lib9: use opendir/readdir to read directories

getdirentries(2) has been deprecated on macOS since 10.5 (ten releases ago).
Using it requires disabling 64-bit inodes, but that in turn makes binaries
incompatible with some dynamic libraries, most notably ASAN.

At some point getdirentries(2) will actually be removed.

For both these reasons, switch to opendir/readdir.
A little clunky since we have to keep the DIR* hidden away
to preserve the int fd interfaces, but it lets us remove a bunch
of OS-specific code too.

1 files changed, 187 insertions, 183 deletions

diff --git a/src/lib9/open.c b/src/lib9/open.c
index ffee7931..65ea99ec 100644
--- a/src/lib9/open.c
+++ b/src/lib9/open.c
@@ -1,15 +1,76 @@
 #define _GNU_SOURCE	/* for Linux O_DIRECT */
 #include <u.h>
-#define NOPLAN9DEFINES
+#include <dirent.h>
+#include <errno.h>
 #include <sys/file.h>
-#include <unistd.h>
-#include <fcntl.h>
-#include <libc.h>
 #include <sys/stat.h>
-#include <dirent.h>
-#ifndef O_DIRECT
-#define O_DIRECT 0
-#endif
+#define NOPLAN9DEFINES
+#include <libc.h>
+
+static struct {
+	Lock lk;
+	DIR **d;
+	int nd;
+} dirs;
+
+static int
+dirput(int fd, DIR *d)
+{
+	int i, nd;
+	DIR **dp;
+
+	if(fd < 0) {
+		werrstr("invalid fd");
+		return -1;
+	}
+	lock(&dirs.lk);
+	if(fd >= dirs.nd) {
+		nd = dirs.nd*2;
+		if(nd <= fd)
+			nd = fd+1;
+		dp = realloc(dirs.d, nd*sizeof dirs.d[0]);
+		if(dp == nil) {
+			werrstr("out of memory");
+			unlock(&dirs.lk);
+			return -1;
+		}
+		for(i=dirs.nd; i<nd; i++)
+			dp[i] = nil;
+		dirs.d = dp;
+		dirs.nd = nd;
+	}
+	dirs.d[fd] = d;
+	unlock(&dirs.lk);
+	return 0;
+}
+
+static DIR*
+dirget(int fd)
+{
+	DIR *d;
+
+	lock(&dirs.lk);
+	d = nil;
+	if(0 <= fd && fd < dirs.nd)
+		d = dirs.d[fd];
+	unlock(&dirs.lk);
+	return d;
+}
+
+static DIR*
+dirdel(int fd)
+{
+	DIR *d;
+
+	lock(&dirs.lk);
+	d = nil;
+	if(0 <= fd && fd < dirs.nd) {
+		d = dirs.d[fd];
+		dirs.d[fd] = nil;
+	}
+	unlock(&dirs.lk);
+	return d;
+}
 
 int
 p9create(char *path, int mode, ulong perm)
@@ -81,6 +142,8 @@ p9open(char *name, int mode)
 	int cexec, rclose;
 	int fd, umode, lock, rdwr;
 	struct flock fl;
+	struct stat st;
+	DIR *d;
 
 	rdwr = mode&3;
 	umode = rdwr;
@@ -123,6 +186,17 @@ p9open(char *name, int mode)
 		}
 		if(cexec)
 			fcntl(fd, F_SETFL, FD_CLOEXEC);
+		if(fstat(fd, &st) >= 0 && S_ISDIR(st.st_mode)) {
+			d = fdopendir(fd);
+			if(d == nil) {
+				close(fd);
+				return -1;
+			}
+			if(dirput(fd, d) < 0) {
+				closedir(d);
+				return -1;
+			}
+		}
 		if(rclose)
 			remove(name);
 	}
@@ -132,213 +206,143 @@ p9open(char *name, int mode)
 vlong
 p9seek(int fd, vlong offset, int whence)
 {
+	DIR *d;
+
+	if((d = dirget(fd)) != nil) {
+		if(whence == 1 && offset == 0)
+			return telldir(d);
+		if(whence == 0) {
+			seekdir(d, offset);
+			return 0;
+		}
+		werrstr("bad seek in directory");
+		return -1;
+	}
+
 	return lseek(fd, offset, whence);
 }
 
 int
 p9close(int fd)
 {
+	DIR *d;
+
+	if((d = dirdel(fd)) != nil)
+		return closedir(d);
 	return close(fd);
 }
 
