commit 8cb7308f3a24249ed091c7decf22005c64099783
from: Russ Cox <rsc@swtch.com>
date: Mon May 18 00:15:41 2020 UTC

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.

commit - 16f60479e16e3714b376e633c6b902a32e0607ea
commit + 8cb7308f3a24249ed091c7decf22005c64099783
blob - 10fc72573ca3ee5061b80bf9197e233d5d813b47
blob + 297df70ae54649e3f9de37d03e150ef7d6fa3fe3
--- include/u.h
+++ include/u.h
@@ -39,9 +39,6 @@ extern "C" {
 #	define _ALL_SOURCE
 #	undef HAS_SYS_TERMIOS
 #endif
-#if defined(__APPLE__)
-#	define _DARWIN_NO_64_BIT_INODE	/* Snow Leopard */
-#endif
 #define _LARGEFILE64_SOURCE 1
 #define _FILE_OFFSET_BITS 64
 
blob - ffee793100f0168f2cb785bf7f9371e177e60f56
blob + 65ea99ec73760fc2776d7fec98caba7fb7b0ff67
--- src/lib9/open.c
+++ src/lib9/open.c
@@ -1,16 +1,77 @@
 #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);
 }
 
+typedef struct DirBuild DirBuild;
+struct DirBuild {
+	Dir *d;
+	int nd;
+	int md;
+	char *str;
+	char *estr;
+};
+
 extern int _p9dir(struct stat*, struct stat*, char*, Dir*, char**, char*);
 
-#if defined(__linux__)
 static int
-mygetdents(int fd, struct dirent *buf, int n)
+dirbuild1(DirBuild *b, struct stat *lst, struct stat *st, char *name)
 {
-	off_t off;
-	int nn;
+	int i, nstr;
+	Dir *d;
+	int md, mstr;
+	char *lo, *hi, *newlo;
 
-	/* 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
-
-#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
-
-static int
-countde(char *p, int n)
-{
-	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);
+	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)
+	if((dir = dirget(fd)) == nil) {
+		werrstr("not a directory");
 		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);
-		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);
 }