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 +1,82 @@
+#ifndef VLIBC_SYS_STATVFS_H
+#define VLIBC_SYS_STATVFS_H
+
+/*
+ * vlibc — <sys/statvfs.h>.
+ *
+ * Filesystem statistics in an ABI-independent POSIX shape: block and file
+ * counts as unsigned counts over a reported block size, plus the read-only
+ * and setuid-disabling mount flags and the longest file name. This header
+ * carries only the portable view; the Linux kernel's private <linux/statfs.h>
+ * layout (signed longs, an int-pair f_fsid, a f_spare tail) never leaks
+ * into it.
+ *
+ *   Level 2 (muslmimic): the whole header (statvfs and fstatvfs are XSI
+ *                        [CX] in POSIX.1-2008, not base; the base filesystem
+ *                        queries are stat()/fstat() in <sys/stat.h>).
+ *
+ * f_flag holds ST_RDONLY and/or ST_NOSUID, and f_fsid is a best-effort
+ * filesystem identifier (the kernel does not populate it for every
+ * filesystem). The block counts are measured in f_frsize units (which is
+ * f_bsize when the filesystem does not distinguish a transfer size).
+ *
+ * None of these declarations carries an intent attribute: both functions
+ * perform I/O with side effects and report failures through errno, so
+ * const/pure would be unsound.
+ */
+
+#include <vlibc/features.h>
+
+#include <sys/types.h> /* fsblkcnt_t, fsfilcnt_t */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#if VLIBC_LEVEL_GE(2)
+/* Level 2 (muslmimic): XSI. */
+
+/*
+ * Filesystem statistics. f_flag is a bitwise OR of ST_RDONLY and
+ * ST_NOSUID; f_frsize is the fundamental block size the count fields are
+ * expressed in. f_fsid is 0 when the filesystem provides no identifier.
+ */
+struct statvfs
+{
+    unsigned long f_bsize;   /* preferred I/O block size, bytes */
+    unsigned long f_frsize;  /* fundamental block size, bytes */
+    fsblkcnt_t f_blocks;     /* total blocks, in f_frsize units */
+    fsblkcnt_t f_bfree;      /* free blocks */
+    fsblkcnt_t f_bavail;     /* free blocks available to an unprivileged process */
+    fsfilcnt_t f_files;      /* total file serial numbers (inodes) */
+    fsfilcnt_t f_ffree;      /* free file serial numbers */
+    fsfilcnt_t f_favail;     /* free serial numbers available to an unprivileged process */
+    unsigned long f_fsid;    /* filesystem ID (best effort) */
+    unsigned long f_flag;    /* mount flags: ST_RDONLY | ST_NOSUID */
+    unsigned long f_namemax; /* maximum file name length */
+};
+
+/* f_flag values (also the kernel's f_flags bits on Linux). */
+#define ST_RDONLY 1 /* read-only filesystem */
+#define ST_NOSUID 2 /* set-user-ID/set-group-ID bits ignored on exec */
+
+/*
+ * Store statistics for the filesystem holding path into buf; return 0, or
+ * -1 with errno set. XSI.
+ */
+int
+statvfs(const char *restrict path, struct statvfs *restrict buf);
+
+/*
+ * Like statvfs(), for the filesystem holding the open descriptor fildes;
+ * return 0, or -1 with errno set. XSI.
+ */
+int
+fstatvfs(int fildes, struct statvfs *buf);
+#endif /* VLIBC_LEVEL_GE(2) */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* VLIBC_SYS_STATVFS_H */