klibc - Apr 2014 - [klibc:master] fwrite: use memrchr() to find the final ' \n' in _IOLBF mode

Commit-ID:  a51893a6d52a8cdf247cb1bd10dd8987d4d7eb49
Gitweb:    
http://git.kernel.org/?p=libs/klibc/klibc.git;a=commit;h=a51893a6d52a8cdf247cb1bd10dd8987d4d7eb49
Author:     H. Peter Anvin <hpa at linux.intel.com>
AuthorDate: Wed, 9 Apr 2014 16:51:10 -0700
Committer:  H. Peter Anvin <hpa at linux.intel.com>
CommitDate: Wed, 9 Apr 2014 16:51:10 -0700

[klibc] fwrite: use memrchr() to find the final '\n' in _IOLBF mode

In line buffered mode, we need to split the write at the final '\n'
(which usually, but not always, is the last character in the string.)

Use memrchr() instead of open-coding it.

Signed-off-by: H. Peter Anvin <hpa at linux.intel.com>

---
 usr/klibc/stdio/fwrite.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/usr/klibc/stdio/fwrite.c b/usr/klibc/stdio/fwrite.c
index 5d2c3f0..71ee75c 100644
--- a/usr/klibc/stdio/fwrite.c
+++ b/usr/klibc/stdio/fwrite.c
@@ -59,6 +59,7 @@ size_t _fwrite(const void *buf, size_t count, FILE *file)
 	size_t bytes = 0;
 	size_t pf_len, pu_len;
 	const char *p = buf;
+	const char *q;
 
 	/* We divide the data into two chunks, flushed (pf)
 	   and unflushed (pu) depending on buffering mode
@@ -67,23 +68,16 @@ size_t _fwrite(const void *buf, size_t count, FILE *file)
 	switch (f->bufmode) {
 	case _IOFBF:
 		pf_len = 0;
-		pu_len = count;
 		break;
 
 	case _IOLBF:
-		pf_len = count;
-		pu_len = 0;
-
-		while (pf_len && p[pf_len-1] != '\n') {
-			pf_len--;
-			pu_len++;
-		}
+		q = memrchr(p, '\n', count);
+		pf_len = q ? q - p + 1 : 0;
 		break;
 
 	case _IONBF:
 	default:
 		pf_len = count;
-		pu_len = 0;
 		break;
 	}
 
@@ -94,6 +88,7 @@ size_t _fwrite(const void *buf, size_t count, FILE *file)
 			return bytes;
 	}
 
+	pu_len = count - pf_len;
 	if (pu_len)
 		bytes += fwrite_noflush(p, pu_len, f);