Fix potential char overflow bug

[hellkite500]

A potential overflow flow bug exists in the read_file_line_counts function. Depending on system, compiler, and hardware, this can lead to a infinite loop.

This bug has also been patched in these repositories as discovered.

• fix potential overflow that can lead to infinite loop in file reading cfe#85
• noaa-owp/alt-modular#50
• fix potential overflow that can lead to infinite loop in file reading aorc_bmi#6
• fix potential overflow that can lead to infinite loop in file reading SoilFreezeThaw#6
• fix potential overflow that can lead to infinite loop in file reading evapotranspiration#22

It may pop again in the future in different modules if the original bug was copy/pasted more. If you think you are stuck initializing a module that shouldn't take forever...grep for fgetc and check if it is reading into a char, if so, it should be an int.

Changes

• Change the i/o buffer type for character reading to int from char to avoid overflowing a possible unsigned char type.

Testing

1. Tested through ngen unit tests

Checklist

• PR has an informative and human-readable title
• Changes are limited to a single goal (no scope creep)
• Code can be automatically merged (no conflicts)
• Code follows project standards (link if applicable)
• Passes all existing automated tests
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged / future todos are captured in comments
• Project documentation has been updated (including the "Unreleased" section of the CHANGELOG)
• Reviewers requested with the Reviewers tool ➡️

Testing checklist

Target Environment support

• Linux (x86 and arm)
• MacOS (x86 and arm)

[donaldwj]

Looks good, I think this is on the list of classic Fortran errors.