The new call will read from a file descriptor into a strbuf once. The
underlying call xread_nonblock is meant to execute without blocking if
the file descriptor is set to O_NONBLOCK. It is a bug to call
strbuf_read_once on a file descriptor which would block.
Signed-off-by: Stefan Beller <sbel...@google.com>
Signed-off-by: Junio C Hamano <gits...@pobox.com>
---
strbuf.c | 11 +++++++++++
strbuf.h | 9 +++++++++
2 files changed, 20 insertions(+)
diff --git a/strbuf.c b/strbuf.c
index cce5eed..35e71b8 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -384,6 +384,17 @@ ssize_t strbuf_read(struct strbuf *sb, int fd, size_t hint)
return sb->len - oldlen;
}
+ssize_t strbuf_read_once(struct strbuf *sb, int fd, size_t hint)
+{
+ ssize_t cnt;
+
+ strbuf_grow(sb, hint ? hint : 8192);
+ cnt = xread_nonblock(fd, sb->buf + sb->len, sb->alloc - sb->len - 1);
+ if (cnt > 0)
+ strbuf_setlen(sb, sb->len + cnt);
+ return cnt;
+}
+
#define STRBUF_MAXLINK (2*PATH_MAX)
int strbuf_readlink(struct strbuf *sb, const char *path, size_t hint)
diff --git a/strbuf.h b/strbuf.h
index aef2794..ea69665 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -367,6 +367,15 @@ extern size_t strbuf_fread(struct strbuf *, size_t, FILE
*);
extern ssize_t strbuf_read(struct strbuf *, int fd, size_t hint);
/**
+ * Read from a file descriptor that is marked as O_NONBLOCK without
+ * blocking. Returns the number of new bytes appended to the sb.
+ * Negative return value signals there was an error returned from
+ * underlying read(2), in which case the caller should check errno.
+ * e.g. errno == EAGAIN when the read may have blocked.
+ */
+extern ssize_t strbuf_read_once(struct strbuf *, int fd, size_t hint);
+
+/**
* Read the contents of a file, specified by its path. The third argument
* can be used to give a hint about the file size, to avoid reallocs.
*/
--
2.5.0.273.g6fa2560.dirty
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