PARSECMD(9) PARSECMD(9)
NAME
parsecmd, cmderror, lookupcmd - parse device commands
SYNOPSIS
Cmdbuf* parsecmd(char *a, int n)
void cmderror(Cmdbuf *cb, char *s)
Cmdtab* lookupcmd(Cmdbuf *cb, Cmdtab *ctab, int nctab)
DESCRIPTION
Parsecmd is an interface to tokenize (see getfields(2)),
that safely parses a command, with blank-separated fields,
as might be written to a device's ctl file. The buffer a
and count n can be those passed to the driver's write func-
tion. Parsecmd converts the byte array (which might not be
null-terminated) to a null-terminated string, trimming any
trailing new line, before invoking tokenize to break the
string into arguments, interpreting blank and tab as field
separators when they are not quoted (in the style of rc(1)).
It returns a pointer to a dynamically-allocated Cmdbuf
structure, which holds a copy of the string and the result-
ing fields; it is defined as follows:
typedef
struct Cmdbuf
{
char *buf;
char **f;
int nf;
} Cmdbuf;
The array f holds the field pointers; nf gives the number of
fields. Cmdbuf is allocated by smalloc (see malloc(9)), and
the caller is responsible for freeing it using free.
Cmderror prepends the given format with the original com-
mand, then calls error(9).
Command strings may be turned into a (typically enumerated)
integer with lookupcmd. The catchall `*' matches any text.
Unrecognized commands, or commands given an unacceptable
number of arguments generate a call to error. The definition
is as follows
typedef
struct Cmdtab
{
int index; /* used by client to switch on result */
char *cmd; /* command name */
int narg; /* expected #args; 0 ==> variadic */
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PARSECMD(9) PARSECMD(9)
} Cmdtab;
The integer index is the number returned on command match.
The string cmd is the command name, and narg is 0 (indicat-
ing a variadic function) or the number of arguments.
SOURCE
/sys/src/9/port/parse.c
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