I'd like to make this modification to fix PR #8868 (pax(1) fails on SIGINFO).
Please review.

The cause of the problem is that if the SIGINFO is caught
in the middle of write(2) system call, write() does not
continue the operation after the signal and returns with
partial operation.

The signal(3) manpage says that the read(2) may also does
partial operation on signals.

To fix the problem, we should either
 1. disable SIGINFO hack, or
 2. retry every partial read(2)/write(2).

The following changes implements 2.

On 4.2BSD and later BSD systems, read(2)/write(2) is
restarted if no operation performed yet (not even partial),
and the "#ifdef SYS_NO_RESTART" parts are not required.
They are to help porting to other systems.

OK to commit this?

Regards,
-- 
ITOH, Yasufumi <itohy@netbsd.org>

diff -uF^[a-zA-Z_][a-z 	A-Z0-9_]*(.*[^;]$ ar_io.c.orig ar_io.c
--- ar_io.c.orig	Mon Oct 25 08:16:15 1999
+++ ar_io.c	Thu Feb 10 07:59:13 2000
@@ -438,7 +438,7 @@ ar_drain()
 	/*
 	 * keep reading until pipe is drained
 	 */
-	while ((res = read(arfd, drbuf, sizeof(drbuf))) > 0)
+	while ((res = read_with_restart(arfd, drbuf, sizeof(drbuf))) > 0)
 		;
 	lstrval = res;
 }
@@ -518,6 +518,132 @@ ar_app_ok()
 	return(-1);
 }
 
+#ifdef SYS_NO_RESTART
+/*
+ * read_with_restart()
+ *	Equivalent to read() but does retry on signals.
+ *	This function is not needed on 4.2BSD and later.
+ * Return:
+ *	Number of bytes written.  -1 indicates an error.
+ */
+
+#if __STDC__
+int
+read_with_restart(int fd, void *buf, int bsz)
+#else
+int
+read_with_restart(fd, buf, bsz)
+	int fd;
+	void *buf;
+	int bsz;
+#endif
+{
+	int r;
+
+	while (((r = read(fd, buf, bsz)) < 0) && errno == EINTR)
+		;
+
+	return(r);
+}
+#endif
+
+/*
+ * xread()
+ *	Equivalent to read() but does retry on partial read, which may occur
+ *	on signals.
+ * Return:
+ *	Number of bytes read.  0 for end of file, -1 for an error.
+ */
+
+#if __STDC__
+int
+xread(int fd, void *buf, int bsz)
+#else
+int
+xread(fd, buf, bsz)
+	int fd;
+	void *buf;
+	int bsz;
+#endif
+{
+	char *b = buf;
+	int nread = 0;
+	int r;
+
+	do {
+		if ((r = read_with_restart(fd, b, bsz)) <= 0)
+			break;
+		b += r;
+		bsz -= r;
+		nread += r;
+	} while (bsz > 0);
+
+	return(nread ? nread : r);
+}
+
+#ifdef SYS_NO_RESTART
+/*
+ * write_with_restart()
+ *	Equivalent to write() but does retry on signals.
+ *	This function is not needed on 4.2BSD and later.
+ * Return:
+ *	Number of bytes written.  -1 indicates an error.
+ */
+
+#if __STDC__
+int
+write_with_restart(int fd, void *buf, int bsz)
+#else
+int
+write_with_restart(fd, buf, bsz)
+	int fd;
+	void *buf;
+	int bsz;
+#endif
+{
+	int r;
+
+	while (((r = write(fd, buf, bsz)) < 0) && errno == EINTR)
+		;
+
+	return(r);
+}
+#endif
+
+/*
+ * xwrite()
+ *	Equivalent to write() but does retry on partial write, which may occur
+ *	on signals.
+ * Return:
+ *	Number of bytes written.  -1 indicates an error.
+ */
+
+#if __STDC__
+int
+xwrite(int fd, void *buf, int bsz)
+#else
+int
+xwrite(fd, buf, bsz)
+	int fd;
+	void *buf;
+	int bsz;
+#endif
+{
+	char *b = buf;
+	int written = 0;
+	int r;
+
+	do {
+		if ((r = write_with_restart(fd, b, bsz)) <= 0)
+			break;
+		b += r;
+		bsz -= r;
+		written += r;
+	} while (bsz > 0);
+
+	return(written ? written : r);
+}
+
 /*
  * ar_read()
  *	read up to a specified number of bytes from the archive into the
@@ -550,7 +676,7 @@ ar_read(buf, cnt)
 	 */
 	switch (artyp) {
 	case ISTAPE:
-		if ((res = read(arfd, buf, cnt)) > 0) {
+		if ((res = read_with_restart(arfd, buf, cnt)) > 0) {
 			/*
 			 * CAUTION: tape systems may not always return the same
 			 * sized records so we leave blksz == MAXBLK. The
@@ -588,7 +714,7 @@ ar_read(buf, cnt)
 		 * and return. Trying to do anything else with them runs the
 		 * risk of failure.
 		 */
-		if ((res = read(arfd, buf, cnt)) > 0) {
+		if ((res = read_with_restart(arfd, buf, cnt)) > 0) {
 			io_ok = 1;
 			return(res);
 		}
@@ -637,7 +763,7 @@ ar_write(buf, bsz)
 	if (lstrval <= 0)
 		return(lstrval);
 
