There are no "at" variants for xattr syscalls. This patch implement them using a separate process.
Signed-off-by: Greg Kurz <gr...@kaod.org> --- hw/9pfs/9p-xattr.c | 156 ++++++++++++++++++++++++++++++++++++++++++++++++++++ hw/9pfs/9p-xattr.h | 11 ++++ 2 files changed, 167 insertions(+) diff --git a/hw/9pfs/9p-xattr.c b/hw/9pfs/9p-xattr.c index 19a2daf02f5c..ea0695f37242 100644 --- a/hw/9pfs/9p-xattr.c +++ b/hw/9pfs/9p-xattr.c @@ -15,7 +15,163 @@ #include "9p.h" #include "fsdev/file-op-9p.h" #include "9p-xattr.h" +#include "9p-util.h" +enum { + XATTRAT_OP_GET = 0, + XATTRAT_OP_LIST, + XATTRAT_OP_SET, + XATTRAT_OP_REMOVE +}; + +struct xattrat_data { + ssize_t ret; + int serrno; + char value[0]; +}; + +static void munmap_preserver_errno(void *addr, size_t length) +{ + int serrno = errno; + munmap(addr, length); + errno = serrno; +} + +static ssize_t do_xattrat_op(int op_type, int dirfd, const char *path, + const char *name, void *value, size_t size, + int flags) +{ + struct xattrat_data *data; + pid_t pid; + ssize_t ret = -1; + int wstatus; + + data = mmap(NULL, sizeof(*data) + size, PROT_READ | PROT_WRITE, + MAP_SHARED | MAP_ANONYMOUS, -1, 0); + if (data == MAP_FAILED) { + return -1; + } + data->ret = -1; + + pid = fork(); + if (pid < 0) { + goto err_out; + } else if (pid == 0) { + if (fchdir(dirfd) == 0) { + switch (op_type) { + case XATTRAT_OP_GET: + data->ret = lgetxattr(path, name, data->value, size); + break; + case XATTRAT_OP_LIST: + data->ret = llistxattr(path, data->value, size); + break; + case XATTRAT_OP_SET: + data->ret = lsetxattr(path, name, data->value, size, flags); + break; + case XATTRAT_OP_REMOVE: + data->ret = lremovexattr(path, name); + break; + default: + g_assert_not_reached(); + } + } + data->serrno = errno; + _exit(0); + } + assert(waitpid(pid, &wstatus, 0) == pid && WIFEXITED(wstatus)); + + ret = data->ret; + if (ret < 0) { + errno = data->serrno; + goto err_out; + } + memcpy(value, data->value, data->ret); + +err_out: + munmap_preserver_errno(data, sizeof(*data) + size); + return ret; +} + +ssize_t fgetxattrat(int dirfd, const char *path, const char *name, void *value, + size_t size) +{ + return do_xattrat_op(XATTRAT_OP_GET, dirfd, path, name, value, size, 0); +} + +ssize_t local_getxattr_nofollow(FsContext *ctx, const char *path, + const char *name, void *value, size_t size) +{ + char *dirpath = local_dirname(path); + char *filename = local_basename(path); + int dirfd; + ssize_t ret = -1; + + dirfd = local_opendir_nofollow(ctx, dirpath); + if (dirfd == -1) { + goto out; + } + + ret = fgetxattrat(dirfd, filename, name, value, size); + close_preserve_errno(dirfd); +out: + g_free(dirpath); + g_free(filename); + return ret; +} + +static ssize_t fsetxattrat(int dirfd, const char *path, const char *name, + void *value, size_t size, int flags) +{ + return do_xattrat_op(XATTRAT_OP_SET, dirfd, path, name, value, size, flags); +} + +ssize_t local_setxattr_nofollow(FsContext *ctx, const char *path, + const char *name, void *value, size_t size, + int flags) +{ + char *dirpath = local_dirname(path); + char *filename = local_basename(path); + int dirfd; + ssize_t ret = -1; + + dirfd = local_opendir_nofollow(ctx, dirpath); + if (dirfd == -1) { + goto out; + } + + ret = fsetxattrat(dirfd, filename, name, value, size, flags); + close_preserve_errno(dirfd); +out: + g_free(dirpath); + g_free(filename); + return ret; +} + +static ssize_t fremovexattrat(int dirfd, const char *path, const char *name) +{ + return do_xattrat_op(XATTRAT_OP_GET, dirfd, path, name, NULL, 0, 0); +} + +ssize_t local_removexattr_nofollow(FsContext *ctx, const char *path, + const char *name) +{ + char *dirpath = local_dirname(path); + char *filename = local_basename(path); + int dirfd; + ssize_t ret = -1; + + dirfd = local_opendir_nofollow(ctx, dirpath); + if (dirfd == -1) { + goto out; + } + + ret = fremovexattrat(dirfd, filename, name); + close_preserve_errno(dirfd); +out: + g_free(dirpath); + g_free(filename); + return ret; +} static XattrOperations *get_xattr_operations(XattrOperations **h, const char *name) diff --git a/hw/9pfs/9p-xattr.h b/hw/9pfs/9p-xattr.h index 3f43f5153f3c..d95ccc26a18d 100644 --- a/hw/9pfs/9p-xattr.h +++ b/hw/9pfs/9p-xattr.h @@ -15,6 +15,7 @@ #define QEMU_9P_XATTR_H #include "qemu/xattr.h" +#include "9p-local.h" typedef struct xattr_operations { @@ -29,6 +30,16 @@ typedef struct xattr_operations const char *path, const char *name); } XattrOperations; +ssize_t fgetxattrat(int dirfd, const char *path, const char *name, void *value, + size_t size); + +ssize_t local_getxattr_nofollow(FsContext *ctx, const char *path, + const char *name, void *value, size_t size); +ssize_t local_setxattr_nofollow(FsContext *ctx, const char *path, + const char *name, void *value, size_t size, + int flags); +ssize_t local_removexattr_nofollow(FsContext *ctx, const char *path, + const char *name); extern XattrOperations mapped_user_xattr; extern XattrOperations passthrough_user_xattr;