From 9870b77f9000c55bbe507bbb11d6d20fac2e8da0 Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@tavianator.com>
Date: Thu, 15 Apr 2021 14:34:55 -0400
Subject: util: Tweak the safe read/write functions

---
 util.c | 71 +++++++++++++++++++++++++++++-------------------------------------
 1 file changed, 31 insertions(+), 40 deletions(-)

(limited to 'util.c')

diff --git a/util.c b/util.c
index 00f5b78..19656e9 100644
--- a/util.c
+++ b/util.c
@@ -369,57 +369,48 @@ int bfs_minor(dev_t dev) {
 #endif
 }
 
-ssize_t safe_read(int fd, void *buf, size_t nbytes) {
-	for (;;) {
-		ssize_t ret = read(fd, buf, nbytes);
-		if (ret < 0 && errno == EINTR) {
-			continue;
-		}
-		return ret;
-	}
-}
-
-ssize_t safe_read_all(int fd, void *buf, size_t nbytes) {
+size_t xread(int fd, void *buf, size_t nbytes) {
 	size_t count = 0;
-	for (;;) {
+
+	while (count < nbytes) {
 		ssize_t ret = read(fd, (char *)buf + count, nbytes - count);
-		if (ret < 0 && errno == EINTR) {
-			continue;
-		}
 		if (ret < 0) {
-			return ret; // always return error < 0
-		}
-		count += ret;
-		if (ret == 0 || count == nbytes) { // EOF or success
-			return count;
+			if (errno == EINTR) {
+				continue;
+			} else {
+				break;
+			}
+		} else if (ret == 0) {
+			// EOF
+			errno = 0;
+			break;
+		} else {
+			count += ret;
 		}
 	}
-}
 
-ssize_t safe_write(int fd, const void *buf, size_t nbytes) {
-	for (;;) {
-		ssize_t ret = write(fd, buf, nbytes);
-		if (ret < 0 && errno == EINTR) {
-			continue;
-		}
-		return ret;
-	}
+	return count;
 }
 
-ssize_t safe_write_all(int fd, const void *buf, size_t nbytes)
-{
+size_t xwrite(int fd, const void *buf, size_t nbytes) {
 	size_t count = 0;
-	for (;;) {
+
+	while (count < nbytes) {
 		ssize_t ret = write(fd, (const char *)buf + count, nbytes - count);
-		if (ret < 0 && errno == EINTR) {
-			continue;
-		}
 		if (ret < 0) {
-			return ret; // always return error < 0
-		}
-		count += ret;
-		if (ret == 0 || count == nbytes) { // EOF (should never happen with write) or success
-			return count;
+			if (errno == EINTR) {
+				continue;
+			} else {
+				break;
+			}
+		} else if (ret == 0) {
+			// EOF?
+			errno = 0;
+			break;
+		} else {
+			count += ret;
 		}
 	}
+
+	return count;
 }
-- 
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