-	if ((res = write(arfd, buf, bsz)) == bsz) {
+	if ((res = xwrite(arfd, buf, bsz)) == bsz) {
 		wr_trail = 1;
 		io_ok = 1;
 		return(bsz);
@@ -1064,7 +1190,7 @@ get_phys()
 		 * we know we are at file mark when we get back a 0 from
 		 * read()
 		 */
-		while ((res = read(arfd, scbuf, sizeof(scbuf))) > 0)
+		while ((res = read_with_restart(arfd, scbuf, sizeof(scbuf))) > 0)
 			padsz += res;
 		if (res < 0) {
 			syswarn(1, errno, "Unable to locate tape filemark.");
@@ -1093,16 +1219,16 @@ get_phys()
 		syswarn(1, errno, "Unable to backspace over last tape block.");
 		return(-1);
 	}
-	if ((phyblk = read(arfd, scbuf, sizeof(scbuf))) <= 0) {
+	if ((phyblk = read_with_restart(arfd, scbuf, sizeof(scbuf))) <= 0) {
 		syswarn(1, errno, "Cannot determine archive tape blocksize.");
 		return(-1);
 	}
 
 	/*
-	 * read foward to the file mark, then back up in front of the filemark
+	 * read forward to the file mark, then back up in front of the filemark
 	 * (this is a bit paranoid, but should be safe to do).
 	 */
-	while ((res = read(arfd, scbuf, sizeof(scbuf))) > 0)
+	while ((res = read_with_restart(arfd, scbuf, sizeof(scbuf))) > 0)
 		;
 	if (res < 0) {
 		syswarn(1, errno, "Unable to locate tape filemark.");
diff -uF^[a-zA-Z_][a-z 	A-Z0-9_]*(.*[^;]$ buf_subs.c.orig buf_subs.c
--- buf_subs.c.orig	Mon Oct 25 08:16:15 1999
+++ buf_subs.c	Wed Feb  9 22:40:45 2000
@@ -699,7 +699,7 @@ wr_rdfile(arcn, ifd, left)
 			return(-1);
 		}
 		cnt = MIN(cnt, size);
-		if ((res = read(ifd, bufpt, cnt)) <= 0)
+		if ((res = read_with_restart(ifd, bufpt, cnt)) <= 0)
 			break;
 		size -= res;
 		bufpt += res;
@@ -884,10 +884,10 @@ cp_file(arcn, fd1, fd2)
 	 * read the source file and copy to destination file until EOF
 	 */
 	for(;;) {
-		if ((cnt = read(fd1, buf, blksz)) <= 0)
+		if ((cnt = read_with_restart(fd1, buf, blksz)) <= 0)
 			break;
 		if (no_hole)
-			res = write(fd2, buf, cnt);
+			res = xwrite(fd2, buf, cnt);
 		else
 			res = file_write(fd2, buf, cnt, &rem, &isem, sz, fnm);
 		if (res != cnt)
diff -u extern.h.orig extern.h
--- extern.h.orig	Tue Nov  2 16:13:03 1999
+++ extern.h	Wed Feb  9 22:25:46 2000
@@ -57,6 +57,15 @@
 void ar_drain __P((void));
 int ar_set_wr __P((void));
 int ar_app_ok __P((void));
+#ifdef SYS_NO_RESTART
+int read_with_restart __P((int, void *, int));
+int write_with_restart __P((int, void *, int));
+#else
+#define read_with_restart	read
+#define write_with_restart	write
+#endif
+int xread __P((int, void *, int));
