glob.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

#include "rc.h"
#include "exec.h"
#include "fns.h"
char *globname;
struct word *globv;
/*
 * delete all the GLOB marks from s, in place
 */

void
deglob(char *s)
{
	char *t = s;
	do{
		if(*t==GLOB)
			t++;
		*s++=*t;
	}while(*t++);
}

int
globcmp(const void *s, const void *t)
{
	return strcmp(*(char**)s, *(char**)t);
}

void
globsort(word *left, word *right)
{
	char **list;
	word *a;
	int n = 0;
	for(a = left;a!=right;a = a->next) n++;
	list = (char **)emalloc(n*sizeof(char *));
	for(a = left,n = 0;a!=right;a = a->next,n++) list[n] = a->word;
	qsort((void *)list, n, sizeof(void *), globcmp);
	for(a = left,n = 0;a!=right;a = a->next,n++) a->word = list[n];
	efree((char *)list);
}
/*
 * Push names prefixed by globname and suffixed by a match of p onto the astack.
 * namep points to the end of the prefix in globname.
 */

void
globdir(char *p, char *namep)
{
	char *t, *newp;
	int f;
	/* scan the pattern looking for a component with a metacharacter in it */
	if(*p=='\0'){
		globv = newword(globname, globv);
		return;
	}
	t = namep;
	newp = p;
	while(*newp){
		if(*newp==GLOB)
			break;
		*t=*newp++;
		if(*t++=='/'){
			namep = t;
			p = newp;
		}
	}
	/* If we ran out of pattern, append the name if accessible */
	if(*newp=='\0'){
		*t='\0';
		if(access(globname, 0)==0)
			globv = newword(globname, globv);
		return;
	}
	/* read the directory and recur for any entry that matches */
	*namep='\0';
	if((f = Opendir(globname[0]?globname:"."))<0) return;
	while(*newp!='/' && *newp!='\0') newp++;
	while(Readdir(f, namep, *newp=='/')){
		if(matchfn(namep, p)){
			for(t = namep;*t;t++);
			globdir(newp, t);
		}
	}
	Closedir(f);
}
/*
 * Push all file names matched by p on the current thread's stack.
 * If there are no matches, the list consists of p.
 */

void
glob(char *p)
{
	word *svglobv = globv;
	int globlen = Globsize(p);
	if(!globlen){
		deglob(p);
		globv = newword(p, globv);
		return;
	}
	globname = emalloc(globlen);
	globname[0]='\0';
	globdir(p, globname);
	efree(globname);
	if(svglobv==globv){
		deglob(p);
		globv = newword(p, globv);
	}
	else
		globsort(globv, svglobv);
}
/*
 * Do p and q point at equal utf codes
 */

int
equtf(char *p, char *q)
{
	if(*p!=*q)
		return 0;
	if(twobyte(*p)) return p[1]==q[1];
	if(threebyte(*p)){
		if(p[1]!=q[1])
			return 0;
		if(p[1]=='\0')
			return 1;	/* broken code at end of string! */
		return p[2]==q[2];
	}
	return 1;
}
/*
 * Return a pointer to the next utf code in the string,
 * not jumping past nuls in broken utf codes!
 */

char*
nextutf(char *p)
{
	if(twobyte(*p)) return p[1]=='\0'?p+1:p+2;
	if(threebyte(*p)) return p[1]=='\0'?p+1:p[2]=='\0'?p+2:p+3;
	return p+1;
}
/*
 * Convert the utf code at *p to a unicode value
 */

int
unicode(char *p)
{
	int u=*p&0xff;
	if(twobyte(u)) return ((u&0x1f)<<6)|(p[1]&0x3f);
	if(threebyte(u)) return (u<<12)|((p[1]&0x3f)<<6)|(p[2]&0x3f);
	return u;
}
/*
 * Does the string s match the pattern p
 * . and .. are only matched by patterns starting with .
 * * matches any sequence of characters
 * ? matches any single character
 * [...] matches the enclosed list of characters
 */

int
matchfn(char *s, char *p)
{
	if(s[0]=='.' && (s[1]=='\0' || s[1]=='.' && s[2]=='\0') && p[0]!='.')
		return 0;
	return match(s, p, '/');
}

int
match(char *s, char *p, int stop)
{
	int compl, hit, lo, hi, t, c;
	for(;*p!=stop && *p!='\0';s = nextutf(s),p = nextutf(p)){
		if(*p!=GLOB){
			if(!equtf(p, s)) return 0;
		}
		else switch(*++p){
		case GLOB:
			if(*s!=GLOB)
				return 0;
			break;
		case '*':
			for(;;){
				if(match(s, nextutf(p), stop)) return 1;
				if(!*s)
					break;
				s = nextutf(s);
			}
			return 0;
		case '?':
			if(*s=='\0')
				return 0;
			break;
		case '[':
			if(*s=='\0')
				return 0;
			c = unicode(s);
			p++;
			compl=*p=='~';
			if(compl)
				p++;
			hit = 0;
			while(*p!=']'){
				if(*p=='\0')
					return 0;		/* syntax error */
				lo = unicode(p);
				p = nextutf(p);
				if(*p!='-')
					hi = lo;
				else{
					p++;
					if(*p=='\0')
						return 0;	/* syntax error */
					hi = unicode(p);
					p = nextutf(p);
					if(hi<lo){ t = lo; lo = hi; hi = t; }
				}
				if(lo<=c && c<=hi)
					hit = 1;
			}
			if(compl)
				hit=!hit;
			if(!hit)
				return 0;
			break;
		}
	}
	return *s=='\0';
}

void
globlist1(word *gl)
{
	if(gl){
		globlist1(gl->next);
		glob(gl->word);
	}
}

void
globlist(void)
{
	word *a;
	globv = 0;
	globlist1(runq->argv->words);
	poplist();
	pushlist();
	if(globv){
		for(a = globv;a->next;a = a->next);
		a->next = runq->argv->words;
		runq->argv->words = globv;
	}
}