lstring370

Reentrant, length-prefixed string library for MVS 3.8j with a pluggable allocator.

lstring370 provides a rich set of string operations on length-prefixed auto-growing buffers. It has no global state and no hardcoded allocator — consumers inject alloc/dealloc callbacks via struct lstr_alloc, so the same library can sit underneath REXX/370 (routed through irxstor), HTTPD (malloc), UFSD (pool allocator), or any other mvslovers project.

Design goals

• Reentrant. No static mutable state, no extern mutables, no global error callback. The allocator is a parameter, not a global.
• Embeddable. Each consumer chooses its own allocator. The default allocator (malloc/free from <stdlib.h>) is provided for convenience and tests.
• Memory-conscious. Length-prefixed buffers, explicit capacity growth, no surprise reallocation. Targets MVS 3.8j (24-bit AMODE).
• EBCDIC-safe. Character classification via <ctype.h> from crent370. No hardcoded ASCII values in the logic.
• No REXX type caching. The type field on Lstr is always LSTRING_TY — REXX-specific number caching lives in the rexx370 adapter (WP-11b), not here.

Project layout

include/
  lstring.h        Lstr struct, macros, function prototypes
  lstralloc.h      pluggable allocator interface
src/
  lstr#cor.c       core: Lfx, Lscpy, Lstrcpy, Lcat, Lstrcat, Lfree,
                   Lupper, Llower
  ... more in follow-up PRs (sub, wrd, srch, xlt, cvt, fmt)
test/
  test_lstring.c   cross-compile unit tests (Linux/gcc)
project.toml       mbt build configuration

Build

The library builds entirely on the host with the cc370 toolchain (mbt v2); MVS is not touched at build time.

make lib           # cc370 compile + ar370 archive -> build/lstring370.a
make package       # release tarball (lib + headers) in dist/
make doctor        # verify the cc370 toolchain

Consumers (rexx370, httpd, …) pull the library in via mbt dependencies — make deps stages build/lstring370.a and the public headers automatically.

Cross-compile the host unit tests with the native compiler:

gcc -I include -Wall -Wextra -std=gnu99 -o test/test_lstring \
    test/test_lstring.c 'src/lstr#'*.c
./test/test_lstring

Status

Early development. Phase 2 of REXX/370 is the first consumer. See https://github.com/mvslovers/lstring370/issues for open work packages.