-extern int _p9dir(struct stat*, struct stat*, char*, Dir*, char**, char*);
-
-#if defined(__linux__)
-static int
-mygetdents(int fd, struct dirent *buf, int n)
-{
-	off_t off;
-	int nn;
-
-	/* This doesn't match the man page, but it works in Debian with a 2.2 kernel */
-	off = p9seek(fd, 0, 1);
-	nn = getdirentries(fd, (void*)buf, n, &off);
-	return nn;
-}
-#elif defined(__APPLE__)
-static int
-mygetdents(int fd, struct dirent *buf, int n)
-{
-	long off;
-	return getdirentries(fd, (void*)buf, n, &off);
-}
-#elif defined(__FreeBSD__) || defined(__DragonFly__)
-static int
-mygetdents(int fd, struct dirent *buf, int n)
-{
-	off_t off;
-	return getdirentries(fd, (void*)buf, n, &off);
-}
-#elif defined(__sun__) || defined(__NetBSD__) || defined(__OpenBSD__)
-static int
-mygetdents(int fd, struct dirent *buf, int n)
-{
-	return getdents(fd, (void*)buf, n);
-}
-#elif defined(__AIX__)
-static int
-mygetdents(int fd, struct dirent *buf, int n)
-{
-	return getdirent(fd, (void*)buf, n);
-}
-#endif
+typedef struct DirBuild DirBuild;
+struct DirBuild {
+	Dir *d;
+	int nd;
+	int md;
+	char *str;
+	char *estr;
+};
 
-#if defined(__DragonFly__)
-static inline int d_reclen(struct dirent *de) { return _DIRENT_DIRSIZ(de); }
-#else
-static inline int d_reclen(struct dirent *de) { return de->d_reclen; }
-#endif
+extern int _p9dir(struct stat*, struct stat*, char*, Dir*, char**, char*);
 
 static int
-countde(char *p, int n)
+dirbuild1(DirBuild *b, struct stat *lst, struct stat *st, char *name)
 {
-	char *e;
-	int m;
-	struct dirent *de;
-
-	e = p+n;
-	m = 0;
-	while(p < e){
-		de = (struct dirent*)p;
-		if(d_reclen(de) <= 4+2+2+1 || p+d_reclen(de) > e)
-			break;
-		if(de->d_name[0]=='.' && de->d_name[1]==0)
-			de->d_name[0] = 0;
-		else if(de->d_name[0]=='.' && de->d_name[1]=='.' && de->d_name[2]==0)
-			de->d_name[0] = 0;
-		m++;
-		p += d_reclen(de);
+	int i, nstr;
+	Dir *d;
+	int md, mstr;
+	char *lo, *hi, *newlo;
+
+	nstr = _p9dir(lst, st, name, nil, nil, nil);
+	if(b->md-b->nd < 1 || b->estr-b->str < nstr) {
+		// expand either d space or str space or both.
+		md = b->md;
+		if(b->md-b->nd < 1) {
+			md *= 2;
+			if(md < 16)
+				md = 16;
+		}
+		mstr = b->estr-(char*)&b->d[b->md];
+		if(b->estr-b->str < nstr) {
+			mstr += nstr;
+			mstr += mstr/2;
+		}
+		if(mstr < 512)
+			mstr = 512;
+		d = realloc(b->d, md*sizeof d[0] + mstr);
+		if(d == nil)
+			return -1;
+		// move strings and update pointers in Dirs
+		lo = (char*)&b->d[b->md];
+		newlo = (char*)&d[md];
+		hi = b->str;
+		memmove(newlo, lo+((char*)d-(char*)b->d), hi-lo);
+		for(i=0; i<b->nd; i++) {
+			if(lo <= d[i].name && d[i].name < hi)
+				d[i].name += newlo - lo;
+			if(lo <= d[i].uid && d[i].uid < hi)
+				d[i].uid += newlo - lo;
+			if(lo <= d[i].gid && d[i].gid < hi)
+				d[i].gid += newlo - lo;
+			if(lo <= d[i].muid && d[i].muid < hi)
+				d[i].muid += newlo - lo;
+		}
+		b->d = d;
+		b->md = md;
+		b->str += newlo - lo;
+		b->estr = newlo + mstr;
 	}
-	return m;
+	_p9dir(lst, st, name, &b->d[b->nd], &b->str, b->estr);
+	b->nd++;
+	return 0;
 }
 