+int xwrite __P((int, void *, int));
 int ar_read __P((char *, int));
 int ar_write __P((char *, int));
 int ar_rdsync __P((void));
diff -uF^[a-zA-Z_][a-z 	A-Z0-9_]*(.*[^;]$ tables.c.orig tables.c
--- tables.c.orig	Tue Nov  2 16:13:04 1999
+++ tables.c	Wed Feb  9 12:14:26 2000
@@ -446,7 +446,7 @@ chk_ftime(arcn)
 					    "Failed ftime table seek");
 					return(-1);
 				}
-				if (read(ffd, ckname, namelen) != namelen) {
+				if (xread(ffd, ckname, namelen) != namelen) {
 					syswarn(1, errno,
 					    "Failed ftime table read");
 					return(-1);
@@ -492,7 +492,7 @@ chk_ftime(arcn)
 		 * offset. add the file to the head of the hash chain
 		 */
 		if ((pt->seek = lseek(ffd, (off_t)0, SEEK_END)) >= 0) {
-			if (write(ffd, arcn->name, namelen) == namelen) {
+			if (xwrite(ffd, arcn->name, namelen) == namelen) {
 				pt->mtime = arcn->sb.st_mtime;
 				pt->namelen = namelen;
 				pt->fow = ftab[indx];
@@ -1288,8 +1288,8 @@ add_dir(name, nlen, psb, frc_mode)
 	dblk.atime = psb->st_atime;
 	dblk.fflags = psb->st_flags;
 	dblk.frc_mode = frc_mode;
-	if ((write(dirfd, name, dblk.nlen) == dblk.nlen) &&
-	    (write(dirfd, (char *)&dblk, sizeof(dblk)) == sizeof(dblk))) {
+	if ((xwrite(dirfd, name, dblk.nlen) == dblk.nlen) &&
+	    (xwrite(dirfd, (char *)&dblk, sizeof(dblk)) == sizeof(dblk))) {
 		++dircnt;
 		return;
 	}
@@ -1329,11 +1329,11 @@ proc_dir()
 		 */
 		if (lseek(dirfd, -((off_t)sizeof(dblk)), SEEK_CUR) < 0) 
 			break;
-		if (read(dirfd,(char *)&dblk, sizeof(dblk)) != sizeof(dblk))
+		if (xread(dirfd,(char *)&dblk, sizeof(dblk)) != sizeof(dblk))
 			break;
 		if (lseek(dirfd, dblk.npos, SEEK_SET) < 0) 
 			break;
-		if (read(dirfd, name, dblk.nlen) != dblk.nlen)
+		if (xread(dirfd, name, dblk.nlen) != dblk.nlen)
 			break;
 		if (lseek(dirfd, dblk.npos, SEEK_SET) < 0) 
 			break;
diff -uF^[a-zA-Z_][a-z 	A-Z0-9_]*(.*[^;]$ file_subs.c.orig file_subs.c
--- file_subs.c.orig	Mon Nov  8 09:46:29 1999
+++ file_subs.c	Wed Feb  9 22:40:56 2000
@@ -948,7 +948,7 @@ file_write(fd, str, cnt, rem, isempt, sz
 			}
 			strncpy(gnu_hack_string, st, wcnt);
 			gnu_hack_string[wcnt] = 0;
-		} else if (write(fd, st, wcnt) != wcnt) {
+		} else if (xwrite(fd, st, wcnt) != wcnt) {
 			syswarn(1, errno, "Failed write to file %s", name);
 			return(-1);
 		}
@@ -992,7 +992,7 @@ file_flush(fd, fname, isempt)
 		return;
 	}
 
-	if (write(fd, blnk, 1) < 0)
+	if (write_with_restart(fd, blnk, 1) < 0)
 		syswarn(1, errno, "Failed write to file %s", fname);
 	return;
 }