rockbox/apps/plugins/windows_lnk.c
Sebastian Leonhardt 443ad25e75 plugin windows_lnk: fix missing return-on-error
(found by peachy & clang's static analyzer)

Change-Id: Idcc9b3bd0c3c1164892002b8f814d74b4a6b2a2d
2020-07-07 02:36:33 +00:00

345 lines
11 KiB
C

/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2017 Sebastian Leonhardt
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include "plugin.h"
/**
* Follow Windows shortcuts (*.lnk files) in Rockbox.
* If the destination is a file, it will be selected in the file browser,
* a directory will be entered.
* For now, only relative links are supported.
*/
/* a selection of link flags */
#define HAS_LINK_TARGET_ID_LIST 0x01
#define HAS_LINK_INFO 0x02
#define HAS_NAME 0x04
#define HAS_RELATIVE_PATH 0x08
#define HAS_WORKING_DIR 0x10
#define HAS_ARGUMENTS 0x20
#define HAS_ICON_LOCATION 0x40
#define IS_UNICODE 0x80
#define FORCE_NO_LINK_INFO 0x100
/* a selection of file attributes flags */
#define FILE_ATTRIBUTE_DIRECTORY 0x10
#define FILE_ATTRIBUTE_NORMAL 0x80
/**
* Read one byte from file
* \param fd file descriptor
* \param *a where the data should go
* \return false if an error occured, true on success
*/
static bool read_byte(const int fd, unsigned char *a)
{
if (!rb->read(fd, a, 1))
return false;
return true;
}
/**
* Read 16-bit word from file, respecting windows endianness (little endian)
* \param fd file descriptor
* \param *a where the data should go
* \return false if an error occured, true on success
*/
static bool read_word(const int fd, int *a)
{
unsigned char a1,a2;
int r;
r = read_byte(fd, &a1);
if (!r)
return false;
r = read_byte(fd, &a2);
if (!r)
return false;
*a = (a2<<8) + a1;
return true;
}
/**
* Read 32-bit word from file, respecting windows endianness (little endian)
* \param fd file descriptor
* \param *a where the data should go
* \return false if an error occured, true on success
*/
static bool read_lword(const int fd, uint32_t *a)
{
int a1,a2;
int r;
r = read_word(fd, &a1);
if (!r)
return false;
r = read_word(fd, &a2);
if (!r)
return false;
*a = (a2<<16) + a1;
return true;
}
/**
* Scan *.lnk file for relative link target
* \param fd file descriptor
* \param link_target the extracted link destination
* \param target_size available space for the extracted link (in bytes)
* \param link_flags the link flags are stored here
* \param file_atts file attributes are stored here
* \return returns false if extraction failed.
*/
static bool extract_link_destination(const int fd,
char *link_target, const int target_size,
uint32_t *link_flags, uint32_t *file_atts)
{
int r;
/* Read ShellLinkHeader */
uint32_t size;
r = read_lword(fd, &size);
if (!r) return false;
if (size!=0x4c) { /* header size MUST be 76 bytes */
DEBUGF("unexpected header size 0x%08x (must be 0x0000004c)\n", size);
return false;
}
/* Skip LinkCLSID (class identifier) */
rb->lseek(fd, 0x10, SEEK_CUR);
/* We need the LinkFlags and File attribute (to see if target is a directory) */
r = read_lword(fd, link_flags);
if (!r) return false;
r = read_lword(fd, file_atts);
if (!r) return false;
rb->lseek(fd, size, SEEK_SET); /* Skip to end of header */
/* For now we only support relative links, so we can exit right away
if no relative link structure is present */
if (!(*link_flags & HAS_RELATIVE_PATH)) {
DEBUGF("Link doesn't have relative path information\n");
return false;
}
/* Read (skip) LinkTargetIDList structure if present */
if (*link_flags & HAS_LINK_TARGET_ID_LIST) {
int size;
if (!read_word(fd, &size))
return false;
rb->lseek(fd, size, SEEK_CUR);
}
/* Read (skip) LinkInfo structure if present */
if (*link_flags & HAS_LINK_INFO) {
uint32_t size;
r = read_lword(fd, &size);
if (!r) return false;
rb->lseek(fd, size-4, SEEK_CUR);
}
/* String Data section */
/* Read (skip) NAME_STRING StringData structure if present */
if (*link_flags & HAS_NAME) {
int ccount;
if (!read_word(fd, &ccount))
return false;
if (*link_flags & IS_UNICODE)
rb->lseek(fd, ccount*2, SEEK_CUR);
else
rb->lseek(fd, ccount, SEEK_CUR);
}
/* Read RELATIVE_PATH StringData structure if present */
/* This is finally the data we are searching for! */
if (*link_flags & HAS_RELATIVE_PATH) {
int ccount;
r = read_word(fd, &ccount);
if (!r) return false;
if (*link_flags & IS_UNICODE) {
unsigned char utf16[4], utf8[10];
