Configuring librcheck for Memory Analysis

QNX SDP8.0Programmer's GuideDeveloper

To start a program that uses librcheck and can send heap trace data to the Memory Analysis tool in the QNX Momentics IDE, you must preload the librcheck library and set environment variables to configure Memory Analysis options. Here, we give examples with minimal settings.

To start an application so the Memory Analysis tool can later be attached to the process from the IDE:
```
LD_PRELOAD=librcheck.so MALLOC_CTHREAD=1 MALLOC_FILE=/tmp/trace.rmat ./my_app
```
To start an application with allocations tracing so you can later do postmortem analysis:
```
LD_PRELOAD=librcheck.so MALLOC_FILE=/tmp/trace.rmat MALLOC_START_TRACING=1 ./my_app
```
To start an application with tracing initially disabled so you can use API controls to enable and disable tracing as the program runs:
```
LD_PRELOAD=librcheck.so MALLOC_FILE=/tmp/trace.rmat MALLOC_START_TRACING=0 ./my_app
```
To set the environment so all subsequent processes launched with Memory Analysis enabled have only memory errors logged:
```
export LD_PRELOAD=librcheck.so 
export MALLOC_FILE=/tmp/trace.rmat
export MALLOC_TRUNCATE=1
./my_app1
./my_app2
```
To display a list of the environment variables for librcheck:
```
LD_PRELOAD=librcheck.so MALLOC_HELP=1 ./my_app
```

librcheck environment variables

The librcheck environment variables and their corresponding UI options in the IDE (if any) are:


Environment variable	Where to find in Memory Analysis UI	What option to set	Additional information
LD_PRELOAD=librcheck.so	Advanced Settings	Runtime library	The library file is librcheck.so.
MALLOC_ACTION=`number`	Memory Errors	When an error is detected	Set the error-handling action: 0 to ignore, 1 to abort, 2 to exit, 3 to core, 4 to stop.
MALLOC_CKACCESS=0\|1	Memory Errors	Verify parameters in string and memory functions	Turn boundary checking on or off for string and memory functions.
MALLOC_CKALLOC=0\|1	Memory Errors	Enable check on realloc()/free() argument	Enable or disable the checking that the pointers passed to realloc() and free() point to memory that the allocator manages.
MALLOC_CTHREAD=0\|1	Advanced Settings	Create control thread	Don't start a control thread (0), or do start the thread and allow the IDE to send commands to the application through signals (1).
MALLOC_CTRL_FILE=`file`	N/A	N/A	Specify a file for the control command (to use with the control signal).
MALLOC_CTRL_SIG=`sigs`	N/A	N/A	Override the default signals; for example: `"control:41,leaks:42, start:44,stop:43"`
MALLOC_DUMP_LEAKS=0\|1	Memory Errors	Perform leak check when process exits	Enable or disable the dumping of leaks on exit.
MALLOC_EVENTBTDEPTH=`number`	Memory Tracing	Limit back-trace depth to	Set the depth of allocation backtraces to a specific number. The default is 5.
MALLOC_EVENTFILE=`file`	Advanced Settings	Target output file or device	Redirect the event output to a file.
MALLOC_FILE=`file`	Advanced Settings	Target output file or device	Redirect the event and trace output to a file. Use a hyphen (-) to redirect the output to standard output (the default).
MALLOC_HANDLE_SIGNALS=0\|1	N/A	N/A	Whether to install handlers for the SIGSEGV, SIGBUS, SIGILL, and SIGFPE signals.
MALLOC_HELP=1	N/A	N/A	Print a list of used environment variables.
MALLOC_START_TRACING=0\|1	Memory Tracing	Enable memory allocation or deallocation tracing	Whether to automatically start tracing memory when the program starts.
MALLOC_TRACEBTDEPTH=`number`	Memory Tracing	Limit back-trace depth to	Set the allocation backtraces depth to a specific number.
MALLOC_TRACEMAX=`number`	Memory Tracing	Maximum allocation to trace	Only trace allocations of <= `number` of bytes.
MALLOC_TRACEMIN=`number`	Memory Tracing	Minimum allocation to trace	Only trace allocations of >= `number` of bytes.
MALLOC_TRUNCATE=0\|1	N/A	N/A	Whether to truncate the output files.
MALLOC_VERBOSE=0\|1	Advanced Settings	Show debug output on console	A value of 1 makes the library send debug information to standard error.

Page updated: March 05, 2025