From 1b0edd3d0a2ee5c097bcf3501c1dfa937f02e473 Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Mon, 27 Jan 2020 19:01:21 +0100 Subject: [PATCH 050/116] virtiofsd: add fuse_mbuf_iter API MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit RH-Author: Dr. David Alan Gilbert Message-id: <20200127190227.40942-47-dgilbert@redhat.com> Patchwork-id: 93502 O-Subject: [RHEL-AV-8.2 qemu-kvm PATCH 046/112] virtiofsd: add fuse_mbuf_iter API Bugzilla: 1694164 RH-Acked-by: Philippe Mathieu-Daudé RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Sergio Lopez Pascual From: Stefan Hajnoczi Introduce an API for consuming bytes from a buffer with size checks. All FUSE operations will be converted to use this safe API instead of void *inarg. Signed-off-by: Stefan Hajnoczi Signed-off-by: Dr. David Alan Gilbert (cherry picked from commit dad157e880416ab3a0e45beaa0e81977516568bc) Signed-off-by: Miroslav Rezanina --- tools/virtiofsd/buffer.c | 28 +++++++++++++++++++++++++ tools/virtiofsd/fuse_common.h | 49 ++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 76 insertions(+), 1 deletion(-) diff --git a/tools/virtiofsd/buffer.c b/tools/virtiofsd/buffer.c index 772efa9..42a608f 100644 --- a/tools/virtiofsd/buffer.c +++ b/tools/virtiofsd/buffer.c @@ -267,3 +267,31 @@ ssize_t fuse_buf_copy(struct fuse_bufvec *dstv, struct fuse_bufvec *srcv) return copied; } + +void *fuse_mbuf_iter_advance(struct fuse_mbuf_iter *iter, size_t len) +{ + void *ptr; + + if (len > iter->size - iter->pos) { + return NULL; + } + + ptr = iter->mem + iter->pos; + iter->pos += len; + return ptr; +} + +const char *fuse_mbuf_iter_advance_str(struct fuse_mbuf_iter *iter) +{ + const char *str = iter->mem + iter->pos; + size_t remaining = iter->size - iter->pos; + size_t i; + + for (i = 0; i < remaining; i++) { + if (str[i] == '\0') { + iter->pos += i + 1; + return str; + } + } + return NULL; +} diff --git a/tools/virtiofsd/fuse_common.h b/tools/virtiofsd/fuse_common.h index 0cb33ac..f8f6433 100644 --- a/tools/virtiofsd/fuse_common.h +++ b/tools/virtiofsd/fuse_common.h @@ -703,10 +703,57 @@ size_t fuse_buf_size(const struct fuse_bufvec *bufv); */ ssize_t fuse_buf_copy(struct fuse_bufvec *dst, struct fuse_bufvec *src); +/** + * Memory buffer iterator + * + */ +struct fuse_mbuf_iter { + /** + * Data pointer + */ + void *mem; + + /** + * Total length, in bytes + */ + size_t size; + + /** + * Offset from start of buffer + */ + size_t pos; +}; + +/* Initialize memory buffer iterator from a fuse_buf */ +#define FUSE_MBUF_ITER_INIT(fbuf) \ + ((struct fuse_mbuf_iter){ \ + .mem = fbuf->mem, \ + .size = fbuf->size, \ + .pos = 0, \ + }) + +/** + * Consume bytes from a memory buffer iterator + * + * @param iter memory buffer iterator + * @param len number of bytes to consume + * @return pointer to start of consumed bytes or + * NULL if advancing beyond end of buffer + */ +void *fuse_mbuf_iter_advance(struct fuse_mbuf_iter *iter, size_t len); + +/** + * Consume a NUL-terminated string from a memory buffer iterator + * + * @param iter memory buffer iterator + * @return pointer to the string or + * NULL if advancing beyond end of buffer or there is no NUL-terminator + */ +const char *fuse_mbuf_iter_advance_str(struct fuse_mbuf_iter *iter); + /* * Signal handling */ - /** * Exit session on HUP, TERM and INT signals and ignore PIPE signal * -- 1.8.3.1