feat(statvfs): statvfs/fstatvfs (L2 XSI)

2026-09-05 23:10:06 -04:00
parent 9ffe86fc55
commit f9a055f547
3 changed files with 325 additions and 0 deletions
@@ -0,0 +1,88 @@
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <sys/statvfs.h>
+
+#include "../internal/syscall.h"
+
+#if VLIBC_LEVEL_GE(2)
+
+/*
+ * Linux struct statfs (kernel ABI, x86_64; linux/statfs.h). Layout and
+ * sizes are LP64 facts: f_type..f_ffree are longs, f_fsid is an int pair,
+ * then f_namelen/f_frsize/f_flags/f_spare[4] complete the 120 bytes the
+ * kernel copies out (the same layout src/misc/pathconf.c pins for
+ * pathconf()/fpathconf()). The signed kernel longs are non-negative on
+ * every real filesystem, so they convert straight into the unsigned POSIX
+ * counts below.
+ */
+struct vlibc_kstatfs
+{
+    long f_type;
+    long f_bsize;
+    long f_blocks;
+    long f_bfree;
+    long f_bavail;
+    long f_files;
+    long f_ffree;
+    int f_fsid[2];
+    long f_namelen;
+    long f_frsize;
+    long f_flags;
+    long f_spare[4];
+};
+
+/* Map one kernel statfs record into the portable POSIX statvfs view. */
+static void
+statvfs_fill(struct statvfs *out, const struct vlibc_kstatfs *in)
+{
+    out->f_bsize = (unsigned long)in->f_bsize;
+    out->f_frsize = in->f_frsize != 0 ? (unsigned long)in->f_frsize : (unsigned long)in->f_bsize;
+    out->f_blocks = (unsigned long)in->f_blocks;
+    out->f_bfree = (unsigned long)in->f_bfree;
+    out->f_bavail = (unsigned long)in->f_bavail;
+    out->f_files = (unsigned long)in->f_files;
+    out->f_ffree = (unsigned long)in->f_ffree;
+    out->f_favail = (unsigned long)in->f_ffree;
+    /* Reconstruct the kernel's 64-bit fsid (val[0] holds the low word on
+     * the little-endian x86_64; the same packing glibc's statvfs reports). */
+    out->f_fsid = ((unsigned long)(unsigned int)in->f_fsid[1] << 32) |
+                  (unsigned long)(unsigned int)in->f_fsid[0];
+    out->f_flag = (unsigned long)(in->f_flags & (ST_RDONLY | ST_NOSUID));
+    out->f_namemax = (unsigned long)in->f_namelen;
+}
+
+/*
+ * statvfs()/fstatvfs(): filesystem statistics in the portable POSIX shape,
+ * over SYS_statfs/SYS_fstatfs (which share the same kernel struct and the
+ * same mapping). The kernel returns 0 on success after filling all 120
+ * bytes; failures come back as -errno and are translated by syscall_ret.
+ */
+int
+statvfs(const char *restrict path, struct statvfs *restrict buf)
+{
+    struct vlibc_kstatfs fs;
+
+    if (syscall_ret(__syscall2(SYS_statfs, (long)path, (long)&fs)) != 0)
+    {
+        return -1;
+    }
+    statvfs_fill(buf, &fs);
+    return 0;
+}
+
+int
+fstatvfs(int fildes, struct statvfs *buf)
+{
+    struct vlibc_kstatfs fs;
+
+    if (syscall_ret(__syscall2(SYS_fstatfs, fildes, (long)&fs)) != 0)
+    {
+        return -1;
+    }
+    statvfs_fill(buf, &fs);
+    return 0;
+}
+
+#endif /* VLIBC_LEVEL_GE(2) */