-static int
-dirpackage(int fd, char *buf, int n, Dir **dp)
+static long
+dirreadmax(int fd, Dir **dp, int max)
 {
-	int oldwd;
-	char *p, *str, *estr;
-	int i, nstr, m;
+	int i;
+	DIR *dir;
+	DirBuild b;
 	struct dirent *de;
 	struct stat st, lst;
-	Dir *d;
-
-	n = countde(buf, n);
-	if(n <= 0)
-		return n;
-
-	if((oldwd = open(".", O_RDONLY)) < 0)
-		return -1;
-	if(fchdir(fd) < 0)
-		return -1;
-
-	p = buf;
-	nstr = 0;
-
-	for(i=0; i<n; i++){
-		de = (struct dirent*)p;
-		memset(&lst, 0, sizeof lst);
-		if(de->d_name[0] == 0)
-			/* nothing */ {}
-		else if(lstat(de->d_name, &lst) < 0)
-			de->d_name[0] = 0;
-		else{
-			st = lst;
-			if(S_ISLNK(lst.st_mode))
-				stat(de->d_name, &st);
-			nstr += _p9dir(&lst, &st, de->d_name, nil, nil, nil);
-		}
-		p += d_reclen(de);
-	}
 
-	d = malloc(sizeof(Dir)*n+nstr);
-	if(d == nil){
-		fchdir(oldwd);
-		close(oldwd);
+	if((dir = dirget(fd)) == nil) {
+		werrstr("not a directory");
 		return -1;
 	}
-	str = (char*)&d[n];
-	estr = str+nstr;
 
-	p = buf;
-	m = 0;
-	for(i=0; i<n; i++){
-		de = (struct dirent*)p;
-		if(de->d_name[0] != 0 && lstat(de->d_name, &lst) >= 0){
-			st = lst;
-			if((lst.st_mode&S_IFMT) == S_IFLNK)
-				stat(de->d_name, &st);
-			_p9dir(&lst, &st, de->d_name, &d[m++], &str, estr);
+	memset(&b, 0, sizeof b);
+	for(i=0; max == -1 || i<max; i++) { // max = not too many, not too few
+		errno = 0;
+		de = readdir(dir);
+		if(de == nil) {
+			if(b.nd == 0 && errno != 0)
+				return -1;
+			break;
 		}
-		p += d_reclen(de);
+		if(de->d_name[de->d_namlen] != 0)
+			sysfatal("bad readdir");
+		if(de->d_name[0]=='.' && de->d_name[1]==0)
+			continue;
+		if(de->d_name[0]=='.' && de->d_name[1]=='.' && de->d_name[2]==0)
+			continue;
+		if(fstatat(fd, de->d_name, &lst, AT_SYMLINK_NOFOLLOW) < 0)
+			continue;
+		st = lst;
+		if(S_ISLNK(lst.st_mode))
+			fstatat(fd, de->d_name, &st, 0);
+		dirbuild1(&b, &lst, &st, de->d_name);
 	}
-
-	fchdir(oldwd);
-	close(oldwd);
-	*dp = d;
-	return m;
+	*dp = b.d;
+	return b.nd;
 }
 
 long
 dirread(int fd, Dir **dp)
 {
-	char *buf;
-	struct stat st;
-	int n;
-
-	*dp = 0;
-
-	if(fstat(fd, &st) < 0)
-		return -1;
-
-	if(st.st_blksize < 8192)
-		st.st_blksize = 8192;
-
-	buf = malloc(st.st_blksize);
-	if(buf == nil)
-		return -1;
-
-	n = mygetdents(fd, (void*)buf, st.st_blksize);
-	if(n < 0){
-		free(buf);
-		return -1;
-	}
-	n = dirpackage(fd, buf, n, dp);
-	free(buf);
-	return n;
+	return dirreadmax(fd, dp, 10);
 }
 
-
 long
-dirreadall(int fd, Dir **d)
+dirreadall(int fd, Dir **dp)
 {
-	uchar *buf, *nbuf;
-	long n, ts;
-	struct stat st;
-
-	if(fstat(fd, &st) < 0)
-		return -1;
-
-	if(st.st_blksize < 8192)
-		st.st_blksize = 8192;
-
-	buf = nil;
-	ts = 0;
-	for(;;){
-		nbuf = realloc(buf, ts+st.st_blksize);
-		if(nbuf == nil){
-			free(buf);
-			return -1;
-		}
-		buf = nbuf;
-		n = mygetdents(fd, (void*)(buf+ts), st.st_blksize);
-		if(n <= 0)
-			break;
-		ts += n;
-	}
-	if(ts >= 0)
-		ts = dirpackage(fd, (char*)buf, ts, d);
-	free(buf);
-	if(ts == 0 && n < 0)
-		return -1;
-	return ts;
+	return dirreadmax(fd, dp, -1);
 }