From: Rusty Russell <rusty@rustcorp.com.au>
Date: Tue, 1 Mar 2011 12:49:20 +0000 (+1030)
Subject: tdb2: remove looping for write
X-Git-Url: http://git.ozlabs.org/?p=ccan;a=commitdiff_plain;h=aa12380008323e14f8d7dabe78b174b72f69e2dd;hp=6dbbfabca414018b4c5acb3e6e597d84e2b19caf

tdb2: remove looping for write

On normal files, pwrite and write should never return short except on error.
As we never create sparse files, so any short write is an I/O error.
---

diff --git a/ccan/tdb2/io.c b/ccan/tdb2/io.c
index 999922b1..bdf86b67 100644
--- a/ccan/tdb2/io.c
+++ b/ccan/tdb2/io.c
@@ -206,25 +206,6 @@ tdb_off_t tdb_read_off(struct tdb_context *tdb, tdb_off_t off)
 	return ret;
 }
 
-/* Even on files, we can get partial writes due to signals. */
-bool tdb_pwrite_all(int fd, const void *buf, size_t len, tdb_off_t off)
-{
-	while (len) {
-		ssize_t ret;
-		ret = pwrite(fd, buf, len, off);
-		if (ret < 0)
-			return false;
-		if (ret == 0) {
-			errno = ENOSPC;
-			return false;
-		}
-		buf = (char *)buf + ret;
-		off += ret;
-		len -= ret;
-	}
-	return true;
-}
-
 /* write a lump of data at a specified offset */
 static int tdb_write(struct tdb_context *tdb, tdb_off_t off, 
 		     const void *buf, tdb_len_t len)
@@ -246,10 +227,17 @@ static int tdb_write(struct tdb_context *tdb, tdb_off_t off,
 	if (tdb->map_ptr) {
 		memcpy(off + (char *)tdb->map_ptr, buf, len);
 	} else {
-		if (!tdb_pwrite_all(tdb->fd, buf, len, off)) {
+		ssize_t ret;
+		ret = pwrite(tdb->fd, buf, len, off);
+		if (ret < len) {
+			/* This shouldn't happen: we avoid sparse files. */
+			if (ret >= 0)
+				errno = ENOSPC;
+
 			tdb_logerr(tdb, TDB_ERR_IO, TDB_DEBUG_FATAL,
-				   "tdb_write failed at %zu len=%zu (%s)",
-				   (size_t)off, (size_t)len, strerror(errno));
+				   "tdb_write: %zi at %zu len=%zu (%s)",
+				   ret, (size_t)off, (size_t)len,
+				   strerror(errno));
 			return -1;
 		}
 	}
@@ -361,10 +349,15 @@ static int fill(struct tdb_context *tdb,
 {
 	while (len) {
 		size_t n = len > size ? size : len;
+		ssize_t ret = pwrite(tdb->fd, buf, n, off);
+		if (ret < n) {
+			if (ret >= 0)
+				errno = ENOSPC;
 
-		if (!tdb_pwrite_all(tdb->fd, buf, n, off)) {
 			tdb_logerr(tdb, TDB_ERR_IO, TDB_DEBUG_FATAL,
-				 "fill write failed: giving up!");
+				   "fill failed: %zi at %zu len=%zu (%s)",
+				   ret, (size_t)off, (size_t)len,
+				   strerror(errno));
 			return -1;
 		}
 		len -= n;
diff --git a/ccan/tdb2/private.h b/ccan/tdb2/private.h
index 1092f171..75e49c83 100644
--- a/ccan/tdb2/private.h
+++ b/ccan/tdb2/private.h
@@ -474,9 +474,6 @@ tdb_off_t tdb_find_nonzero_off(struct tdb_context *tdb,
 tdb_off_t tdb_find_zero_off(struct tdb_context *tdb, tdb_off_t off,
 			    uint64_t num);
 
-/* Even on files, we can get partial writes due to signals. */
-bool tdb_pwrite_all(int fd, const void *buf, size_t len, tdb_off_t off);
-
 /* Allocate and make a copy of some offset. */
 void *tdb_alloc_read(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t len);
 
diff --git a/ccan/tdb2/tdb.c b/ccan/tdb2/tdb.c
index e3b579d0..1aa3baa4 100644
--- a/ccan/tdb2/tdb.c
+++ b/ccan/tdb2/tdb.c
@@ -101,6 +101,7 @@ static int tdb_new_database(struct tdb_context *tdb,
 	/* We make it up in memory, then write it out if not internal */
 	struct new_database newdb;
 	unsigned int magic_len;
+	ssize_t rlen;
 
 	/* Fill in the header */
 	newdb.hdr.version = TDB_VERSION;
@@ -153,10 +154,13 @@ static int tdb_new_database(struct tdb_context *tdb,
 	if (ftruncate(tdb->fd, 0) == -1)
 		return -1;
 
-	if (!tdb_pwrite_all(tdb->fd, &newdb, sizeof(newdb), 0)) {
+	rlen = write(tdb->fd, &newdb, sizeof(newdb));
+	if (rlen != sizeof(newdb)) {
+		if (rlen >= 0)
+			errno = ENOSPC;
 		tdb_logerr(tdb, TDB_ERR_IO, TDB_DEBUG_FATAL,
-			   "tdb_new_database: failed to write: %s",
-			   strerror(errno));
+			   "tdb_new_database: %zi writing header: %s",
+			   rlen, strerror(errno));
 		return -1;
 	}
 	return 0;