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phantomptrandClaude Opus 5.5
c14782944d
Upload, install, convert and manage PS5 game packages over the network. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
57 lines
2.2 KiB
C
57 lines
2.2 KiB
C
#ifndef PS5UPLOAD_LIBC_BACKPORT_H
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#define PS5UPLOAD_LIBC_BACKPORT_H
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#include <stddef.h>
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#include <string.h>
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/* BestPig's `sce_module/libc.prx` compatibility edit.
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*
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* Some titles will not start on a downgraded firmware until one symbol NID in
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* libc.prx is swapped. BackPork documents it as a perl substitution over the
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* base64 NID text; MacPork applies the same edit to the decoded bytes:
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*
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* base64("4h6F1LLbTiw") == e2 1e 85 d4 b2 db 4e 2c (BackPork's FIND)
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* base64("IWIBBdTHit4") == 21 62 01 05 d4 c7 8a de (BackPork's REPLACE)
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*
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* Two projects, two encodings, one edit — which is a useful cross-check that
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* the pattern below is the right one. We patch the ASCII form because that is
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* what the symbol table actually stores: on a real title the text form is
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* present exactly once and the raw-byte form not at all.
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*
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* Both strings are the same length, so this never moves anything: no offsets
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* shift, no segment sizes change, and the surrounding SELF container stays
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* consistent.
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*
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* Tests: payload/tests/libc_backport_selftest.c */
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#define LIBC_BACKPORT_FIND "4h6F1LLbTiw#A#B"
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#define LIBC_BACKPORT_REPLACE "IWIBBdTHit4#A#B"
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#define LIBC_BACKPORT_LEN 15u
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/* Replace every occurrence in `buf`, in place. Returns how many were
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* rewritten — 0 means the file is already patched or is a libc build that
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* does not carry this symbol, which is not an error. */
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static inline int libc_backport_apply(unsigned char *buf, size_t len) {
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if (!buf || len < LIBC_BACKPORT_LEN) return 0;
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int n = 0;
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for (size_t i = 0; i + LIBC_BACKPORT_LEN <= len; i++) {
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if (memcmp(buf + i, LIBC_BACKPORT_FIND, LIBC_BACKPORT_LEN) != 0) continue;
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memcpy(buf + i, LIBC_BACKPORT_REPLACE, LIBC_BACKPORT_LEN);
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i += LIBC_BACKPORT_LEN - 1;
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n++;
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}
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return n;
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}
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/* Already carrying the replacement? Used to report "nothing to do" distinctly
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* from "this libc does not need it". */
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static inline int libc_backport_is_applied(const unsigned char *buf, size_t len) {
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if (!buf || len < LIBC_BACKPORT_LEN) return 0;
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for (size_t i = 0; i + LIBC_BACKPORT_LEN <= len; i++) {
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if (memcmp(buf + i, LIBC_BACKPORT_REPLACE, LIBC_BACKPORT_LEN) == 0) return 1;
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}
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return 0;
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}
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#endif
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