diff options
Diffstat (limited to 'net/9p/protocol.c')
| -rw-r--r-- | net/9p/protocol.c | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/net/9p/protocol.c b/net/9p/protocol.c index 83694c631989..4e3a2a1ffcb3 100644 --- a/net/9p/protocol.c +++ b/net/9p/protocol.c @@ -23,6 +23,173 @@ #include <trace/events/9p.h> +/* len[2] text[len] */ +#define P9_STRLEN(s) \ + (2 + min_t(size_t, s ? strlen(s) : 0, USHRT_MAX)) + +/** + * p9_msg_buf_size - Returns a buffer size sufficiently large to hold the + * intended 9p message. + * @c: client + * @type: message type + * @fmt: format template for assembling request message + * (see p9pdu_vwritef) + * @ap: variable arguments to be fed to passed format template + * (see p9pdu_vwritef) + * + * Note: Even for response types (P9_R*) the format template and variable + * arguments must always be for the originating request type (P9_T*). + */ +size_t p9_msg_buf_size(struct p9_client *c, enum p9_msg_t type, + const char *fmt, va_list ap) +{ + /* size[4] type[1] tag[2] */ + const int hdr = 4 + 1 + 2; + /* ename[s] errno[4] */ + const int rerror_size = hdr + P9_ERRMAX + 4; + /* ecode[4] */ + const int rlerror_size = hdr + 4; + const int err_size = + c->proto_version == p9_proto_2000L ? rlerror_size : rerror_size; + + static_assert(NAME_MAX <= 4*1024, "p9_msg_buf_size() currently assumes " + "a max. allowed directory entry name length of 4k"); + + switch (type) { + + /* message types not used at all */ + case P9_TERROR: + case P9_TLERROR: + case P9_TAUTH: + case P9_RAUTH: + BUG(); + + /* variable length & potentially large message types */ + case P9_TATTACH: + BUG_ON(strcmp("ddss?u", fmt)); + va_arg(ap, int32_t); + va_arg(ap, int32_t); + { + const char *uname = va_arg(ap, const char *); + const char *aname = va_arg(ap, const char *); + /* fid[4] afid[4] uname[s] aname[s] n_uname[4] */ + return hdr + 4 + 4 + P9_STRLEN(uname) + P9_STRLEN(aname) + 4; + } + case P9_TWALK: + BUG_ON(strcmp("ddT", fmt)); + va_arg(ap, int32_t); + va_arg(ap, int32_t); + { + uint i, nwname = va_arg(ap, int); + size_t wname_all; + const char **wnames = va_arg(ap, const char **); + for (i = 0, wname_all = 0; i < nwname; ++i) { + wname_all += P9_STRLEN(wnames[i]); + } + /* fid[4] newfid[4] nwname[2] nwname*(wname[s]) */ + return hdr + 4 + 4 + 2 + wname_all; + } + case P9_RWALK: + BUG_ON(strcmp("ddT", fmt)); + va_arg(ap, int32_t); + va_arg(ap, int32_t); + { + uint nwname = va_arg(ap, int); + /* nwqid[2] nwqid*(wqid[13]) */ + return max_t(size_t, hdr + 2 + nwname * 13, err_size); + } + case P9_TCREATE: + BUG_ON(strcmp("dsdb?s", fmt)); + va_arg(ap, int32_t); + { + const char *name = va_arg(ap, const char *); + if (c->proto_version == p9_proto_legacy) { + /* fid[4] name[s] perm[4] mode[1] */ + return hdr + 4 + P9_STRLEN(name) + 4 + 1; + } else { + va_arg(ap, int32_t); + va_arg(ap, int); + { + const char *ext = va_arg(ap, const char *); + /* fid[4] name[s] perm[4] mode[1] extension[s] */ + return hdr + 4 + P9_STRLEN(name) + 4 + 1 + P9_STRLEN(ext); + } + } + } + case P9_TLCREATE: + BUG_ON(strcmp("dsddg", fmt)); + va_arg(ap, int32_t); + { + const char *name = va_arg(ap, const char *); + /* fid[4] name[s] flags[4] mode[4] gid[4] */ + return hdr + 4 + P9_STRLEN(name) + 4 + 4 + 4; + } + case P9_RREAD: + case P9_RREADDIR: + BUG_ON(strcmp("dqd", fmt)); + va_arg(ap, int32_t); + va_arg(ap, int64_t); + { + const int32_t count = va_arg(ap, int32_t); + /* count[4] data[count] */ + return max_t(size_t, hdr + 4 + count, err_size); + } + case P9_TWRITE: + BUG_ON(strcmp("dqV", fmt)); + va_arg(ap, int32_t); + va_arg(ap, int64_t); + { + const int32_t count = va_arg(ap, int32_t); + /* fid[4] offset[8] count[4] data[count] */ + return hdr + 4 + 8 + 4 + count; + } + case P9_TRENAMEAT: + BUG_ON(strcmp("dsds", fmt)); + va_arg(ap, int32_t); + { + const char *oldname, *newname; + oldname = va_arg(ap, const char *); + va_arg(ap, int32_t); + newname = va_arg(ap, const char *); + /* olddirfid[4] oldname[s] newdirfid[4] newname[s] */ + return hdr + 4 + P9_STRLEN(oldname) + 4 + P9_STRLEN(newname); + } + case P9_TSYMLINK: + BUG_ON(strcmp("dssg", fmt)); + va_arg(ap, int32_t); + { + const char *name = va_arg(ap, const char *); + const char *symtgt = va_arg(ap, const char *); + /* fid[4] name[s] symtgt[s] gid[4] */ + return hdr + 4 + P9_STRLEN(name) + P9_STRLEN(symtgt) + 4; + } + + case P9_RERROR: + return rerror_size; + case P9_RLERROR: + return rlerror_size; + + /* small message types */ + case P9_TWSTAT: + case P9_RSTAT: + case P9_RREADLINK: + case P9_TXATTRWALK: + case P9_TXATTRCREATE: + case P9_TLINK: + case P9_TMKDIR: + case P9_TMKNOD: + case P9_TRENAME: + case P9_TUNLINKAT: + case P9_TLOCK: + return 8 * 1024; + + /* tiny message types */ + default: + return 4 * 1024; + + } +} + static int p9pdu_writef(struct p9_fcall *pdu, int proto_version, const char *fmt, ...); |