Bug Type: Security / Buffer Overflow / Crash

Description:
In src/conv/nastran-g.c, the PBAR and PSHELL conversion loops use sprintf to write group names into a fixed-size stack buffer:

char name[NAMESIZE+1];  // 17 bytes
sprintf(name, "pbar_group.%d", pbp->pid);
sprintf(name, "pshell.%d", psh->pid);

If the PID has more than 6 digits (or 10 digits for 32-bit max int), the resulting string exceeds the buffer size, causing a stack buffer overflow. This can crash nastran-g and theoretically allow code execution.

Proposed Fix:

Increase the buffer size to 32 bytes:

char name[32];

Use snprintf instead of sprintf:

snprintf(name, sizeof(name), "pbar_group.%d", pbp->pid);
snprintf(name, sizeof(name), "pshell.%d", psh->pid);