd_p) fdopendir(*(dirfd_p)) @@ -99,6 +104,189 @@ my_fdopendir(int *dirfd_p) # define AT_SYMLINK_NOFOLLOW 0x100 #endif +#ifdef HAVE_XATTR_SUPPORT +/* + * Retrieves the values of the xattrs named by the null-terminated @names of the + * file at @path and serializes the xattr names and values into @entries. If + * successful, returns the number of bytes used in @entries. If unsuccessful, + * returns -1 and sets errno (ERANGE if @entries was too small). + */ +static ssize_t +gather_xattr_entries(const char *path, const char *names, size_t names_size, + void *entries, size_t entries_size) +{ + const char * const names_end = names + names_size; + void * const entries_end = entries + entries_size; + const char *name = names; + struct wimlib_xattr_entry *entry = entries; + + wimlib_assert((uintptr_t)entries % 4 == 0 && + entries_size % 4 == 0 && names_size != 0); + do { + size_t name_len = strnlen(name, names_end - name); + void *value; + ssize_t value_len; + + if (name_len == 0 || name_len >= names_end - name || + (u16)name_len != name_len) { + ERROR("\"%s\": malformed extended attribute names list", + path); + errno = EINVAL; + return -1; + } + + /* + * Note: we take care to always call lgetxattr() with a nonzero + * size, since zero size means to return the value length only. + */ + if (entries_end - (void *)entry <= sizeof(*entry) + name_len) { + errno = ERANGE; + return -1; + } + + entry->name_len = cpu_to_le16(name_len); + entry->reserved = 0; + value = mempcpy(entry->name, name, name_len); + + value_len = lgetxattr(path, name, value, entries_end - value); + if (value_len < 0) { + if (errno != ERANGE) { + ERROR_WITH_ERRNO("\"%s\": unable to read extended attribute \"%s\"", + path, name); + } + return -1; + } + if ((u32)value_len != value_len) { + ERROR("\"%s\": value of extended attribute \"%s\" is too large", + path, name); + errno = EINVAL; + return -1; + } + entry->value_len = cpu_to_le32(value_len); + + /* + * Zero-pad the entry to the next 4-byte boundary. + * Note: because we've guaranteed that @entries_size is a + * multiple of 4, this cannot overflow the @entries buffer. + */ + value += value_len; + while ((uintptr_t)value & 3) { + *(u8 *)value = 0; + value++; + } + + entry = value; + name += name_len + 1; + } while (name < names_end); + + return (void *)entry - entries; +} + +static int +create_xattr_item(const char *path, struct wim_inode *inode, + const char *names, size_t names_size) +{ + char _entries[1024] _aligned_attribute(4); + char *entries = _entries; + size_t entries_avail = ARRAY_LEN(_entries); + ssize_t entries_size; + int ret; + +retry: + /* Serialize the xattrs into @entries */ + entries_size = gather_xattr_entries(path, names, names_size, + entries, entries_avail); + if (entries_size < 0) { + ret = WIMLIB_ERR_STAT; + if (errno != ERANGE) + goto out; + /* Not enough space in @entries. Reallocate it. */ + if (entries != _entries) + FREE(entries); + ret = WIMLIB_ERR_NOMEM; + entries_avail *= 2; + entries = MALLOC(entries_avail); + if (!entries) + goto out; + goto retry; + } + + /* Copy @entries into an xattr item associated with @inode */ + if ((u32)entries_size != entries_size) { + ERROR("\"%s\": too much xattr data!", path); + ret = WIMLIB_ERR_STAT; + goto out; + } + ret = WIMLIB_ERR_NOMEM; + if (!inode_set_linux_xattrs(inode, entries, entries_size)) + goto out; + + ret = 0; +out: + if (entries != _entries) + FREE(entries); + return ret; +} + +/* + * If the file at @path has Linux-style extended attributes, read them into + * memory and add them to @inode as a tagged item. + */ +static noinline_for_stack int +scan_linux_xattrs(const char *path, struct wim_inode *inode) +{ + char _names[256]; + char *names = _names; + ssize_t names_size = ARRAY_LEN(_names); + int ret = 0; + +retry: + /* Gather the names of the xattrs of the file at @path */ + names_size = llistxattr(path, names, names_size); + if (names_size == 0) /* No xattrs? */ + goto out; + if (names_size < 0) { + /* xattrs unsupported or disabled? */ + if (errno == ENOTSUP || errno == ENOSYS) + goto out; + if (errno == ERANGE) { + /* + * Not enough space in @names. Ask for how much space + * we need, then try again. + */ + names_size = llistxattr(path, NULL, 0); + if (names_size == 0) + goto out; + if (names_size > 0) { + if (names != _names) + FREE(names); + names = MALLOC(names_size); + if (!names) { + ret = WIMLIB_ERR_NOMEM; + goto out; + } + goto retry; + } + } + /* Some other error occurred. */ + ERROR_WITH_ERRNO("\"%s\": unable to list extended attributes", + path); + ret = WIMLIB_ERR_STAT; + goto out; + } + + /* + * We have a nonempty list of xattr names. Gather the xattr values and + * add them as a tagged item. + */ + ret = create_xattr_item(path, inode, names, names_size); +out: + if (names != _names) + FREE(names); + return ret; +} +#endif /* HAVE_XATTR_SUPPORT */ + static int unix_scan_regular_file(const char *path, u64 blocks, u64 size, struct wim_inode *inode, @@ -436,6 +624,11 @@ unix_build_dentry_tree_recursive(struct wim_dentry **tree_ret, ret = WIMLIB_ERR_NOMEM; goto out; } +#ifdef HAVE_XATTR_SUPPORT + ret = scan_linux_xattrs(full_path, inode); + if (ret) + goto out; +#endif } if (params->add_flags & WIMLIB_ADD_FLAG_ROOT) {