musl - musl - an implementation of the standard library for Linux-based systems

musl - an implementation of the standard library for Linux-based systems

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author	Rich Felker <dalias@aerifal.cx>	2013年07月19日 02:48:18 -0400
committer	Rich Felker <dalias@aerifal.cx>	2013年07月19日 02:48:18 -0400
commit	6567db65f495cf7c11f5c1e60a3e54543d5a69bc (patch)
tree	37b05447d32a30ac2ff47353d4e499abec339578 /src
parent	648c3b4e18b2ce2b6af7d44783e42ca267ea49f5 (diff)
download	musl-6567db65f495cf7c11f5c1e60a3e54543d5a69bc.tar.gz

improve [f]stat[v]fs functions, and possibly work around old kernels

the main aim of this patch is to ensure that if not all fields are filled in, they contain zeros, so as not to confuse applications. reportedly some older kernels, including commonly used openvz kernels, lack the f_flags field, resulting in applications reading random junk as the mount flags; the common symptom seems to be wrongly considering the filesystem to be mounted read-only and refusing to operate. glibc has some amazingly ugly fallback code to get the mount flags for old kernels, but having them really is not that important anyway; what matters most is not presenting incorrect flags to the application. I have also aimed to fill in some fields of statvfs that were previously missing, and added code to explicitly zero the reserved space at the end of the structure, which will make things easier in the future if this space someday needs to be used.

Diffstat (limited to 'src')

-rw-r--r--

src/stat/statvfs.c

1 files changed, 5 insertions, 2 deletions

diff --git a/src/stat/statvfs.c b/src/stat/statvfs.c
index 637bf82f..30d58797 100644
--- a/src/stat/statvfs.c
+++ b/src/stat/statvfs.c

@@ -5,6 +5,7 @@

int __statfs(const char *path, struct statfs *buf)

{

+ *buf = (struct statfs){0};

#ifdef SYS_statfs64

return syscall(SYS_statfs64, path, sizeof *buf, buf);

#else

@@ -14,6 +15,7 @@ int __statfs(const char *path, struct statfs *buf)

int __fstatfs(int fd, struct statfs *buf)

{

+ *buf = (struct statfs){0};

#ifdef SYS_fstatfs64

return syscall(SYS_fstatfs64, fd, sizeof *buf, buf);

#else

@@ -26,14 +28,15 @@ weak_alias(__fstatfs, fstatfs);

static void fixup(struct statvfs *out, const struct statfs *in)

{

+ *out = (struct statvfs){0};

out->f_bsize = in->f_bsize;

- out->f_frsize = in->f_bsize;

+ out->f_frsize = in->f_frsize ? in->f_frsize : in->f_bsize;

out->f_blocks = in->f_blocks;

out->f_bfree = in->f_bfree;

out->f_bavail = in->f_bavail;

out->f_files = in->f_files;

out->f_ffree = in->f_ffree;

- out->f_favail = 0;

+ out->f_favail = in->f_ffree;

out->f_fsid = in->f_fsid.__val[0];

out->f_flag = in->f_flags;

out->f_namemax = in->f_namelen;

generated by cgit v1.2.1 (git 2.18.0) at 2025年09月16日 19:34:12 +0000