Handle EINTR on the spot instead of restarting the entire loop

- The previous code was violating the "golden rules of select()" by
  possibly skipping processing of fd's that were included in the
  select() set. Also restarting the entire loop should not be
  necessary in case of EINTR select(), our conditions do not change
  in that situation.

1 files changed, 20 insertions, 14 deletions

diff --git a/build/rpmfc.c b/build/rpmfc.c
index 031001507..60ab0e390 100644
--- a/build/rpmfc.c
+++ b/build/rpmfc.c
@@ -243,7 +243,7 @@ static StringBuf getOutputFrom(ARGV_t argv,
     while (1) {
 	fd_set ibits, obits;
 	int nfd = 0;
-	int rc;
+	ssize_t iorc;
 	char buf[BUFSIZ+1];
 
 	FD_ZERO(&ibits);
@@ -261,9 +261,11 @@ static StringBuf getOutputFrom(ARGV_t argv,
 	    toProg[1] = -1;
 	}
 
-	rc = select(nfd + 1, &ibits, &obits, NULL, NULL);
-	if (rc < 0 && errno == EINTR) continue;
-	if (rc < 0) {
+	do {
+	    iorc = select(nfd + 1, &ibits, &obits, NULL, NULL);
+	} while (iorc == -1 && errno == EINTR);
+
+	if (iorc < 0) {
 	    myerrno = errno;
 	    break;
 	}
@@ -271,26 +273,30 @@ static StringBuf getOutputFrom(ARGV_t argv,
 	/* Write data to child */
 	if (writeBytesLeft > 0 && FD_ISSET(toProg[1], &obits)) {
 	    size_t nb = (1024 < writeBytesLeft) ? 1024 : writeBytesLeft;
-	    int nbw = write(toProg[1], writePtr, nb);
-	    if (nbw < 0 && errno == EINTR) continue;
-	    if (nbw < 0) {
+	    do {
+		iorc = write(toProg[1], writePtr, nb);
+	    } while (iorc == -1 && errno == EINTR);
+
+	    if (iorc < 0) {
 		myerrno = errno;
 		break;
 	    }
-	    writeBytesLeft -= nbw;
-	    writePtr += nbw;
+	    writeBytesLeft -= iorc;
+	    writePtr += iorc;
 	}
 	
 	/* Read when we get data back from the child */
 	if (FD_ISSET(fromProg[0], &ibits)) {
-	    int nbr = read(fromProg[0], buf, sizeof(buf)-1);
-	    if (nbr == 0) break; /* EOF, we're done */
-	    if (nbr < 0 && errno == EINTR) continue;
-	    if (nbr < 0) {
+	    do {
+		iorc = read(fromProg[0], buf, sizeof(buf)-1);
+	    } while (iorc == -1 && errno == EINTR);
+
+	    if (iorc == 0) break; /* EOF, we're done */
+	    if (iorc < 0) {
 		myerrno = errno;
 		break;
 	    }
-	    buf[nbr] = '\0';
+	    buf[iorc] = '\0';
 	    appendStringBuf(readBuff, buf);
 	}
     }