## Problem
`readFileToMemory()` allocates an output buffer via `malloc()` at line
120 but doesn't check if allocation succeeds. On low memory, the NULL
pointer is passed to `fread()` causing a crash.
## Fix
Add NULL check after `malloc()` for the output buffer. Follows the
existing pattern already used for `deflatedData` at line 141.
Changed `lib/ZipFile/ZipFile.cpp`.
## Test
- Follows existing validated pattern from same function
- Defensive addition only - no logic changes
## Problem
`invertScreen()`, `storeBwBuffer()`, and `restoreBwBuffer()` dereference
`frameBuffer` without NULL validation. If the display isn't initialized,
these functions will crash.
## Fix
Add NULL checks before using `frameBuffer` in all three functions.
Follows the existing pattern from `drawPixel()` (line 11) which already
validates the pointer.
Changed `lib/GfxRenderer/GfxRenderer.cpp`.
## Test
- Follows existing validated pattern from `drawPixel()`
- No logic changes - only adds early return on NULL
- Manual device testing appreciated
## Problem
Three `fopen()` calls in ZipFile.cpp did not check for NULL before using
the file handle. If files cannot be opened, `fseek`/`fread`/`fclose`
receive NULL and crash.
## Fix
Added NULL checks with appropriate error logging and early returns for
all three locations:
- `getDataOffset()`
- `readFileToMemory()`
- `readFileToStream()`
## Testing
- Builds successfully with `pio run`
- Affects: `lib/ZipFile/ZipFile.cpp`
## Problem
- `getBookSize()` calls `getCumulativeSpineItemSize(getSpineItemsCount()
- 1)` which passes -1 when spine is empty
- `calculateProgress()` then divides by zero when book size is 0
## Fix
- Return 0 from `getBookSize()` if spine is empty
- Return 0 from `calculateProgress()` if book size is 0
## Testing
- Builds successfully with `pio run`
- Affects: `lib/Epub/Epub.cpp`
## Problem
Reading progress.bin used `SD.exists()` then `SD.open()` without
checking if open succeeded. Race conditions or SD errors could cause
file handle to be invalid.
## Fix
- Removed redundant `SD.exists()` check
- Check if file opened successfully before reading
- Verify correct number of bytes were read
## Testing
- Builds successfully with `pio run`
- Affects: `src/activities/reader/EpubReaderActivity.cpp`
## Problem
`SD.begin()` return value was ignored. If the SD card fails to
initialize, the device continues and crashes when trying to load
settings/state.
## Fix
Check return value and display "SD card error" message instead of
proceeding with undefined state.
## Testing
- Builds successfully with `pio run`
- Affects: `src/main.cpp`
## Problem
The status bar title truncation loop crashes when the chapter title is
shorter than 8 characters.
```cpp
// title.length() - 8 underflows when length < 8 (size_t is unsigned)
title = title.substr(0, title.length() - 8) + "...";
```
## Fix
Added a length guard to skip truncation for titles that are too short to
truncate safely.
## Testing
- Builds successfully with `pio run`
- Affects: `src/activities/reader/EpubReaderActivity.cpp`
## Problem
`getSpineIndexForTocIndex()` and `getTocIndexForSpineIndex()` access
`toc[tocIndex]` and `spine[spineIndex]` without validating indices are
within bounds. Malformed EPUBs or edge cases could trigger out-of-bounds
access.
## Fix
Added bounds validation at the start of both functions before accessing
the arrays.
## Testing
- Builds successfully with `pio run`
- Affects: `lib/Epub/Epub.cpp`
IFAKA