Ncurses crashes programs on anything other than PuTTY

Question

I have an older ncurses based program that performs a few simple I / O operations in multiple files (i.e.: installer). However, from a terminal other than PuTTY, it crashes with SIGBUS

Program received signal SIGBUS, Bus error. 0x00000000004028b1 in fDisplay (ptr=Variable "ptr" is not available. ) at file_cpy.c:676 676 sprintf(p, " %-36s ", (*ptr)->datainfo.option); (gdb) where #0 0x00000000004028b1 in fDisplay (ptr=Variable "ptr" is not available. ) at file_cpy.c:676 #1 0x0000000000402cdb in fredraw (c=0x7fffffffe860) at file_cpy.c:696 #2 0x0000000000401996 in ls_dispatch (c=0x2020202020202020) at ds_cell.c:324 #3 0x0000000000403bf2 in main_dir (c=0x2020202020202020) at file_cpy.c:811 #4 0x0000000000403cb3 in main () at file_cpy.c:1345 (gdb) x/i $pc 0x4028b1 <fDisplay+17>: mov (%rax),%rdx (gdb) 

This happens on Linux and FreeBSD, regardless of the ncurses version and 32/64-bit architecture. I am completely at a dead end.

fDisplay () is called here:

 /* * File redraw routine. Draws current list on screen. */ int fredraw (CELL * c) { register int row = c->srow; dlistptr p = c->list_start; int i = 0; char buff[200]; if (c->ecol - c->scol) sprintf(buff, "%*s",c->ecol - c->scol + 1, " "); while (i <= c->erow - c->srow && p != NULL) { if (p == c->current) wattron(c->window,A_REVERSE); mvaddstr (row , c->scol, fDisplay(&p)); if (p == c->current) wattroff(c->window,A_REVERSE); row++; i++; p = p->nextlistptr; } if (row <= c -> erow) for (; row <= c -> erow ; row++) mvaddstr(row, c->scol, buff); wrefresh(c->window); c -> redraw = FALSE; return TRUE; } 

This calls fredraw ():

 int main_dir(CELL *c) { int i; getcwd(current_path, sizeof(current_path)); strcat(current_path, "/.config.h"); load_file(current_path); c->keytable = file_cpy_menu; c->func_table = file_cpy_table; c->ListEntryProc = File_Entry; c->UpdateStatusProc = status_update; c->redraw = TRUE; c->ListExitProc = List_Exit; c->ListPaintProc = fredraw; c->srow = 3; c->scol = 1; c->erow = c->window->_maxy - 5; c->ecol = c->window->_maxx - 1; c->max_rows = c->window->_maxy; c->max_cols = c->window->_maxx; c->filename = "[ Config ]"; c->menu_bar = 0; c->normcolor = 0x07; c->barcolor = 0x1f; init_dlist(c); for (i = 0; config_type[i].option; i++) insert_fdlist(c, &config_type[i]); /* * Go Do It */ do { c->redraw = TRUE; ls_dispatch(c); } while (c->termkey != ESC && c->termkey != ALT_X); return TRUE; } 

Finally, main () calls the above functions:

 int main() { CELL file_cpy = {0}; WINDOW *mainwin; mainwin = initscr(); start_color(); setup_colors(); cbreak(); noecho(); keypad(mainwin, TRUE); meta(mainwin, TRUE); raw(); leaveok(mainwin, TRUE); wbkgd(mainwin, COLOR_PAIR(COLOR_MAIN)); wattron(mainwin, COLOR_PAIR(COLOR_MAIN)); werase(mainwin); refresh(); file_cpy.window = mainwin; main_dir(&file_cpy); wbkgd(mainwin, A_NORMAL); werase(mainwin); echo(); nocbreak(); noraw(); refresh(); endwin(); return TRUE; } 

Answer 1

Apparently you are calling main_dir and ls_dispatch with pointer c initialized to 0x2020202020202020 . Although this is not entirely impossible, I find it very unlikely, and it looks like you are rewriting a pointer with spaces.

valgrind will probably help or do some kind of memory check or stack check.

Why it depends on the terminal, I could not say; there may be some TERM-specific code (for example, "select as many lines as there are on the screen"). In any case, this is not an error: it is only a condition that brings an error to the open. Such an error is usually caused by a wired constant, which sometimes exceeds the real value (in the example above, I could say “select 96 lines”, assuming that 96 lines will always be sufficient for everyone, while TERM with 100 lines suppresses the assumption and leads to overflow buffers).

It can also be a debugger artifact, seeing how c stands out on the stack (but I don’t think so: it should be c=0x7fffsomething - at least on the systems where I checked). Anyway, I would repeat this test as follows: file_cpy dynamic dynamics:

 int main() { CELL *file_cpy = NULL; WINDOW *mainwin; file_cpy = malloc(sizeof(CELL)); ... file_cpy->window = mainwin; main_dir(file_cpy); ... free(file_cpy); // file_cpy = NULL; // we immediately return return TRUE; 

and then I will try to tabulate the pointer value in the whole main_dir function if it is overwritten.