f63a673a8b
modified: stub/src/include/linux.h new file: stub/src/upxfd_android.c new file: stub/src/upxfd_create.c
53 lines
1.5 KiB
C
53 lines
1.5 KiB
C
/* upxfd_create.c -- workaround for 32-bit Android
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This file is part of the UPX executable compressor.
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Copyright (C) 2023 John F. Reiser
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All Rights Reserved.
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*/
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// Like memfd_create, but early 32-bit Android lacks.
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// Also 32-bit Android has inconsistent __NR_ftruncate,
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// so use direct write().
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extern void *alloca(unsigned long size);
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#include "include/linux.h" // syscalls; i386 inlines via "int 0x80"
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// 1. Try memfd_create
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// 2. If Android or emulator, try /data/data/$APP_NAME/cache/upxAAA
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// where APP_NAME is discovered as basename($(< /proc/self/cmdline))
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// If Android, then write zeroes to desired length, then lseek back to offset 0.
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// (Except make_hatch() just writes the actual data, and closes the file.)
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// If not Android then ftruncate() to desired length.
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// Return (mapped_addr | (1+ fd))
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//
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extern int upxfd_android(int len);
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void *upxfd_create(void *addr, unsigned len)
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{
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char str_upx[] = "upx";
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int fd = memfd_create(str_upx, 0);
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#if defined(__arm__) || defined(__i386__) //{ workaround: android & emulators
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if (fd < 0) {
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fd = upxfd_android(len); // also emulates ftruncate(fd, len)
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}
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#else //}{
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if (0 > ftruncate(fd, len)) {
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return (void *)-1ul;
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}
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#endif //}
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addr = mmap(addr, len, PROT_READ|PROT_WRITE,
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(addr ? MAP_FIXED : 0)|MAP_SHARED, fd, 0);
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if (PAGE_MASK <= (unsigned long)addr) {
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return addr;
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}
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return (void *)((long)addr + (1+ (unsigned)fd));
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}
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#if 0 //{ test
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int main(int argc, char *argv[])
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{
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upxfd_create(0, 100);
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return 0;
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}
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#endif //}
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