/* splitline.c – commmand reading and parsing functions for smsh
*
* char *next_cmd(char *prompt, FILE *fp) – get next command
* char **splitline(char *str); – parse a string
*/
#include
#include
#include
#include “smsh.h”
char * next_cmd(char *prompt, FILE *fp)
/*
* purpose: read next command line from fp
* returns: dynamically allocated string holding command line
* errors: NULL at EOF (not really an error)
* calls fatal from emalloc()
* notes: allocates space in BUFSIZ chunks.
*/
{
char *buf ; /* the buffer */
int bufspace = 0; /* total size */
int pos = 0; /* current position */
int c; /* input char */
printf(“%s”, prompt); /* prompt user */
while( ( c = getc(fp)) != EOF ) {
/* need space? */
if( pos+1 >= bufspace ){ /* 1 for \0 */
if ( bufspace == 0 ) /* y: 1st time */
buf = emalloc(BUFSIZ);
else /* or expand */
buf = erealloc(buf,bufspace+BUFSIZ);
bufspace += BUFSIZ; /* update size */
}
/* end of command? */
if ( c == ‘\n’ )
break;
/* no, add to buffer */
buf[pos++] = c;
}
if ( c == EOF && pos == 0 ) /* EOF and no input */
return NULL; /* say so */
buf[pos] = ‘\0′;
return buf;
}
/**
** splitline ( parse a line into an array of strings )
**/
#define is_delim(x) ((x)==’ ‘||(x)==’\t’)
char ** splitline(char *line)
/*
* purpose: split a line into array of white-space separated tokens
* returns: a NULL-terminated array of pointers to copies of the tokens
* or NULL if line if no tokens on the line
* action: traverse the array, locate strings, make copies
* note: strtok() could work, but we may want to add quotes later
*/
{
char *newstr();
char **args ;
int spots = 0; /* spots in table */
int bufspace = 0; /* bytes in table */
int argnum = 0; /* slots used */
char *cp = line; /* pos in string */
char *start;
int len;
if ( line == NULL ) /* handle special case */
return NULL;
args = emalloc(BUFSIZ); /* initialize array */
bufspace = BUFSIZ;
spots = BUFSIZ/sizeof(char *);
while( *cp != ‘\0’ )
{
while ( is_delim(*cp) ) /* skip leading spaces */
cp++;
if ( *cp == ‘\0’ ) /* quit at end-o-string */
break;
/* make sure the array has room (+1 for NULL) */
if ( argnum+1 >= spots ){
args = erealloc(args,bufspace+BUFSIZ);
bufspace += BUFSIZ;
spots += (BUFSIZ/sizeof(char *));
}
/* mark start, then find end of word */
start = cp;
len = 1;
while (*++cp != ‘\0’ && !(is_delim(*cp)) )
len++;
args[argnum++] = newstr(start, len);
}
args[argnum] = NULL;
return args;
}
/*
* purpose: constructor for strings
* returns: a string, never NULL
*/
char *newstr(char *s, int l)
{
char *rv = emalloc(l+1);
rv[l] = ‘\0’;
strncpy(rv, s, l);
return rv;
}
void
freelist(char **list)
/*
* purpose: free the list returned by splitline
* returns: nothing
* action: free all strings in list and then free the list
*/
{
char **cp = list;
while( *cp )
free(*cp++);
free(list);
}
void * emalloc(size_t n)
{
void *rv ;
if ( (rv = malloc(n)) == NULL )
fatal(“out of memory”,””,1);
return rv;
}
void * erealloc(void *p, size_t n)
{
void *rv;
if ( (rv = realloc(p,n)) == NULL )
fatal(“realloc() failed”,””,1);
return rv;
}