application/system.c

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2024 Olaf Wintermann. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <libidav/utils.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <errno.h>

#include <cx/string.h>

#ifndef _WIN32
#include <unistd.h>
#endif

#include "system.h"

void sys_freedirent(SysDirEnt *ent) {
    free(ent->name);
    free(ent);
}

#ifndef _WIN32
/* ---------- POSIX implementation ---------- */

void sys_init(void) {
    
}
void sys_uninit(void) {
    
}

SYS_DIR sys_opendir(const char *path) {
    DIR *dir = opendir(path);
    if(!dir) {
        return NULL;
    }
    SysDir *d = malloc(sizeof(SysDir));
    d->dir = dir;
    d->ent = NULL;
    return d;
}

SysDirEnt* sys_readdir(SYS_DIR dir) {
    if(dir->ent) {
        free(dir->ent->name);
        free(dir->ent);
        dir->ent = NULL;
    }
    struct dirent *ent = readdir(dir->dir);
    if(ent) {
        SysDirEnt *e = malloc(sizeof(SysDirEnt));
        e->name = strdup(ent->d_name);
        dir->ent = e;
        return e;
    }
    return NULL;
}

void sys_closedir(SYS_DIR dir) {
    closedir(dir->dir);
    if(dir->ent) {
        free(dir->ent->name);
        free(dir->ent);
    }
    free(dir);
}

FILE* sys_fopen(const char *path, const char *mode) {
    return fopen(path, mode);
}

int sys_stat(const char *path, SYS_STAT *s) {
    return stat(path, s);
}

int sys_lstat(const char *path, SYS_STAT *s) {
    return lstat(path, s);
}

int sys_islink(const char *path) {
    struct stat s;
    if(!lstat(path, &s)) {
        return S_ISLNK(s.st_mode);
    }
    return 0;
}

int sys_rename(const char *oldpath, const char *newpath) {
    return rename(oldpath, newpath);
}

int sys_unlink(const char *path) {
    return unlink(path);
}

int sys_mkdir(const char *path) {
    return mkdir(path, S_IRWXU | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH);
}

char* sys_readlink(const char *path, SYS_STAT *s) {
    char *ret = NULL;
    
    off_t l_sz = s->st_size + 16;
    size_t lnksize = l_sz > 256 ? l_sz : 256;
    char *lnkbuf = malloc(lnksize);
    
    ssize_t len = 0;
    for(int i=0;i<4;i++) {
        // we try to read the link at most 4 times
        // only repeat if the buffer is too small
        len = readlink(path, lnkbuf, lnksize);
        if(len < lnksize) {
            ret = lnkbuf; // success
            lnkbuf[len] = 0; // terminate buffer
            break;
        }
        lnksize *= 2; // retry with bigger buffer
        lnkbuf = realloc(lnkbuf, lnksize);
    }
    
    if(!ret) {
        free(lnkbuf);
    }
    return ret;
}

int sys_symlink(const char *target, const char *linkpath) {
    int err = symlink(target, linkpath);
    if(err && errno == EEXIST) {
        if(unlink(linkpath)) {
            return 1;
        }
        return sys_symlink(target, linkpath);
    }
    return err;
}

int sys_truncate(const char* path, off_t length) {
    return truncate(path, length);
}

#else
/* ---------- Windows implementation ---------- */

#include <windows.h>
#include <winnls.h>
#include <shobjidl.h>
#include <objbase.h>
#include <objidl.h>

#include <direct.h>
#include <wchar.h>

void sys_init(void) {
    HRESULT res =  CoInitialize(NULL);
    if(res != S_OK) {
        fprintf(stderr, "Error: CoInitialize failed\n");
    }
}

void sys_uninit(void) {
    CoUninitialize();
}

static wchar_t* path2winpath(const char *path, int dir, int *newlen) {
    size_t len = strlen(path);
    size_t lenadd = dir ? 2 : 0;
    
    
    wchar_t *wpath = calloc(len+lenadd+1, sizeof(wchar_t));
    int wlen = MultiByteToWideChar(
            CP_UTF8,
            0,
            path,
            len,
            wpath,
            len+1
            );
    if(newlen) {
        *newlen = wlen;
    }
    for(int i=0;i<wlen;i++) {
        if(wpath[i] == L'/') {
            wpath[i] = L'\\';
        }
    }
    
    if(dir) {
        if(wpath[wlen-1] != L'\\') {
            wpath[wlen++] = L'\\';
        }
        wpath[wlen++] = L'*';
    }
    wpath[wlen] = 0;
    
    return wpath;
}

static char* winpath2multibyte(const wchar_t *wpath, size_t wlen) {
    size_t maxlen = wlen * 4;
    char *ret = malloc(maxlen + 1);
    int ret_len = WideCharToMultiByte(
        CP_UTF8,
        0,
        wpath,
        wlen,
        ret,
        maxlen,
        NULL,
        NULL);
    ret[ret_len] = 0;
    return ret;
}


