26bca020b6
Nexoniarz is the sole author and SchOS was never published under Apache-2.0, so this is a straight relicence. LICENSE is the FSF GPLv2 text, every first-party SPDX header moves to GPL-2.0-or-later, and NOTICE, README.md, docs/licensing.md and the site say so. projects/schfs-linux follows the rest of the tree. The GPL gives copyleft: a fork has to ship its source. It also lifts the old "Linux drivers, never" rule, since GPL-2.0-only code combines with GPL-2.0-or-later. "Or later" leaves room for GPLv3, but one binary still has to pick one version, so docs/licensing.md now keeps Apache-2.0 and GPLv3 code out of the kernel to keep Linux code possible there. BSD 4-clause code goes from "avoid" to "no", because the advertising clause is GPL-incompatible. LDLS still ships no .ko. That boundary is now project policy rather than a legal requirement, and ldls.md, devices.md and licensing.md section 6 say so. refmod declares license=GPL, and ldls-check passes (27 checks). Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
111 lines
3.3 KiB
C
111 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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// SchOS — first-party userland runtime: _start entry and exit.
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#include "types.h"
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#include "user.h"
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// The raw syscall. It takes the status in %rdi, and both callers below must
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// pass one: this declaration used to be `void _xv6_exit(void)`, so the status
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// was whatever the caller happened to leave in that register. Every program
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// that ended with a bare exit() reported a random number, which is why
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// `if socktest; then` could not work for any of them.
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extern void _xv6_exit(int status);
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// exit(void) in this library means exit(0). A program that wants to report
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// something returns it from main -- lib/start.S passes that through now -- or
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// calls exit_group(n).
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void
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exit(void)
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{
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_xv6_exit(0);
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for (;;);
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}
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/* _start lives in lib/start.S — it must read incoming registers, which
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* cannot be expressed portably in C. See that file. */
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// The four the compiler is allowed to call without being asked.
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//
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// A freestanding build gets no libc, but it does not get a compiler that
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// promises never to *call* one: the C standard lets an implementation emit
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// calls to memcpy, memmove, memset and memcmp for things that look nothing
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// like a function call. A struct assignment is the common one --
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//
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// *out = in; /* struct pciuser_info, 96 bytes */
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//
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// -- which gcc unrolled into stores and clang turned into `call memcpy`, so
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// ldlsd linked for months and then did not, on a machine where nothing about
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// it had changed except which compiler ran. The fix is not to avoid struct
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// assignment; it is to provide the four functions, because the compiler is
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// within its rights either way.
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//
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// Deliberately simple. These are not the hot path of anything here, and a
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// clever one risks being turned back into a call to itself.
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void *
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memcpy(void *dst, const void *src, unsigned long n)
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{
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unsigned char *d = dst;
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const unsigned char *s = src;
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while (n--) *d++ = *s++;
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return dst;
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}
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void *
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memmove(void *dst, const void *src, unsigned long n)
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{
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unsigned char *d = dst;
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const unsigned char *s = src;
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if (d == s || n == 0)
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return dst;
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// Backwards when they overlap the wrong way, which is the whole reason
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// this is not memcpy.
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if (d < s) {
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while (n--) *d++ = *s++;
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} else {
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d += n; s += n;
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while (n--) *--d = *--s;
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}
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return dst;
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}
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void *
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memset(void *dst, int c, unsigned long n)
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{
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unsigned char *d = dst;
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while (n--) *d++ = (unsigned char)c;
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return dst;
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}
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int
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memcmp(const void *a, const void *b, unsigned long n)
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{
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const unsigned char *p = a, *q = b;
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while (n--) {
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if (*p != *q)
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return *p - *q;
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p++; q++;
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}
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return 0;
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}
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void
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__stack_chk_fail(void)
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{
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// A smashed stack is not a successful run. 134 is what a shell reports for
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// SIGABRT, which is the nearest true thing this can say.
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_xv6_exit(134);
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for (;;);
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}
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// exec() without an environment.
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//
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// The syscall is execve, three arguments, because that is what Linux numbers
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// 59 and what musl calls. The two-argument spelling stays because most of
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// cmd/ has no environment to pass and should not have to say so -- but it
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// says so *here*, explicitly, rather than leaving %rdx to chance.
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int
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exec(char *path, char **argv)
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{
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return execve(path, argv, 0);
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}
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