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Mint APE Loader 1.6

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This change fixes a bug with loading pure bss program headers.
This commit is contained in:
Justine Tunney 2023-08-09 00:25:18 -07:00
parent c48ee8e4fe
commit 1a5ef5ba13
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GPG key ID: BE714B4575D6E328
11 changed files with 87 additions and 51 deletions
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47
ape/loader.c
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@ -698,6 +698,8 @@ __attribute__((__noreturn__)) static void Spawn(int os, const char *exe, int fd,
/* load elf */
for (i = 0; i < e->e_phnum; ++i) {
void *addr;
unsigned long size;
if (p[i].p_type != PT_LOAD) continue;
/* configure mapping */
@ -707,38 +709,53 @@ __attribute__((__noreturn__)) static void Spawn(int os, const char *exe, int fd,
if (p[i].p_flags & PF_W) prot |= PROT_WRITE;
if (p[i].p_flags & PF_X) prot |= PROT_EXEC;
/* load from file */
if (p[i].p_filesz) {
void *addr;
/* load from file */
int prot1, prot2;
unsigned long size;
unsigned long wipe;
prot1 = prot;
prot2 = prot;
/*
* when we ask the system to map the interval [vaddr,vaddr+filesz)
* it might schlep extra file content into memory on both the left
* and the righthand side. that's because elf doesn't require that
* either side of the interval be aligned on the system page size.
*
* normally we can get away with ignoring these junk bytes. but if
* the segment defines bss memory (i.e. memsz > filesz) then we'll
* need to clear the extra bytes in the page, if they exist.
*
* since we can't do that if we're mapping a read-only page, we'll
* actually map it with write permissions and protect it afterward
*/
a = p[i].p_vaddr + p[i].p_filesz; /* end of file content */
b = (a + (pagesz - 1)) & -pagesz; /* first pure bss page */
c = p[i].p_vaddr + p[i].p_memsz; /* end of segment data */
if (b > c) b = c;
if (c > b && (~prot1 & PROT_WRITE)) {
wipe = MIN(b - a, c - a);
if (wipe && (~prot1 & PROT_WRITE)) {
prot1 = PROT_READ | PROT_WRITE;
}
addr = (void *)(dynbase + (p[i].p_vaddr & -pagesz));
size = (p[i].p_vaddr & (pagesz - 1)) + p[i].p_filesz;
rc = Mmap(addr, size, prot1, flags, fd, p[i].p_offset & -pagesz, os);
if (rc < 0) Pexit(os, exe, rc, "prog mmap");
if (c > b) Bzero((void *)(dynbase + a), b - a);
if (wipe) Bzero((void *)(dynbase + a), wipe);
if (prot2 != prot1) {
rc = Mprotect(addr, size, prot2, os);
if (rc < 0) Pexit(os, exe, rc, "prog mprotect");
}
}
/* allocate extra bss */
a = p[i].p_vaddr + p[i].p_filesz;
a = (a + (pagesz - 1)) & -pagesz;
b = p[i].p_vaddr + p[i].p_memsz;
if (b > a) {
/* allocate extra bss */
if (c > b) {
flags |= MAP_ANONYMOUS;
rc = Mmap((void *)(dynbase + b), c - b, prot, flags, -1, 0, os);
if (rc < 0) Pexit(os, exe, rc, "extra bss mmap");
}
} else {
/* allocate pure bss */
addr = (void *)(dynbase + (p[i].p_vaddr & -pagesz));
size = (p[i].p_vaddr & (pagesz - 1)) + p[i].p_memsz;
flags |= MAP_ANONYMOUS;
rc = Mmap((void *)(dynbase + a), b - a, prot, flags, -1, 0, os);
rc = Mmap(addr, size, prot, flags, -1, 0, os);
if (rc < 0) Pexit(os, exe, rc, "bss mmap");
}
}
@ -874,7 +891,7 @@ static __attribute__((__noreturn__)) void ShowUsage(int os, int fd, int rc) {
Print(os, fd,
"NAME\n"
"\n"
" actually portable executable loader version 1.5\n"
" actually portable executable loader version 1.6\n"
" copyright 2023 justine alexandra roberts tunney\n"
" https://justine.lol/ape.html\n"
"\n"