SYS_DIR sys_opendir(const char *path) {
    struct WinDir *dir = malloc(sizeof(struct WinDir));
    wchar_t *dirpath = path2winpath(path, TRUE, NULL);
    if(!dirpath) {
        fprintf(stderr, "Cannot convert path \"%s\" to UTF16\n", path);
        free(dir);
        return NULL;
    }
    dir->first = 1;
    dir->handle = FindFirstFileW(dirpath, &dir->finddata);
    free(dirpath);
    if(dir->handle == INVALID_HANDLE_VALUE) {
        free(dir);
        return NULL;
    }
    dir->ent = NULL;
    return dir;
}

SysDirEnt* sys_readdir(SYS_DIR dir) {
    if(dir->ent) {
        free(dir->ent->name);
        free(dir->ent);
        dir->ent = NULL;
    }
    if(dir->first) {
        dir->first = 0;
    } else {
        if(FindNextFileW(dir->handle, &dir->finddata) == 0) {
            return NULL;
        }
    }
    
    size_t namelen = wcslen(dir->finddata.cFileName);
    
    char *name = malloc((namelen+1)*4);
    int nlen = WideCharToMultiByte(
            CP_UTF8,
            0,
            dir->finddata.cFileName,
            -1,
            name,
            256,
            NULL,
            NULL);
    if(nlen > 0) {
        name[nlen] = 0;
        SysDirEnt *ent = malloc(sizeof(SysDirEnt));
        ent->name = name;
        dir->ent = ent;
        return ent;
    } else {
        return NULL;
    }
}

void sys_closedir(SYS_DIR dir) {
    if(dir->ent) {
        free(dir->ent->name);
        free(dir->ent);
    }
    FindClose(dir->handle);
    free(dir);
}

FILE* sys_fopen(const char *path, const char *mode) {
    wchar_t *fpath = path2winpath(path, FALSE, NULL); 
    wchar_t *fmode = path2winpath(mode, FALSE, NULL);
    
    FILE *file = (fpath && fmode) ? _wfopen(fpath, fmode) : NULL;
    free(fpath);
    free(fmode);
    return file;
}

int sys_stat(const char *path, SYS_STAT *s) {
    wchar_t *fpath = path2winpath(path, FALSE, NULL);
    if(!fpath) {
        fprintf(stderr, "Cannot convert path \"%s\" to UTF16\n", path);
        return -1;
    }
    int ret = _wstat64(fpath, s);
    free(fpath);
    return ret;
}

int sys_lstat(const char *path, SYS_STAT *s) {
    return sys_stat(path, s); // unsupported on windows
}

int sys_islink(const char *path) {
    // don't use symlinks on windows, because it is not really useful
    // however, we interpret .lnk files as symlinks
    int ret = 0;
    
    cxstring path_s = cx_str(path);
    if(cx_strsuffix(path_s, CX_STR(".lnk"))) {
        // looks like a .lnk file
        // check content
        IShellLink *sl;
        HRESULT hres;
        hres = CoCreateInstance(&CLSID_ShellLink, NULL, CLSCTX_INPROC_SERVER, &IID_IShellLinkW, (LPVOID*)&sl);
        if(SUCCEEDED(hres)) { 
            IPersistFile *file;
            hres = sl->lpVtbl->QueryInterface(sl, &IID_IPersistFile, (void**)&file);
            if(!SUCCEEDED(hres)) {
                sl->lpVtbl->Release(sl);
                return ret;
            }
            
            int newlen = 0;
            wchar_t *wpath = path2winpath(path, 0, &newlen);
            
            hres = file->lpVtbl->Load(file, wpath, STGM_READ);
            if(SUCCEEDED(hres)) {
                ret = 1;
                file->lpVtbl->Release(file);
            }
            free(wpath);
            
            sl->lpVtbl->Release(sl);
        }
    }
    return ret;
}

int sys_rename(const char *oldpath, const char *newpath) {
    wchar_t *o = path2winpath(oldpath, FALSE, NULL);
    wchar_t *n = path2winpath(newpath, FALSE, NULL);
    if(!o || !n) {
        return -1;
    }
    
    struct __stat64 s;
    if(!_wstat64(n, &s)) {
        if(_wunlink(n)) {
            fprintf(stderr, "sys_rename: cannot delete existing file: %ls\n", n);
        }
    }
    
