NAME

parsefields, parsecmd − parse strings and device commands

SYNOPSIS

intparsefields(char ∗s, char ∗∗fields, int n, char ∗sep);

Cmdbuf∗parsecmd(char ∗a, int n);

DESCRIPTION

­Parsefields breaks the null-terminated string ­s into at most ­n null-terminated strings and places pointers to the start of those strings in the array fields. It returns the number of fields. A field is a maximal sequence of non-separator characters. The field separators are listed in sep. ­Parsefields overwrites the separator characters in the input string s.

­Parsecmd is an interface to ­parsefields 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 function.  ­Parsecmd converts the byte array (which might not be null-terminated) to a null-terminated string, trimming any trailing new line, before invoking parsefields with space as the only field separator.  It returns a pointer to a dynamically-allocated ­Cmdbuf structure, which holds a copy of the string as modified by parsefields, and the resulting fields; it is defined as follows:

typedef
struct Cmdbuf
{
charbuf[128];
char∗f[16];
intnf;
} Cmdbuf;

The array ­f holds the field pointers; ­nf gives the number of fields.  ­Cmdbuf is allocated by ­smalloc (see malloc(10.2)), and the caller is responsible for freeing it using free.

SOURCE

­/os/port/utils.c
­/emu/dev.c

Plan 9  —  April 13, 2000