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Improve docs of more system calls

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This change also found a few POSIX compliance bugs with errnos. Another
bug was discovered where, on Windows, pread() and pwrite() could modify
the file position in cases where ReadFile() returned an error e.g. when
seeking past the end of file. We also have more tests!
This commit is contained in:
Justine Tunney 2022-10-02 22:14:33 -07:00
parent af24c19db3
commit ccbae7799e
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GPG key ID: BE714B4575D6E328
39 changed files with 589 additions and 175 deletions
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30
libc/calls/chroot.c
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@ -17,17 +17,43 @@
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/intrin/strace.internal.h"
#include "libc/calls/syscall-sysv.internal.h"
#include "libc/dce.h"
#include "libc/intrin/asan.internal.h"
#include "libc/intrin/strace.internal.h"
#include "libc/sysv/errfuns.h"
/**
* Changes root directory.
*
* Please consider using unveil() instead of chroot(). If you use this
* system call then consider using both chdir() and closefrom() before
* calling this function. Otherwise there's a small risk that fchdir()
* could be used to escape the chroot() environment. Cosmopolitan Libc
* focuses on static binaries which make chroot() infinitely easier to
* use since you don't need to construct an entire userspace each time
* however unveil() is still better to use on modern Linux and OpenBSD
* because it doesn't require root privileges.
*
* @param path shall become the new root directory
* @return 0 on success, or -1 w/ errno
* @raise EACCES if we don't have permission to search a component of `path`
* @raise ENOTDIR if a directory component in `path` exists as non-directory
* @raise ENAMETOOLONG if symlink-resolved `path` length exceeds `PATH_MAX`
* @raise ENAMETOOLONG if component in `path` exists longer than `NAME_MAX`
* @raise EPERM if not root or pledge() is in play
* @raise EIO if a low-level i/o error occurred
* @raise EFAULT if `path` is bad memory
* @raise ENOENT if `path` doesn't exist
* @raise ENOSYS on Windows
*/
int chroot(const char *path) {
int rc;
rc = sys_chroot(path);
if (!path || (IsAsan() && !__asan_is_valid(path, 1))) {
rc = efault();
} else {
rc = sys_chroot(path);
}
STRACE("chroot(%s) → %d% m", path, rc);
return rc;
}