    int ret = _wrename(o, n);
    free(o);
    free(n);
    return ret;
}

int sys_unlink(const char *path) {
    wchar_t *wpath = path2winpath(path, FALSE, NULL);
    if(!wpath) {
        fprintf(stderr, "sys_unlink: cannot convert path\n");
        return -1;
    }
    int ret = _wunlink(wpath);
    free(wpath);
    return ret;
}

int sys_mkdir(const char *path) {
    wchar_t *wpath = path2winpath(path, FALSE, NULL);
    if(!wpath) {
        fprintf(stderr, "sys_mkdir: cannot convert path\n");
        return -1;
    }
    int ret = _wmkdir(wpath);
    free(wpath);
    return ret;
}

char* sys_readlink(const char *path, SYS_STAT *s) {
    char *ret_link = NULL;
    
    // create COM object for using the ShellLink interface
    IShellLinkW *sl;
    HRESULT hres = CoCreateInstance(&CLSID_ShellLink, NULL, CLSCTX_INPROC_SERVER, &IID_IShellLinkW, (LPVOID*)&sl);
    if(!SUCCEEDED(hres)) {
        return NULL;
    }
    
    IPersistFile *file;
    hres = sl->lpVtbl->QueryInterface(sl, &IID_IPersistFile, (void**)&file);
    if(!SUCCEEDED(hres)) {
        sl->lpVtbl->Release(sl);
        return NULL;
    }
    
    // load .lnk file
    int newlen = 0;
    wchar_t *wpath = path2winpath(path, 0, &newlen);
    hres = file->lpVtbl->Load(file, wpath, STGM_READ);
    if(SUCCEEDED(hres)) {
        WCHAR link_path[MAX_PATH];
        memset(link_path, 0, MAX_PATH);
        
        hres = sl->lpVtbl->Resolve(sl, 0, SLR_NO_UI);
        if(SUCCEEDED(hres)) {
            hres = sl->lpVtbl->GetPath(sl, link_path, MAX_PATH, NULL, SLGP_SHORTPATH);
            if(SUCCEEDED(hres)) {
                ret_link = winpath2multibyte(link_path, wcslen(link_path));
            }
        }
    }
    // cleanup
    free(wpath);
    file->lpVtbl->Release(file);
    sl->lpVtbl->Release(sl);
    
    return ret_link;
}

int sys_symlink(const char *target, const char *linkpath) {
    // convert relative target to absolut path
    char *link_parent = util_parent_path(linkpath);
    char *target_unnormalized = util_concat_path(link_parent, target);
    char *target_normalized = util_path_normalize(target_unnormalized);
    
    free(link_parent);
    free(target_unnormalized);
    
    // convert to wchar_t*
    int wtargetlen = 0;
    wchar_t *wtarget = path2winpath(target_normalized, FALSE, &wtargetlen);
    free(target_normalized);
    if(!wtarget) {
        return 1;
    }
    
    int wlinkpathlen = 0;
    wchar_t *wlinkpath = path2winpath(linkpath, FALSE, &wlinkpathlen);
    if(!wlinkpath) {
        free(wtarget);
        return 1;
    }
    
    int ret = 1;
    
    // create COM object for using the ShellLink interface
    IShellLinkW *sl;
    HRESULT hres = CoCreateInstance(&CLSID_ShellLink, NULL, CLSCTX_INPROC_SERVER, &IID_IShellLinkW, (LPVOID*)&sl);
    if(SUCCEEDED(hres)) {    
        IPersistFile *file;
        hres = sl->lpVtbl->QueryInterface(sl, &IID_IPersistFile, (void**)&file);
        if(SUCCEEDED(hres)) {
            // try to load the shortcut
            file->lpVtbl->Load(file, wlinkpath, STGM_READ); // ignore error
            
            // set path
            hres = sl->lpVtbl->SetPath(sl, wtarget);
            if(SUCCEEDED(hres)) {
                hres = file->lpVtbl->Save(file, wlinkpath, TRUE);
                if(SUCCEEDED(hres)) {
                    // successfully created/modified shortcut
                    ret = 0; // ok
                }
            }
            
            file->lpVtbl->Release(file);
        }
        
        sl->lpVtbl->Release(sl);
    }

    free(wtarget);
    free(wlinkpath);
    
    return ret;
}

int sys_truncate(const char* path, off_t length) {
    wchar_t* wpath = path2winpath(path, FALSE, NULL);
    if (!wpath) {
        fprintf(stderr, "sys_truncate: cannot convert path\n");
        return -1;
    }

    FILE* file = _wfopen(wpath, L"wb");
    int ret = 1;
    if (file) {
        ret = _chsize(fileno(file), length);
        fclose(file);
    }

    free(wpath);
    return ret;
}

#endif