djstdlib/os_linux.cpp

#ifndef OS_IMPL_LINUX_CPP
#define OS_IMPL_LINUX_CPP

#include "os.h"

#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>

void *os_alloc(size_t capacity) {
    return mmap(0, capacity, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
}

void os_commit(void *ptr) {
}

void os_decommit(void *ptr) {
}

void os_free(void *ptr, size_t size) {
    int err = munmap(ptr, size);
    Assert(err != -1);
}

string os_readEntireFile(Arena *arena, string filename) {
    Scratch temp = scratchStart(&arena, 1);

    FILE *input = fopen(cstring(temp.arena, filename), "r");
    string readBuffer;
    if (input) {
        struct stat st;
        stat((char *)filename.str, &st);
        size_t fsize = st.st_size;
        readBuffer = PushString(arena, fsize);
        fread(readBuffer.str, sizeof(byte), readBuffer.length, input);
        fclose(input);
    } else {
        readBuffer = PushString(arena, 0);
    }

    scratchEnd(temp);
    return readBuffer;
}

bool os_writeEntireFile(Arena *arena, string filename, const byte *contents, size_t contentsLength) {
    Scratch temp = scratchStart(&arena, 1);

    bool result = false;
    FILE *output = fopen(cstring(temp.arena, filename), "w");
    if (output) {
        fwrite(contents, sizeof(byte), contentsLength, output);
        fclose(output);
        result = true;
    }

    scratchEnd(temp);
    return result;
}

bool os_fileAppend(Arena *arena, string filename, const byte *contents, size_t contentsLength) {
    Scratch temp = scratchStart(&arena, 1);

    bool result = false;
    FILE *output = fopen(cstring(temp.arena, filename), "a");
    if (output) {
        fwrite(contents, sizeof(byte), contentsLength, output);
        fclose(output);
        result = true;
    }

    scratchEnd(temp);
    return result;
}

void os_print(StdStream target, const char *fmt, va_list argList) {
    Scratch temp = scratchStart(0, 0);

    string result = strPrintfv(temp.arena, fmt, argList);
    // TODO(djledda): finish implementation without cstdlib
    switch (target) {
        case StdStream_stdin: 
            write(0, (const void *)result.str, result.length);
            break;
        case StdStream_stderr: 
            fflush(stderr);
            write(2, (const void *)result.str, result.length);
            break;
        case StdStream_stdout: 
        default:
            fflush(stdout);
            write(1, (const void *)result.str, result.length);
            break;
    }

    scratchEnd(temp);
}

#endif