Atmosphere/stratosphere/loader/source/ldr_patcher.cpp

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#include <cstdlib>
#include <cstdint>
#include <cstdio>
#include <cstring>
#include <dirent.h>
#include <switch.h>
#include "ldr_patcher.hpp"
#define IPS_MAGIC "PATCH"
#define IPS_TAIL "EOF"
#define IPS32_MAGIC "IPS32"
#define IPS32_TAIL "EEOF"
static inline u8 HexNybbleToU8(const char nybble) {
if ('0' <= nybble && nybble <= '9') {
return nybble - '0';
} else if ('a' <= nybble && nybble <= 'f') {
return nybble - 'a';
} else {
return nybble - 'A';
}
}
static bool MatchesBuildId(const char *name, size_t name_len, const u8 *build_id) {
/* Validate name is hex build id. */
for (unsigned int i = 0; i < name_len - 4; i++) {
if (!(('0' <= name[i] && name[i] <= '9') ||
('a' <= name[i] && name[i] <= 'f') ||
('A' <= name[i] && name[i] <= 'F'))) {
return false;
}
}
/* Read build id from name. */
u8 build_id_from_name[0x20] = {0};
for (unsigned int name_ofs = 0, id_ofs = 0; name_ofs < name_len - 4; id_ofs++) {
build_id_from_name[id_ofs] |= HexNybbleToU8(name[name_ofs++]) << 4;
build_id_from_name[id_ofs] |= HexNybbleToU8(name[name_ofs++]);
}
return memcmp(build_id, build_id_from_name, sizeof(build_id_from_name)) == 0;
}
static inline void PatchNsoByte(u8 *nso, size_t max_size, size_t offset, u8 val) {
/* TODO: Be smarter about this. */
if (sizeof(NsoUtils::NsoHeader) <= offset && offset < max_size) {
nso[offset - sizeof(NsoUtils::NsoHeader)] = val;
}
}
static void ApplyIpsPatch(u8 *mapped_nso, size_t mapped_size, FILE *ips) {
/* TODO */
}
static void ApplyIps32Patch(u8 *mapped_nso, size_t mapped_size, FILE *ips) {
/* TODO */
}
void PatchUtils::ApplyPatches(u64 title_id, const NsoUtils::NsoHeader *header, u8 *mapped_nso, size_t mapped_size) {
/* Inspect all patches from /<title>/exefs/patches/<*>/<*>.ips. */
char path[FS_MAX_PATH+1] = {0};
snprintf(path, sizeof(path) - 1, "sdmc:/atmosphere/titles/%016lx/exefs/patches", title_id);
DIR *patches_dir = opendir(path);
struct dirent *pdir_ent;
if (patches_dir != NULL) {
/* Iterate over the patches directory to find patch subdirectories. */
while ((pdir_ent = readdir(patches_dir)) != NULL) {
if (strcmp(pdir_ent->d_name, ".") == 0 || strcmp(pdir_ent->d_name, "..") == 0) {
continue;
}
snprintf(path, sizeof(path) - 1, "sdmc:/atmosphere/titles/%016lx/exefs/patches/%s", title_id, pdir_ent->d_name);
DIR *patch_dir = opendir(path);
struct dirent *ent;
if (patch_dir != NULL) {
/* Iterate over the patch subdirectory to find .ips patches. */
while ((ent = readdir(patch_dir)) != NULL) {
if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0) {
continue;
}
size_t name_len = strlen(ent->d_name);
if ((4 < name_len && name_len <= 0x44) && ((name_len & 1) == 0) && strcmp(ent->d_name + name_len - 4, ".ips") == 0 && MatchesBuildId(ent->d_name, name_len, header->build_id)) {
snprintf(path, sizeof(path) - 1, "sdmc:/atmosphere/titles/%016lx/exefs/patches/%s/%s", title_id, pdir_ent->d_name, ent->d_name);
FILE *f_ips = fopen(path, "rb");
if (f_ips != NULL) {
u8 header[5];
if (fread(header, 5, 1, f_ips) == 1) {
if (memcmp(header, IPS_MAGIC, 5) == 0) {
ApplyIpsPatch(mapped_nso, mapped_size, f_ips);
} else if (memcmp(header, IPS32_MAGIC, 5) == 0) {
ApplyIps32Patch(mapped_nso, mapped_size, f_ips);
}
}
fclose(f_ips);
}
}
}
closedir(patch_dir);
}
}
closedir(patches_dir);
}
}