4a032c9c62
`make` had been failing since the e1000 work and I did not see it, because I was checking build output with `grep error` -- which matches neither "Błąd" nor mkfs's "image full". Checking the exit status instead found all of this in a minute. **usbstick.img was full.** `make ldls-stage` puts a module and its BTF in sysroot/lib/modules, and a vmlinux BTF is 5 MB on its own; the 16 MB test image could not hold it. The size cannot move -- tools/windows/bootcheck.ps1 asserts READ CAPACITY returns exactly 32768 sectors -- so the exclusions grew instead: lib and usr as well as bin. That image exists to prove the USB driver can read one block, so its contents were never the point. It also stopped a GPL module riding into a test artifact, which RAMDISK_EXCLUDE does for the ramdisk and nothing was doing for this one. **toybox's httpd was shadowing ours.** /bin/httpd answered `-p` with toybox's "Unknown option 'p'", because whichever install rule ran second won the name. TOYBOX_SKIP existed for exactly this and held one entry, `ping`, found the same hard way. It is now generated from cmd/ -- a list you have to remember is a list that is wrong the next time cmd/ grows, and it already was: `chvt` had been silently toybox's, whose VT ioctls are Linux's and not ours. **ldlsd would not link with clang.** `*out = in;` on a 96-byte struct is a call to memcpy as far as the C standard is concerned; gcc unrolled it and clang emitted the call, so a freestanding program linked for months and then did not on a machine where nothing about it had changed but the compiler. lib/glue.c now provides memcpy, memmove, memset and memcmp -- the four an implementation may call without being asked. **OVMF was never found on NixOS.** `$(dir $(QEMU))share` is the *bin* directory plus "share", so it looked in /usr/bin/share. The absolute paths after it covered that up on distributions that keep firmware in /usr; on one that keeps nothing there it meant the firmware was undiscoverable on a machine that had it, and the only way to build was to copy the file in by hand. It resolves the prefix properly now and looks in <prefix>/share/qemu too. Verified by exit status, from a clean tree and a no-op: both 0. ldls-check passes 27. The guest boots, serves /srv to the host and answers 403 to %2e%2e/etc/passwd. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01VQ7Qx8E1q1M1bbCq8QLHS2
101 lines
2.6 KiB
C
101 lines
2.6 KiB
C
// SPDX-License-Identifier: Apache-2.0
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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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extern void _xv6_exit(void);
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void
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exit(void)
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{
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_xv6_exit();
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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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_xv6_exit();
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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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