link_target[0] = '\0';
for (int i=0; i<ccount; ++i) {
r = read_byte(fd, &utf16[0]);
if (!r) return false;
r = read_byte(fd, &utf16[1]);
if (!r) return false;
/* check for surrogate pair and read the second char */
if (utf16[1] >= 0xD8 && utf16[1] < 0xE0) {
r = read_byte(fd, &utf16[2]);
if (!r) return false;
r = read_byte(fd, &utf16[3]);
if (!r) return false;
++i;
}
char *ptr = rb->utf16LEdecode(utf16, utf8, 1);
*ptr = '\0';
rb->strlcat(link_target, utf8, target_size);
}
}
else { /* non-unicode */
if (ccount >= target_size) {
DEBUGF("ERROR: link target filename exceeds size!");
return false;
}
rb->read(fd, link_target, ccount);
link_target[ccount] = '\0';
}
}
/* convert from windows to unix subdir separators */
for (int i=0; link_target[i] != '\0'; ++i) {
if (link_target[i]=='\\')
link_target[i] = '/';
}
return true;
}
/**
* strip rightmost part of file/pathname to next '/', i.e. remove filename
* or last subdirectory. Leaves a trailing '/' character.
* \param pathname full path or filename
*/
static void strip_rightmost_part(char *pathname)
{
for (int i = rb->strlen(pathname)-2; i >= 0; --i) {
if (pathname[i] == '/') {
pathname[i+1] = '\0'; /* cut off */
return;
}
}
pathname[0] = '\0';
}
/**
* Combine link file's absolute path with relative link target to form
* (absolute) link destination
* \param abs_path full shortcut filename (including path)
* \param rel_path the extracted relative link target
* \param max_len maximum lengt of combined filename
*/
static void assemble_link_dest(char *const abs_path, char const *rel_path,
const size_t max_len)
{
strip_rightmost_part(abs_path); /* cut off link filename */
for (;;) {
if (rb->strncmp(rel_path, "../", 3)==0) {
rel_path += 3;
strip_rightmost_part(abs_path);
}
else if (rb->strncmp(rel_path, "./", 2)==0) {
rel_path += 2;
}
else
break;
}
if (*rel_path=='/')
++rel_path; /* avoid double '/' chars when concatenating */
rb->strlcat(abs_path, rel_path, max_len);
}
/**
* Select the chosen file in the file browser. A directory (filename ending
* with '/') will be entered.
* \param link_target link target to be selected in the browser
* \return returns false if the target doesn't exist
*/
static bool goto_entry(char *link_target)
{
DEBUGF("Trying to go to '%s'...\n", link_target);
if (!rb->file_exists(link_target))
return false;
/* Set the browsers dirfilter to the global setting.
* This is required in case the plugin was launched
* from the plugins browser, in which case the
* dirfilter is set to only display .rock files */
rb->set_dirfilter(rb->global_settings->dirfilter);
/* Change directory to the entry selected by the user */
rb->set_current_file(link_target);
return true;
}
enum plugin_status plugin_start(const void* void_parameter)
{
char *link_filename;
char extracted_link[MAX_PATH];
char link_target[MAX_PATH];
uint32_t lnk_flags;
uint32_t file_atts;
/* This is a viewer, so a parameter must have been specified */
if (void_parameter == NULL) {
rb->splash(HZ*3, "No *.lnk file selected");
return PLUGIN_OK;
}
link_filename = (char*)void_parameter;
DEBUGF("Shortcut filename: \"%s\"\n", link_filename);
int fd = rb->open(link_filename, O_RDONLY);
if (fd < 0) {
DEBUGF("Can't open link file\n");
rb->splashf(HZ*3, "Can't open link file!");
return PLUGIN_OK;
}
if (!extract_link_destination(fd, extracted_link, sizeof(extracted_link),
&lnk_flags, &file_atts)) {
rb->close(fd);
DEBUGF("Error in extract_link_destination()\n");
rb->splashf(HZ*3, "Unsupported or erroneous link file format");
return PLUGIN_OK;
}
rb->close(fd);
DEBUGF("Shortcut destination: \"%s\"\n", extracted_link);
rb->strcpy(link_target, link_filename);
assemble_link_dest(link_target, extracted_link, sizeof(link_target));
DEBUGF("Link absolute path: \"%s\"\n", link_target);
/* if target is a directory, add '/' to the dir name,
so that the directory gets entered instead of just highlighted */
if (file_atts & FILE_ATTRIBUTE_DIRECTORY)
if (link_target[rb->strlen(link_target)-1] != '/')
rb->strlcat(link_target, "/", sizeof(link_target));
if (!goto_entry(link_target)) {
char *what;
if (file_atts & FILE_ATTRIBUTE_DIRECTORY)
what = "directory";
else
what = "file";
rb->splashf(HZ*3, "Can't find %s %s", what, link_target);
DEBUGF("Can't find %s %s", what, link_target);
return PLUGIN_OK;
}
return PLUGIN_OK;
}