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Diffstat (limited to 'man/man3/9pcmdbuf.3')
| -rw-r--r-- | man/man3/9pcmdbuf.3 | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/man/man3/9pcmdbuf.3 b/man/man3/9pcmdbuf.3 new file mode 100644 index 00000000..ccb5419b --- /dev/null +++ b/man/man3/9pcmdbuf.3 @@ -0,0 +1,116 @@ +.TH 9PCMDBUF 3 +.SH NAME +Cmdbuf, parsecmd, respondcmderror, lookupcmd \- control message parsing +.SH SYNOPSIS +.ft L +.nf +#include <u.h> +#include <libc.h> +#include <fcall.h> +#include <thread.h> +#include <9p.h> +.fi +.PP +.ft L +.nf +.ta \w'\fL1234'u +\w'\fL12345678'u +typedef struct Cmdbuf +{ + char *buf; + char **f; + int nf; +} Cmdbuf; + +typedef struct Cmdtab +{ + int index; + char *cmd; + int narg; +}; + +Cmdbuf *parsecmd(char *p, int n) +Cmdtab *lookupcmd(Cmdbuf *cb, Cmdtab *tab, int ntab) +void respondcmderror(Req *r, Cmdbuf *cb, char *fmt, ...) +.fi +.SH DESCRIPTION +These data structures and functions provide parsing of textual control messages. +.PP +.I Parsecmd +treats the +.I n +bytes at +.I p +(which need not be NUL-terminated) as a UTF string and splits it +using +.IR tokenize (2). +It returns a +.B Cmdbuf +structure holding pointers to each field in the message. +.PP +.I Lookupcmd +walks through the array +.IR ctab , +which has +.I ntab +entries, +looking for the first +.B Cmdtab +that matches the parsed command. +(If the parsed command is empty, +.I lookupcmd +returns nil immediately.) +A +.B Cmdtab +matches the command if +.I cmd +is equal to +.IB cb -> f [0] +or if +.I cmd +is +.LR * . +Once a matching +.B Cmdtab +has been found, if +.I narg +is not zero, then the parsed command +must have exactly +.I narg +fields (including the command string itself). +If the command has the wrong number of arguments, +.I lookupcmd +returns nil. +Otherwise, it returns a pointer to the +.B Cmdtab +entry. +If +.I lookupcmd +does not find a matching command at all, +it returns nil. +Whenever +.I lookupcmd +returns nil, it sets the system error string. +.PP +.I Respondcmderror +resoponds to request +.I r +with an error of the form +`\fIfmt\fB:\fI cmd\fR,' +where +.I fmt +is the formatted string and +.I cmd +is a reconstruction of the parsed command. +Fmt +is often simply +.B "%r" . +.SH EXAMPLES +This interface is not used in any distributed 9P servers. +It was lifted from the Plan 9 kernel. +Almost any kernel driver +.RB ( /sys/src/9/*/dev*.c ) +is a good example. +.SH SOURCE +.B /sys/src/lib9p/parse.c +.SH SEE ALSO +.IR 9p (2) |