Remove old zip base skew hack

Since 8ff48201ca we no longer need the
hack where, when running .com.dbg files, we scanned for the embedded
.com file offset, and then computed zip offsets realtive to that. It
wasn't very reliable in the first place, and was causing issues with
running our new .com.dbg executables, which are true zip files.

libc/str/findembeddedape.c

@@ -1,50 +0,0 @@
-/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
-│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
-╞══════════════════════════════════════════════════════════════════════════════╡
-│ Copyright 2021 Justine Alexandra Roberts Tunney                              │
-│                                                                              │
-│ Permission to use, copy, modify, and/or distribute this software for         │
-│ any purpose with or without fee is hereby granted, provided that the         │
-│ above copyright notice and this permission notice appear in all copies.      │
-│                                                                              │
-│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
-│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
-│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
-│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
-│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
-│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
-│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
-│ PERFORMANCE OF THIS SOFTWARE.                                                │
-╚─────────────────────────────────────────────────────────────────────────────*/
-#include "libc/intrin/bits.h"
-#include "libc/log/libfatal.internal.h"
-#include "libc/macros.internal.h"
-#include "libc/str/str.h"
-
-#define TRIES 8
-
-/**
- * Returns offset of binary embedded inside binary.
- *
- * This can be used to load zip assets from an executable that hasn't
- * gone through the `objcopy -S -O binary` step. We make the assumption
- * that an x86_64-pc-linux-gnu toolchain is being used. This routine
- * would need to be changed to accommodate binaries built locally on
- * Apple, FreeBSD, etc.
- *
- * @param p needs to be page aligned
- * @param n is byte length of p
- * @return base address of image or NULL if not found
- */
-uint8_t *FindEmbeddedApe(const uint8_t *p, size_t n) {
-  size_t i;
-  uint64_t w;
-  n = MIN(n, TRIES * PAGESIZE);
-  for (i = 0; i + 8 <= n; i += PAGESIZE) {
-    w = READ64LE(p + i);
-    if (w == READ64LE("MZqFpD='") || w == READ64LE("\177ELF\2\1\1\11")) {
-      return (/*unconst*/ uint8_t *)(p + i);
-    }
-  }
-  return 0;
-}

libc/str/iszipeocd32.c

@@ -16,12 +16,14 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/stdckdint.h"
 #include "libc/zip.internal.h"
 
 /**
  * Determines if ZIP EOCD record seems legit.
  */
 int IsZipEocd32(const uint8_t *p, size_t n, size_t i) {
+  size_t offset;
   if (i > n || n - i < kZipCdirHdrMinSize) {
     return kZipErrorEocdOffsetOverflow;
   }
@@ -35,12 +37,15 @@ int IsZipEocd32(const uint8_t *p, size_t n, size_t i) {
     return kZipErrorEocdDiskMismatch;
   }
   if (ZIP_CDIR_RECORDSONDISK(p + i) != ZIP_CDIR_RECORDS(p + i)) {
-    return kZipErrorCdirRecordsMismatch;
+    return kZipErrorEocdRecordsMismatch;
   }
   if (ZIP_CDIR_RECORDS(p + i) * kZipCfileHdrMinSize > ZIP_CDIR_SIZE(p + i)) {
-    return kZipErrorCdirRecordsOverflow;
+    return kZipErrorEocdRecordsOverflow;
   }
-  if (ZIP_CDIR_OFFSET(p + i) + ZIP_CDIR_SIZE(p + i) > i) {
+  if (ckd_add(&offset, ZIP_CDIR_OFFSET(p + i), ZIP_CDIR_SIZE(p + i))) {
+    return kZipErrorEocdOffsetSizeOverflow;
+  }
+  if (offset > i) {
     return kZipErrorCdirOffsetPastEocd;
   }
   return kZipOk;

libc/str/iszipeocd64.c

@@ -16,34 +16,41 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/stdckdint.h"
 #include "libc/zip.internal.h"
 
 /**
  * Returns kZipOk if zip64 end of central directory header seems legit.
  */
 int IsZipEocd64(const uint8_t *p, size_t n, size_t i) {
-  if (i + kZipCdir64HdrMinSize > n) {
+  size_t off, loc;
+  uint64_t cdsize;
+  if (i > n || i + kZipCdir64HdrMinSize > n) {
     return kZipErrorEocdOffsetOverflow;
   }
   if (READ32LE(p + i) != kZipCdir64HdrMagic) {
     return kZipErrorEocdMagicNotFound;
   }
-  if (i + ZIP_CDIR64_HDRSIZE(p + i) + kZipCdir64LocatorSize > n) {
+  if (ckd_add(&loc, i, ZIP_CDIR64_HDRSIZE(p + i)) ||  //
+      ckd_add(&off, loc, kZipCdir64LocatorSize) ||    //
+      off > n) {                                      //
     return kZipErrorEocdSizeOverflow;
   }
-  if (ZIP_LOCATE64_MAGIC(p + i + ZIP_CDIR64_HDRSIZE(p + i)) !=
-      kZipCdir64LocatorMagic) {
-    return kZipErrorCdirLocatorMagic;
+  if (ZIP_LOCATE64_MAGIC(p + loc) != kZipCdir64LocatorMagic) {
+    return kZipErrorEocdLocatorMagic;
   }
-  if (ZIP_LOCATE64_OFFSET(p + i + ZIP_CDIR64_HDRSIZE(p + i)) != i) {
-    return kZipErrorCdirLocatorOffset;
+  if (ZIP_LOCATE64_OFFSET(p + loc) != i) {
+    return kZipErrorEocdLocatorOffset;
   }
-  if (ZIP_CDIR64_RECORDS(p + i) * kZipCfileHdrMinSize >
-      ZIP_CDIR64_SIZE(p + i)) {
-    return kZipErrorCdirRecordsOverflow;
+  if (ckd_add(&off, ZIP_CDIR64_OFFSET(p + i), ZIP_CDIR64_SIZE(p + i))) {
+    return kZipErrorEocdOffsetSizeOverflow;
   }
-  if (ZIP_CDIR64_OFFSET(p + i) + ZIP_CDIR64_SIZE(p + i) > i) {
+  if (off > i) {
     return kZipErrorCdirOffsetPastEocd;
   }
+  if (ckd_mul(&cdsize, ZIP_CDIR64_RECORDS(p + i), kZipCfileHdrMinSize) ||
+      cdsize > ZIP_CDIR64_SIZE(p + i)) {
+    return kZipErrorEocdRecordsOverflow;
+  }
   return kZipOk;
 }