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authorRich Felker <dalias@aerifal.cx>2018-02-24 11:19:54 -0500
committerRich Felker <dalias@aerifal.cx>2018-02-24 11:19:54 -0500
commite7eeeb9f2a4a358fb0bbed81e145ef5538ff60f0 (patch)
tree0632ca84dcfa25c74f610e74d3241d91291eea88 /src/stdio/__stdio_read.c
parentf92804188eb464536d638548e51e835b6c49e373 (diff)
downloadmusl-e7eeeb9f2a4a358fb0bbed81e145ef5538ff60f0.tar.gz
avoid use of readv syscall in __stdio_read backend when not needed
formally, calling readv with a zero-length first iov component should behave identically to calling read on just the second component, but presence of a zero-length iov component has triggered bugs in some kernels and performs significantly worse than a simple read on some file types.
Diffstat (limited to 'src/stdio/__stdio_read.c')
-rw-r--r--src/stdio/__stdio_read.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/src/stdio/__stdio_read.c b/src/stdio/__stdio_read.c
index 909c36a9..ea675da3 100644
--- a/src/stdio/__stdio_read.c
+++ b/src/stdio/__stdio_read.c
@@ -9,7 +9,8 @@ size_t __stdio_read(FILE *f, unsigned char *buf, size_t len)
};
ssize_t cnt;
- cnt = syscall(SYS_readv, f->fd, iov, 2);
+ cnt = iov[0].iov_len ? syscall(SYS_readv, f->fd, iov, 2)
+ : syscall(SYS_read, f->fd, iov[1].iov_base, iov[1].iov_len);
if (cnt <= 0) {
f->flags |= cnt ? F_ERR : F_EOF;
return 0;