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MontaukOS/kernel/src/Api/Path.hpp
T

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4.6 KiB
C++

/*
* Path.hpp
* Per-process working-directory path resolution helpers
* Copyright (c) 2026 Daniel Hammer
*/
#pragma once
#include <cstddef>
#include <Sched/Scheduler.hpp>
#include <Libraries/Memory.hpp>
namespace montauk::abi {
static int ParseDrivePrefix(const char* path, int* outPrefixLen = nullptr) {
if (path == nullptr || path[0] < '0' || path[0] > '9') return -1;
int drive = 0;
int i = 0;
while (path[i] >= '0' && path[i] <= '9') {
drive = drive * 10 + (path[i] - '0');
i++;
}
if (path[i] != ':') return -1;
if (outPrefixLen) *outPrefixLen = i + 1;
return drive;
}
static int WriteDriveRoot(char* out, int outMax, int drive) {
if (out == nullptr || outMax < 4 || drive < 0) return -1;
char digits[12];
int digitCount = 0;
do {
digits[digitCount++] = (char)('0' + (drive % 10));
drive /= 10;
} while (drive > 0 && digitCount < (int)sizeof(digits));
if (digitCount + 2 >= outMax) return -1;
int len = 0;
for (int i = digitCount - 1; i >= 0; i--) out[len++] = digits[i];
out[len++] = ':';
out[len++] = '/';
out[len] = '\0';
return len;
}
static bool AppendPathSegment(char* out, int outMax, int& len, int rootLen,
int* segmentBases, int& segmentCount,
const char* segment, int segmentLen) {
if (segmentLen <= 0) return true;
if (segmentLen == 1 && segment[0] == '.') return true;
if (segmentLen == 2 && segment[0] == '.' && segment[1] == '.') {
if (segmentCount > 0) {
len = segmentBases[--segmentCount];
out[len] = '\0';
}
return true;
}
if (segmentCount >= 64) return false;
int baseLen = len;
if (len > rootLen) {
if (len >= outMax - 1) return false;
out[len++] = '/';
}
if (len + segmentLen >= outMax) return false;
memcpy(out + len, segment, (std::size_t)segmentLen);
len += segmentLen;
out[len] = '\0';
segmentBases[segmentCount++] = baseLen;
return true;
}
static bool NormalizePathInto(char* out, int outMax, int& len, int rootLen,
int* segmentBases, int& segmentCount,
const char* path) {
const char* segmentStart = path;
for (const char* p = path;; ++p) {
if (*p == '/' || *p == '\0') {
if (!AppendPathSegment(out, outMax, len, rootLen, segmentBases,
segmentCount, segmentStart, (int)(p - segmentStart))) {
return false;
}
if (*p == '\0') break;
segmentStart = p + 1;
}
}
return true;
}
static bool ResolvePathAgainst(const char* cwd, const char* path, char* out, int outMax) {
if (cwd == nullptr || path == nullptr || out == nullptr || outMax < 4 || path[0] == '\0') return false;
int drive = -1;
int inputPrefixLen = 0;
const char* remainder = path;
bool useCwdBase = false;
drive = ParseDrivePrefix(path, &inputPrefixLen);
if (drive >= 0) {
remainder = path + inputPrefixLen;
if (*remainder == '/') remainder++;
} else if (path[0] == '/') {
drive = ParseDrivePrefix(cwd);
if (drive < 0) return false;
remainder = path + 1;
} else {
drive = ParseDrivePrefix(cwd);
if (drive < 0) return false;
useCwdBase = true;
}
int segmentBases[64];
int segmentCount = 0;
int len = WriteDriveRoot(out, outMax, drive);
if (len < 0) return false;
int rootLen = len;
if (useCwdBase) {
int cwdPrefixLen = 0;
if (ParseDrivePrefix(cwd, &cwdPrefixLen) < 0) return false;
const char* cwdRemainder = cwd + cwdPrefixLen;
if (*cwdRemainder == '/') cwdRemainder++;
if (!NormalizePathInto(out, outMax, len, rootLen, segmentBases, segmentCount, cwdRemainder)) {
return false;
}
}
return NormalizePathInto(out, outMax, len, rootLen, segmentBases, segmentCount, remainder);
}
static bool ResolveProcessPath(const char* path, char* out, int outMax) {
auto* proc = Sched::GetCurrentProcessPtr();
const char* cwd = (proc && proc->cwd[0]) ? proc->cwd : "0:/";
return ResolvePathAgainst(cwd, path, out, outMax);
}
}