CppCheck errors for realloc() usage

[scovetta]

I'd like to report that CppCheck is reporting issues with a few of the C/C++ files' use of realloc without testing to ensure the result isn't NULL, resulting in possible memory leaks.

You can gather results by running:

cppcheck --quiet /path/to/libsvm

[/src/libsvm/matlab/libsvmread.c:48]: (error) Common realloc mistake: 'line' nulled but not freed upon failure
[/src/libsvm/svm-predict.c:31]: (error) Common realloc mistake: 'line' nulled but not freed upon failure
[/src/libsvm/svm-predict.c:96]: (error) Common realloc mistake: 'x' nulled but not freed upon failure
[/src/libsvm/svm-scale.c:342]: (error) Common realloc mistake: 'line' nulled but not freed upon failure
[/src/libsvm/svm-train.c:75]: (error) Common realloc mistake: 'line' nulled but not freed upon failure
[/src/libsvm/svm.cpp:2042]: (error) Common realloc mistake: 'label' nulled but not freed upon failure
[src/libsvm/svm.cpp:2043]: (error) Common realloc mistake: 'count' nulled but not freed upon failure
[/src/libsvm/svm.cpp:2757]: (error) Common realloc mistake: 'line' nulled but not freed upon failure
[/src/libsvm/svm.cpp:3137]: (error) Common realloc mistake: 'label' nulled but not freed upon failure
[/src/libsvm/svm.cpp:3138]: (error) Common realloc mistake: 'count' nulled but not freed upon failure

Drilling into the first one:

...
line = (char *) realloc(line, max_line_len);
...

To fix these, you should check to see if realloc returns NULL. If it does, then free(line). If not, then assign the pointer to line. Without this, line will be assigned to NULL and the original object pointed to by line will dangle. More detailed guidance at:

• https://www.mantidproject.org/How_to_fix_CppCheck_Errors
• https://stackoverflow.com/questions/27589846/dynamic-arrays-using-realloc-without-memory-leaks

Thanks!